carbohydrate metabolism

Question 1

define metabolism

Answer 1

chemical conversions - changing one chemical to another

Question 2

what does metabolism involve and why

Answer 2

pathways - as chemical conversions do not occur spontaneously, they require enzymes

Question 3

if amino acid chemistry isn’t enough to metabolise something what is used/ added

Answer 3

cofactors (coenzymes)

Question 4

what are the two types of coenzyme

Answer 4

1. Permanent part of enzyme - prosthetic group
2. Reversible binding - comes on and off the enzyme when required

Question 5

what are the two kinds of metabolism

Answer 5

1. Anabolism - synthesis of a simple compound into a complex compound
2. Catabolism - the breakdown of complex compounds into simpler molecules

Question 6

define carbohydrate catabolism and give an example

Answer 6

the breakdown of a complex carbohydrate into simpler molecules e.g. the breakdown of glucose to carbon dioxide and water

Question 7

what are the three main pathways is the catabolism of glucose via aerobic respiration

Answer 7

glycolysis
Kreb’s cycle
Electron transfer chain

Question 8

explain the break down of the word glycolysis

Answer 8

glyco = sugar
lysis = to split

Question 9

where is glycolysis located

Answer 9

in the cytoplasm

Question 10

does glycolysis require oxygen

Answer 10

no

Question 11

where does the energy go during glycolysis

Answer 11

it is stored in hydrogen ions in NADH

Question 12

how many ATP molecules does glycolysis require, how many does it produce, and what is the net production

Answer 12

requires 2
produces 4
net = 2

Question 13

overall what are the 3 net products of glycolysis

Answer 13

2 ATP
2 NADH
2 Pyruvate

Question 14

what is glucose turned into during glycolysis

Answer 14

2 pyruvate molecules

Question 15

what is the name of the enzyme that adds the first phosphate group to glucose in glycolysis

Answer 15

hexokinase

Question 16

what is the name of the enzyme that adds the second phosphate group to the glucose molecule in glycolysis

Answer 16

phosphofructokinase

Question 17

what is a kinase

Answer 17

an enzyme that adds phosphate groups to molecules

Question 18

what is the glucose turned into during glycolysis before it divides into pyruvate

Answer 18

fructose 1,6 Bisphosphate (6C)

Question 19

what is the name of the enzyme that helps to catalyse the removal of phosphates from pyruvate molecules in order to make ATP

Answer 19

pyruvate kinase

Question 20

what does NAD stand for

Answer 20

Nicotinamide adenine dinucleotide

Question 21

what does FAD stand for

Answer 21

Flavin adenine dinucleotide

Question 22

what does ATP stand for and where is the energy stored in the molecule

Answer 22

adenosine triphosphate - it the bonds between phosphate groups

Question 23

what are the 4 fates of pyruvate

Answer 23

1. Gluconeogenesis
2. Absorption of NH3 to form alanine
3. Anaerobic respiration
4. Aerobic respiration

Question 24

what is gluconeogenesis and why does it occur

Answer 24

it is the conversion of pyruvate back to glucose - if the body has too much pyruvate when it requires glucose, the liver will convert it back. things like the brain and muscles require more glucose

Question 25

why does gluconeogenesis require different enzymes than glycolysis

Answer 25

as glycolysis is an irreversible chain of reactions

Question 26

why do pyruvate molecules absorb ammonia to form alanine and where does this ammonia come from

Answer 26

ammonia is produced when amino acids are broken down (when there is a lack of carbohydrates available) for fuel pyruvate absorbs this ammonia as it is toxic to cells

Question 27

what are the two different products of anaerobic respiration and who performs them

Answer 27

1. conversion of pyruvate to ethanol via the use of carbon dioxide - alcoholic fermentation - performed by microorganisms 2. conversion of pyruvate into lactate due to the lack of oxygen - lactic acid fermentation - performed by animals e.g. in muscles

Question 28

what is required for aerobic respiration to occur

Answer 28

oxygen

Question 29

where does pyruvate travel to in order to aerobically respire

Answer 29

the mitochondria

Question 30

what is pyruvate converted to before entering the Krebs cycle

Answer 30

2x Acetyl CoA (2C)

Question 31

what can also happen to Acetyl CoA instead of entering the Kreb's cycle

Answer 31

it can be converted to fatty acids for storage

Question 32

what is the aim of the Kreb's cycle

Answer 32

to break down Acetyl CoA into 2CO2 molecules, create NADH and FADH, and recycle oxaloacetate

Question 33

explain the process of the Kreb's cycle

Answer 33

1. Acetyl CoA (2C) is combined with oxaloacetate (4C) to form a 6 carbon molecule 2. A Carbon is then lost via CO2 to form a 5 carbon molecule 3. Another carbon is then lost via CO2 to form a 4 carbon molecule 4. This 4 carbon molecule then converts back to oxaloacetate in order to be reused in the cycle 5. During the cycle energy is stripped out in the form of hydrogen ions, that go onto the carrier NAD and FAD - these are used later in the ETC

Question 34

where is the electron transport chain located

Answer 34

in the inner membrane of the mitochondria

Question 35

what starts the electron transport chain and how

Answer 35

NADH and FADH from the Kreb's cycle and glycolysis release their H+ ions to be fed into the ETC

Question 36

explain the pathway of a H+ ion in the electron transport chain

Answer 36

It will enter the ETC and begin to pass through a series of proteins, generating energy as it goes through. This energy is used to create a H+ gradient from one side of the inner membrane to the other The H+ ion will be pumped out of the matrix via the energy its created, but will then flow back into the matrix via ATP synthase (due to the gradient) to generate ATP

Question 37

what is oxygen in the ETC

Answer 37

the final electron acceptor (produces water)