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Spring 2014 > Metabolism, Part 2 - Exam #1 > Flashcards

Metabolism, Part 2 - Exam #1 Flashcards

1
Q

Protein composition in the body

A
  • 40% skeletal muscle
  • 25% organs
  • other contained in skin and blood
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2
Q

How are proteins Catalytic Enzymes?

A
  • Speed up rate of reactions that allow life sustaining bodily reactions to occur;
  • Some require coenzymes (B-vits) or cofactors (minerals)
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3
Q

What are the types of Catalytic enzymes?

A
  • Hydrolases – cleave compounds
  • Isomerases – transfer atoms in a molecule
  • Ligases – (syntheses) join compounds
  • Oxidoreductases – transfer electrons
  • Transferases – move functional groups
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4
Q

How are proteins Messengers?

A

Hormones (insulin, glucagon)

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5
Q

How are proteins used Structurally?

A

contractile, fibrous, globular

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6
Q

How are proteins Immunoprotectors?

A
  • Both innate and adaptive immunity;
  • Immunoproteins (AKA immunoglobulins or antibodies) ;
  • IgG, IgA, IgM, IgE, and IgD
  • Immune Response → Bind to antigens creating an immunoprotein-antigen complex that will be destroyed by reactions with complement proteins or cytokines; destruction also can occur by macrophages and neutrophils through phagocytosis
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7
Q

How are proteins Transporters?

A
  • Carry substances in the blood, in and out of cell through membranes, and within cells;
  • Albumin;
  • Transthyretin (prealbumin) = complexes with retinal binding protein to transport retinol (Vit. A);
  • Transferrin = iron transport;
  • Ceruloplasmin = copper transport;
  • Lipoproteins - lipid transport;
  • Hemoglobin = oxygen/CO2 transport
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8
Q

How are proteins Buffers?

A
  • Acid-base regulation;
  • pH too LOW – amino acids ACCEPT hydrogens so pH of solution will increase
  • pH too HIGH – amino acids DONATE hydrogens so pH of solution will decrease
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9
Q

How are proteins Fluid Balancers?

A
  • Balance osmotic pressure of blood and tissue by H2O attraction;
  • Prevents edema and concentration of fluid within the tissues and maintains it in circulation (Albumin)
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10
Q

What are Conjugated Proteins?

A
  • Protein that functions in interaction with other chemical groups attached by covalent bonds or by weak interactions;
  • EX: Glycoproteins
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11
Q

What are Glycoproteins?

A
  • Proteins that contain an oligosaccharides (glycan chain) covalently attached to the polypeptide side-chain through the process of Glycosylation;
  • Can be a variety of sugars and proteins;
  • Carb as the nonprotein component;
  • Typically branched and uncharged
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12
Q

What is Glycosylation that forms glycoproteins?

A
  • Carbohydrate is attached to a hydroxyl or other functional group of another molecule - protein for glycoproteins;
  • N-glycosylation – attached at the Amide Nitrogen of the polypeptide side chain
  • O-glycosylation – attached at the Hydroxyl Oxygen of the polypeptide side chain
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13
Q

What are Proteoglcyans?

A
  • Class of Glycoproteins with extra carbs;
  • Heavily glycosylated proteins;
  • Core proteins with many glycosaminoglycan chains;
  • High molecular weight;
  • Skin, bone, cartilage (connective tissues)
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14
Q

What are Glycosaminoglycans (GAGs) or mycopolysaccharides ?

A
  • Forms of Proteoglycans;

- Long unbranched polysaccharides with repeating disaccharides

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15
Q

What is Primary Protein Structure?

A

-Sequence of amino acids covalently bound together

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16
Q

What is Secondary Protein Structure?

A

– 3-D form achieved through HYDROGEN BONDING between amide groups;

  • Alpha-helix;
  • Beta-conformation or Beta-Pleated Sheet;
  • Random coils (least stable)
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17
Q

What is Tertiary Protein Structure?

A
  • Linear, globular, or spherical;
  • Affects the shape and function of the type of protein;
  • Forms SINGLE polypeptide chains;
  • Hydrophobic AA’s cluster toward center;
  • Electrostatic (ionic) interactions between the amino acid SIDE CHAINS;
  • Strong covalent bonds between Cysteine residues (disulfide bridges)
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18
Q

What is Quaternary Protein Structure?

A

–Interaction between 2 or more polypeptide chains;

  • Oligopolymers (a few monomer units);
  • Form multi-unit complexes of polypeptide subunits
  • EX: Hemoglobin
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19
Q

What is basic structure of an Amino Acids?

A

Central Carbon
+ 1 amino (NH2)
+ 1 carboxyl (COOH)
+ R-group side chain (Amino acid specific)

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20
Q

AA’s with Aliphatic Side Chains (non-aromatic)

A
  • Glycine
  • Alanine
  • Valine
  • Leucine
  • Isoleucine
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21
Q

AA’s with Hydrolytic Groups (-OH)

A
  • Serine

- Threonine

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22
Q

AA’s with Sulfur Atoms

A
  • Cysteine

- Methionine

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23
Q

AA’s with Acidic groups or their Amides

A
  • Aspartic Acid
  • Glutamic Acid
  • Asparagine
  • Glutamine (may be important for gut health)
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24
Q

AA’s with Basic Groups

A
  • Arginine
  • Lysine
  • Histidine
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25
Q

AA’s with Aromatic Groups

A
  • Phenylalanine;
  • Tyrosine;
  • Tryptophan
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26
Q

How else can Amino acids be classified?

A
  • Charge = neutral, negative, positive;

- Polarization = polar neutral, polar charged, non polar neutral, relatively nonpolar

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27
Q

What are Zwitterions?

A

Overall neutral charge due to the presence of a positive and a negative charge in the molecule

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28
Q

What are NONSESSENTIAL AA’s?

A

DO NOT need to be consumed, but body can make

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29
Q

What are Conditionally Essential AA’s?

A
  • Must consume an essential AA’s to in order to make those conditionally essential;
  • MUST consume during times of GROWTH;
  • Or when cannot consume the precursor essential amino acid
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30
Q

What are Essential/Indispensable AA’s?

A
  • MUST consume in the diet; body CANNOT make;
  • Phenylalanine (essential) will be used to make Tyrosine (conditionally essential)
  • Methionine (essential) will be used to make Cysteine (conditionally essential)
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31
Q

What is the problem associated with PKU?

A
  • CANNOT consume Phenylalanine in the diet, so therefore cannot make Tyrosine;
  • So must consume Tyrosine = now becomes essential
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32
Q

What is the basis for Amino Acid SYNTHESIS?

A
  • Focuses on the NONESSENTIAL (the ones the body makes), but if you consume them in high quality protein, your body will not waste the energy to make them;
  • Occurs through Transamination
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33
Q

What is needed for Amino Acid synthesis?

A

-Need the ESSENTIAL Alpha-amino acids’ precursor carbon skeleton (minus the amino group to make a new AA) to synthesize the NONESSENTIAL Amino Acids

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34
Q

What is Transamination?

A
  • The removal of the amino group from the carbon skeleton of the essential and then transfer of the needed amino group to make the new AA;
  • EX: Glutamate is produced through transamination of alpha-ketoglutarate and an alpha-amino acid;
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35
Q

What are the 4 truly essential Amino Acids?

A
  • Lysine, Threonine, and maybe Histidine and Tryptophan are truly essential;
  • CANNOT be synthesized from precursor carbon-skeletons in the body and must be consumed preformed in the diet;
  • Carbon skeletons CANNOT be transaminated
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36
Q

What are Exogenous sources of Protein?

A

-Sources of proteins are provided in the DIET through animal products (except purified fats) and certain plant products (grains/grain products, legumes, vegetables)

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37
Q

What are Endogenous sources of Protein?

A

-Sources of proteins are broken down from WITHIN the body → Desquamated

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38
Q

What is the role of enzymes in the utilization of proteins?

A
  • Catalyze the catabolism and digestion of proteins;
  • FREE amino acids are then absorbed and utilized by the body for anabolic processes or for energy in times of gluconeogenesis
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39
Q

What is the mechanism for Transamination for amino acid synthesis?

A
  • Alpha-keto acid + Alpha-Amino acid;
  • Transaminate (transfer) the AMINO group from the alpha-amino acid to the alpha-keto acid;
  • Catalyzed by Aminotransferases
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40
Q

What protein digestion occurs in the MOUTH and ESOPHAGUS?

A

None, no enzymes present

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41
Q

What proteins digestion occurs in the STOMACH?

A
  • Gastrin (peptide-hormone) released into blood stimulating gastric juices
  • HCl denatures proteins and converts pepsinogen to pepsin (active; from parietal cells)
  • Pepsin from stomach chief cells hydrolyzes peptide bonds
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42
Q

What protein digestion takes place in the SMALL INTESTINE?

A
  • Partially digested proteins stimulate release of secretin and CCK (hormones)
  • Pro-enzymes and bicarbonate (acid neutralizer) are released due to hormones presence
  • Pro-enzymes are converted to active enzymes digesting proteins to tri- and dipeptides and free amino acids
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43
Q

What Pancreatic Enzymes play a role in protein digestion?

A
  • Trypsinogen → trypsin (small peptides, some free);
  • Chymotrypsinogen → chymotrypsin (small peptides, some free);
  • Procarboxypeptidases A & B → carboxypeptidases (free amines);
  • Proelastase;
  • Collagenase
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44
Q

What are the Brush Border peptidases that aid protein digestion?

A
  • Aminopeptidases, dipeptdylaminopeptidases, tripeptidases

- Tripeptides hydrolyzed or absorbed at brush border

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45
Q

How are peptides/amino acids absorbed in the Brush Border?

A
  • Amino acids transport requires CARRIERS (active or passive)
  • EX: Sodium (Na+) dependent transport into cell
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46
Q

How is peptide transport carried out by PEPT1?

A
  • Peptide transport into cells carried out by PEPT1 and the co-movement of protons (H+)
  • H+ are pumped back into the lumen in exchange for Na+
  • Na+, K+ ATPase pumps Na+ out fo the cell in exchange for K+ to cross the membrane
  • Then broken to amino acids
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47
Q

How is there competition for protein carriers?

A
  • There is an overlap and competition for certain carriers between amino acids;
  • Not all amino acids have a specific carrier but they are shared;
  • Can create deficiency problems if the AA with the higher affinity if consumed in higher amounts
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48
Q

What happens to all Water-Soluble Substances?

A
  • ALL WATER-SOLUBLE substances are transported/diffuse into the portal blood and go to liver;
  • This includes amino acids and short-chain fatty acids;
  • (Other LIPIDS become chylomicrons and enter the LYMPH)
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49
Q

What is the Lymph?

A
  • Clear fluid that is basically recycled blood plasma;

- Moves directionally toward the heart

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50
Q

What are the Nitrogen-containing NONPROTEIN compounds?

A
  • Glutathione - antioxidant, reacts with H2O2, AA transport, conversion of prostaglandin H2 to D2 & E2
  • Carnitine - FA transport
  • Creatine - part of phosphocreatine (high-energy compound)
  • Carnosine - may be antioxidant
  • Choline - methyl donor, part of acetylcholine & lecithin & sphingomyelin
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51
Q

What are Pyrimidines?

A

Main component of DNA and RNA nucleotide bases;

  • 6-membered rings containing N in positions 1 & 3
  • Uracil, cytosine & thymidine
  • Cytosine → DNA and RNA
  • Thymidine → ONLY DNA (=Uracil → RNA)
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52
Q

What are Purines?

A

Main component of DNA and RNA nuleoctide bases

  • 2 fused rings, N in positions 1, 3, 7, 9
  • Adenine & guanine → Found in DNA and RNDA
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53
Q

What are the main protein SYNTHESIS hormones?

A
  • ANABOLIC

- Insulin and growth hormone

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54
Q

What are the main protein DEGRADATION hormones?

A
  • CATABOLIC

- Glucagon and stress hormone

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55
Q

What is Deamination?

A

REMOVAL of amino group

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56
Q

What is Transamination?

A

TRANSFER of amino group from one AA to AA carbon skeleton or α-keto acid → Catalyzed by aminotransferases

57
Q

What is the purpose of the Urea Cycle?

A
  • Disposal of ammonia;
  • Occurs in the Liver, Urea sent to blood, excreted by the kidney;
  • Overall: Amino acids degraded and Arginine synthesized
58
Q

What is the source of NITROGEN in Urea?

A

Glutamate

59
Q

What is the Mechanism of the Urea Cycle?

A
  • NH3, basically from glutamate, combines with CO2 or HCO3- to form carbamoyl phosphate
  • Carbamoyl phosphate reacts with ornithine transcarbamoylase (OTC) to form citruline
  • Aspartate reacts with citruline to form argininosuccinate
  • Arginosuccinate is SPLIT to form fumarate & arginine
  • Urea is formed and ornithine is re-formed from cleavage of arginine
60
Q

How does the TCA and Urea Cycle interact?

A

-Glutamate combines with products from the point of OAA (TCA cycle) and released CO2 to make Aspartate which then enters the Urea Cycle

61
Q

What is the normal serum concentration of ammonium?

A

-20–40μM;
-Increase of serum ammonium to 400μM causes alkalosis and neurotoxicity.
(Alkalosis – reduction of hydrogen ion concentration in arterial blood plasma (pH ~ 7.45) )

62
Q

What are Aminotransferases?

A
  • Carry out transamination;

- EXCEPT for except threonine and lysine and maybe tryptophan and histidine (TRULY ESSENTIALS)

63
Q

How is Glutamate degraded to Ammonia?

A
  • Catalyzed by liver glutamate dehydrogenase through oxidative deamination;
  • Generates Ammonia and Alpha-Ketoglutarate;
  • Produced Ammonia is then used in the Urea Cycle the excreted in urine as NH4+ (Urine pH = 4-8)
64
Q

How is Glutamate degraded to Glutamine?

A

-Carried out by glutamine synthase and sent to kidneys where it is sequentially deaminated by glutaminase and then kidney glutamate dehydrogenase

65
Q

What is Glutamine?

A
  • Major circulatory amino acid;
  • Transports ammonia throughout the body (mostly peripheral tissue to kidneys)
  • Ammonia when CARRIED in peripheral tissues with does NOT cause alkalosis → non-ionizable form;
  • Only free ammonia causes toxicity
66
Q

What is the role of the LIVER in Glutamate degradation?

A
  • Contains glutamine synthetase (make) an glutaminase (break) in different areas;
  • Liver is not a net producer or consumer of Glutamine, but gathers free ammonia NOT in urea
  • Duality of enzymes controls how much ammonia is in urea or carried in glutamine
  • Urea cycle enzymes are located with glutaminase (break) → leads to excretion
67
Q

What is the purpose of Urea and Glutamine?

A

Rid of excess AMINOS → KIDNEY EXCRETION

68
Q

What happens to the amino group from lysine, threonine, tryptophan and histidine?:

A
  • Intermediates of their metabolism (NOT by TRANSAMINATION) can then be converted to glutamates, which will then ultimately undergo transamination to ammonia and turn into urea and the excess aminos excreted;
  • Threonine = to Glycine then transaminated;
  • Lysine;
  • Tryptophan;
  • Histdine = through glutamate to urea or glutamine
69
Q

What is produced by the metabolism of the carbon skeleton or alpha-keto acid from protein catabolism?

A
  • Energy
  • Glucose and ketones
  • Cholesterol
  • Fatty acids
70
Q

What are the Branched Chain Fatty Acids?

A
  • Leucine, Isoleucine, and Valine;
  • Catabolized/oxidized to corresponding alpha-keto acids for fuel in the extrahepatic tissues of the muscle, adipose, kidney and brain;
  • These tissues contain aminotransferases NOT in the liver;
  • Increased metabolism of BCAA’s during exercise for energy!
71
Q

How are BCAA’s catabolized in extrahepatic tissues>

A

First two enzymes are the same for all 3 =

  • Branched-chain aminotransferase then,
  • Branched-chain alpha-keto acid dehydrogenase complex (analogous to pyruvate and alpha-ketoglutarate complexes and requires the same 5 cofactors);
  • These are then followed by Acyl-CoA derivatives
72
Q

How is Leucine (BCAA) degraded for energy?

A
  • Acetoacetyl-CoA → (Acetyl-CoA → TCA ) OR Ketone Bodies

- Acetyl-CoA → TCA

73
Q

How is Isoleucine (BCAA) degraded for energy?

A
  • Acetyl-CoA → TCA

- Succinyl-CoA → TCA

74
Q

How id Valine (BCAA) degraded for energy?

A

→ Succinyl-CoA → TCA

75
Q

What is the Glucose-Alanine cycle?

A
  • Alanine (amino acid) carries ammonia and carbon skeleton of pyruvate from MUSCLE PROTEIN BREAKDOWN to the LIVER
  • Ammonia → Excreted;
  • Pyruvate → Glucose → Energy goes back to the muscle
76
Q

What is the mechanism of the Glucose-Alanine cycle?

A
  • Pyruvate from glycolysis in muscle takes NH4+ from glutamate to make Alanine (alanine aminotransferase);
  • Alanine travels through the blood to the liver;
  • Liver (alanine animotransferase) removes NH4+ from Alanine and combines it with Alpha-ketoglutarate;
  • Regenerates Pyruvate (back to gluconeogenesis) and Glutamate;
  • Glutamate goes to urea cycle and excretes NH4+
77
Q

Amino Acids (dietary or endogenous protein) can be used to MAKE ….

A
  • Biogenic amines
  • Peptide hormones
  • Plasma proteins
  • Structural Proteins
  • Enzymes
  • Immunoproteins
  • Transport proteins
78
Q

What are amino acids composed of?

A

Amino Group + Carbon Skeleton (alpha-keto acid)

79
Q

What happens to extra amino groups?

A

Amino group → Urea Ammonia → Excretion by kidney (most) or intestine (trace)

80
Q

What can the carbon skeleton be used for?

A
  • Energy + CO2 or,
  • Glucose/ketones or,
  • Fatty acids
81
Q

How can tissue proteins go through CATABOLISM?

A

-Cellular proteins can be degraded by either …
=Lysosomal
=Proteasomal
=Calcium/calcium-activated proteolytic degradation;
-Yields Amino Acids to synthesize other bodily compounds

82
Q

What are High Quality/Complete Proteins?

A

Supplies ALL the essential amino acids in adequate amounts

EX: Animal products

83
Q

What are Low Quality/Incomplete Proteins?

A

-Low in one or more of the essential amino acids and require complementation to adequately supply the diet of needed amino acids;
-Missing/low content amino acid is know as the “Limiting Amino Acid”
-EX: Wheat, rice, other grains → Low in Lysine, threonine (some) and tryptophan (some)
-EX: Legumes → Low in Methionine
=Grain + Legume = Complement Complete Protein Source

84
Q

What is Protein QUALITY based on?

A
  • Nitrogen balance or status
  • Chemical or Amino Acid Score
  • Protein digestibility corrected amino acid score
85
Q

What is the RDA for protein?

A
  • RDA Adults = 0.8 k/kg → Based on ESSENTIAL Amino Acids
  • NO difference in RDA for athletes
  • No UL currently sited for protein intake
  • AMDR = 10-35% of total kcal intake
86
Q

What is Kwashiorkor?

A

Adequate kcals, but NOT enough PROTEIN → Edema (water retention) due to lack of blood proteins balancing osmotic pressure in tissues

87
Q

What is Marasmus?

A

Wasting, emaciation from chronic insufficiency of kcals AND protein

88
Q

What is Nutritional Genomics (Nutrigenomics)?

A

“the field of study concerned with complex interaction among genes and environmental factors”;
Fueled by research such as the Human Genome Project

89
Q

What is Nutrigenetics?

A
  • “concerned with the effects of gene variations (also called gene variants) on the organism’s functional ability, specifically its ability to digest, absorb, and use food to sustain life”;
  • Genes AFFECTING foods;
90
Q

What is Nutrigenomics?

A
  • “concerned with how bioactive components within food affect gene expression and function;
  • Food AFFECTING genes
91
Q

What is Pharmacogenomics?

A
  • Studying dealing with how genes interact with pharmaceutical drugs;
  • More advanced and easier to research due to controlled composition of the drugs
92
Q

What might be an effect of various alleles on drug use?

A

-People potentially catabolize drugs at different rates, therefore changing the dose that they would require

93
Q

What do various alleles have on Vitamin K Epoxide Reductase Complex and coagulation?

A
  • Vitamin K Epoxide Reductase Complex subunit 1 (VKORC1) enzyme recycles reduced Vitamin K and promotes blood clotting through its association with Vitamin K-dependent coagulation factors;
  • Different alleles between people might cause them to require higher or lower doses of anticoagulants to act on VKORC1 to prevent clots
94
Q

What are the Advantages of Pharmacogeneomics?

A
  • Prior research in drugs and metabolism

- Usually only a single, purified compound with a defined chemical make-up

95
Q

What is the main disadvantage of Nutrigenomics?

A

-Foods contain so many various compounds in such varying amounts its hard to be totally sure of an outcome

96
Q

What is mostly studied in Nutrigenetics?

A

-single gene disorders – INBORN errors of metabolism caused by a mutation (different allele in the gene) with different degrees of rarity

97
Q

What are Single Nucleotide Polymorphisms (SNPs)?

A
  • Single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population;
  • Changes the function or causes loss of protein function;
  • -Some mutations or subtle variations only slightly effect protein function and only may increase/decrease potential risk of disease;
  • Sometimes might even pose a benefit
  • EX: PKU;
  • EX: Familial dyslipidemias
98
Q

What are most diseases?

A
  • Multifactorial = meaning a combo of gene changes are the cause
  • EX: Obesity – usually seen as multifactorial, but some studies have shown people who don’t make leptin or have a defective receptor, melanocortin-4
99
Q

What are Nutrition/Lifestyle changes NOT likely to have an effect on?

A
  • Highly penetrant SINGLE GENE disorders especially the homozygous individuals;
  • Heterozygous would be more responsive
100
Q

How do GENES factor into disease risk?

A

may give you greater/lesser risk of disease development

101
Q

How does Diet/Lifestyle factor into disease risk?

A

nutrition and lifestyle choices greatly affect your risk of disease and can also factor into or act on the tendency found within the inherited genes in developing nutrition-related diseases

102
Q

What is the Folate genetic variation for SNP 667>T?

A
  • Genetic variation = SNP 677C>T in the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR)
  • Frequency of T-homozygosity = 1% or less among Blacks to 20% or more among Italians and Hispanics
  • Result of variation = WITH SNP have problems when consume less than adequate folate and might actually REQUIRE MORE
  • Disease risks = colon cancer, fetal neural tube defects, and CVD
103
Q

What effect can genome variation have on nutrient utilization?

A
  • Variant in genome can alter how the nutrient is handled and can affect the requirement or increase/decrease sensitivity;
  • Folate example
104
Q

What are the protein genes associated with lipids receptors?

A
  • APOE (apoprotein E) = IDLs
  • APOA1 (apoprotein A1) = HDL
  • CETP (cholesterol ester transport protein)
105
Q

What are the common allele variations for APOE?

A 
–E2, E3, E4
Possible Genotypes = each gives a different response to diet/lifestyle changes 
•E2/E2, E2/E3, E2/E4
•E3/E3, E3/E4
•E4/E4
106
Q

For APOE, those with at least ONE E4…

A
  • Highest basal levels of lipids and respond BEST to low fat diets to lower lipid levels;
  • But DON’T respond to soluble fiber to lower or exercise to higher HDLs
  • Fish Oil Supps. = increase serum cholesterol
  • Alcohol and Smoking = increases LDL and increases carotid artery intima-media thickening which enhances risk of atherosclerosis (around age 40)
107
Q

For APOE, those with ONE or MORE E2…

A
  • Low LDL cholesterols, but high triglycerides and respond to soluble fibers, fish oil, and exercise to increase HDL;
  • But DO NOT responds to low fat diets
108
Q

For APOA1, what variant change in women due to diet intervention?

A
  • 75G>A ;
  • Women with 2 G alleles HDL levels drop with increased polyunsaturated fat intake → better response to monounsaturated
  • Women with A allele (2 is best) increase HDL with increase polyunsaturated intake and EVEN BETTER with mono-’s than those with G
109
Q

What changes does Nutrigenetics deal with?

A

deals with DNA differences that cause changes in the protein made that alters nutrition requirements

110
Q

What other field does Nutrigenomics overlap?

A

-Enters the field of epigenetic and short-term gene regulation or expression as brought about by nutrient intake

111
Q

How can knowing a person’s genotype aid nutrition intervention?

A
  • Knowing a particular persons genotype and the mechanism of the nutrient affect could yield much more effective and specific nutritional interventions!
  • EX: Omega-3 fatty acids can reduce inflammation through genes → Meaning knowing the genotype can have diet
112
Q

What is Epigenetics?

A
  • Changes in gene expression that does NOT involve any change in the actual DNA sequence;
  • Information is passed through generations, but without being encoded;
  • Expression passes from parent to daughter cells during cell division, and sometimes parent to offspring
113
Q

How do Epigenetic changes occur?

A

Changes in expression due to covalent modification of histones and/or the location of histone variants

114
Q

What are Histones?

A
  • Highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes;
  • The chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation;
  • Condenses the long strands of DNA
115
Q

Does the in utero environment contribute to adult health?

A
  • In utero (in the womb) environment has shown a great contributor to health and susceptibility in a adulthood
  • EX: Deprivation in the womb, might lend someone to obesity and T2DM due to overindulgence to counter having one been deprived
116
Q

What are Paramutations?

A
  • Gene expression passed from cell to daughter cell, but NOT parents to child
  • EX: X-inactivation and imprinting – Only ONE allele of two being expressed
117
Q

What is DNA methylation?

A
  • Adds a methyl to the Cytosine/Adenine DNA nucleotide;
  • When methylated strands of DNA are replicated, initially they are produced unmethylated.;
  • But, DNMT1 DNA methylase will specifically methylate the new strand and maintain the DNA methylation expressed in the daughter sequences;
  • DNMT! makes methylation irreversible! and alters gene expression
118
Q

What is Histone Modification?

A
  • Epigenetic gene variation;

- SHORT-TERM, not inherited, and regulate gene expression

119
Q

What might control Epigenetic memory?

A
  • Might be dependent upon polycomb groups of proteins;
  • Humans have at least two polycomb-group repressive complexes = PRC1 and PRC2;
  • They methylate H3K27 in target genes.
120
Q

How do Polycomb -groups control histones and gene expression?

A

have the ability to remodel chromatin and so that epigenetic silencing will occur and turn off gene expression

121
Q

What are the variants of Histones?

A
  • H3, H2A and H2B;

- Active, expressed genes have histones H3 and H2A replaced by variants H3.3 and H2AZ

122
Q

What is HFD?

A

-Histone-fold domain = structural area common to all core histones

123
Q

How are histones modified?

A
  • TYPICALLY single and specific, but some sites will undergo more than one type;
  • Individual function is associated with these changes;
  • N-terminal tails of H3 and H4 have many sites of modification
124
Q

What are the types of modifications for the N-terminal of H3 and and H4?

A
  • Methylation
  • Acetylation
  • Phosphorylation
  • EX: ACETYLATION of H3 and H4 = ACTIVE chromatin while METHYLATION = INACTIVE chromatin;
  • EX: Arg residue methylation and Ser phosphorylation
125
Q

What is the histone modifciation nomenclature?

A
  • TYPE of HISTONE, one-letter AA code, and position of the residue counting from the N-terminal
  • Ac – acetylation
  • Me – methylation
  • Ph – phosphorylation
  • Ub – ubiquitylation
  • Su – sumolaytion
126
Q

What are the functions of Euchromatin and Heterochromatin?

A
  • gene expression, gene repression and DNA transcription;

- different types of histone modifications occur at the different states

127
Q

What is Euchromatin?

A

-Nucleosomes are loosely packed w/ nucleosome-free regions that can bind regulatory proteins; Active; replicate in the early stages of the cell cycle

128
Q

What is Heterochromatin?

A

-Nucleosomes are densely packed and associated with heterochromatin protein 1 (HP1); “gene poor” w/ much repetitious DNA and replicates in late S phase of cell cycle (gene-poor = non-coding regions)

129
Q

What are some nutrients required for gene expression?

A
  • Resistant Starch → Butyrate
  • Folate and choline → Methyl group transfers
  • Vitamins A and D (and many others) → Bind to binding proteins that function as transcription factors
130
Q

What is Transcription of proteins?

A

DNA → mRNA;

-mRNA – coding RNA, meaning it is TRANSCRIBED into protein

131
Q

What are miRNA and siRNA?

A

NON-CODING RNAs that compose RNA interference or RNAi

132
Q

What is miRNA?

A

(microRNA) which functions in transcriptional and post-transcriptional regulation of gene expression;

  • Function via base-pairing with complementary sequences within mRNA molecules
  • Results in gene SILENCING via translational repression or target degradation
133
Q

What is siRNA?

A

(silencing RNA) acts in the RNA interference (RNAi) pathway;

-Interferes with the expression of specific genes with complementary nucleotide sequence

134
Q

What is Translation of proteins?

A

mRNA → Protein

135
Q

What is Post-translation modification>

A

Protein → Modified Protein

136
Q

How can miRNA prevent translation of proteins?

A
  • Directly – by hybridizing to it mRNA
  • Indirectly – by hybridizing to mRNA for transcription factors for one or more earlier transcription of the final protein
  • Inhibitor – miRNA promotes inhibition of an inhibitor by preventing its mRNA from being translated to protein
137
Q

What are the steps of gene expression that can be regulated?

A
  1. Open DNA so transcription “machinery” can reach the gene to be transcribed
  2. Transcription of transcription factors, other activators, and repressors/inhibitors
  3. Reading the gene
  4. Transcribing the gene
  5. Make mRNA
  6. miRNA prevents mRNA genes directly or indirectly; or promotes inhibition of an inhibitor
  7. Regulate ribosomal function and tRNA
  8. Regulate post-translational modification
138
Q

What is the potential for nutritional genomics?

A
  • Bioactive foods components;
  • Functional foods;
  • Dietary supps. for specified genotypes

Spring 2014 (22 decks)

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