Development of Critical Thinking Skills: An Analysis of Academic ...

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study examines data from the College Student Experiences Question ... to determine the greatest influences on gains in critical thinking devel opment. Results of ...

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Evaluation of the Effectiveness of Online Resources in Developing ... File Format: PDF/Adobe Acrobat Developing Student Critical Thinking: Review of Literature and Case Study of a ... critical thinking; effective student learning; higher education; technology as a ... ro.uow.edu.au/cgi/viewcontent.cgi?article=1246&context=jutlp Faculty perceptions of critical thinking at a health sciences university File Format: PDF/Adobe Acrobat promote critical thinking among their students. This study reports the perceptions of critical thinkingheld by health sciences faculty representing multiple ... files.eric.ed.gov/fulltext/EJ1017052.pdf Learning to Improve: Using Writing to Increase Critical Thinking ... @U.S. National Library of Medicine - Bethesda MD As an instructional method, writing has long been perceived as a way to improve critical thinking. In the current study, the researchers compared critical thinking ... www.ncbi.nlm.nih.gov/pmc/articles/PMC1885902/ The role of critical thinking skills and learning styles of university ... @U.S. National Library of Medicine - Bethesda MD This study aimed to determine the relationship between learning styles and critical thinking of students and their academic performance in Alborz University of ... www.ncbi.nlm.nih.gov/pmc/articles/PMC4235550/ .

Exercise on chemistry 1
Exercise on electrochemistry
Exercise on organic chemistry
Exercise on rate of reaction lab
Exercise on thermochemistry

Nervous System: Facts, Function & Diseases

Neurons in the brain communicate via electrical impulses and neurotransmitters.

The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body. It is essentially the body’s electrical wiring. 

Structurally, the nervous system has two components: the central nervous system and the peripheral nervous system. According to the National Institutes of Health, the central nervous system is made up of the brain, spinal cord and nerves. The peripheral nervous system consists of sensory neurons, ganglia (clusters of neurons) and nerves that connect to one another and to the central nervous system.

Functionally, the nervous system has two main subdivisions: the somatic, or voluntary, component; and the autonomic, or involuntary, component. The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing, that work without conscious effort, according to Merck Manuals. The somatic system consists of nerves that connect the brain and spinal cord with muscles and sensory receptors in the skin.

Description of the nervous system

Nerves are cylindrical bundles of fibers that start at the brain and central cord and branch out to every other part of the body, according to the University of Michigan Medical School. 

Neurons send signals to other cells through thin fibers called axons, which cause chemicals known as neurotransmitters to be released at junctions called synapses, the NIH noted. A synapse gives a command to the cell and the entire communication process typically takes only a fraction of a millisecond.

Sensory neurons react to physical stimuli such as light, sound and touch and send feedback to the central nervous system about the body’s surrounding environment, according to the American Psychological Association. Motor neurons, located in the central nervous system or in peripheral ganglia, transmit signals to activate the muscles or glands.

Glial cells, derived from the Greek word for "glue," are specialized cells that support, protect or nourish nerve cells, according to the National Institute on Aging. 

Diagnosing nervous system conditions

There are a number of tests and procedures to diagnose conditions involving the nervous system. In addition to the traditional X-ray, a specialized X-ray called a fluoroscopy examines the body in motion, such as blood flowing through arteries, according to the NIH. Other standard neurological exams include an MRI (magnetic resonance imaging), CT scan, and an electroencephalogram (EEG), which records the brain's continuous electrical activity. Positron emission tomography (PET) is a procedure that measures cell or tissue metabolism and brain activity to detect tumors or diseased tissue or tumors, the NIH noted.A spinal tap places a needle into the spinal canal to drain a small amount of cerebral spinal fluid that is tested for infection or other abnormalities, according to the NIH.

Diseases of the nervous system

“Of all the diseases of the nervous system, the most common difficulty that people have is pain, and much of that is nerve-related,” according to Dr. Shai Gozani, founder and CEO of NeuroMetrix, a medical device company. “There are 100 million people who live with chronic pain.”According to the Mayo Clinic, patients with nerve disorders experience functional difficulties, which result in conditions such as:

• Epilepsy, in which abnormal electrical discharges from brain cells cause seizures 
• Parkinson's disease, which is a progressive nerve disease that affects movement
• Multiple sclerosis (MS), in which the protective lining of the nerves is attacked by the body’s immune system
• Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a motor neuron disease which weakens the muscles and progressively hampers physical function
• Huntington's disease, which is an inherited condition that cause the nerve cells in the brain to degenerate
• Alzheimer's disease, which covers a wide range of disorders that impacts mental functions, particularly memory. 

Mayo Clinic also noted that the nervous system can also be affected by vascular disorders such as:

• Stroke, which occurs when there is bleeding on the brain or the blow flow to the brain is obstructed;
• Transient ischemic attack (TIA), which are mini-type strokes that last a shorter period of time but mimic stroke symptoms; and
• Subarachnoid hemorrhage,  which is specifically bleeding in the space between your brain and the surrounding membrane that can be the result of a trauma or rupturing of a weak blood vessel; 

Infections such as meningitis, encephalitis, polio, and epidural abscess can also affect the nervous system, the NIH noted.

Treatments vary from anti inflammatory medications and pain medications such as opiates , to implanted nerve stimulators and wearable devices, Gozani said. “Many people also turn to herbal and holistic methods to reduce pain, such as acupuncture.” 

Study of the nervous system

The branch of medicine that studies and treats the nervous system is called neurology, and doctors who practice in this field of medicine are called neurologists. Once they have completed medical training, neurologists complete additional training for their specialty and are certified by the American Board of Psychiatry and Neurology (ABPN).

There are also physiatrists, who are physicians who work to rehabilitate patients who have experienced disease or injury to their nervous systems that impact their ability to function, according to the ABPN.

Neurosurgeons perform surgeries involving the nervous system and are certified by the American Association of Neurological Surgeons
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Reaction Kinetics:

-Reaction Rate

-Collision Theory

-Factors Affecting Reaction Rate

Thermochemistry

Electrochemistry

Hydrocarbons:

-Alkane

-Alkene

Exercises on Human Circulatory System
Exercises on Lympatic System
Exercises on Human Nervous System
Exercises on Protein Synthesis
Exercises on Cellular Respiration

Hi there! Thanks for visiting our blog. Our blog is entitled The Unsung Heroes, (you can read the description about our title in the Advertising column). First and foremost, let us address all of you the purpose of this blog.This blog is developed to help students out there who need help to seek informations related to their studies notably Biology and Chemistry. In this blog, we have included some graphical notes regarding Biology and Chemistry as well as some links of tutorials. 2 in 1 isn't it?Haha..Okay, the second one which is our main priority is to give some brief explanations with regard to the Study & Critical Thinking Subject in terms of how this subject grasps the attention in learning and how to apply it in daily life. From our point of view, what we obtained from this subject is that, it helps the students on how to organize and synthesize learned materials in college learning,such as doing the Cornell Notes, apply note-taking skills in college learning, apply exam/test-taking strategies in taking exams and apply appropriate writing skills in written assignments especially when conducting reports on surveys.Next,with this subject, it actually helps to boost up collaborative learning in class, how to work in team whilst conducting projects as well as incorporating professionalism in group.Furthermore,  it also helps to build  provisions for students to implement better communications, leaderships and team skills when conducting assignments as these aspects are an utmost necessities during job hunting later. Last but not least, this subject really helps to transfer the lifelong learning skills by developing note-taking skills, practice good time management to produce great productivities, help someone to think critically and analytically when solving problems and this subject is undeniably really helps to widen the scope of mentality of students as it usually involves outdoor assignments rather than  inside-the-class environment. So, from the bottom of our hearts, we really hope that this blog will be a platform for delivering knowledges as well as having harmonious academic discussions. Enjoy!

Lymphatic System: Facts, Functions & Diseases

Lymphocytes attack a cancer cell.

The lymphatic system is a network of tissues and organs that help rid the body of toxins, waste and other unwanted materials. The primary function of the lymphatic system is to transport lymph, a fluid containing infection-fighting white blood cells, throughout the body. 

The lymphatic system primarily consists of lymphatic vessels, which are similar to the circulatory system's veins and capillaries. The vessels are connected to lymph nodes, where the lymph is filtered. The tonsils, adenoids, spleen and thymus are all part of the lymphatic system.

Description of the lymphatic system

There are hundreds of lymph nodes in the human body. They are located deep inside the body, such as around the lungs and heart, or closer to the surface, such as under the arm or groin, according to the American Cancer Society. The spleen, which is located on the left side of the body just above the kidney, is the largest lymphatic organ, according to the U.S. National Library of Medicine (NLM). It controls the amount of red blood cells and blood storage in the body, and helps to fight infection. If the spleen detects potentially dangerous bacteria, viruses, or other microorganisms in the blood, it — along with the lymph nodes — creates white blood cells called lymphocytes, which act as defenders against invaders. The lymphocytes produce antibodies to kill the foreign microorganisms and stop infections from spreading. Humans can live without a spleen, although people who have lost their spleen to disease or injury are more prone to infections.

The lymphatic system helps keep the body healthy by eliminating infections and diseases.

The thymus is located in the chest just above the heart, according to Merck Manual. This small organ stores immature lymphocytes (specialized white blood cells) and prepares them to become active T cells, which help destroy infected or cancerous cells. 

Tonsils are large clusters of lymphatic cells found in the pharynx. According to the American Academy of Otolaryngology, they are the body's "first line of defense as part of the immune system. They sample bacteria and viruses that enter the body through the mouth or nose." They sometimes become infected, and although tonsillectomies occur much less frequently today then they did in the 1950s, it is still among the most common operations performed and typically follows frequent throat infections.

Lymph is a clear and colorless fluid; the word "lymph" comes from the Latin word lympha, which means "connected to water," according to the National Lymphadema Network. 

Plasma leaves the body's cells once it has delivered its nutrients and removed debris. Most of this fluid returns to the venous circulation through tiny blood vessels called venules and continues as venous blood. The remainder becomes lymph, according to the Mayo Clinic.

Unlike blood, which flows throughout the body in a continue loop, lymph flows in only one direction — upward toward the neck. Lymphatic vessels connect to two subclavian veins, which are located on either sides of the neck near the collarbones, and the fluid re-enters the circulatory system, according to the Mayo Clinic.

Diseases and disorders of the lymphatic system

Diseases and disorders of the lymphatic system are typically treated by immunologists. Vascular surgeons, dermatologists, oncologists and physiatrists also get involved in treatment of various lymphatic ailments. There are also lymphedema therapists who specialize in the manual drainage of the lymphatic system.

The most common diseases of the lymphatic system are enlargement of the lymph nodes (also known as lymphadenopathy), swelling due to lymph node blockage (also known as lymphedema) and cancers involving the lymphatic system, according to Dr. James Hamrick, chief of medical oncology and hematology at Kaiser Permanente in Atlanta.

When bacteria are recognized in the lymph fluid, the lymph nodes make more infection-fighting white blood cells, which can cause swelling. The swollen nodes can sometimes be felt in the neck, underarms and groin, according to the NLM.

Lymphadenopathy is usually caused by infection, inflammation, or cancer. Infections that cause lymphadenopathy include bacterial infections such as strep throat, locally infected skin wounds, or viral infections such as mononucleosis or HIV infection, Hamrick stated. “The enlargement of the lymph nodes may be localized to the area of infection, as in strep throat, or more generalized as in HIV infection. In some areas of the body the enlarged lymph nodes are palpable, while others are to deep to feel and can be seen on CT scan or MRI.”

Inflammatory or autoimmune conditions occur when a person's immune system is active, and can result in enlargement of lymph nodes. This can happen in lupus, according to Hamrick. 

Lymphoma is cancer of the lymph nodes. It occurs when lymphocytes grow and multiply uncontrollably. There are a number of different types of lymphoma, according to Dr. Jeffrey P. Sharman, director of research at Willamette Valley Cancer Institute and medical director of hematology research for the U.S. Oncology Network.

“The first ‘branch point’ is the difference between Hodgkin lymphoma and non-Hodgkin lymphoma (NHL),” Sharman said. Non-Hodgkin lymphoma is more common of the two, according to the Lymphoma Research Foundation. 

The most common types of NHL are follicular, which accounts for about 30 percent of all NHL cases; diffuse large B-cell lymphoma (DLBCL), which comprises 40 to 50 percent of NHL cases; and Burkitt's lymphoma, which accounts for 5 percent of NHL cases.  "The remainder of cases makes up the bewildering complexity of NHL,” Sharman said.

“Though there can be a significant range within an individual category, the clinical approach to each category is unique and the expectations of patient outcome varies by category," Sharman said.

When a person has had surgery and/or radiation to remove a cancer, the lymphatic flow back to the heart and can result in swelling or lymphedema, Hamrick noted. This most commonly occurs in women who have had surgery to remove a breast cancer. Part of the operation to remove the breast cancer involves removing lymph nodes in the armpit. 

The more lymph nodes removed the higher the risk of chronic bothersome swelling and pain due to lymphedema in the arm, Hamrick explained. “Fortunately modern surgical techniques are allowing for fewer lymph nodes to be removed, and thus fewer cases of severe lymphedema for breast cancer survivors.”

Castleman disease is a group of inflammatory disorders that cause lymph node enlargement and can result in multiple-organ dysfunction, according to the Castleman Disease Cooperative Network. While not specifically a cancer, it is a similar to a lymphoma and is often treated with chemotherapy. It can be unicentric (one lymph node) or multicentric, involving multiple lymph nodes. 

Lymphangiomatosis is a disease involving multiple cysts or lesions formed from lymphatic vessels, according to the Lymphangiomatosis & Gorham's Disease Alliance. It is thought to be the result of a genetic mutation. 

Diagnosis and treatment

Diseases of the lymphatic system are usually diagnosed when lymph nodes are enlarged, Hamrick noted. This may be discovered when the lymph nodes become enlarged enough to be felt ("palpable lymphadenopathy") or are seen on imaging studies such as CT scans or MRIs.

The majority of enlarged lymph nodes are not dangerous; they are the body's way of fighting off an infection, such as a viral upper respiratory infection. If the lymph nodes become significantly enlarged and persist longer than the infection then they are more worrisome. There is no specific size cutoff, but typically nodes that persist at larger than a centimeter are more worrisome and warrant examination by a doctor.

Common symptoms of any lymphatic disorder include swelling of the arm or groin, weight loss, fever and night sweats, according to Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York.  “A PET or CAT scan is usually ordered to further investigate.” 

The diagnosis of lymphadenopathy depends on the location of the abnormal lymph nodes and other things that are going on with the patient. If the patient has a known infection, then the lymph nodes can simply be followed to await resolution with treatment of the infection. If the nodes are growing quickly and there is no obvious explanation then typically a biopsy is warranted to look for a cancer or an infection. If the node can be felt then this can be done at the bedside with a needle, according to Hamrick. 

If the lymph node is deeper, such as in the abdomen or pelvis, Hamrick said the biopsy might need to be done by an interventional radiologist using image guidance to place the needle into the node. Sometimes the biopsy needs to be done by a surgeon in the operating room. This is often where the most tissue can be obtained to make a diagnosis, he said.

With many types of lymphoma and leukemia, there are unique treatment options for each type, according to Sharman. “There is no one ‘summary’ of treatment options.  Treatment options can include traditional chemotherapy, immunotherapy (such as using antibodies or immune modulating drugs), and even radiation.”

Treatment of lymphatic diseases depends on treating the underlying cause. Infections are treated with antibiotics, supportive care (while the immune system does its job, as in a viral infection) or antivirals. Lymphedema can be treated by elevation, compression and physical therapy. Cancers of the lymphatic system are treated by chemotherapy, radiotherapy, surgery, or a combination of those modalities, Hamrick noted. 

In last several years, Sharman noted that there has been explosion of new treatment options.  “There are a handful of newly approved drugs that target the actual disease causing processes within cells. Ibrutinib, idelalisib, obinutuzumab, lenalidomide have been approved in various indications and it is likely that we will see multiple more in coming year.”

Circulatory System: Facts, Function & Diseases

The circulatory system is a vast network of organs and vessels that is responsible for the flow of blood, nutrients, hormones, oxygen and other gases to and from cells. Without the circulatory system, the body would not be able to fight disease or maintain a stable internal environment — such as proper temperature and pH — known as homeostasis.

Description of the circulatory system

While many view the circulatory system, also known as the cardiovascular system, as simply a highway for blood, it is made up of three independent systems that work together: the heart (cardiovascular); lungs (pulmonary); and arteries, veins, coronary and portal vessels (systemic), according to the U.S National Library of Medicine (NLM).

In the average human, about 2,000 gallons (7,572 liters) of blood travel daily through about 60,000 miles (96,560 kilometers) of blood vessels, according to the Arkansas Heart Hospital. An average adult has 5 to 6 quarts (4.7 to 5.6 liters) of blood, which is made up of plasma, red blood cells, white blood cells and platelets. In addition to blood, the circulatory system moves lymph, which is a clear fluid that helps rid the body of unwanted material.The heart, blood, and blood vessels make up the cardiovascular component of the circulatory system. It includes the pulmonary circulation, a "loop" through the lungs where blood is oxygenated. It also incorporates the systemic circulation, which runs through the rest of the body to provide oxygenated blood, according to NLM. 

The pulmonary circulatory system sends oxygen-depleted blood away from the heart through the pulmonary artery to the lungs and returns oxygenated blood to the heart through the pulmonary veins, according to the Mayo Clinic. 

Oxygen-deprived blood enters the right atrium of the heart and flows through the tricuspid valve (right atrioventricular valve) into the right ventricle. From there it is pumped through the pulmonary semilunar valve into the pulmonary artery on its way to the lungs. When it gets to the lungs, carbon dioxide is released from the blood and oxygen is absorbed. The pulmonary vein sends the oxygen-rich blood back to the heart, according to NLM.

The systemic circulation is the portion of the circulatory system is the network of veins, arteries and blood vessels that transports blood from heart, services the body's cells and then re-enters the heart, the Mayo Clinic noted.

Diseases of the circulatory system

According to the American Heart Association, cardiovascular disease is the leading cause of death in the United States. Because of its vastness and critical nature, it is one of the systems of the body most prone to disease.

One of the most common diseases of the circulatory system is arteriosclerosis, in which the fatty deposits in the arteries causes the walls to stiffen and thicken the walls. According to the Mayo Clinic, the causes are a buildup of fat, cholesterol and other material in the artery walls. This can restrict blood flow or in severe cases stop it all together, resulting in a heart attack or stroke.

Stroke involves blockage of the blood vessels to the brain and is another major condition of the circulatory system, according to Mitchell Weinberg of the North Shore-LIJ Health System.  “Risk factors include smoking, diabetes and high cholesterol,” he noted. 

Another circulatory disease, hypertension — commonly called high blood pressure — causes the heart to work harder and can lead to such complications as a heart attack, a stroke, or kidney failure, the NLM noted.

An aortic aneurysm occurs when the aorta is damaged and starts to bulge or eventually tear, which can cause severe internal bleeding. This weakness can be present at birth or the result of atherosclerosis, obesity, high blood pressure or a combination of these conditions, according to Weinberg. 

Peripheral arterial disease (also known as PAD) typically involves areas of narrowing or blockage within an artery, according to Jay Radhakrishnan, an interventional radiologist in Houston, Texas. In addition, chronic venous insufficiency (also known as CVI) involves areas reflux (or backward flow) within the superficial veins of the lower extremities.

PAD is diagnosed with noninvasive testing including ultrasound, CT scan, and/or MRI.  Ultrasound is the least expensive of these methods, but also gives the least amount of detail, as CT and MRI show a much higher degree of anatomic detail when identifying areas of narrowing/blockage within an artery. CVI is diagnosed with ultrasound as the venous reflux can be measured accurately by ultrasound, which ultimately guides treatment.

Study of the circulatory system

Cardiologists are specialists who are certified to diagnose, treat and prevent disease of the heart, arteries and veins. Cardiologists are certified by the American Board of Internal Medicine (ABIM) after meeting educational and practice requirements. Before being certified as cardiologists, those aspiring to the specialty must be certified in internal medicine. 

Then cardiologists can become certified in one of several cardiology subspecialties, including transplant cardiology, cardiovascular disease, clinical cardiac electrophysiology and interventional cardiology.

  Protein Synthesis Notes

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PROTEIN SYNTHESIS 

• All metabolic reactions are catalyzed by proteins (enzymes), including energy releasing and energy capturing reactions.
• Proteins offer structure to cells and organisms, such as the cytoskeleton.
• DNA has the stored information needed to determine the sequence of amino acids in proteins.
• It is essential to understand how proteins are synthesized in order to fully understand how they work.
• The building of proteins is called protein synthesis.
• The assembly of proteins occurs outside the nucleus in the ribosomes.

DNA and RNA

Remember DNA is in the nucleus and cant leave – so how does DNA get to the ribosomes?

• DNA sends instructions for building proteins to the ribosomes in the form of messenger RNA (mRNA).

RNA

• RNA is a nucleic acid.  RNA is made up of a chain of nucleotides (phosphate + sugar + nitrogen base).

• RNA - consists of only a single strand of nucleotide (Remember DNA is two strands).  RNA is half a ladder or zipper.

• The sugar in RNA differs from the DNA sugar.  The sugar in RNA is ribose.
• The bases found in RNA differ as well.  DNA is made up of adenine, guanine, thymine and cytosine.  Adenine, guanine and cytosine also are found in RNA.  But instead of thymine RNA contains the base uracil.

• In RNA, cytosine bonds to guanine, and adenine bonds to uracil.

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Types of RNA

RNA are the “workers” for protein synthesis.  DNA provides the workers with the instructions for making the proteins and the workers build the proteins amino acid by amino acid (Remember amino acid + amino acid + amino acid = Protein).

3 Types of RNA that makes proteins (Workers in the protein assembly line)

1. mRNA – RNA messenger – brings instructions from the DNA in the nucleus to the cells factory floor, the cytoplasm.  Once the mRNA is on the factory floor (cytoplasm) it moves to the assembly line, a ribosome.
2. The ribosome is made up of ribosomal RNA (rRNA); it binds the mRNA and uses the instructions to assemble the amino acids in the correct order.
3. The transfer RNA (tRNA) is the supplier – tRNA delivers the amino acids to the ribosome to be assembled into a protein. 

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Transcription

The process by which the DNA message is copied into a strand of mRNA is called transcription.  This mRNA is then used for the construction of a protein molecule.

Transcription takes places in the NUCLEUS because DNA cannot leave.

The steps:

1. The DNA double helix starts to uncoil.
2. Once the two strands of DNA separate from one another only one strand participates in the synthesis of a complementary mRNA strand.
3. The mRNA strand is synthesized “made” with the help of an enzyme called RNA polymerase.
4. After mRNA synthesis is complete, the two strands of DNA recouple and the molecules of DNA recoils to assume its double helix.
5. The proceeded mRNA leaves the nucleus and enters the cytoplasm.                                

mRNA carries the instructions that direct the assembly of a specific protein to a designated area on the ribosome.  The instructions are carried in a sequence of three nitrogen bases called a codon.

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Codon Chart

Codon is the code – needed to convert mRNA into protein language.   Each codon (3 nitrogen bases) codes for one amino acid.  This is the genetic code.  The genetic code is universal.

64 possible combinations – (see Table 11.1 in book) – Note some do not code for an amino acid, but provide instructions for making a protein (UAA is a STOP codon indicating that the protein chain ends at that point).

AUG is a START codon as well as  the codon for methionine.

Note that more than one codon can code for the same amino acid. 

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Translation

Once the message has reached the ribosome, the protein is ready to be assembled.  The process of building the protein from the mRNA instructions is called translation.  The transfer RNA (tRNA) and the ribosomal RNA (rRNA) are involved in translation.

In the cytoplasm, a ribosome attaches to the strand of mRNA like a clothes pin clamped to a close line.

tRNA is responsible for carrying the amino acid acids (the building blocks of proteins) to the ribosome so they can be linked in a specific order that makes up a single protein.  Each tRNA attaches to only one type of amino acid (correct translation of mRNA depends on the joining of each mRNA codon with the correct tRNA molecule).

How does this happen? One end of the tRNA carries a three-base sequence called an anticodon, which matches up with a particular codon on the mRNA.  They are complementary to each other.  

The Translation Process

1. The tRNA carries the first amino acid to the to the mRNA strand (see Figure 11.9A).  
2. The anticodon forms as base pair with codon mRNA (see figure 11.9B).  This places the amino acid in the correct position for forming a peptide bond with the next amino acid (Remember peptide bonds bond amino acids together in proteins). 
3. The ribosome slides down the mRNA chain top the next codon and a new tRNA  molecule bring another molecule (Figure 11.9C).  
4. The amino acids bond, the first tRNA releases its amino acid and detaches from the mRNA (Figure 11.9D).  The tRNA molecule is now free to pick up and deliver another molecule of its specific amino acid to a ribosome.  Again the ribosome slides down to the next codon; a new tRNA molecule arrives and its amino acid bonds with the previous one.   rRNA helps bond the amino acids together to form the final protein.
5. When the STOP codon is reached on the mRNA strand translation ends and amino acid strand is released from the ribosome (Figure 11E)
6. Amino acid chains become proteins when they are released from the ribosome.

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The Central Dogma

Crick and Watson had a model for the flow of information in cells. This model incorporates  DNA, RNA, and proteins.

DNA may replicate itself
DNA may be transcribed to RNA
RNA may be translated into proteins
RNA and DNA are NOT  made from protein
DNA is NOT made from RNA

Called the Central Dogma of Molecular Biology – DNA to RNA to protein

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Summing It All Up!

The genetic code between DNA and protein is in the sequence of nucleotides in DNA within genes.

DNA is transcribed into mRNA
mRNA is translated into a polypeptide with the help of tRNA
tRNA with a specific sequence that matches mRNA,  carries the specific amino acid to the ribosome to help form a polypeptide
Ribosomes are the site of protein synthesis.

Transcription involves making a strand of RNA complementary to DNA.
RNA is single stranded-only one strand of DNA is transcribed.
RNA produced is messenger RNA (mRNA) because it carries the genetic message from DNA to the site of protein production.
DNA does not leave the nucleus!!!

this information is used to code for a protein made up of amino acids

if there are 4 letters in DNA language, and there are 20 amino acids that make up proteins

Amino acids are coded for by groups of 3 nucleotides, called CODONS.

• There are 4x4x4 = 64 codons.
• With these and only 20 amino acids, there are extra codons.
• Each amino acid is coded by more than 1 codon.
• NO codon codes for more than 1 amino acid

Four codons have special functions in the genetic code

• one start AUG codes for methionine
• 3 stop codons you do not have to memorize these.
• These determine the beginning and end of the polypeptide production.

What is an Organic Compound?

When you drive up to the pump at some gas stations you are faced with a variety of choices.
You can buy "leaded" gas or different forms of "unleaded" gas that have different octane numbers. As you filled the tank, you might wonder, "What is 'leaded' gas, and why do they add lead to gas?" Or, "What would I get for my money if I bought premium gas, with a higher octane number?"

You then stop to buy drugs for a sore back that has been bothering you since you helped a friend move into a new apartment. Once again, you are faced with choices (see the figure below). You could buy aspirin, which has been used for almost a hundred years. Or Tylenol, which contains acetaminophen. Or a more modern pain-killer, such as ibuprofen. While you are deciding which drug to buy, you might wonder, "What is the difference between these drugs?," and even, "How do they work?"

You then drive to campus, where you sit in a "plastic" chair to eat a sandwich that has been wrapped in "plastic," without worrying about why one of these plastics is flexibile while the other is rigid. While you're eating, a friend stops by and starts to tease you about the effect of your diet on the level of cholesterol in your blood, which brings up the questions, "What is cholesterol?" and "Why do so many people worry about it?"
Answers to each of these questions fall within the realm of a field known as organic chemistry. For more than 200 years, chemists have divided materials into two categories. Those isolated from plants and animals were classified asorganic, while those that trace back to minerals were inorganic. At one time, chemists believed that organic compounds were fundamentally different from those that were inorganic because organic compounds contained a vital force that was only found in living systems.
The first step in the decline of the vital force theory occurred in 1828, when Friederich Wohler synthesized urea from inorganic starting materials. Wohler was trying to make ammonium cyanate (NH₄OCN) from silver cyanate (AgOCN) and ammonium chloride (NH₄Cl). What he expected is described by the following equation.

AgOCN(aq) + NH₄Cl(aq) AgCl(s) + NH₄OCN(aq)

The product he isolated from this reaction had none of the properties of cyanate compounds. It was a white, crystalline material that was identical to urea, H₂NCONH₂, which could be isolated from urine.

Neither Wohler nor his contemporaries claimed that his results disproved the vital force theory. But his results set in motion a series of experiments that led to the synthesis of a variety of organic compounds from inorganic starting materials. This inevitably led to the disappearance of "vital force" from the list of theories that had any relevance to chemistry, although it did not lead to the death of the theory, which still had proponents more than 90 years later.
If the difference between organic and inorganic compounds isn't the presence of some mysterious vital force required for their synthesis, what is the basis for distinguishing between these classes of compounds? Most compounds extracted from living organisms contain carbon. It is therefore tempting to identify organic chemistry as the chemistry of carbon. But this definition would include compounds such as calcium carbonate (CaCO₃), as well as the elemental forms of carbon diamond and graphite that are clearly inorganic. We will therefore define organic chemistry as the chemistry of compounds that contain both carbon and hydrogen.
Even though organic chemistry focuses on compounds that contain carbon and hydrogen, more than 95% of the compounds that have isolated from natural sources or synthesized in the laboratory are organic. The special role of carbon in the chemistry of the elements is the result of a combination of factors, including the number of valence electrons on a neutral carbon atom, the electronegativity of carbon, and the atomic radius of carbon atoms (see the table below).

The Physical Properties of Carbon

Electronic configuration		1s2 2s2 2p2
Electronegativity		2.55
Covalent radius		0.077 nm

Carbon has four valence electrons 2s² 2p² and it must either gain four electrons or lose four electrons to reach a rare-gas configuration. The electronegativity of carbon is too small for carbon to gain electrons from most elements to form C^4- ions, and too large for carbon to lose electrons to form C⁴⁺ ions. Carbon therefore forms covalent bonds with a large number of other elements, including the hydrogen, nitrogen, oxygen, phosphorus, and sulfur found in living systems.
Because they are relatively small, carbon atoms can come close enough together to form strong C=C double bonds or even CC triple bonds. Carbon also forms strong double and triple bonds to nitrogen and oxygen. It can even form double bonds to elements such as phosphorus or sulfur that do not form double bonds to themselves.
Several years ago, the unmanned Viking spacecraft carried out experiments designed to search for evidence of life on Mars. These experiments were based on the assumption that living systems contain carbon, and the absence of any evidence for carbon-based life on that planet was presumed to mean that no life existed. Several factors make carbon essential to life.

• The ease with which carbon atoms form bonds to other carbon atoms.
• The strength of CC single bonds and the covalent bonds carbon forms to other nonmetals, such as N, O, P, and S.
• The ability of carbon to form multiple bonds to other nonmetals, including C, N, O, P, and S atoms.

These factors provide an almost infinite variety of potential structures for organic compounds, such as vitamin C shown in the figure below.

No other element can provide the variety of combinations and permutations necessary for life to exist.

The Saturated Hydrocarbons, or Alkanes

Compounds that contain only carbon and hydrogen are known as hydrocarbons. Those that contain as many hydrogen atoms as possible are said to be saturated. The saturated hydrocarbons are also known as alkanes.
The simplest alkane is methane: CH₄. The Lewis structure of methane can be generated by combining the four electrons in the valence shell of a neutral carbon atom with four hydrogen atoms to form a compound in which the carbon atom shares a total of eight valence electrons with the four hydrogen atoms.

Methane is an example of a general rule that carbon is tetravalent; it forms a total of four bonds in almost all of its compounds. To minimize the repulsion between pairs of electrons in the four CH bonds, the geometry around the carbon atom is tetrahedral, as shown in the figure below.

The alkane that contains three carbon atoms is known as propane, which has the formula C₃H₈ and the following skeleton structure.

The four-carbon alkane is butane, with the formula C₄H₁₀.

The names, formulas, and physical properties for a variety of alkanes with the generic formula C_nH_2n+2 are given in the table below. The boiling points of the alkanes gradually increase with the molecular weight of these compounds. At room temperature, the lighter alkanes are gases; the midweight alkanes are liquids; and the heavier alkanes are solids, or tars.

The Saturated Hydrocarbons, or Alkanes

Name		Molecular Formula		Melting Point (oC)		Boiling Point (oC)		State at 25oC
methane		CH4		-182.5		-164		gas
ethane		C2H6		-183.3		-88.6		gas
propane		C3H8		-189.7		-42.1		gas
butane		C4H10		-138.4		-0.5		gas
pentane		C5H12		-129.7		36.1		liquid
hexane		C6H14		-95		68.9		liquid
heptane		C7H16		-90.6		98.4		liquid
octane		C8H18		-56.8		124.7		liquid
nonane		C9H20		-51		150.8		liquid
decane		C10H22		-29.7		174.1		liquid
undecane		C11H24		-24.6		195.9		liquid
dodecane		C12H26		-9.6		216.3		liquid
eicosane		C20H42		36.8		343		solid
triacontane		C30H62		65.8		449.7		solid

The alkanes in the table above are all straight-chain hydrocarbons, in which the carbon atoms form a chain that runs from one end of the molecule to the other. The generic formula for these compounds can be understood by assuming that they contain chains of CH₂ groups with an additional hydrogen atom capping either end of the chain. Thus, for every n carbon atoms there must be 2n + 2 hydrogen atoms: C_nH_2n+2.
Because two points define a line, the carbon skeleton of the ethane molecule is linear, as shown in the figure below.

Because the bond angle in a tetrahedron is 109.5, alkanes molecules that contain three or four carbon atoms can no longer be thought of as "linear," as shown in the figure below.

Propane			Butane

In addition to the straight-chain examples considered so far, alkanes also form branched structures. The smallest hydrocarbon in which a branch can occur has four carbon atoms. This compound has the same formula as butane (C₄H₁₀), but a different structure. Compounds with the same formula and different structures are known as isomers(from the Greek isos, "equal," and meros, "parts"). When it was first discovered, the branched isomer with the formula C₄H₁₀ was therefore given the name isobutane.

 Isobutane

The best way to understand the difference between the structures of butane and isobutane is to compare the ball-and-stick models of these compounds shown in the figure below.

Butane			Isobutane

Butane and isobutane are called constitutional isomers because they literally differ in their constitution. One contains two CH₃ groups and two CH₂ groups; the other contains three CH₃ groups and one CH group.
There are three constitutional isomers of pentane, C₅H₁₂. The first is "normal" pentane, or n-pentane.

A branched isomer is also possible, which was originally named isopentane. When a more highly branched isomer was discovered, it was named neopentane (the new isomer of pentane).

Ball-and-stick models of the three isomers of pentane are shown in the figure below.

n-Pentane			Isopentane

Neopentane