PS5 Chapter 11: Proteins
What is translation?
After mRNA reaches the ribosomes, process of protein synthesis begins.
Nonessential amino acids (list)
Alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glycine, proline, serine, tyrosine, glutamine
What foods are considered to have complete proteins?
All types of meat and animal products (egg whites and cow milk). From a plant source, soybeans.
What foods do dietary proteins exist in?
All types of meat, dairy products, soy products, legumes (beans), whole grains, and nuts.
How are proteins produced?
Synthesized locally in cells.
Give two examples of cells in the body that produce proteins for specific functions.
Stomach cells produce proteins which enable them to function in digestion. Muscle cells produce proteins which enable them to function in contraction.
What does the rate of cell division depend on? Give one example.
The activity of the cell. For example, red blood cells have a life span of about 120 days. Cells of the small intestine have a life span of a few days in contrast.
True or false: No significant chemical digestion of protein occurs in oral cavity
True
True or false: Protein synthesis in the cell is not permanent.
True
What is mitosis?
The process of cell division. New cells are generated and maintained and it is highly regulated by proteins. Many different types of proteins also mediate cell repair during the healing process after injury.
What are the two major proteins found in muscles?
Actin and myosin. (Amino acids from the circulation build these proteins).
What is the problem with too much water leaving the cell?
Causes cell to shrink.
Explain the quaternary structure (protein).
Certain proteins interact further, where multiple tertiary structures associate with each other.
What is deamination?
Chemical reaction in which the amino group is removed in order for amino acids to be used for energy.
What are the functions of proteins in our cells?
Chemical reactions, signaling, fluid balance, acid-base balance, protection, transport, growth and development, and movement.
What is bolus?
Chewed food in the mouth
What is Alkalosis?
Condition associated with high concentrations of bases in the circulation. Leads to deleterious effects.
What are the characteristics of protein synthesis?
It is not random, it is very complex and expressed through genes in the DNA.
Rugae
Macroscopic folds in the stomach lining that causes the stomach to have such a large surface area.
What makes a protein unique from a carb or lipid?
Made up of unique sequence of different amino acids. Also, carbs and lipids are made of carbon, hydrogen, and oxygen atoms; proteins can also contain nitrogen atoms. Some also contain sulfur atoms.
What is a vital function of insulin and glucagon?
Maintaining the sugar level in the blood constantly.
What is pepsinogen called once it becomes active?
Pepsin
What is the function of pepsin in protein digestion?
Pepsin breaks down the dietary large proteins into smaller peptide fragments.
Explain pepsinogen in the process of protein digestion.
Pepsinogen is a potent enzyme that breaks down dietary proteins. Must be exposed to acidic environment to be activated. Parietal cells of stomach produce and secrete hydrochloric acid, which activates pepsinogen.
Where are proteins found?
Plants and animals
What are the four levels of the protein structure that have been identified?
Primary structure, Secondary structure, tertiary structure, quaternary structure.
Define gene expression
Process for protein synthesis that starts with our DNA.
What helps us have a rigid regulation of pH balance?
Production of buffers
Transamination
chemical reaction that involves converting an essential amino acid into a nonessential one
What are amino acids?
Building blocks of proteins. Organic molecules made up of a central carbon that is connected to four other groups: amino group, carboxyl group, hydrogen atom, and an R group.
How are skeletal, cardiac, and smooth muscle contraction achieved?
By proteins.
What are nonessential amino acids?
Can be synthesized in body if not consumed in the diet.
What is the problem with too much water entering a cell?
Can lead to cell expansion and eventually cause the cell to burst
Because of metabolic activities in cells, acidic and basic molecules are constantly produced. What happens if these substances are not regulated properly?
Can lead to major shifts in the body's pH balance.
What is the overall recommended dietary allowance of protein (RDA)?
0.8 g per 1 kg of body weight.
How many different amino acids exist in our body?
20
What is a complete protein?
A protein source that has all of the essential amino acids.
What are many hormones made from?
Amino acid and/or proteins
What happens in the small intestine that aids in protein digestion?
Amino acids are absorbed into the circulation. Taken to the major storage places in the liver and muscles.
Where do we have water in our bodies? (in relation to cells)
Around our cells (interstitial fluid) and in the plasma (fluid component of our blood)
What is chyme?
Bolus broken down into paste/liquid form. Chyme passes through the pyloric sphincter and transferred to the duodenum of the small intestine.
Explain digestion of protein after it is swallowed
Bolus swallowed and taken to esophagus, where more mucus secretion occurs.
Explain beans as a source of protein. What are they lacking?
Deficient in essential amino acid methionine, and vitamin B12, A, and C.
Explain the secondary structure (protein).
Different amino acids in the chain interact causing chain to undergo twists called alpha helices and folds called beta pleated sheets.
What are the characteristics of amino acids?
Each amino acid has an identical amino, carboxyl, and hydrogen group. The chemical structure of an amino acid's R group is what makes it different.
What is edema? What causes edema?
Edema is swelling. Not having enough proteins in the blood leads to water exiting cells into the interstitial fluid causing edema.
How do proteins help ions and energy molecules?
Enable them to enter or exit the cell.
What are proteins?
Essential macromolecules that exist in every cell of our bodies. Function in metabolism, heredity, regulation, immunity, transport, fluid balance, and kidney functions. Critical components of hormones, blood, bones, and connective tissue.
True or false: All cells in the body synthesize the same proteins.
False, all cells in the body do not synthesize the same proteins. Instead, they make the proteins needed for their specific functions.
True or false: Most Americans do not consume a diverse diet that is rich in all of the essential proteins
False: Most Americans do consume a diverse diet that is rich in all of the essential proteins.
True or false: The synthesis of a protein in the cell is universal.
False: The synthesis of a protein in the cell is not universal.
Explain the process of protein synthesis in a simplified way.
Genes in DNA are copied onto mRNA. The mRNA is exported to the cytoplasm to synthesize proteins.
Essential amino acids (list)
Histidine, Isoleucine, Leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine
Explain the importance of the essential amino acid leucine.
Important component of insulin. Body can't make, must obtain through diet. Without leucine, insulin can't be synthesized and glucose maintenance in plasma would be affected causing complications.
Can proteins be used for energy?
In healthy individuals, proteins are used very RARELY for energy. We rely on carbohydrates and lipids as major sources of energy.
Where is the largest amount of water in our bodies located?
In our cells
What is gluconeogenesis?
In some cases, amino acids are converted to glucose. Gluconeogenesis is unhealthy and occurs in malnutrition or during prolonged starvation.
When is edema observed in individuals?
Individuals who consume very low energy diets as a result of starvation, famine, or malnutrition
What are hormones made up of small proteins?
Insulin and glucagon
Give two examples of how cells only produce proteins that they need.
Insulin is only produced in pancreatic cells. Pepsin is only produced in the stomach cells.
Explain digestion of protein in the mouth
Mastication and saliva released from salivary glands fragment large clusters into smaller aggregates.
What happens during deamination?
Nitrogen shuttled to the liver and converted to toxic product called urea. Then taken to kidneys to be excreted in urine.
Can all of these chemicals travel easily?
No, because of the watery composition of blood. Substances that are water insoluble (cholesterol and lipid hormones) cannot travel at all.
Explain the primary structure (protein).
Occurs when amino acids are covalently linked together in a specific sequence.
How are body tissues constantly maintained?
Old cells die and new cells are generated. With the exception of neurons, all cells are constantly dividing as children grow.
What are essential amino acids?
Ones that our body cannot synthesize on its own so we must obtain them in our diet. Vegetarians/Vegans must ensure consumption (soy, eggs, beans).
How do proteins function in terms of transport?
Proteins function in transporting chemicals and nutrients in the circulation. They also transport chemicals across cells and can move molecules within a cell.
Which proteins allow the entry of needed substances into the cell?
Proteins that function as channels and transporters?
What are antibodies?
Proteins that the immune system cells produce and release in the circulation. They defend against harmful pathogens.
What are some of the common buffers in our circulation? Please explain.
Proteins. Because of their molecularly charged amino and carboxyl groups, they serve as efficient molecules to bind acids and bases.
Explain the digestion of protein in the stomach
Rugae increase contact of the bolus with the gastric secretion. Stomach lining contains secretory cells that produce various substances: gastric juice. Mucous cells of stomach produce mucus to lubricate and moisten food. Stomach's chief cells release inactive form of proteolytic enzymes called pepsinogen.
What is the chemical score given to foods?
Score reflects their digestibility and composition whether they contain essential amino acids or not. Foods high in essential amino acids and are highly digestible (ex. meats) have a high score.
Where does the blood circulating in the vesicle carry the chemicals?
Specific organs.
Explain the tertiary structure (protein).
The folding of the polypeptide continues, forming a three-dimensional shape. Once in this structure, the protein has a unique shape, which enables it to perform a specific function in the cell.
What is transcription?
The molecule of RNA is called messenger RNA (mRNA). Transcription is the process of copying the gene into mRNA.
What determines the function of a protein?
The number and the types of amino acids found in the protein.
Why is it important to have a balanced amount of electrolytes and proteins?
They affect cellular water movements.
What happens when we consume proteins in our diet?
They are broken down to amino acids in the digestive system and then transported into our cells. Once in the cell, they are made into proteins.
What is significant about motor proteins?
They are inside cells and can bind molecules and facilitate their transport within cells.
When hormones are made in glands, what happens to them afterwards?
They are stored in vesicles and then released in the circulation as needed to induce changes in the body.
What is the purpose of transport proteins (such as albumin and lipoprotein)?
They bind the hydrophobic substances and enable them to travel in the circulation.
Legumes in general are high in fiber. How is this beneficial?
They can play a role in lowering the risk of cardiovascular diseases and certain forms of cancer.
Why are soy products an excellent source of protein?
They contain all of the essential amino acids and have very low amounts of saturated fat and cholesterol.
Why are meats considered complete proteins? Also, why can it be bad to consume too much of them?
They contain all the essential amino acids. May be bad too consume too much because they are high in saturated fat and cholesterol.
Why should one's intake of nuts be in low quantities (2-5 oz per week)?
They have a high fat content.
What hormone is made up of one amino acid and functions in metabolism?
Thyroid hormone
What is acidosis?
Too much acid in the blood, which can have deleterious effects on the body. Condition can change someone's respiratory pattern and have significant effects on the digestive system as well.
What is interstitial fluid?
Water around our cells
What happens first in protein synthesis?
We inherit the genetic material from our parents.
What are buffers?
molecules that resist acid-base changes.
