Unit 1 - proteins

Question 1

Proteins

Answer 1

• most diverse mol
• 50% of dry mass of cells
• protein is a polymer w many subunits folded into a three-dimensional structure

Question 2

Function of Protein (7)

Answer 2

Support
- collagen/elastin
Transport
- hemoglobin
Communication
-Hormones (insulin)
Receptors
- cell membrane proteins
Movement
- actin / myosin
Defense
-antibodies
Reaction Catalysis
- enzymes

Question 3

Amino Acids

Answer 3

all proteins r polymers made from amino acids
structure: central carbon bonded to an amino group (NH2), carboxyl group (COOH) and a hydrogen atom.
-diff lies in the R group

Question 4

How Many Amino Acids r there

Answer 4

20 different amino acids
- 9 amino acids essential to consume in r diets
-11 amino acids r non essential our cells build

Question 5

Amino Acids determine what

Answer 5

a proteins shape, size, and function

Question 6

Acidic amino acids

Answer 6

posses a carboxyl group on their R-group

Question 7

Basic amino acids

Answer 7

possess an amino group on their R-group

Question 8

Proteins bonds

Answer 8

holds AA together through peptide bonds
( a form of dehydration synthesis rxn)
- occurs between amino group + carboxyl group

each polypeptide is code for one gene in DNA

Question 9

Peptides

Answer 9

• covalent bonds hold aa together through peptide bonds
• a polypeptide is a peptide greater than 50 aa in length

Question 10

Protein shape = 4 structures

Answer 10

• primary
• secondary
• teriatry
• quaternary

Question 11

1) primary structure

Answer 11

sequence of amino acids in a polypeptide chain
- altering one amino acid can alter the 3D shape or function making it a non -functional protein
ie. sickle cell anemia

Question 12

Sickle cell anemia

Answer 12

when one single amino acid substitution at the 6 position (6th AA)
go from GLU to VAL

Question 13

2) secondary structure

Answer 13

as the PPC grows, it coils and folds at various locations along its length. this results in H-bonding between diff parts of same AA.
ie. B-pleated sheets vs a-helix

Question 14

a-helix

Answer 14

H-bonds form between the partially negative O of the carboxyl group in one peptide bond and the partially positive H of the amino group four peptide bonds away = chain to coil making an a-helix.

Question 15

b-pleated sheet

Answer 15

a b-pleated sheet forms when hydrogen bonds form between portions of a polypeptide chain that lie parallel to one another (strength of silk)

Question 16

3) tertiary structure

Answer 16

OVERALL 3D SHAPE of polypeptide (how it folds)
due to bonding interactions of R group

the force of attraction and repulsion between pp and its environment cause folding.

Question 17

3) tertiary structure r group inportance

w water

Answer 17

aa w a polar R group r attracted to water while non-polar R groups r not. this cause non-polar R groups to fold into the interior of the structure.

Question 18

3) tertiary structure types of bonds

Answer 18

1) hydrogen bond
2) ionic interactions
3) hydrophobic interactions
4)disulfide bridge

Question 19

hydrogen bonds

Answer 19

between polar R groups (POLAR)

Question 20

ionic interactions

Answer 20

between charged (acidic or basic) R groups
ie. salt bridge

Question 21

hydrophobic interactions

Answer 21

between non-polar R groups

Question 22

disulfide bridge

Answer 22

bond that is formed when the -SH groups of 2 cysteine amino acids line up and react to form an S-S covalent bond
(strong bond that can stabilize shape)

Question 23

4) quaternary structure

Answer 23

clustering of two or more 3) polypeptides
- functional proteins
ie. hemoglobin is composed of 4 polypeptides, each w more than 140 aa.

Question 24

protein prosthetic groups

Answer 24

many proteins require non-protein components called prosthetic groups
-often enzymes require these groups that contain metal ions in order to function

Question 25

protein folding

Answer 25

• is spontaneous
• aided by chaperone protein

Question 26

prtoen denaturation

Answer 26

if a protein’s 3D shape is changed due to the environment, ph, temperature etc. and bonds r broken the protein is denatured and can no longer carry out its intended biological function. this process is often irreversible.

Question 27

ex of denaturation

Answer 27

cooking and egg as hydrogen bonds r hydrophobic interactions between non-polar R groups

Question 28

level or protein structure in each
a) beta-pleated sheets
b) order of aa in protein
c) a protein w 2 or more peptide chains
d) shape of globular protein
e) disulfide bonds between R group

Answer 28

a) 2
b) 1
c) 4
d) 3
e) 3