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SPH-N430 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Types of Regulation

A

Allosteric, Covalent, Induction, Directional shift.

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2
Q

Allosteric

A

Affects how well the enzyme works. Effectors bind the enzyme (not covalent / not at active site) and either helps or inhibits reaction by:
Helping or hurting substrate binding to enzyme or enzyme activity. NADH/+ ratio affects several allosteric enzymes. Catalyze undirectional, non-reversible reactions

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3
Q

Induction

A

More enzyme protein is made when inducer is present (alcohol example). Allows for more product to be made and allows body to react to changing circumstances. Sometimes hormones use this mechanism.

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4
Q

Covalent Modification

A

Binds enzymes covalently (usually phosphate) which affects activity +/-. Occasionally used by hormones and mediated by cAMP

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5
Q

Directional Shift

A

Direction of a reversible enzyme is often affected by the concentration of r/p; consider glucose-1-phosphate or glucose-6-phosphate.

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6
Q

Phosphorylation of Glucose

A

Glucose + ATP -> glucose-6-phosphate + ADP
If in Liver Tissue, rxn is catalyzed by Glucokinase (Hexokinase type 4) - high Km and inducible by insulin
If in Muscle Tissue, rxn catalyzed by hexokinase (type 1 and 2) - low Km and inhibited by glucose-6-phosphate

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7
Q

When a cell needs to generate energy or deposit glucose

A

glucose first needs to be inside of the cell

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8
Q

Km

A

= [substrate] at half maximum velocity

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9
Q

Glycolysis

A

Process that oxidizes glucose into 2 units of pyruvate. 2 units of ATP are initially invested, but four are generated along with 2 NADH as byproducts. Aerobic -> pyruvate, anaerobic -> lactate

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10
Q

What happens to NADH generated in the cytosol during glycolysis (Anaerobic)

A

Used to regenerate NAD+ and maintain glycolysis

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11
Q

What happens to NADH generated in the cytosol during glycolysis (Aerobic)

A

NADH travels to mitochondria through one of two shuttles (because NADH cannot travel through mitochondrial inner membrane). Malate - Apartate, and Glycerol 3-phosphate shuttle

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12
Q

Malate - Aspartate Shuttle

A

Cytosol:
Apartate > (a-ketoglutarate > > glutamate) > Oxaloacetate > ( NADH + H+&raquo_space; NAD+) > Malate then crosses over.
The reverse occurs in the matrix then crosses back to cytosol.
Regenerates NADH so more energy than the other shuttle

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13
Q

Glycerol 3-phosphate Shuttle

A

Glycerol-3-phosphate gets converted back to dihydroxyacetone phosphate by a membrane-bound mitochondrial glycerol-3-phosphate dehydrogenase 2, reducing one molecule of enzyme-bound FAD to FADH2. FADH2 then reduces ubiquinone to ubiquinol, which enters into oxidative phosphorylation.
Regenerates FADH so ultimately less energy that it’s counterpart.

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14
Q

Glycogenesis

A

Synthesis of glycogen, occurs in cytoplasm. Requires 1 unit of ATP, UTP/molecule of glucose.

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15
Q

Glycogenolysis

A

Breakdown of glycogen to form glucose-1-phosphate in cytoplasm
glycogen n + Pi glucose-1-phosphate + glycogen (n-1)
(glycogen phosphorylase, which hydrolyzes alpha 1,4 links, repeated until branch is only four glucose units in length)

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16
Q

Which hormone(s) favor glycogenesis

A

insulin

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17
Q

Which hormone(s) favor glycogenolysis

A

glucagon (affects liver) or

epinephrine (affects muscle)

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18
Q

Allosteric Modulation examples

A

phosphorylase A and B, phosphofructokinase, hexokinase, pyruvate kinase, pyruvate dehydrogenase

19
Q

Covalent Modification examples

A

One of two ways that hormones work (regulate). Use Protein kinases and use ATP as a phosphate donor. Phosphatase is used to remove the P group from enzyme by phosphotase.

20
Q

Glucocorticoids

A

induce gluconeogenic enzymes

21
Q

Inducible Enzyme

A

Concentrations rise and fall in response to molecular signals.

22
Q

Noninducible Enzyme

A

Basal rate, constitutive

Required all the time at relatively constant levels of activity (housekeeping genes)

23
Q

Dietary fiber

A

carbohydrates and lignin from plants that are not digestible by human enzymes.
Cellulose, hemicellulose, pectin, lignin, gums, beta-glucans, fructans, resistant starches

24
Q

Functional fiber

A

non-digestible carbohydrates that have been isolated, extracted, or manufactures and have been shown to have beneficial physiological effects in humans.
Cellulose, pectins, gums, beta-glucans

25
Q

The only dietary fiber that is not also a functional fiber

A

Hemicellulose

26
Q

Cellulose

A

Beta 1,4 linkage in glucose polymer
water insoluble
poorly fermented
Present in bran, legumes, nuts, peas, root vegetables, cabbages, apples

27
Q

Hemicellulose

A

Heterogeneous group of polysaccharides substances containing different sugars
solubility depends on side chain
fermentability depends on sugar position
Present in bran, whole grains, nuts, legumes

28
Q

Pectin

A 
First degree galacturonic acid
water soluble
gel forming
high ion bonding potential
completely digested by colonic M.O.
Present in apples, strawberries, citrus, legumes, nuts.
29
Q

Lignin

A

Not a carbohydrate, but is a 3d polymer composed of three different phenol forms (trans-coniferyl, trans-sinapyl, trans-p-courmaryl

30
Q

Gums

A 
Hydrocolloids
composed of sugars and sugar derivatives
highly soluble
gel-forming
highly fermentable by colonic bacteria
31
Q

Soluble fibers

A

fructans, some hemicelluloses, psyllium, beta-glucans, pectins, and gums (these last four are viscous

32
Q

Insolube

A

Lignin, Cellulose, and some hemicellulose. All conssidered non-viscuous.
Chitosan, chitin, and some pectins and resistant starches are also considered insoluble or less soluble.

33
Q

Soluble fibers are

A
  • The water soluble components or fiber (Pectin, gums, some hemicelluloses, beta-glucans)
  • Fermented by intestinal bacteria
  • Delay gastric emptying time and decrease nutrition absorption
  • Present in fruits, barley, oats, and beans
34
Q

Insoluble fibers are

A
  • Not water soluble
  • Not fermented by intestinal bacteria
  • Decrease intestinal transit time, reduce fecal bulk
  • Present in wheat bran, vegetables, and grains
35
Q

Characteristics of water-holding fibers

A

decreased transit time, increase fecal volume, softer stool

36
Q

Characteristics of viscous fibers

A

delayed gastric emptying, decreased nutrient absorption, and decreased digestive function

37
Q

Characteristics of absorbent fibers

A

decrease serum cholesterol, dimish lipid absorption, alter mineral balance, and increase fecal bile acid excretion.

38
Q

Other plant sugars that are not absorbed in small intestine

A

Raffinose, stachyose, verbascose

39
Q

Byproducts of fermentation of fibers in the Colon

A

Gasses (H2, CO2, and CH4), Short chain fatty acids: acetic, butyric, and propionic
Increased Na+ and water absorption
Nonfermentable fibers lead to microbial proliferation and contribute to fecal bulk and detoxification.

40
Q

Diseases prevented by fiber

A

Colectoral cancer, GI diseases, atherosclerosis (disease serum cholesterol), NIDDM, controlling body weight.

41
Q

Bifunctional enzymes

A

Non-inducible: phosphoglucoisomerase, aldolase, glyceraldehyde-3-P-dehydrogenase, phosphoglycerate kinase, phosphoglyceromutase, enolase, lactate dehydrogenase.

42
Q

Glycolytic

A

Inducible: glucokinase, phosphofructokinase, pyruvate kinase

43
Q

Gluconeogenic:

A

Inducible: glucose 6-phophatase, fructose-1,6-bisphosphatase, PEP carboxykinase, pyruvate carboxylase

SPH-N430 (17 decks)

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