B1.2: Proteins

Question 1

Monomers of proteins?

Answer 1

Amino acids.

Question 2

How many amino acids are there?

Answer 2

20 amino acids only

Question 3

Which organelle produces proteins

Answer 3

Ribosomes

Question 4

Why do we still need to consume meat/soya for protein if we have a lot of them due to ribosomes?

Answer 4

We don’t have all types of amino acids, therefore, they need to be supplemented via meat or soya, etc.

Question 5

Define muscle wasting (DOUBLE CHECK)

Answer 5

the wasting (thinning) or loss of muscle tissue
- when proteins as a source of energy when carbs and lipids aren’t there

Question 6

Outline the two types of amino acids

Answer 6

Essential and non-essential

Question 7

Define essential proteins

Answer 7

Protein from other organism

Question 8

Define non-essential proteins

Answer 8

Come from our body (thus it’s not essential to consume from external sources)

Question 9

What are a 2 amino acids tgt called?

Answer 9

Dipeptide

Question 10

Outline the sequence of complexity

Answer 10

amino acid (monomer) -> dipeptide -> polypeptide -> proteins

Question 11

Define denatured on terms of proteins

Answer 11

The (natural quality which is specifically:) functional shape of protein is disrupted

Question 12

Outline the different structures found in an amino acid

Answer 12

Amine grp (NH2)

Carboxyl grp (COOH)

Hydrogen atom (H)

Variable side chain (R)

Question 13

What is the chemical composition of proteins?

Answer 13

CHON/S
(Carbon, Hydrogen, Oxygen, Nitrogen and with or without?? Sulfur)

Question 14

Draw the structure of a generalised amino acid

Answer 14

(no need to draw a box)

Question 15

What is the bond between protein?

Answer 15

Peptide bond

Question 16

What makes an amino acid different from eachother

Answer 16

Their R (variable side chain)
- determines type of protein (polar or non-polar)

Question 17

What determines the charge of the amino acid/protein?

Answer 17

The R

Question 18

Describe the folding of long amino acid chains

Answer 18

The R’s can be attracted to each other and thus “fold” the chain which affects the structure and function

Question 19

Most natural polypeptide chains contain between how many amino acid residues?

Answer 19

50 - 2000

Question 20

Describe peptide bonds

Answer 20

• covalent bond
• condensation to dipeptide and water
• broken by hydrolysis (?)

(between C and N — the one in green. btw they bind at one’s carboxylic group and amine group)

Question 21

amino acid + amino acid —> ?

Answer 21

dipeptide + water

Question 22

Outline the types of structure in proteins

Answer 22

1.) Primary
2.) Secondary
3.) Tertiary
4.) Quaternary

Question 23

Describe the primary structure of amino acid

Answer 23

Purely the sequence/arrangement

e.g.: Amino acid 1 - amino acid 2 - amino acid 3 - …

Question 24

Describe the secondary structure

Answer 24

Folding (depends on R)
- Two stable forms:
1.) B (beta)-pleated
2.) A (Alpha)-helices (helical)

• both result from hydrogen bonds (and peptide) between amino acids
• Bonding of amino acids not to the neighbor - non-adjacent

Question 25

Describe the B-pleated secondary structure (CONT.)

Answer 25

It consists of various beta strands linked by hydrogen bonds between adjacent strands. - Unique folding (zigzag)

Question 26

Define helical bond in the secondary structure

Answer 26

Circular

Question 27

Describe the tertiary structure of the protein

Answer 27

Determined by the *interactions between the R chains* - *3D configuration* - hydrophobic inside; hydrophilic outside

Question 28

Describe quarternary structure

Answer 28

Made up of different polypeptides folded to one another with diff. *prosthetic grps* e.g.: tertiary and tertiary, tert and secondary, quarternary and..

Question 29

Define denaturation

Answer 29

*a structural change that results in the loss of its biological properties* - additionally, can also break bonds

Question 30

What is the denaturation of proteins caused by?

Answer 30

Temp and pH

Question 31

Describe tertiary structure

Answer 31

**R side groups bond tgt**, **3D Configuration/Arrangement** - (relation to the R groups and 3D-ness): *Polar amino acids stick outside whereas non-polar amino acids hide inside*

Question 32

Where do peptide bonds form?

Answer 32

***Carboxyl group and Amine group*** *by condensation* (removal of the OH from the carboxyl group and the H atom from the amine group of another amino acid -> water byproduct -> allows one more bond for the carbon and nitrogen to create a peptide bond!)

Question 33

Why are prosthetic groups not the same as the R group

Answer 33

**Prosthetic groups are not part of the amino acid** - R group is pat of the amino acid, therefore, not part of the amino acid - But prosthetic groups, despite not being an amino acid, are bonded to the polypeptides in quaternary structures

Question 34

Outline the two types of proteins according to structure and function

Answer 34

1.) Globular, functional (reactions) — round - e.g. enzymes 2.) Fibrous, on structure — long and thin

Question 35

Outline the two causes of denaturation of proteins

Answer 35

1.) Temperature 2.) PH level

Question 36

Why is protein sensitive to temperature?

Answer 36

**High thermal energy can disrupt the hydrogen bonds that hold the protein together (2nd structure)** - Also note: peptide bond within amino acid, hydrogen bond between amino acid (like covalent bonds and hydrogen bonds in water) - *will cause protein to unfold and therefore not function*

Question 37

Why is protein sensitive to pH

Answer 37

**amine grp and carboxyl grp not bonding tgt, attracted to other atoms (H if more acidic and OH if more alkaline)** - thus, it’ll alter the shape of the protein (primary structure?) -> protein shape and protein solubility (-> function?)

Question 38

What determines the type of protein?

Answer 38

By the sequence of genes (Translation) - *usually 1 gene 1 protein type??, e,g, 1 gene -> hair color* (DOUBLE CHECK) - *But the grouping of genes to proteins is different due to translation* (ADD PHOTO) e.g.: The reason why some people are lactose-intolerant is that their genes have “turned off” the lactose-tolerating proteins (? DB) The genes determine the hair-color

Question 39

Define proteome

Answer 39

total proteins expressed with a cell, tissue, organism at a certain time

Question 40

Which do we have more of? Proteins or genes?

Answer 40

Proteins > genes

Question 41

Explain the 1 gene to 1 protein type ratio

Answer 41

**1 gene -> 1 type/purpose (e.g. hair color) -> different variations of proteins (e.g. brown blue and green in one person** - *The proteome depends on the expression of proteins (dom vs recess.)*

Question 42

Describe fibrous proteins

Answer 42

- Long, narrow - Structural -Repetitive amino acid sequence - Less sensitive to changes in pH and temp, etc. - Generally insoluble in water e.g.: collagen, myosin, fibrin. actin and keratin, etc.

Question 43

Describe globular proteins

Answer 43

- Round/spherical - Functional - Irregular amino acid sequence - More sensitive to changes in pH, temp. etc. (they have optimum pH level and temp for chem reactions — enzymes) - Generally soluble in water (ig related to the chemical reaction function??) e,g, enzymes

Question 44

Give the function of the enzyme Rubisco

Answer 44

Catalyzes photosynthesis — **carbon-fixation** - fixes carbon dioxide from the atmosphere — *provides carbon needed by living organisms*

Question 45

Give the function of the hormone Insulin

Answer 45

Lowers blood glucose levels

Question 46

Give the function of the structural protein, Collagen

Answer 46

To prevent skin tearing by wounding three polypeptides in a rope-like way. - (which is why you oft see collagen in shampoo ads)

Question 47

Give the function of the antibody, immunoglobulin

Answer 47

bind to antigens (substances that illicit a bodily reaction) in pathogens

Question 48

Give the function of the pigment Rhodopsin

Answer 48

makes the rod cells of the retina light-sensitive

Question 49

Which atom makes a bond covalent?

Answer 49

Oxygen — has electrons for electron sharing (covalent bond)