3.4 Proteins

Question 1

What are the 5 functions of proteins?

Answer 1

Enzymes that catalyze chemical reactions
provide structural support
regulate the passage of substances across the cell membrane
protect against disease
coordinate cell signalling pathways

Question 2

What are enzymes?

Answer 2

are complex proteins and aid in digestion; enzyme specific to its substrate; helps in breakdown

Question 3

What is a substrate?

Answer 3

a reactant that binds to an enzyme

Question 4

Catabolic enzymes?

Answer 4

enzymes that break down their substrates

Question 5

Anabolic enzymes

Answer 5

enzymes that build more complex molecules from their substrates

Question 6

Catalytic enzymes

Answer 6

enzymes that affect the rate of reaction

Question 7

Salivary amylase

Answer 7

hydrolyses its substrate amylose (a component of starch)

Question 8

What are hormones?

Answer 8

chemical signalling molecules- proteins or steroids secreted by endocrine cells that control or regular specific physiological processes- growth, repro, develop, metabolism

Question 9

What is insulin?

Answer 9

protein hormone- regulate blood glucose level

Question 10

2 different protein shapes & examples

Answer 10

globular- hemoglobin
fibrous- collagen

Question 11

What is the protein function determined by?

Answer 11

Shape which is maintained by interactions and bonds

Question 12

WHat is a amino acid molecule composed of?

Answer 12

amino group (NH2), alpha carbon, R group (side chain), and a carboxyl group

Question 13

Where do you get amino acids from?

Answer 13

diet

Question 14

What does the R group determine?

Answer 14

nature of an amino acid ex. hydrophillic

Question 15

What are essential amino acids? Do?

Answer 15

necessary a.a. in diet; construction of proteins

Question 16

What are the 3 essential amino acids?

Answer 16

isoleucine, leucine, cysteine

Question 17

Peptide bond

Answer 17

dehydration reaction; covalent bond- amino acids
product: peptides- polypeptides

Question 18

N terminal (amino terminal)

Answer 18

NH2 group at the end of a polypeptide

Question 19

C or carboxyl terminal:

Answer 19

a free carboxyl group

Question 20

protein

Answer 20

polypetide(s)

Question 21

primary structure

Answer 21

amino acid chain- peptide bonds

Question 22

sickle cell anemia mutation:

Answer 22

single a.a. substitution - clogs blood vessels

Question 23

secondary structure

Answer 23

alpha helix & beta pleated sheet –> hydrogen bonds

Question 24

alpha helix

Answer 24

hydrogen bonds between oxygen in carbonyl group in one a.a & other a.a.

Question 25

beta pleated

Answer 25

hydrogen bonds w/ atoms on the backbone
* found in fibrous and globular proteins

Question 26

Tertiary structure

Answer 26

interactions between R groups; ionic bonds may form
R group nature: hydrophilic - outside
hydrophobic- inside

Question 27

Quaternary structure

Answer 27

interactions between subunits: several polypeptides

Question 28

Denaturation

Answer 28

changes in temperature, changes in pH, or exposure to chemicals, the protein structure may change, losing its shape without losing its primary sequence; can be reversible or irreversible

Question 29

chaperones

Answer 29

assist proteins in protein folding; prevent aggregation of polypeptides & disassociated when protein is folded