Proteins

Question 1

Functions of proteins

Answer 1

1) structural components- e.g. muscle (actin, myosin), bone
2) membrane carriers and pores
3) enzymes (all)
4) antibodies (all)
5) hormones (many)

Question 2

Structural components

Answer 2

• form part of the body of an organism

* e.g. spider silk, collagen (tendons, ligaments), keratin (hair)

Question 3

Membrane carriers and pores

Answer 3

• signal proteins
• contractile proteins
• transport proteins
• storage proteins

Question 4

Describe signal proteins

Answer 4

Carry messages around the body

Question 5

Describe contractile proteins

Answer 5

Involved in movement

Question 6

Describe transport proteins

Answer 6

• e.g. haemoglobin

Question 7

Describe storage proteins

Answer 7

• e.g. albumen -> protein store which forms the whites of eggs

Question 8

Describe enzymes

Answer 8

• biological catalysts
• control biochemical reactions
• e.g. amylase (catalyses digestion of starch)
• e.g. ATPase (catalyses the breakdown and formation of ATP)

Question 9

Describe hormones

Answer 9

• e.g. insulin (controls glucose levels in blood)

Question 10

Describe antibodies

Answer 10

• fight infections

Question 11

How many naturally occurring amino acids are there?

Answer 11

20

Question 12

Describe the R-group of amino acids

Answer 12

• causes amino acids to be different
• determines their properties
• glycine -> single hydrogen atom
• can be non-polar and hydrophobic (e.g. leucine)
• can be polar and hydrophilic (e.g. cysteine, serine)

Question 13

Describe the amino group of an amino acid

Answer 13

• attaches by a covalent bond to the α-carbon

Question 14

Define hydrophilic

Answer 14

• can dissolve more readily in solutions within cells

Question 15

Describe buffers

Answer 15

• amphoteric
• carboxyl group -> causes acidic properties
• amino group -> causes basic properties

Question 16

Define zwitterions

Answer 16

Ions with both positive and negative charges caused by ionisation of the molecule at a specific pH

Question 17

Describe a buffer solution

Answer 17

• tends to resist changes in pH when an acid or base is added to it
• keep pH of Blood and other fluids at tolerable levels

Question 18

Describe the carboxyl group in buffers

Answer 18

Can donate a proton so the molecule becomes negatively charged when in an alkaline solution

Question 19

Define the amino group in buffers

Answer 19

Can take up a proton so the molecule becomes positively charged in acidic solutions