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148 Cards in this Set
- Front
- Back
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What is a protein?
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compounds composed of carbon, hydrogen, oxygen, and nitrogen atoms, arranged into amino acids (AAs) linked in a chain
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How many proteins does the human body contain?
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about 10,000-50,000 different kinds of proteins
(only about 1000 studied) |
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What makes proteins different from lipids and carbohydrates?
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besides containing C,H,O, also contains N (nitrogen)
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What does amino mean?
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suffix that means nitrogen containing
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NH3 group?
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amino group, alkaline (basic), negative charge
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What do some amino acids contain?
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S (sulfur atoms)
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What is the basic amino acid structure which makes up proteins?
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an alkaline neg. charge end, carboxyl group/acidic/+ charge end, unique side group, and a central carbon
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How do side groups differ?
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in size, shape, electrical charge
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There are 20 common amino acids that may be classified into _____ groups based on ____.
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seven; structure
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What are the nine essential amino acids?
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Histidine, Tryptophan, Valine, Threonine, Isoleucine, Leucine, Lysine, Phenylalanine, Methionone
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What is the acconim for the nine essential amino acids?
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Maybe I'LL Pass That Very Hard Test
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Essential AA qualities
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body can't synthesize in sufficient quantity; must be obtained in diet
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Nonessential amino acids qualities
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body can synthesize; provided by proteins in foods
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What is the beginning of protein synthesis?
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condensation of 2 AAs to form a dipeptide
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Peptide bond?
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bond that connects the acid end of one AA with the amino end of another forming a link in a protein chain
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Dipeptide? Tripeptide? Oligopeptide? Polypeptide?
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di- 2 AA
tri-3 AA Oligo- 4-9 AA Poly- > 10 |
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Amino acid sequence of insulin?
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51 AAs in 2 short polypeptide chains...disulfide bridges (formed by S atoms) link cysteine molecules together
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disulfide bridges?
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in aa sequence of insulin. formed by S atoms. link cysteine molecules together.
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small differences in body proteins determined by?
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unique AA sequence of proteins; determined by genes
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Where are the instructions for making every protein?
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filed in DNA within each cell nucleus
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Steps of protein synthesis?
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1. DNA template to make strands of mRNA. mRNA copies instructions for making some protein.
2. mRNA attaches itself to the protein making ribosomes. 3. mRNA leaves through cell membrane. DNA remains. 4.tRNA collects AAs from cell fluid. tRNA carries AA to mRNA. mRNA make sure amino acids line up in correct sequence 5. ribosome moves down mRNA bonding AA to protein strand.tRNA return for more AA. All AA attached, protein is released. 6. mRNA and ribosome seperate. |
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How many amino acids can be added to a growing protein per second?
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40-100 Amino Acids
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Protein Synthesis sequencing errors?
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erros alter AA sequence/mistakes made in copying genetic code;
Ex. sickle cell anemia |
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sickle cell anemia?
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sickle or cresent shaped RBCs.
defective hemoglobin that results in decreased oxygen transport and blood flow. |
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sickle cell anemia symptoms?
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hemolytic anemia (RBCs burst), fever, joint and abdomen pain
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Amino acid sequence of sickle cell hemoglobin?
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Val-His-Leu-Thr-Pro-Val-Glu
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Protein's shape?
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determine function in the body
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hollow sphere
protein shape |
act as carrier proteins
Ex. albumin |
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rod-like structure
protein shape |
strong
Ex. tendons |
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folded globular polypeptide chains
protein shape |
contain other compounds
Ex. hemoglobin that contains the mineral iron |
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Structure of hemoglobin
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packed by the billions in RBCs and functions to carry O2 in bloodstream;made of 4 associated polypeptide chains- each with a non-protein portion portion called heme contains iron
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Heme
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the nonprotein portion of hemoglobin, holds iron
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when a cell makes a protein, the gene for that protein has been
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expressed
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PUFAs decrease CVD risk by influencing gene expression for
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lipid enzymes
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Nutrients play key roles in...
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activating and silencing genes
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epigenetics
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switching genes on and off, without changing the genetic sequence
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When do proteins undergo denaturation?
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subjected to heat, acid, or other conditions that disturb their stability
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What happens when a protein is denatured?
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it uncoils, loses its shape, and loses its function;
past a certain point denaturation is irreversible |
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Denaturation caused by?
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heat, acids, alcohol, agitation, bases, heavy metals, other agents
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Protein digestion in the stomach
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HCl secreted by stomach--protein uncoils/pepsinogen--pepsin (protease)---smaller polypeptides
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what is the major organ of protein digestion?
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stomach
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the inactive form of an enzyme in called a
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proenzyme or zymogen
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pepsinogen is a
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zymogen
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peptidase
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enzyme that hydrolyzes peptide bonds
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endopeptidase
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enzyme that cleaves peptide bonds within protein chain
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exopeptidase
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enzyme that cleaves bonds at the chain end to release free AAs
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Protein Digestion in small intestine
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pancreatice and intestinal proteases hydrolyze polypeptides into: tripeptides, dipeptides, free AAs
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intestinal tripeptidases and dipeptidases (made on surface of intestinal cells) hydrolyze tripeptides and dipeptides into
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free AAs
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what are the end products of protein hydrolysis
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amino acids
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protein (amino acid) absorption
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transported from small intestines to the liver via the bloodstream
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Roles of proteins?
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1. building materials for growth and maintenance
2. enzymes 3. hormones 4. regulation of fluid balance 5. acid bade regulation 6. transporters of substances 7. antibodies 9. energy source |
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Proteins building material of growth and maintanence
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form integral parts of most body structures such as skin, tendons, membranes, muscles, organs, and bones.
support growth and repair of body tissue |
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collagen
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quantitatively the #1 protein in body; connective tissue found in scars, tendons, ligaments
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Roles of proteins: enzymes
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faciliatate chemical reactions without being changed in the process.
proteins catalysts. |
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Role of proteins: hormones
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chemical messengers secreted by endocrine glands in response to altered conditions in body.
travel to specific target tissues or organs. |
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Role of proteins: Regulation of fluid balance
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maintain the proper types and amounts of fluids in each body compartment
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fluids are contained in body compartments:
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inside cells (intracellular)
outside cells (extracellular) spaces between cells (intercellular) within blood vessels (intravascular) |
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proteins cannot flow freely between compartments because
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proteins are too large;
wherever proteins are they attract water |
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roles of proteins: regulation of fluid balancewhat occurs when fluids get out of balance?
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fluids (not proteins) in the bloodstream and cells are exchanged through capillary walls; some proteins leak out into interstitual fluid
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Proteins that leak out of capillaries into interstitial fluid between cells...
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1. cannot be reabsorbed back into the bloodstream2. Reenter circulation via the hymphatic system
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If plasma proteins leak into interstitual fluid faster than they can be cleared, fluid accumulates and swelling occurs because?
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proteins attract water
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Edema?
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swelling due to an excess of interstitual fluid
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Protein related causes of edema?
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1. excessice proteins losses in kidney disease/wounds/burns
2. Inadequate protein synthesis in liver disease 3. inadequate dietary protein |
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Roles of proteins: acid base regulation
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called buffers
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buffers
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compounds that help keep a solution's acidity or alkalinity constant
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Why are proteins good buffers?
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All proteins contain acidic components (carboxyl groups) and basic components (amino groups)
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When blood gets too acidic (acidosis too many + charges)
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- charges on the alkaline amino groups neutralize the excess + charges
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When blood gets too alkaline (alkalosis: too many - charges)
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+ charges on the acidic carboxly groups neutralize the excess - charges
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extremes of acidosis or alkalosis leads to...
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coma and death
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Whenever plasma proteins act as buffers...
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proteins are denatured BAD
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Roles of proteins: Transporters of other substances: examples
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hemoglobin (transports O2 from lungs to cells)
lipoproteins (transports lipids throughout the body) |
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Roles of proteins: antibodies
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large proteins produced by the immune system in response to the invasion of the body by foreign molecules (proteins called antigens)
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antibodies role
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combine with and inactivate the foreign invaders, thus protecting the body from diseases
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antigens
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substances that elicit the formation of antibodies or an inflammation reaction from the immune system
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examples of antigens
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bacteria, virus, taxins, proteins in foods that elicit an allergic reaction
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Immunity
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the body's ability to defend itself against diseases. Provided by antibodies and vaccinations
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other roles for proteins
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blood clotting, vision, scar formation
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roles of proteins: energy -- BAD
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proteins are needed to do work only proteins can do.
proteins used for energy and glucose when carb. nor supplied (gluconeogenesis) |
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what percent of AAs are gluconeogenic?
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50%
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The brain and nervous system falter without...
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glucose...BAD
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protein turnover:
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constant degradation and synthesis of protein that occurs within each cell
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amino acid pool
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supply of AAs derived from either food proteins (exogenous AAs) or body proteins (endogenous) that collect in cells and circulating blood
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AAs of AA pool...
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ready to be incorporated into proteins, other compounds, or used for energy
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Nitrogen balance
(Zero nitrogen balance) (Nitrogen equilibrium) |
amount of nitrogen consumed as compared with the amount of nitrogen excreted in given time period
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Positive nitrogen balance
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N in > N out; protein in > protein out; protein synthesis > degration
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when is there a positive nitrogen balance?
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pregnant women, growing children
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Negative nitrogen balance
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N in < N out; protein in > protein out; protein degration > sythesis
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when is there a negative nitrogen balance?
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starvation, stress, burns, trauma
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Using AAs to make proteins or nonessential AAs
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cells assemble AAs (from pool) into proteins as needed using genetic code in DNA
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Needed nonessential AAs can be made from...
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EAAs
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Needed EAAs must be obtained from...
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breaking down body protein...BAD
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Using AAs to make other compounds
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cells assemble AAs from AA poole into other compounds as needed
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Using AAs for energy and glucose...
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when need arises, body dismantles tissue proteins and uses them for energy
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Starvation causes
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wasting of lean body tissue (protein) as well as fat loss
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Dietary carbohydrates and fats...
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spare AAs from being used for energy and allows AAs to perform their functions as proteins
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AAs broken down for energy...
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stripped of N- containing amino groups (deamination)
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Deaminated amino groups are converted into
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ammonia (toxic)
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Ammonia is released into
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the bloodstream
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ammonia + CO2 converted into
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urea (less toxic) in liver
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urea filtered from blood in
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the kidneys
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amino nitrogen ends up in the
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urine
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excretion of deaminated AAs
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liver makes urea from ammonia produced from deaminated AAs + CO2;
kidneys excrete |
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Using AAs to make fat
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energy and protein intakes exceed needs and carbohydrate intake is adequate
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How do you make fat from AAs?
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AAs are deaminated, nitrogen excreted, remaining carbon fragments converted into fat
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High - quality proteins
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proteins contain all EAAs in relatively the same amount that human beings require
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2 factors influence protein quality
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1. digestibility
2. amino acid composition |
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protein digestibility
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measure of the amount of AAs absorbed from a given protein intake
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digestibility: animal proteins
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90-99% digestible
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digestibility: plant proteins
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70-90% digestible; except soy/legumes >90% digestible
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amino acid composition
(protein quality factor) |
to make proteins, all needed AAs must be available simultaneously
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Limiting amino acid
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EAA found in the shortest supply relative to the amounts needed for protein synthesis
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reference protein
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standard against which the quality of other proteins is measured
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reference protein is the EAA requirements of
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preschool aged children
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complementary proteins
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two or more dietary proteins whose AA assortments complement each other is such a way that the EAAs missing from one are supplied by the other
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example of complementary protein?
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black beans and rice
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protein-energy malnutrition (PEM)
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a deficiency of protein, energy or both including kwashiorkor, marasmus, and overlapping conditions
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how many children does PEM afflict?
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over 500 million
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most of the 33,000children who die each day are...
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malnourished
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Where is PEM most prevalent?
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Africa, Central/South America, the Middle East, and East/ Southeast Asia
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who is PEM common with in the US?
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homeless, people living in poverty, elderly who live alone, drug/ alcohol addicts, hospitalized people with TB, AIDS, and cancer
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acute PEM
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recent severe food deprivation;children are thin for their height (wasting)
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chronic PEM
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long term food deprivation;children are short for age (growth is stunted)
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marasmus
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form of PEM that results from a severe deprication of or impaired absorption of energy, protein, vitamins and minerals over a long time (chronic PEM); starvation
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marasmus is named for the Greek word meaning
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"dying away"
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kwashiorkor
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form of PEM results either from a sudden/recent inadequate protein intake, or commonly, infection (acute PEM)
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kwashiorkor named for the Ghanaian word meaning:
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"the evil spirit that infects the first child when the second child is born"
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marasum characteristics
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infancy (less than 2); impaired absorption protein ect; develops slowly; severe weight loss, muscle wasting; growth < 60%; no detecable edema; good appetite possible
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kwashiorkor characteristics
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older infants and young children; inadequate protein; rapid onset; edema, ascites; flag sign (spots of white in hair); flaky paint permatitis
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edema, ascites and enlarged liver are characteristics of
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kwashiorkor;edema mask muscle wasting
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extreme loss of muscle and fat are characteristics of
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marasmus; "matchstick" arms
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marasmus-kwashiorkor mix
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characterized by the edema of kwashiorkor with wasting of marasmus
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marasmus-kwashiorkor mix research:
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marasmus= body's adaptation to starvation;kwashiorkor= occurs when adaptation fails
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proteins and heart disease
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increase animal proteins -- increased risk of CVD
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increased homocysteine
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increased risk of CVD;
heavy coffee consumption, cigarettes, alcohol, low intakes vit B12, B6, folate |
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proteins and cancer
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increase animal proteins increased risk of cancer (colon, breast, pancreas, kidneys, and prostate)
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protein and osteoporosis
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high protein increases calcium;
with osteoporosis- inadequate protein compromises bone health |
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proteins and weight control
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balanced diet = weight loss
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proteins and kidney disease
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high protein increases the work of the kidneys; doesnt cause kidney disease
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RDA recommended protein intake?
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0.8 g/kg/day
10%-35% of energy intake |
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How much protein would a 5'4", 125 # female need to consume each day?
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125lbs / 2.2lbs/kg = 56.8 kg
56.8kg * .8 g/kg = 45 g Pro/day |
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To find how many kcals from PRO you would...
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multiply by 4
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protein and AA supplements
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muscle work builds proteins, protein supplements do not (harmful)
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protein consumption above 35%...
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places strain of kidneys
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excess of one AA can create such a demand for carrier...
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it limits the absorption of other AAs
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vegetarians
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general term to describe people who exclude meat, poultry, fish or other animal derived food from their diets
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lacto-ovo- vegetarians
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people include milk, milk products, and eggs
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vegans
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people who exclude all animal-derived foods; will not support life (lacks Vit B12)
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health benefits of vegetarian diets?
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diets higher in fiber and low in total fat; maintain healthier body weight; lower blood pressure and rates of hypertension; lower incidence of CVD and cancer
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