BS120: Lsn 2 & 3 in amino acids & protein chemistry

Question 1

What are the 3 ways proteins can be classified?

Answer 1

based on:
1. function
2. shape of protein molecule
3. composition & solubility

Question 2

What are the 8 types of protein based on function?

Answer 2

1. Storage proteins
2. Transport proteins
3. Contractile proteins
4. Catalytic proteins (enzymes)
5. Protective/ defensive proteins
6. Structural proteins
7. Proteins that act as buffers
8. Regulatory proteins

Question 3

What are storage proteins?

w examples

Answer 3

proteins that store metals and amino acids
examples include:
1. Ferritin [stores iron]
2. Ovalbumin [stores amino acids in egg]
3. Casein [stores amino acids in milk]

Question 4

What are transport proteins?

Answer 4

involved in binding and carrying metals & substances.
examples include:
1. Serum albumin [calcium, fatty acids, hormones, & many drugs]
2. Transferrin [transports iron, Fe]
3. Ceruloplasmin [transports copper, Cu]
4. Hemoglobin [transports O2 from lungs to tissue and CO2 back to the lungs]

Question 5

What are catalytic proteins? (enzymes)

Answer 5

involved in catalyzing biochemical reactions.
examples include:
1. DNA polymerase
2. Amylase
3. Pepsin
4. Lipase

Question 6

What are structural proteins?

Answer 6

involved in providing structural support to cells & tissue.
examples include:
1. Collagen
2. Keratine

Question 7

What is the most abundant protein in mammals?

Answer 7

Collagen

Question 8

Where is keratine found?

Answer 8

it is a major component in nails, hair, & outer skin layer

Question 9

What are contractile proteins?

Answer 9

proteins that aid in Muscle Movement.
examples include:
1. Actin
2. Myosin

Question 10

What shape is actin and what are other proteins that share that shape?

Answer 10

It is fibrous protein, likefibrin, myosin, & keratine + collagen

Question 11

What are regulatory proteins?

Answer 11

2 Types of regulatory proteins:
1. Transcription factors
2. Hormones

Question 12

What are transcription factors?

Answer 12

proteins that are involved in regulating gene expression. (no examples listed)

Question 13

What are hormones?

Answer 13

regulatory proteins that are involved in regulating metabolic processes.
examples include:
1. insulin
2. glucose
3. growth hormone

Question 14

What are defensive/protective protein?

Answer 14

proteins that are involved in the immune response.
examples include:
1. Cytokines
2. Immunoglobins/antibodies
3. Clotting factors

Question 15

Do all proteins act as buffers? Where & how do they act as buffers?

Answer 15

Almost all proteins can act as buffers due to the ionizable groups present within their amino acid composition. This buffering capacity is fundamental in maintaing the acid-base balance of the body.
Where: in blood & tissues

Question 16

Which are the 2 most important proteins for buffering in the body?

Answer 16

1. Hemoglobin
2. plasma proteins, ex. albumin

Question 17

What are the types of protein based on shape?

Answer 17

1. Globular proteins
2. Fibrous proteins

Question 18

What are the properties of globular protein?

Answer 18

1. Compact & dense
2. Roughly spherical shape
3. Water soluble
4. Digestible
5. Physiological/ functional roles
6. Tertiary structure folding

Question 19

What are the properties of fibrous proteins?

Answer 19

1. Elongated fibres
2. Long polypeptide chains
3. Water insoluble
4. Limited no. of AAs with highly repetitive sequence
5. Strong
6. Structural roles
7. Secondary structures, with litte tertiary structure

Question 20

What makes globular protein water soluble & fibrous protein water insoluble?

Answer 20

• In globular protein, the hydrophilic AA residues are on the outside while the hydrophobic AA residues face the inside. this orientation enables globular proteins to be soluble in water.
• In fibrous protein, there is simply a large number of hydrophobic R groups, making them insoluble in water.

Question 21

What enables enzymes to catalyze specific rxns?

Answer 21

Being globular, the shape of the protein is rendered from the unique folding of it due to interactions between the R groups. These specific shapes are what allow enzymes to catalyse specific reactions.

Question 22

What does the shape of immunoglobins due to the folding caused by the interaction between the R groups cause?

Answer 22

They allow immunoglobins to respond to specific antigens

Question 23

What bond can be found in quaternary structures?

Answer 23

Disulfide bonds; they can occur between polypeptide chains

Question 24

What does the highly repetitive sequence in fibrous proteins cause?

Answer 24

It makes the protein very organized structures that are strong.
- this makes them well-suited for structural roles.

Question 24

What makes fibrous proteins suited for structural roles?

Answer 24

1. insolubility property 2. strong & very organized structures

Question 25

What is another name for fibrous proteins?

Answer 25

AKA scleroproteins

Question 26

What gives scleroproteins their distinct structural & functional characteristics?

Answer 26

Due to elongated & filamentous forms.

Question 27

What are the types of protein based on composition & solubility?

Answer 27

1. Simple Proteins 2. Conjugated Proteins 3. Derived Proteins

Question 28

What are the types of simple proteins?

Answer 28

1. Albumins 2. Histones 3. Protamines 4. Globulins 5. Glutelins 6. Scleroproteins

Question 29

What are simple proteins?

Answer 29

proteins composed of only AA residues linked by peptide bonds.

Question 30

What do these proteins yield?

Answer 30

They only yield amino acids upon their hydrolysis

Question 31

Properties of albumins include:

Answer 31

- soluble in water - coagulate by heat - precipitate by high salt concentrations

Question 32

Examples of albumins:

Answer 32

1. Serum albumin 2. Ovalbumin (egg whites)

Question 33

Properties of Histones:

Answer 33

1. basic protein 2. soluble in water 2. insoluble in dilute ammonium hydroxide 3. do not coagulate with heat

Question 34

Where are histones found?

Answer 34

In association with nucleic acids

Question 35

Properties of protamines:

Answer 35

1. basic proteins 2. resemble histones but: smaller & soluble in dilute ammonium hydroxide 3. also associated with nucleic acids

Question 36

Properties of globulins:

Answer 36

1. insoluble in pure water 2. dissolve in dilute salt concentrations 3. coagulate by heat 4. precipitate using half-saturated salt solutions

Question 37

What makes globulins special compared to other plasma proteins?

Answer 37

They can be isolated from the other plasma proteins when placed in a half-saturated salt solution, where it precipitates.

Question 38

What is an example of globulins?

Answer 38

Plasma globulin

Question 39

Properties of glutelins:

Answer 39

- soluble in dilute acids & alkalies - mainly found in plants

Question 40

Properties of scleroproteins: | with examples

Answer 40

- insoluble in water - ex: collagen & keratin

Question 41

What are the types of conjugated proteins?

Answer 41

1. Nucleoproteins 2. Lipoproteins 3. Glycoproteins 4. Phosphoproteins 5. Metalloproteins 6. Chromoproteins 7. Flavoproteins

Question 42

What are conjugated proteins?

Answer 42

simple proteins that are combined with non-protein substances (prosthetic group)

Question 43

What role does the prosthetic group have in conjugated proteins?

Answer 43

The nature of the prosthetic group is the basis for the sub classification of conjugated proteins

Question 44

What are nucleoproteins?

Answer 44

- they are formed by the combination of histones (simple proteins) and DNA (prosthetic group) - they are essential components of chromatin

Question 45

What are Lipoproteins?

Answer 45

- these are lipid-conjugated proteins - examples include LDL & HDL (low & high density lipids)

Question 46

What are glycoproteins?

Answer 46

- carbohydrate prosthetic group: less than 4% of the protein is carb. - majority of the membrane proteins are glycoproteins - if carb content of protein is greater than 4%: it is called a mucoprotein