extremes of metabolism

Question 1

what are the two types of muscle fibres?

Answer 1

type 1 slow twitch

type 2 fast twitch

Question 2

how to type 1 muscle fibres make energy?

Answer 2

oxidative metabolism from glucose

fatty acids in the longer term

Question 3

what is an adaptation of type 1 slow twitch muscles?

Answer 3

lots of mitochondria

Question 4

how do type 2 muscle fibres make energy?

Answer 4

glycolysis to make lactate

Question 5

what is the main fuel of type 2 muscle fibres?

Answer 5

glycogen

Question 6

what are the subtypes of type 2 muscle fibres?

Answer 6

A - contain myoglobin - aeorbic

B - anaerobic

Question 7

what causes the balance of the type 2 muscle fibre subtypes to change?

Answer 7

levels of exercise

Question 8

how much can ATP demand increase in exercise in skeletal muscle?

Answer 8

100x

Question 9

what energy sources are used in exercise and in what order?

Answer 9

phosphocreatine –> muscle glycogen –> blood glucose/fatty acids

Question 10

how do the levels of ATP, ADP and AMP change with the intensity of exercise?

Answer 10

as intensity increase
ATP decreases
ADP and AMP increase

Question 11

what does AMP signal for during exercise?

Answer 11

increases glucose uptake in the short term and FA oxidation in the long term

Question 12

what vitamin is needed for muscle contraction?

Answer 12

calcium

Question 13

what activates phosphorylase kinase?

Answer 13

calcium bound to calmodulin

Question 14

what does Pyruvate dehydrogenase complex do?

Answer 14

controls entry to TCA

Question 15

what enzymes control pyruvate dehydrogenase complex and what effect do they have on it?

Answer 15

PDH kinase - inactivates PDC by phosphorylation in response to low NADH and ATP

PDH phosphatase - activates PDC in response to calcium

Question 16

what enzymes are allosterically controlled by calcium?

Answer 16

alpha-ketoglutarate dehydrogenase

isocitrate dehydrogenase

Question 17

how does AMP promote glycogen breakdown?

Answer 17

activates enzymes such as glycogen phosphorylase (when its not phosphorylated) and
phosphofructokinase-1

increases number of GLUT4 channels

Question 18

what allosterically inhibits phosphofructokinase?

Answer 18

high levels of ATP

Question 19

explain the mechanism in the heart to activate PFK1

Answer 19

PFK2 produces F-2,6-BP which is an allosteric activator of PFK1 - controlled by phosphorylation via AMP kinase

Question 20

explain the structure of AMP dependent protein kinase

Answer 20

heterotrimeric

3 subunits - 2 regulatory and 1 catalytic

Question 21

what is the function of AMPK?

Answer 21

sensor for energy status
Detects levels of AMP – when AMP is high, AMPK is activated –> increases no. of GLUT4

activating the carnitine shuttle

Question 22

how does AMPK sense AMP levels?

Answer 22

specific domain on its gamma subunit

Question 23

what controls AMPK?

Answer 23

phosphorylation on the Thr172 of the alpha subunit –> not dependent on AMP

Question 24

how does AMPK activate the carnitine shuttle?

Answer 24

phosphorylates Acetyl-CoA carboxylase
stops acetyl-CoA from building up
malonyl-CoA is therefore made
inhibits CPT-1 which activates the carnitine shuttle

Question 25

what happens to muscles in muscle fatigue?

Answer 25

running out of glycogen depletion of phosphocreatine excessive conversion of glycogen to glucose to lactic acid --> decreases pH and inhibits glycolysis inefficient mitochondria

Question 26

how does exercise affect the density of mitochondria

Answer 26

increases the density

Question 27

what is ethanol metabolised to in the body?

Answer 27

acetyl-CoA

Question 28

what are the 3 stages of alcohol metabolism in the body?

Answer 28

ethanol --> acetylaldehyde Acetylaldehyde + NAD+ --> Acetate + NADH ATP + Acetate + CoA --> AMP + PPi + Acetyl-CoA

Question 29

in what ways can ethanol be converted to acetylaldehyde?

Answer 29

alcohol dehydrogenase - makes NADH catalase - makes water microsomal ethanol oxidising system - makes NADP and water

Question 30

what is the function of Antabuse and how does it work?

Answer 30

inhibits acetaldehyde dehydrogenase so you get more acetylaldehyde. Makes you feel sick sooner when you start drinking --> stops you from drinking alcohol.

Question 31

what is another name for Antabuse?

Answer 31

disulfiram

Question 32

what are the biochemical effects of alcohol on the body?

Answer 32

High levels of Acetyl-CoA = excess FA synthesis and excess ketone bodies high levels of NADH = inhibition of the TCA cycle. =more pyruvate is converted to lactate as NAD+ needs to be regenerated --> lactic acidosis

Question 33

why does the immune system have a variable energy demand?

Answer 33

needed to produce ROS to kill microbes energy to make antibodies energy is required in phagocytosis

Question 34

why does the immune system require NADPH?

Answer 34

to make ROS

Question 35

how is NADPH needed by the immune system made?

Answer 35

from the pentose phosphate pathway | converting malate to pyruvate in the cytoplasm

Question 36

what is the Warburg effect?

Answer 36

regardless of how much O2, cancer cells have major up regulation of glycolysis (due to mutations of Hif protein)

Question 37

why do cancer cells have increased use of amino acids?

Answer 37

to feed into the TCA cycle to increase energy production