Biochemistry

Question 1

What is lipogenesis?

Answer 1

The formation of FAs from glucose sources (the opposite cannot happen)

Question 2

Name the major sites for lipogenesis

Answer 2

Lipogenesis happens in a lot of cells (liver, kidneys, mammary glands, brain and adipose tissue) - only converted into triglycerides in liver and adipose tissue

Question 3

What are the actions of insulin and glucagon on lipogenesis?

Answer 3

Insulin = increases lipogenesis
Glucagon = inhibits lipogenesis

Question 4

In normal physiology what is starch broken down into?

Answer 4

Acteyl-CoA

Question 5

What is the function of citrate in lipogenesis?

Answer 5

To transport acteyl groups into cytoplasm

Question 6

Explain the function of ACP

Answer 6

ACP is an acyl-carrier protein which binds to a starter chain to begin a FA

Question 7

State and explain the 4 steps of FA synthesis

Answer 7

Condensation (release H20)
Reduction (gain e - more stable)
Dehydration (release H20)
Reduction and release

Question 8

Which molecules acts as an electron donor in lipogenesis?

Answer 8

NADPH

Question 9

What 2 molecules are used to carry C atoms in lipogenesis?

Answer 9

Malonyl-CoA

Acetyl-CoA

Question 10

What 2 molecules are joined together to form triglycerides?

Answer 10

G-3-P (glycerol-3-phosphate)

+ 3x FAs

Question 11

What other similar products are produced in the liver?

Answer 11

Cholesterol
Phospholipids
Lipoproteins

Question 12

What are the 2 parts of glycogen?

Answer 12

Glycogenin and multiple glucose molecules

Question 13

Name the bonds found in glycogen molecules

Answer 13

alpha 1-4 glycosidic - straight

alpha 1-6 glycosidic = branches

Question 14

Where in the body are the largest quantitites of glycogen found?

Answer 14

Liver - to maintain blood sugars

Muscle - provide energy during exercise

Question 15

What is the name of the basic process that produces glycogen from a starter molecule and monomer units?

Answer 15

Glyogenesis

Question 16

UDP-glucose serves what role in producing glycogen?

Answer 16

Acts as an activated form of glucose that gets attached to glycogen chains

Question 17

Glycogen synthase and transglycosylase differ largely in 1 way; what is it?

Answer 17

Glycogen synthase attaches straight chains

Transglycosylase attaches branches

Question 18

What is the rate limiting enzyme of glycogen production?

Answer 18

Hexokinase

Question 19

Gluconeogenesis can produce glucose from what 3 major classes of molecule?

Answer 19

Amino acids
Lactate
Glycerol

Question 20

What is the cori cycle?

Answer 20

The reverse of anaerobic respiration

Turns lactate -> glucose

Question 21

Where does the cori cycle take place?

Answer 21

Liver mitochondria

Question 22

What is the “energy cost” of the cori cycle?

Answer 22

Cori cycle requires more energy than anaerobic respiration releases - not energy efficent

Question 23

What is the name of the process that breaks glycogen to monomer subunits?

Answer 23

Glycolysis

Question 24

What 2 fates befall the monomer subunits of glycogen break down?

Answer 24

Muscles -Further glycolysis

Liver - Converted into glucose

Question 25

What transport molecule is involved in the fate of monomers in the liver?

Answer 25

GLUT2

Question 26

What are the 3 types of lipid, and how do they differ?

Answer 26

Simple Compound Steroids Increasingly complex with added groups

Question 27

What are lipids soluble in?

Answer 27

Non-polar compounds | like dissolve like

Question 28

What are the 2 components in triglycerides?

Answer 28

Glycerol (G-3-P) and 3 FAs

Question 29

Where are triglycerides the major energy storage?

Answer 29

Adipose tissue

Question 30

Where is acyl CoA transported into?

Answer 30

Cytoplasm

Question 31

Draw the mechanism of acyl CoA transport

Answer 31

Sketch of carnitine shuffle

Question 32

How is acyl carnitine formed?

Answer 32

acyl-CoA + carnitine

Question 33

List the products of B-oxidation per cycle

Answer 33

``` FADH Acetyl-CoA Acyl-CoA NADH + H (FAAN) ``` PLUS 1x acetyl-CoA

Question 34

A 14C fatty acid would produce what after B-oxidation

Answer 34

``` C/2 - 1 = 7 - 1 = 6 6x FADH 7x Acteyl-CoA 6x Acyl-CoA 6x NADH + H ```

Question 35

Where does B-oxidation occur?

Answer 35

Mitochondria

Question 36

Are ketones physiologically present?

Answer 36

Yes - in small amounts

Question 37

Which states are ketones dangerous?

Answer 37

Starvation and diabetes - oxcalatone is used up in gluconeogenesis so can't break down acteyl-CoA

Question 38

How do ketones cause damage?

Answer 38

They are slightly acidic so when in high amounts causes metabolic acidosis -> organ damage

Question 39

Which body locations are ketones used ?

Answer 39

Kidneys and heart

Question 40

What atom/molecule do AA contain that mean they need to be excreted?

Answer 40

Nitrogen

Question 41

The dangerous components of AA are excreted as which molecules? Which is most common?

Answer 41

Urea, uric acid, creatinine, NH4 (ammonium) Urea = most common

Question 42

What enzymes act on proteins to form AA?

Answer 42

Proteolytic

Question 43

Where are AA absorbed?

Answer 43

Intestinal cells - small bowel

Question 44

What is transanimation?

Answer 44

Moving amino group from AA to alpha keto acid

Question 45

Where does transanimation occur?

Answer 45

In all body cells

Question 46

What 2 molecules are used to transport molecule products of transanimation to the liver?

Answer 46

Glutamine and alanine | gluty alan

Question 47

What is deanimation?

Answer 47

Conversion of amino groups to free ammonium ions in liver

Question 48

Where is urea synthesised?

Answer 48

Mitochondrial matrix

Question 49

What is the purpose of synthesising urea? (not to get rid of urea)

Answer 49

Less soluble than other forms of nitrogen compunds so less water is needed to be excreted alongside urea

Question 50

What is the fate of carbon skeletons left after AA metabolism?

Answer 50

Converted to glucose | Oxidised in TCA cycle