Carbohydrates

Question 1

Describe the ATP-ADP Cycle ?

Answer 1

Energy is released to be used when ATP is hydrolysed into ADP + P (Catabolism). However when energy is available phosphorylation occurs adding a P back to ADP to form ATP (Anabolism).

Question 2

During max exercise how long does stored ATP in the muscle last?

Answer 2

less than 3 seconds

Question 3

Why is myokinase maintaining ATP during exercise favoured?

Answer 3

Reduced ATP
Increased ADP
AMP is broken down in the liver and excreted by the kidneys by adenylate deaminase to favour more ATP production is needed

Question 4

ATP-PC system?

Answer 4

PC is hydrolysed to Phosphate and creatine so the phosphate can be used to form ATP with ADP

Question 5

Process of Carb digestion and absoprtion?

Answer 5

1) Begins in the mouth (with saliva) and small intestine (with pancreatic juices) where alpha amylase hydrolyses glycosidic bonds leaving oligosaccharides
2) Oligosaccharides are then broken down into disaccharides in the villi of the small intestines
3) Further enzymes, lactase, maltase, sucrase breakdown disaccharides to monosaccharides
4) Monosaccharides are then absorbed into the cytosol of the enterocytes and transported into capillaries that empty into venous blood and the portal vein that supplies the liver

Question 6

Where is glycogen located?

Answer 6

Between thick and thin filaments near mitochondria

Question 7

Glycogen breakdown in skeletal muscle increases during exercise, what mechanisms help?

Answer 7

Glycogen phosphorylase activity increases due to
Increased Phosphates
Increase AMP/ATP ratio
Increase adrenaline
Increase Ca2+

Question 8

Two phases of glycogen resynthesis? timings?

Answer 8

Insulin independent (0-4 hours)
Insulin dependent (4-24 hours)

Question 9

What drives insulin independent glycogen resynthesis ?

Answer 9

Low glycogen in the muscle
Post exercise blood flow
Increase in glucose transports such as GLUT4
Increase in glycogen synthase activity

Question 10

What drives insulin dependent glycogen resynthesis ? Compare to independent?

Answer 10

Lower rate than independent.
Insulin exclusively drives glucose uptake via GLUT4 aswell as glycogen synthase
Carb feeding will also accelerate maximising glucose and insulin levels in the blood

Question 11

What occurs when a substrate is oxidised?

Answer 11

It gives up 2 hydrogen atoms, one is passed as a hydride ion to NAD to make NADH/FADH and the other is released as a proton to the aqueous environment to lower pH

Question 12

What is glycolysis and where does it take place?

Answer 12

anaerobic metabolic pathway to produce Pyruvate, ATP and NAD, takes place in the cytosol

Question 13

How does exercise speed up glycolysis? (4)

Answer 13

Increased substrate availability
Increase blood flow of glucose to muscle
Increased glucose transporters = ^uptake
Allosteric activation of pyruvate kinase and phosphofructokinase

Question 14

What is the Citric acid cycle?

Answer 14

AKA The Krebs cycle, It is an aerboic metabolic pathways producing ATP, NADH and FADH2 from ACetyl CoA to be used in OP

Question 15

What happens to pyruvate?

Answer 15

Pyruvate oxidation - Pyruvate is Oxidised via pyruvate dehydrogenase in the mitochondrial matrix, forming Acetyl CoA (2), NADH, 1 glucose, 2 pyruvate and 2 NADH

Question 16

What is NADH and FADH2 used for?

Answer 16

To pass electrons down the ETC to fuel ATP synthesis

Question 17

What is Oxidative phosphorylation?

Answer 17

Aerobic metabolic pathway with high energy yield, taken place in the mitochondrial matrix and intermembrane space

Question 18

What happens during the ETC?

Answer 18

Reduced coenzymes such as NADH oxidised back to NAD releasing H+ as 2 electrons and a proton, which pass down proteins in the membrane and accepted by the terminal electron acceptor (O2) forming H2O

Question 19

Describe oxidative phosphorylation?

Answer 19

Spontaneous electron flow coupled with H+ ejection causes energy release to pump proton across the membrane creating a proton conc gradient which leads to ATP synthesis down the ATP synthase channel

Question 20

Describe lactate utilisation?

Answer 20

Lactate production leads to H+ prodution increase and decrease Cytosolic pH, once Lactate leaves down a conc gradient it can reform pyruvate which is reoxidised in less active muscles and used in TCA for OP etc.

Question 21

Describe lactate utilisation in the liver? (Lactate/Cori Cycle)

Answer 21

Lactate is formed from pyruvate during glycolysis, once produced lactate can leave fatiguing muscle and enter the liver via the blood to reform pyruvate.
Pyruvate is then used as a substrate for gluconeogenesis and glucose is shuttled back to fatiguing muscle fibres to undergo glycolysis for more ATP

Question 22

What is the role of Insulin and where are they secreted from?

Answer 22

Beta cells of pancreatic islets, Responds to high blood glucose levels, stimulates utilisation of biomolecules such as glucose, ffa’s and amino acids for storage or usage

Question 23

What is the role of Glucagon and where are they secreted from?

Answer 23

Secreted from alpha cells of pancreatic islets in response to low blood glucose levels

Question 24

Types of diabetes?

Answer 24

Type 1 - Impaired insulin secretion
Type 2 - Impaired Insulin sensitivity

Question 25

Complications of diabetes?

Answer 25

Stroke CV Disease Diabetic neuropathy - loss of feeling/amputation Diabetic Nephropathy - Renal disease Diabetic Retinopathy - Blindess

Question 26

Benefits of exercise for people with Diabetes?(6)

Answer 26

^ Glycemic control Reduced autoimmunity ^ psych wellbeing ^Fitness/physical function ^ HDL-LDL ratio Lower risk of CV disease

Question 27

Turnover of ATP during exercise?

Answer 27

Due to the high demand, catabolic pathways increase allowing more production of ATP, as well as anaerobic production. ATP is also hydrolysed and replenished at a higher rate.

Question 28

Function of Myokinase?

Answer 28

Collect ADP and rearrange Phosphates to re-form ATP

Question 29

Describe Phosphocreatine (PCr) ?

Answer 29

Highest phosphoryl transfer potential PCr outweighs Cr 2:1 allowing more conversion to Cr for creatine kinase to form ATP Stores are 4x larger than ATP but resynthesise slower

Question 30

What is the level of ATP during exercise ?

Answer 30

Doesn't drop below 60% due to myo/creatine kinase PCr provides initial demand of ATP then ATP is maintained by aerobic pathways and enzymes.

Question 31

Enzymes involved in PCr to ATP and process?

Answer 31

Creatine kinase (CK) catalyzes the transfer of a phosphate group from phosphocreatine (PCr) to ADP, forming creatine and ATP. Myokinase then catalyzes the transfer of a phosphate group between two ADP molecules, forming one ATP and one AMP

Question 32

Carbs as a source of energy?

Answer 32

Glucose is rich in C-H bonds which can yield energy Breakdown of glucose is associated with negative change in Gibbs free energy

Question 33

Key stages of the Krebs/Citric acid cycle?

Answer 33

1) Acetyl COA from pyruvate oxidation combines with oxaloacetate to form citrate 2) Citrate is then converted to isocitrate which is oxidised and decarboxylated into a-ketoglutarate, releasing co2 and reduction of NAD+ 3) The same occurs again forming succinyl CoA 4) Succinyl CoA is then converted to succinate by hydrolysing the bond, this resulting in production of ATP. 5) Succinate is oxidised to fumarate resulting in reduction of FAD to FADH2 6)Fumarate is then oxidised into Malate which then is oxidised to oxaloacetate leaving the same products to be used in Oxidative phosphorylation and allowing the cycle to repeat.

Question 34

Location of metabolic pathways? (6)

Answer 34

ATP-ADP - Cytoplasm, mitochondria and other organelles Glycolysis - Cytoplasm Fermentation - Cytoplasm Pyruvate Oxidation - Mitochondrial Matrix Krebs - Mitochondrial Matrix Oxidative Phosphorylation -Inner mitochondrial membrane

Question 35

Key phases of the electron transport chain & oxidative phosphorylation?

Answer 35

Electron Transport Chain (ETC) - 1) NADH, generated from glycolysis, pyruvate oxidation, and the citric acid cycle, donates electrons 2) Electrons are passed through a series of protein complexes - electron acceptors 3) Energy is released from each electron transfer and used to pump protons (H+) from the mitochondrial matrix into the intermembrane space, establishing a proton gradient. 4) FADH2 follows similarly however it does not effect the gradient Oxidative Phosphorylation - 1) Proton Gradient = higher concentration of protons in the intermembrane space compared to the mitochondrial matrix, storing potential energy. 2) ATP Synthesis harnesses the energy of the proton gradient to drive the synthesis of ATP from ADP and inorganic phosphate (Pi). 3) Protons flow back into the mitochondrial matrix through ATP synthase and ATP synthesized by ATP synthase is released into the mitochondrial matrix, where it can be used to power cellular processes.

Question 36

Net ATP yields from aerobic and anaerobic metabolism of glucose?

Answer 36

Aerobic = 32-36, 2 from Glycolysis and Krebs and 28-32 from OP Anaerobic = 2 from glycolysis, fermentation allows further glycolysis but does not directly produce ATP

Question 37

Role of Insulin with blood glucose?

Answer 37

Insulin is secreted by beta cells of the islets of langerhans when there is elevated blood glucose levels. Insulin will stimulate utilisation of biomolecules such as glucose, ffa's and amino acids to store or use this glucose to lower the levels.

Question 38

Role of Glucagon with blood glucose?

Answer 38

Glucagon is secreted from alpha cells of the islet of langerhans when there is a decrease in blood glucose levels. Glucagon stimulates glycogenolysis and gluconeogensis in order to produce more and also inhibits glycolysis so less is broken down.

Question 39

Long Term Complications of diabetes?

Answer 39

Diabetic Retinopathy - Leading cause of blindness in adults Diabetic Nephropathy - Leading cause of end stage renal disease Diabetic Neuropathy - Leading cause of non-traumatic lower extremity amputation Stroke - increase in CV mortality and stroke Cardiovascular Disease - 8/10 individuals with diabetes die from CV events

Question 40

Benefits of exercise for people with diabetes ? (10)

Answer 40

Improved psychological well being Improved glycemic control Improved blood lipid profile Improved physical fitness and function Improved endothelial function Lower mortality rate Lower autoimmunity Lower insulin requirements Lower risk of CV disease Preserved beta cell function

Question 41

Affects of exercise on blood glucose responses? Aerobic/Anaerobic?

Answer 41

Aerobic exercise increases GLUT4 expression in muscle Exercise can improve insulin sensitivity, as assessed by routine clinical tests; e.g., oral glucose tolerance test Maximal exercise can rapidly increase blood glucose as epinephrine stimulation to liver outweighs uptake by muscle Prolonged exercise will lower plasma glucose levels as liver glycogen depots are depleted over time

Question 42

For every electron that is transferred from NADH to oxygen via the electron transport chain, how many protons are ejected from the mitochondrial matrix into the intermembrane space?

Answer 42

5 2 from both Complex 1 and 3 1 from complex 5

Question 43

During glycolysis and the Krebs Cycle, what do the cofactors NAD+ and FADH accept during dehydrogenation reactions?

Answer 43

2 hydrogen atoms

Question 44

What would NOT increase the rate of glycogen breakdown?

Answer 44

AMP levels

Question 45

What type of reaction is ATP to ADP

Answer 45

Exergonic and hydrolysis

Question 46

What are the byproducts produced by the ATP/PC energy system?

Answer 46

ADP, AMP, Pi