2.5- Proteins

Question 1

What are proteins made of

Answer 1

recurring monomers called amino acids

Question 2

Draw an amino acid

Answer 2

H R O
\ | //
N — C— C
/ | \
H H O — H

Question 3

Three types of amino acids

Answer 3

essential- cannot be synthesised by body, must be obtained from food

non-essential- synthesised from other amino acids in the body, not required in diet

conditional- non essential, but production might need to be supplemented during particular periods (eg, pregnancy, illness)

Question 4

What is protein deficiency malnutrition and what is it caused by

Answer 4

A shortage of 1+ essential amino acids in the diet prevents production of specific proteins

Question 5

What links amino acids into polupeptides

Answer 5

covalent peptide bonds formed in the ribosomes

Question 6

Draw a dipeptide

Question 7

Four levels of structure in proteins

Answer 7

primary
secondary
tertiary
quaternary

Question 7

Primary structure of a protein

Answer 7

amino acid chain held togehter by peptide bonds

Question 8

Secondary structure

Answer 8

localised repeating structures (alpha helices and beta-pleated sheets) formed by hydrogen bonds

Question 9

Tertiary structure

Answer 9

various bonds between R groups fold the protein into a 3D shape

Question 10

Quaternary structure

Answer 10

multiple polypeptides joined together

Question 11

PROTEIN FUNCTIONS, name examples

Answer 11

Transport- protein channels, haemoglobin

Question 12

What determines a protein’s function?

Answer 12

the way a protein folds, therefore change of 3D structure can affect activity

Question 13

What is denaturation of proteins caused by

Answer 13

high temperatures
extremes of pH

Question 14

How does temperature cause denaturation

Answer 14

high levels of thermal energy disrupt the hydrogen bonds

bonds broken causes the protein to unfold and lose it’s ability

Question 15

How does extreme pHs cause denaturation

Answer 15

amino acids are neutral molecules having both negatively (COO–) and positively (NH3+) charged regions

changing the pH alters the charge of the protein which alters the protein solubility and overall shape

Question 16

PROTEIN FUNCTIONS

Answer 16

Transport – eg. protein channels, haemoglobin
Hormones – eg. insulin, glucagon

Enzymes – eg. Rubisco, amylase

Movement – eg. actin, myosin

Immunity – eg. antibodies

Structure – eg. collagen, spider silk

Sensations – eg. rhodopsin, receptors