Biochemistry Exam II

Question 1

Secreted by B-cells of pancreas

Answer 1

Insulin

Question 2

Secreted by a-cells of pancreas

Answer 2

Glucagon

Question 3

Insulin receptors

Answer 3

autophosphorylate themselves

Question 4

Brings Glu into the cell

Answer 4

GLUT 4

Question 5

Insulin-dependent gucose entry into cell is mediated by _____ which controls glucose uptake in _____ and _____

Answer 5

glucose transporters (GLUT4)
skeletal muscle
adipocytes

Question 6

Most GLUT 4 reside

Answer 6

intracellularly (<10% on PM)

Question 7

_____ Increases the expression of GLUT 4 independently of insulin

Answer 7

muscular contraction

Question 8

____ decrease the expression of GLUT4 in the muscle

Answer 8

Fatty acids

Question 9

Main contribution to type 2 diabetes

Answer 9

–Insulin resistance
Inadequate synthesis
Secretion
Unable to exert normal effect (most common)

Question 10

Main cause of insulin resistance

Answer 10

defect in signaling
-receptor binding
-mutation in receptor gene
-anti-receptor autoantibodies
Signaling defects
-IRS-phosphoiniositol kinase pathway

Question 11

Anti-insulin hormone

Answer 11

Glucagon

Question 12

Mobilizes glucose
Increases blood glucose
stimulates catabolism
Suppresses anabolism

Answer 12

Glucagon–breaks down glycogen (catabolic)

Question 13

Catecholamine

• secreted by AG
• Inhibits glycolysis and lipogenesis
• Stimulates gluconeogenesis

Answer 13

Epinephrine

Question 14

Effect of Epinephrine

Answer 14

decrease glycolysis and lipogenesis

stimulate gluconeogenesis

Question 15

Controlled by changes in plasma ratios of glucagon and insuin

Answer 15

Feed-Fast cycle

Question 16

High insulin/low glucagon

Answer 16

fed state

Question 17

Low insulin/high glucagon

Answer 17

fasting between 6-12 hours state

Question 18

____ low insulin/high glucagon occurs during fasting of ___ or more hours, known as ____

Answer 18

Chronic
12
Starvation

Question 19

Tissues affected in Fed (absorptive state)

Answer 19

Liver
Muscle
Adipose
--Storage tissues
Glucose utilization in brain = unaffected

Question 20

Decrease in glycogen synthesis
Increase in glycogenolysis
Liver switches from glucose usage to glucose production

Answer 20

Fasting (postabsorptive) state

Question 21

Gluconeogenesis key substrates

Answer 21

Lactate, alanine, glycerol

Question 22

During fasting ___% taken up by insulin-dependent tissues
__% glucose goes to brain
Remaining is divided among ____ _____ and ____

Answer 22

80
50
RBC, Muscle, Adipose

Question 23

after 12 hrs.
___% glucose comes from glycogen
Glucose contribution from ____ increases as it continues
-More ketone bodies present in this stage

Answer 23

Prolonged fasting (starvation)

Question 24

During prolonged fasting, ___ help by releasing ____ which goes to liver

Answer 24

Muscles

Lactate

Question 25

In liver, lactate---> | Glucose released goes to muscle =

Answer 25

pyruvate for gluconeogensis | Cori cycle

Question 26

In this stage: Free fatty acids are major energy substrate Oxaloacetate decreases in mito to fuel gluconeogenesis--limiting TCA activity Acetyl CoA accumulates--used for ketogenesis causing inc. plasma ketone body levels

Answer 26

Prolonged fasting (starvation)

Question 27

During starvation, gluconeogensis occurs in

Answer 27

kidney and liver

Question 28

During starvation, muscle proteolysis increases, releasing

Answer 28

Alanine and Gln

Question 29

Anti-insuiln hormones

Answer 29

Epinephrine Glucagon Cortisol

Question 30

Metabolism is effected during stress: Gluconeogenesis? Glycogen breakdown? Ketone body production?

Answer 30

Increases gluconeogenesis Increases glycogen breakdown (glycogenolysis) Increases ketone production by ketogenesis ---Stress response preserves glucose supply ---leaves more for brain utilization

Question 31

Stress induces insulin resistance Cortisol decreases Glu4 expression Cortisol induces expression of Glc-6-Pase and PEP carboxylase carrboxykinase genes which facilitate gluconeogenesis Insulin-independent glu uptake increases

Answer 31

Outcomes of Stress Response

Question 32

develops before age 35 destruction of B-cells Viral infection,toxins, food Autoantibodies to insulin, glutamic acid decarboxylase and protein tyrosine phosphatase

Answer 32

Type I Diabetes

Question 33

Over age 40 Insulin resistance Ketoacidosis rare Obesity normal glucose levels, hyper insulinemia can be reversed with weighloss and exercise

Answer 33

Type 2 diabetes