Module 2 - Biochemistry

Question 1

What are the 3 different ways a sugar can be classified?

Answer 1

1. Position if carbonyl group - aldoses or ketoses
2. Length of carbon chain
3. Spatial arrangement - linear or cyclic

Question 2

What is the difference between starch and cellulose? Which is easier to break down?

Answer 2

Both are storage polysaccharides
alpha 1-4 bonds =starch, beta 1-4 = cellulose
Cellulose is easier to break down

Question 3

How can the rate of a reaction be measured?

Answer 3

Kcat = molecules broken down / second

Question 4

Describe the 4 levels of protein structure.

Answer 4

1. Primary - amino acid sequence
2. Secondary - alpha helices and beta sheets
3. Tertiary - 3D shape of protein - due to interactions between R groups of amino acids
4. Quarternary Structure - assembly of polypeptides to form a complete protein

Question 5

What is the function and structure of myoglobin?

Answer 5

Stores oxygen in muscle cells

Single polypeptide monomer

Question 6

What is the structure and function of hemoglobin?

Answer 6

Transports oxygen through veins and arteries

It is a tetramer with 4 subunits

Question 7

What gives myoglobin and hemoglobin the ability to bind to oxygen?

Answer 7

The heme group - a molecule with an iron atom at its centre

Question 8

What are the similarities and differences of myoglobin and hemoglobin?

Answer 8

They are homologous, meaning they have a similar primary, secondary and tertiary structure - this also means they have similar functions

Due to its tetrahedral shape, hemoglobin can bind to 4 oxygens, whereas myoglobin can only bind to one

Question 9

What is sickle cell anemia?

Answer 9

There is a single amino acid mutation resulting in a different protein formation. The red blood cell is sickle shaped which affects its ability to carry oxygen.

Question 10

What role does insulin play?

Answer 10

Insulin is the key that unlocks the glucose channel

Question 11

What is a denatured protein?

Answer 11

Inactive protein - can be caused by alterations in pH, temperature, etc
- unravelled protein

Question 12

How many different types of collagen are there? What are the differences between them?

Answer 12

1. Most common - found in skin, tendon, bones and organs
2. Cartilage
3. Connective tissue around the liver

Question 13

What is collagen?

Answer 13

Most abundant protein in the body - it is insoluble

Procollagen = inactive form 
Tropocollagen = active

Question 14

Describe the shape and structure of collagen.

Answer 14

Elongated shape, held tightly together and is very crowded with atoms

Question 15

What is osteogenesis imperfecta?

Answer 15

Brittle bone disease
Glycine side changes of collagen are replaced with cysteine - cysteine is too large for the dense helical collagen, and the helical arrangement becomes unstable
Results in more fragile bones that break very easily

Question 16

What are vitamins and why are they so important?

Answer 16

Vitamins are organic compounds that are vital nutrients for our body. They cannot be synthesised by the body, and therefore must come from our diet
Example: vitamin c strengthens collagen and without it, the collagen is much weaker

Question 17

Name 3 different categories of lipids.

Answer 17

1. Phospholipids
2. Fats
3. Steroids

Question 18

What are fats made from?

Answer 18

Glycerol + fatty acids

Glycerol = a 3 carbon alcohol with a hydroxyl group on each carbon

Fatty acids = carboxyl group attached to a long carbon skeleton

Question 19

What is the bond that joins glycerol to fatty acids?

Answer 19

Ester link

Question 20

Describe the structure and function of a phospholipid, and why they self-assemble into bilayers in water.

Answer 20

Phospholipids are composed of a hydrophobic head (phosphate group and glycerol) and a hydrophilic tail (2 fatty acids)
When placed into water, they assemble into a bilayer with the heads facing out and tails facing in. This allows the polar heads to interact with the water.

Question 21

List 3 properties of steroids

Answer 21

• mostly non-polar
• hydrophobic
• 4 rings in their structure

Question 22

What are some functions of steroids?

Answer 22

• signalling
• cell membrane
• hormones
• vitamin D
• anabolic steroids (natural or synthetic - can stimulate muscle growth and other functions)

Question 23

Describe the structure of a nucleotide.

Answer 23

Phosphate group + nitrogenous base + pentose sugar

Question 24

Name either the 2 purines or the 3 pyrimadines

Answer 24

Pyrimidines = cystosine, thymine and uracil

Purines = adenine and guanine

Question 25

Name the 3 stages of cellular respiration

Answer 25

1. Glycolysis
2. Citric acid cycle
3. Oxidative phosphorylation

Question 26

What happens in glycolysis?

Answer 26

Converts glucose into 2 pyruvate molecules

Question 27

What happens in the citric acid cycle?

Answer 27

Pyruvate is converted to acetyl CoA

The citric acid cycle oxidises 2 carbon atoms of acetyl CoA and produces NADH and FADH2

Question 28

Oxidative phosphorylation

Answer 28

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