Biochemistry

Question 1

What are the functions of enzymes, are they anabolic or catabolic? How do they lower activation energy?

Answer 1

Biological catalysts, diagnostic tests
Both
Bring molecules closer together, reduce repulsion

Question 2

What do active sites do? What are multi-enzyme complexes?

Answer 2

Bind with substrate, make/break chemical bonds

Aggregation of several co/enzymes

Question 3

What are isoteric enzymes?

Answer 3

Enzymes which rate of reaction increases with substrate concentration (until saturation)

Question 4

What are allosteric enzymes?

Answer 4

Enzymes which bind with an allosteric site, induces a change in the enzyme and allows easier binding (sigmoidal shape curve)

Question 5

What is cooperativity?

Answer 5

The binding of an enzyme which changes the structure of the active site, which triggers the same in other active sites

Question 6

What are the 3 types of inhibitors? Where do they bind to?

Answer 6

Competitive - active site
Non-competitive/allosteric - binds to allosteric site
Uncompetitive - binds to ES complex

Question 7

What factors affect enzyme activity?

Answer 7

Temperature, concentration, pH, post-translational modification, coenzymes, cofactors

Question 8

What are post-translation modifications?

Answer 8

Changes in the structure of an enzyme

Can be proteolytic activation (activates other enzymes) or phosphorylation

Question 9

What are proteinase?

Answer 9

Enzymes which cleave proteins, can cause proteolytic activations

Question 10

What are isoenzymes?

Answer 10

Different forms of an enzyme which catalyse the same reaction

Question 11

What are the 4 stages of the nitrogen cycle? What happens in each stage?

Answer 11

Nitrogen fixation - nitrogen fixing bacteria convert N gas
Ammonification - conversion to ammonia by saprobionts
Nitrification - conversion to nitrates by nitrifying bacteria
Denitrification - conversion to gas in anaerobic conditions by bacteria

Question 12

How many amino acids are there?

Answer 12

21

1 is rare

Question 13

How do animals obtain essential and non-essential amino acids?

Answer 13

Essential - diet

Non-essential - biosynthesis

Question 14

What are the functions of amino acids?

Answer 14

Build protein
Energy
Neurotransmitters

Question 15

Amino acids can be ketogenic or glucogenic. What do these 2 terms mean? What happens after this?

Answer 15

Converted to ketones or glucose
Broken down to intermediates of acetyl CoA
Enter Krebs cycle

Question 16

What are ureotelic animals?

Answer 16

Animals which produce urea

Question 17

Where is urea excreted?

Answer 17

Kidneys, saliva, sweat

GI in ruminants - used to synthesise AAs as no protein in diet

Question 18

What are urioctelic animals? Give examples?

Answer 18

Animals which excrete uric acid

Birds/reptiles

Question 19

What are ammonotelic animals? Give examples

Answer 19

Animals which can directly excrete ammonia
Aquatic animals (cartilaginous fish are both ammonetlic and ureotelic)

Question 20

What are the stages of protein synthesis?

Answer 20

DNA transcribed to mRNA, then translated to a protein

Question 21

What are the functions of proteins?

Answer 21

Structural - collagen, keratin, fibroin (silk/webs)
Movement - actin/myosin
Immune system - antibodies
Endocrine system - hormones/receptprs
Transport - haemoglobin, transferrin (glycoproteins in blood plasma)
Biocatalysts - enzymes

Question 22

Zwitterions are which type of isomer? What 2 forms can they be in?

Answer 22

Enantiomer

D or L - (L only in the body)

Question 23

What are the 4 protein structures?

Answer 23

1 - sequence of AAs held by peptide bonds
2 - H bonding between peptide bonds - alpha helix and beta pleated sheets
3 - H, disulfide, ionic bonds. 3D structures, metal ions between chains. Hydrophobic interactions
4 - interactions between subunits/polypeptide chains

Question 24

Proteins are mainly globular but can be fibrous or membranous. Give examples of each

Answer 24

Globular - enzymes/antibodies. Soluble, fold into compact molecules
Fibrous - multiple strands held by bonds, e.g. fibroin. 2 rows = protofilaments, dimerise to protofibrils, to microfibrils, then macrofibri;s
Membranous - channel/receptor proteins

Question 25

What is pregnancy toxaemia in sheep? What is a risk factor?

Answer 25

Blood poisoning from hypoglycaemia - high metabolic demand in last trimester of pregnancy Excessive fat

Question 26

How do ruminants obtain glucose?

Answer 26

Gluconeogenesis

Question 27

Which carbohydrates are monosaccharides? Which are disaccharides?

Answer 27

Glucose, galactose, fructose | Maltose, lactose, sucrose

Question 28

Name 4 polysaccharides

Answer 28

Starch - amylopectin (branched) or amylose (coiled) chains of glucose in plants Glycogen - like amylopectin, but in animals Cellulose - straight chains of B glucose in plants Chitin - chains of N-amide in fungi walls

Question 29

Which organ primarily controls blood glucose levels?

Answer 29

Liver

Question 30

Some glycogen storage disease are Van Gierkes, Pompe’s, Cori’s. What do these result in?

Answer 30

Hypoglycaemia | Hepatomegaly (liver enlargement due to glycogen)

Question 31

Which hormones do islets of Langerhans secrete?

Answer 31

Insulin - lower blood glucose. Promotes fat storage, B islets. Work by second messenger Glucagon - increase blood glucose, a islets.

Question 32

What are the 3 types of diabetes?

Answer 32

Type 1- autoimmune, destroy islets. Symptoms emerge when most cells destroyed Type 2 - obesity. Low insulin levels/ unresponsive. Type 3 - Alzheimer’s disease due to insulin resistance in the brain

Question 33

What is hyperinsulinism? Why may this occur?

Answer 33

Abnormally high levels of insulin, results in hypoglycaemia. Pancreatic tumours

Question 34

Why do many neonates get hypoglycaemia at birth? What induces enzymes which synthesise glucose?

Answer 34

Inadequate synthesis Cold Feeding

Question 35

What are the roles of lipids?

Answer 35

``` phospholipid bilayer Fuel Insulation Signalling molecules Vit a/d/e/k Nervous system ```

Question 36

What is arachidonic acid?

Answer 36

Fatty acid present in phospholipid bilayer

Question 37

What is cholesterol?

Answer 37

Precursor for lipid soluble hormones

Question 38

Describe the digestion and transport of lipids

Answer 38

``` Bile salts emulsify fats Degraded by intestinal lipases Taken up by intestinal mucosa FAs enter cells Chylomicrons enter blood stream ```

Question 39

What are chylomicrons?

Answer 39

Fat droplets that have been digested

Question 40

Where are lipids stored and released? What is the purpose of brown fat?

Answer 40

Adipose tissue | Thermogenesis

Question 41

Which multi enzyme complex is responsible for the biosynthesis of fatty acids?

Answer 41

Fatty acid synthase

Question 42

what is beta oxidation?

Answer 42

The breakdown of fatty acids to acetyl coA, which then enters the Krebs cycle.

Question 43

Where does beta oxidation take place? Is it anabolic or catabolic?

Answer 43

Mitochondria | Catabolic

Question 44

What is ketosis? What does it lead to? When might it be present?

Answer 44

Abnormally high levels of ketone bodies in the blood Metabolic acidosis Starvation, pregnancy toxaemia, acetonemia

Question 45

How many ATP are used and gained in glycolysis?

Answer 45

2 used | 4 gained

Question 46

How are monosaccharides transported?

Answer 46

Na/Glucose transporters in intestinal epithelial cells

Question 47

In aerobic glycolysis, what is pyruvate converted to?

Answer 47

Acetyl coenzyme A

Question 48

In anaerobic glycolysis, what is pyruvate converted to? What happens to this after?

Answer 48

Lactate Leaves muscles and travels to liver via blood Converts lactate to glucose by gluconeogenesis

Question 49

What is gluconeogenesis?

Answer 49

The synthesis of glucose from non-carbohydrates e.g. lactate, glucogenic AAs (Ruminants, starvation, intense exercise)

Question 50

What are the 2 types of muscles? What are their properties?

Answer 50

1. Slow twitch, red, high myoglobin, little glycogen, oxidative 2. Fast twitch, white, low myoglobin, high glycogen, glycolytic