Metabolic Science

Question 1

What are the two key components of metabolism?

Answer 1

Anabolism & Catabolism

Question 2

Give a definition of anabolism

Answer 2

Synthesis

Question 3

Give a definition of catabolism

Answer 3

Degradation / Oxidation

Question 4

Give a function of anabolism

Answer 4

Allows for Growth & Structure

Question 5

Give a function of catabolism

Answer 5

Energy release, detoxification, re-synthesis

Question 6

What is the overall generic reaction in the metabolism of food?

Answer 6

Cells release energy from food via a series of oxidation reactions

Question 7

Explain oxidation reactions in reference to the metabolism of food

Answer 7

Food molecules act as electron donors (so undergo oxidation) and allows for a conformational change to the structure of the electron acceptor molecule to allow it to store energy

Question 8

What molecules can store the energy released by oxidated food molecules

Answer 8

NAD & ADP (i.e. NADH and ATP)

Question 9

Why is there a series of small oxidative reactions rather than one large one when it comes to food metabolism?

Answer 9

Performing smaller oxidative reactions allows for less energy to be ‘wasted’ / lost and more ATP / NADH molecules to be formed

Question 10

What are the 3 key metabolic pathways

Answer 10

Glycolysis
Citric Acid Cycle
Oxidative Phosphorylation (not electron transport chain)

Question 11

Where does glycolysis take place?

Answer 11

Cell Cytoplasm

Question 12

What is the start and end products of glycolysis?

Answer 12

1 x 6 carbon glucose molecule

2 x 3 carbon pyruvate molecule

Question 13

What are the energy inputs and outputs of glycolysis?

Answer 13

Input -> 2 ATPs

Output -> 4 ATPs, 2 NADH

Question 14

How many steps are involved in glycolysis?

Answer 14

10 step process

Question 15

What follows glycolysis?

Answer 15

Dependant on oxygen status

If in presence of oxygen the pyruvate can enter the mitochondrion and for a 2 carbon compound called Acetyl CoA (with the 3rd carbon binding with oxygen to form CO2)

If there is an absence of oxygen the pyruvate cannot bind to form CO2 so forms intermediate end products such as lactic acids

Question 16

What is the products of pyruvate to acetyl CoA?

Answer 16

1 x CO2

1 x NADH

Question 17

What is the 2nd step of metabolism?

Answer 17

Citric Acid Cycle

Question 18

What is the start and end product of the citric acid cycle?

Answer 18

Acetyl CoA enters the citric acid cycle allowing for oxaloacetate to be converted to citric acid to restart the cycle

Question 19

What is produced in the citric acid cycle?

Answer 19

2 x NADH
1 x FADH2
1 x GTP

Question 20

What is the third step of metabolism?

Answer 20

Oxidative phosphorylation

Question 21

What is the location of the 3rd step of metabolism

Answer 21

Electron Transport Chain

Question 22

What is the electron transport chain?

Answer 22

A series of proteins and organic molecules found within the inner membrane of the mitochondria

Question 23

What are the 4 key steps of oxidative phosphorylation & the electron transport chain?

Give a description of each step

Answer 23

Delivery of electrons via the reduced electron carriers (NADH and FADH2) to the molecules at the start of the chain.

Electron transfer and proton pumping: the electrons begin to be passed down the chain from a high concentration down to a low concentration. During this transition energy is released. The energy is harnessed by the proteins by pumping hydrogen ions from the inner matrix into the inter-membrane space causing an electrochemical gradient

Splitting oxygen to form water: to finish the transfer of electrons / give the electrons an end goal they bind to a O2 molecule & splits it to form H2O

Synthesis of ATP: when the electrons finish their transfer hydrogen ions can return to the matrix but as they pass through a particular protein which also acts as an enzyme called ATP-synthase - it is able to harness the energy and synthesise ATP

Question 24

What is the name of the enzyme that forms ATP?

Answer 24

ATP-Synthase

Question 25

How many electrons are required to form 1 ATP molecule?

Answer 25

1/3rd -> i.e. 1 electron = 3 ATP molecules

Question 26

How many ATP molecules are formed from the transfer of 5 electrons?

Answer 26

15 ATP molecules -> i.e. 1 electron = 3 ATP molecules

Question 27

How many ATP molecules does 1 glucose molecule form?

Answer 27

38 ATP

Question 28

How is fatty acids metabolised?

Answer 28

beta-oxidation = a process of 2 carbons being removed from the carboxyl end of the fatty acid chain to generate an Acetyl CoA molecule which can enter the citric acid cycle & this is repeated until the remaining acyl-CoA is left

Question 29

How many ATP molecules does palmitic acid produce?

Answer 29

129

Question 30

What is the difference between acetyl-CoA and acyl-CoA molecules?

Answer 30

Acetyl-CoA is a specific structure where the ‘R’ group is a methyl group whereas the Acyl-CoA is a more generic term where the ‘R’ group is variable with regards to the fatty acid type

Question 31

How are proteins & amino acids metabolised to produce energy?

Answer 31

Amino-Acids can undergo two processes that contribute to the production of intermediates of the citric acid cycle or convert to pyruvate/acetyl-CoA. These processes are transamination (interconversion of AAs) and deamination (removal of amino groups)

Question 32

During excessive energy production what mechanisms does the body employ to store the energy?

Answer 32

Glycogenesis & Lipogenesis

Question 33

During fasting how does the body provide glucose for glucose dependant organs?

Answer 33

For the first 12-18 hours of a fast we rely on liver glycogen being broken down however following that we rely on the kidneys and liver to synthesise the glucose from gluconeogenesis etc

Question 34

What requires more energy to synthesise - adipose tissue or glycogen?

Answer 34

Adipose tissue - formation of adipose tissue for storage of energy is an extremely energy expensive task however it is still econmically beneficial as it is twice as energy dense as glycogen stores.