Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

My Gastrointestinal > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

What is glycogenesis?

A

synthesis of glycogen from glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is glycogenolysis?

A

breakdown of glycogen to form glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is gluconeogenesis?

A

formation of glucose from metabolic precursors such as lactate, amino acids and glycerol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When is liver vs muscle glycogen broken down?

A

liver is broken down between meals to maintain plasma glucose concentrations
muscle provides energy during glycolysis and TCA during exercise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are all the glucose levels that are fluctuating in the body?

A
  • glucose from meals fluctuates
  • glycogenolysis acts after each meal
  • gluconeogenesis for glucose overnight when hepatic glycogen is low
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where is glucose added to glycogen?

A

1-4 glycosidic link and branches are 1-6 links

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is glycogenin?

A

a marker that binds at least four glucose residues and acts as a template

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the outline of glycogen synthesis?

A
  • glucose phosphorylated to glucose-6-phosphate
  • phosphoglucomutase makes it glucose-1-phosphate
  • UDP-glucose is made
  • glycogen synthase then makes glycogen by adding glucose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is UDP-glucose and what can it be used to measure?

A

UDP-glucose is activated glucose

important for measuring how much glucose is available and how much glucose is ready to be converted to glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the rate-limiting enzyme of glycogenesis?

A

glycogen synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the branching enzyme that makes branches in glycogen?

A

transglycosylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is glucose released from glycogen?

A
  • glycogen to glucose-phosphate by glycogen phosphorylase
  • then to glucose-6-phosphate by phosphoglucomutase
  • to glycolysis or in the liver to glucose then blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the rate-limiting step of glycogenolysis?

A

glycogen phosphorylase catalysing glycogen to glucose-1-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What enzymes does glycolysis use?

A

hexokinase, phosphofructokinase and pyruvate kinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What can glucose be made from in gluconeogenesis and where does this occur?

A

lactate, amino acids or glycerol

in liver and little bit in kidneys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the four rate-limiting enzymes needed in gluconeogenesis?

A

pyruvate carboxylase, fructose-1,6- bisphosphatase, glucose-6-phosphatase and PEP carboxykinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does gluconeogenesis proceed via?

A

synthesis of oxaloacetate in mitochondria and the process is energy consuming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the Cori cycle?

A

lactate is a precursor of gluconeogenesis, the cycle involves

  • Lactate coming back to liver in blood
  • Lactate causing glucose to be made by gluconeogenesis
  • Glucose moves from liver to muscle in the blood
  • Glucose is converted to lactate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do amino acids cause gluconeogenesis?

A

wherever the amino acids contribute carbon in the TCA there is oxaloacetate made which is then used for gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does glucagon do?

A

stimulates glycogenolysis and activates gluconeogenesis

21
Q

What does insulin do?

A

activates glycogenesis and inhibits gluconeogenesis

22
Q

What are glycogen storage diseases?

A

a group of diseases with increased glycogen deposits in the liver or muscle or both

23
Q

What is fat used for?

A
  • energy source
  • for essential fatty acids
  • for fat-soluble vitamins
24
Q

What are the main natural fatty acids?

A

palmitic acid
stearic acid
oleic acid

25
Q

Where do we get polyunsaturated fats from?

A

diet as the body can’t make them so they are ‘essential’

26
Q

How do fats get absorbed?

A

as glycerol, fatty acids and monoglycerides
they are coated with protein, phospholipid and cholesterol to form chylomicrons
these then enter the lymph then the blood

27
Q

How are the chylomicrons used once absorbed?

A

attacked and cleaved at muscle and adipose tissue by lipoprotein lipases

  • resynthesises into triglycerides for storage
  • or oxidised in muscle to provide energy
28
Q

How are fatty acids oxidised to produce energy?

A
  • cleavage by hormone-sensitive lipases when energy is needed
  • converted to acyl-CoA
  • into the mitochondrial matrix by carnitine shuttle
  • beta oxidation in mitochondrial matrix to produce energy
29
Q

What are the products of beta oxidation of fats to produce energy?

A

1 acetyl-CoA
1 FADH2
1 NADH and H+
1 fatty acyl-CoA shortened by 2 carbon atoms

30
Q

How is glycerol broken down?

A
  • activated to glycerol-3-phosphate by glycerol kinase

- made into dihydroxyacetone phosphate

31
Q

What are ketone bodies and where are they made?

A
  • made in liver mitochondria then move into blood and peripheral tissues
  • made from acetyl-CoA that is produced in beta oxidation
32
Q

What happens to acetyl-CoA normally?

A
  • made from fatty acid oxidation

- enters citrate cycle depending on around of oxaloacetate

33
Q

What happens to acetyl-CoA in starvation or diabetes?

A
  • no oxaloacetate as it is used in gluconeogenesis
  • fatty acids oxidised to provide energy
  • acetyl-CoA made into ketone bodies which are acidic
  • severe acidosis with CNS impairment with smell of acetone on breath
34
Q

What happens to amino acids that aren’t used to make protein?

A

they are degraded in the liver

stomach enzymes make them into peptides that can be absorbed into the blood

35
Q

How is ammonia formed in the body?

A

amino acid breakdown can make ammonia or ammonium ions which are toxic so must be removed

36
Q

How are ammonium ions removed from the body?

A

they are converted to urea in a three step process of transamination, deamination and the urea cycle

37
Q

What happens in each stage of the synthesis of urea?

A
  • Transamination: aminotransferases move the amino group to make glutamate, amino group is then transferred to pyruvate to give alanine or glutamine can be made which carry the nitrogen in the blood to the liver
  • Deamination in the liver: glutamate converted to free ammonium ion
  • Urea cycle: urea is synthesised using aspartic acid
38
Q

What happens to the waste fumigate from urea synthesis?

A

fumarate is an end-product in the cytosol which is the converted back to malate and to mitochondria

39
Q

What happens to remaining carbon skeletons after amino acid metabolism has occurred?

A
  • converted to metabolic intermediates and then can be converted to glucose or oxidised in the TCA cycle
40
Q

What are ketongenic and glucogenic amino acids used for in the body?

A
  • Ketogenic amino acids are made into acetyl-CoA to form ketone bodies or fatty acids
  • Glucogenic amino acids are made into pyruvate then to glucose
41
Q

Where does new synthesis of lipid occur?

A

liver, kidney, mammary glands, adipose tissue and in the brain and occurs when there is excess energy intake

42
Q

What happens when extra carbohydrate is taken in?

A
  • conversion to fatty acids and triglycerides
  • transportation in plasma bound to albumin
  • triglycerides in the liver are taken to adipose tissue for storage
43
Q

What is the main outline of the conversion of carbohydrates to fats?

A

Dietary starch → glucose → pyruvate → acetyl-CoA (made from beta oxidation also) → fatty acids → triglycerides

44
Q

Where does the conversion of acetyl-CoA to fatty acids occur?

A

cytoplasm of liver cells

45
Q

How does the acetyl-CoA for fatty acid synthesis get into the cytoplasm?

A

Acetyl-CoA is generated in the mitochondria by pyruvate dehydrogenase but it can’t leave so citrate (made in TCA cycle) transports the acetyl groups into the cytoplasm

46
Q

What is the precursor compound for the formation of fats and how is this made?

A
  • Acetyl-CoA is activated to malonyl-CoA by acetyl-CoA carboxylase (in liver and adipose tissue)
  • malonyl-CoA is the precursor form of newly formed fatty acids
  • (rate-limiting step for fatty acid synthesis)
47
Q

What enzyme makes fatty acids from malonyl-CoA?

A

fatty acid synthase catalyses the synthesis of long-chain fatty acids from malonyl-CoA, acetyl-CoA and NADPH

48
Q

How is the process of fat formation regulated?

A 
by up or down regulating the work of acetyl-CoA carboxylase
\+	Citrate
\+	Insulin
-	Palmitoyl CoA
-	AMP
-	Glucagon
-	Epinephrine
49
Q

How are triglycerides formed?

A
  • requires glycerol-3-phosphate which is produced by the liver from glycerol or by adipose tissue from glucose (when fed)
  • involves esterification

My Gastrointestinal (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions