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Cells and tissues > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Name the two carbohydrate chains that make up starch

A

Amylose and Amylopectin

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2
Q

Why can cellulose not be browk down by humans?

A

They dont have the enzyme cellulase to break it down

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3
Q

Give 2 functions of chitin

A
  • Cells walls of fungi

- Outer skeletons of insects

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4
Q

Where is N-linked glycosylation added and modified?

A

Added in the endoplasmic reticulum and modified in the golgi complex

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5
Q

What is Aggrecan an example of?

A

A proteoglycan with extensive O-linked glycosylation on the core protein (link protein). Forms a bottlebrush shape.

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6
Q

What is the main enzyme involved in glycogen breakdown?

A

Glycogen phosphorylase

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7
Q

Why is an enlarged liver caused by a type 1 glycogen storage disease?

A

Excessive glycogen storage

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8
Q

Which hormone is released in response to an increase in blood glucose levels?

A

Insulin

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9
Q

Compare the 3 types of diabetes

A

Type 1 = very low insulin and no response to glucose loading
Type 2 = normal/high insulin and no response to glucose loading
Type 3 = normal insulin, delayed response to glucose loading

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10
Q

What is the result of hyperinsulinism?

A

Persistent hypoglycaemia

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11
Q

Which condition in sheep is characterised by hypoglycaemia?

A

Pregnancy toxaemia

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12
Q

Glycogen is primary stored in and used by which type of muscle fibres?

A

white glycolytic skeletal muscle fibres = fast fibres

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13
Q

How many enzymatic reactions are needed to convert glucose to pyruvate?

A

10

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14
Q

What types of tube are used for glucose collection and why?

A

Fluoride

- stop red blood cells from metabolising glucose other levels will be falsely reduced

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15
Q

Give 3 uses of ATP

A
  • Muscle contraction
  • Active transport
  • Biosynthesis
  • Cell signalling
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16
Q

What is the role of NAD+ and FAD as electron carriers?

A

Receive a pair of high energy electrons in chemical reactions

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17
Q

What is the role of acetyl-coenzyme A in biosynthesis?

A

Used to add 2 carbon units

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18
Q

What is gluconeogensis?

A

Biosynthesis of glucose in the liver (some in the kidney)

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19
Q

One molecule of NADH results in how many molecules of ATP in the ETC?

A

2.5

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20
Q

What are the 4 main processes in the nitrogen cycle?

A
  • Nitrogen fixation
  • Ammonification
  • Nitrification
  • Denitrification
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21
Q

Where does symbiotic nitrogen fixation occur?

A

In plants that harbour nitrogen fixing bacteria (Rhizobium) within their tissues

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22
Q

What is mutualism?

A

A symbiotic relationship in which both partners benefit

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23
Q

What are nitrates and nitrites taken up by plants reduced to?

A

Ammonia

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24
Q

What is the biological molecule that transmits signals across synapses and is the main excitatory neurotransmitter in the CNS?

A

Glutamate

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25
Q

What is transamination?

A

Chemical reaction between an amino acid and a keto acid, where groups are exchanged so the amino acid becomes a keto acid and the keto acid becomes an amino acid

26
Q

Where is urea produced?

A

Liver by transamination and deamination reactions

27
Q

Where is urea excreted?

A

In the kidneys, saliva and sweat

28
Q

How is nitrogen excreted in aquatic animals?

A

Directly as ammonium as it is rapidly diluted - ammonotelic

29
Q

How do birds and non-aquatic reptiles excrete nitrogen?

A

Uricotelic - as uric acid

30
Q

Why are there no essential amino acids required by a ruminant?

A

Microbes in the rumen can synthesise all 20

31
Q

What are the functions of protein?

A
  1. structural - collagen, keratin
  2. movement - actin and myosin
  3. immune system - antibodies
  4. endocrine - hormone and receptors
  5. transport - haemoglobin
  6. enzymes
32
Q

Describe a protein’s primary structure

A

Chains of amino acids are joined by peptide bonds between COO groups and NH3 groups

33
Q

Describe the quaternary structure of a protein

A

Interactions between different protein subunits held together by side chain interactions

34
Q

Compare globular and fibrous proteins, giving examples

A 
Globular = folded into compact structures, soluble, e.g. enzymes, antibodies
Fibrous = multiple strands held by strong bonding, insoluble, e.g. collagen, keratin
35
Q

What are prions?

A

Infectious proteins that cause a host’s normal proteins to switch to a conformation that readily aggregates, causing cell death

36
Q

What is the main role of enzymes?

A

Increase the rate of a chemical reaction without being changed at the end - catalysts

37
Q

Where on an enzyme performs the catalytic reaction?

A

Enzymes active site

38
Q

Which weak forces are involved in binding of substrates to amino acid side chains?

A
  • electrostatic attraction
  • hydrogen bonds
  • Van der Waals forces
  • hydrophobic interactions
39
Q

What is isosteric substrate binding?

A

Rate of reaction increases with substrate concentration until enzyme is saturated

40
Q

What is allosteric substrate binding?

A

Substrate induces a conformational change in the enzyme that increases activity - S shaped saturation curve

41
Q

What is the purpose of feedback inhibition?

A

Prevents the build up of intermediates and unnecessary use of energy

42
Q

What is a competitive inhibitor?

A

Binds to the enzymes active site

43
Q

What is a non-competitive inhibitor?

A

Bind to the enzymes allosteric site irrespective of whether a substrate is bound

44
Q

What is an uncompetitive inhibitor?

A

Bind to the enzyme substrate complex

45
Q

What 5 factors affect enzyme activity?

A
  1. substrate conc
  2. temperature
  3. pH
  4. post-translational modification
  5. coenzymes and cofactors
46
Q

How does temperature affect enzyme activity?

A

Proportion of molecules with energy sufficient to overcome the activation energy increases

47
Q

How does pH affect enzyme activity?

A

All enzymes have an optimum. small deviations lead to decreased activity, can lead to denaturation of the enzyme

48
Q

What do many enzymes require to function?

A

Cofactors - small non-protein units

49
Q

What are isoenzymes?

A

Different forms of an enzyme which catalyse the same reaction

50
Q

Name the unsaturated fatty acid present in phospholipids

A

Arachidonic acid

51
Q

What are the roles of lipids?

A
  • Cell membranes
  • Fuel
  • Heat insulation
  • Signalling molecules
  • Vitaminas
  • Nervous system
52
Q

Breifly describe lipid digestion

A
  • Bile salts emulsify fat droplets
  • Absorbed by intestinal epithelia
  • Fats are reassembled and added to chylomicrons
  • Chylomicrons secreted to lymph and transported to the liver
53
Q

How is fat storage altered by insulin?

A

Insulin promotes fat storage

54
Q

What is hydrolysis?

A

Cleavage of chemical bonds by the addition of water

55
Q

Name the catabolic process in which fatty acid molecules are broken down in the mitochondria?

A

B-Oxidation

56
Q

What is generates from B-oxidation?

A

Acetyl-CoA

57
Q

Where do the products of B-oxidation enter?

A

The TCA cycle

58
Q

What is acetyl-CoA converted to if it doesn’t enter the TCA cycle?

A

Acetone, Acetoacetate and D-3-hydroxybutyrate

59
Q

What is acetone used for?

A

It is exhaled as an emergency fuel source

60
Q

How does a high level of ketone bodies affect the blood?

A

Makes it more acidic causing metabolic acidosis as pH buffer systems become exhausted

Cells and tissues (3 decks)

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