Exam 2

Question 1

Types of Regulation

Answer 1

Allosteric, Covalent, Induction, Directional shift.

Question 2

Allosteric

Answer 2

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

Question 3

Induction

Answer 3

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.

Question 4

Covalent Modification

Answer 4

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

Question 5

Directional Shift

Answer 5

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

Question 6

Phosphorylation of Glucose

Answer 6

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

Question 7

When a cell needs to generate energy or deposit glucose

Answer 7

glucose first needs to be inside of the cell

Question 8

Km

Answer 8

= [substrate] at half maximum velocity

Question 9

Glycolysis

Answer 9

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

Question 10

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

Answer 10

Used to regenerate NAD+ and maintain glycolysis

Question 11

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

Answer 11

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

Question 12

Malate - Aspartate Shuttle

Answer 12

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

Question 13

Glycerol 3-phosphate Shuttle

Answer 13

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.

Question 14

Glycogenesis

Answer 14

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

Question 15

Glycogenolysis

Answer 15

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)

Question 16

Which hormone(s) favor glycogenesis

Answer 16

insulin

Question 17

Which hormone(s) favor glycogenolysis

Answer 17

glucagon (affects liver) or

epinephrine (affects muscle)

Question 18

Allosteric Modulation examples

Answer 18

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

Question 19

Covalent Modification examples

Answer 19

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.

Question 20

Glucocorticoids

Answer 20

induce gluconeogenic enzymes

Question 21

Inducible Enzyme

Answer 21

Concentrations rise and fall in response to molecular signals.

Question 22

Noninducible Enzyme

Answer 22

Basal rate, constitutive

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

Question 23

Dietary fiber

Answer 23

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

Question 24

Functional fiber

Answer 24

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

Question 25

The only dietary fiber that is not also a functional fiber

Answer 25

Hemicellulose

Question 26

Cellulose

Answer 26

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

Question 27

Hemicellulose

Answer 27

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

Question 28

Pectin

Answer 28

``` 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. ```

Question 29

Lignin

Answer 29

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

Question 30

Gums

Answer 30

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

Question 31

Soluble fibers

Answer 31

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

Question 32

Insolube

Answer 32

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

Question 33

Soluble fibers are

Answer 33

- 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

Question 34

Insoluble fibers are

Answer 34

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

Question 35

Characteristics of water-holding fibers

Answer 35

decreased transit time, increase fecal volume, softer stool

Question 36

Characteristics of viscous fibers

Answer 36

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

Question 37

Characteristics of absorbent fibers

Answer 37

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

Question 38

Other plant sugars that are not absorbed in small intestine

Answer 38

Raffinose, stachyose, verbascose

Question 39

Byproducts of fermentation of fibers in the Colon

Answer 39

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.

Question 40

Diseases prevented by fiber

Answer 40

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

Question 41

Bifunctional enzymes

Answer 41

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

Question 42

Glycolytic

Answer 42

Inducible: glucokinase, phosphofructokinase, pyruvate kinase

Question 43

Gluconeogenic:

Answer 43

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