2.4 proteins

Question 1

what is a monomer of a protein?

Answer 1

amino acid

Question 2

draw an amino acid

Answer 2

see p. 155

Question 3

polypeptide

Answer 3

long chains of covalently bonded amino acids joined together on the ribosome

Question 4

how many amino acids are there?

Answer 4

20

Question 5

peptide bond

Answer 5

a covalent bond that joins amino acids, at the carboxyl group of one amino acid to the amino group of the other amino acid, with the release of a molecule of water.

Question 6

how can amino acids can be covalently joined together?

Answer 6

via condensation reaction, forming a dipeptide and water

Question 7

how can polypeptide chains be broken?

Answer 7

via hydrolysis reactions

Question 8

draw the formation of a peptide bond

Answer 8

see p. 155

Question 9

primary structure

Answer 9

• determines the way the chain will fold
• Different amino acid sequences will fold into different configurations due to the chemical properties of the variable side chains

Question 10

secondary structures (2 configurations)

Answer 10

• folding into repeat patterns (alpha-helix or beta-pleated sheet)
• By hydrogen bonds between amine and carboxyl groups

Question 11

what happens if there is no secondary structure?

Answer 11

the polypeptide chain will form a random coil

Question 12

tertiary structure

Answer 12

• Overall three-dimensional arrangement of a polypeptide
• Determined by interactions between variable side chains

Question 13

quaternary structure

Answer 13

found in proteins that consist of more than one polypeptide chain linked together OR if they include inorganic prosthetic groups as part of their structure

Question 14

An example of a protein with a quaternary structure

Answer 14

haemoglobin
- composed of four polypeptide chains (two alpha chains and two beta chains)
- It is also composed of iron-containing haeme groups (prosthetic groups responsible for binding oxygen)

Question 15

SHITS ME

Answer 15

structure, hormones, immunity, transport, sensation, movement, enzymes

Question 16

what is SHITS ME

Answer 16

acronym for protein functions

Question 17

collagen

Answer 17

A component of the connective tissue of animals (most abundant protein in mammals)

Question 18

spider silk (fibroin)

Answer 18

A fiber spun by spiders and used to make webs (by weight, is stronger than kevlar and steel)

Question 19

insulin

Answer 19

Protein produced by the pancreas and triggers a reduction in blood glucose levels. is a hormone.

Question 20

glucagon

Answer 20

Protein produced by the pancreas that triggers an increase in blood glucose levels

Question 21

immunoglobulins

Answer 21

Antibodies produced by plasma cells that are capable of targeting specific antigens

Question 22

haemoglobin

Answer 22

A protein found in red blood cells that is responsible for the transport of oxygen

Question 23

cytochrome

Answer 23

A group of proteins located in the mitochondria and involved in the electron transport chain

Question 24

rhodopsin

Answer 24

A pigment in the photoreceptor cells of the retina that is responsible for the detection of light

Question 25

actin

Answer 25

Thin filaments involved in the contraction of muscle fibres

Question 26

myosin

Answer 26

Thick filaments involved in the contraction of muscle fibres

Question 27

rubisco

Answer 27

(ribulose carboxylase) the enzyme that catalyses the first step of photosynthesis (probably the most abundant protein on Earth). involved in carbon fixation during photosynthesis.

Question 28

proteome

Answer 28

The totality of all proteins that are expressed within a cell, tissue or organism at a certain time

Question 29

why are proteome unique?

Answer 29

protein expression patterns are influenced by a unique genome

Question 30

denaturation

Answer 30

structural change in a protein that results in the loss (usually permanent) of its biological properties

Question 31

conditions that cause denaturation

Answer 31

temperature and pH

Question 32

how does temperature cause denaturation

Answer 32

High levels of thermal energy may disrupt the hydrogen bonds that hold the protein together As these bonds are broken, the protein will begin to unfold and lose its capacity to function as intended Temperatures at which proteins denature may vary, but most human proteins function optimally at body temperature (~37ºC)

Question 33

how does pH cause denaturation

Answer 33

alters protein charge ➡ changes solubility & shape

Question 34

albumin

Answer 34

the main protein of human plasma. Its main function is to regulate the osmotic pressure of blood.

Question 35

amino group

Answer 35

NH2

Question 36

carboxylic group

Answer 36

COOH

Question 37

gene

Answer 37

a heritable section of DNA that controls a specific trait.

Question 38

ribosome

Answer 38

cell organelle functioning as the site of protein synthesis.