2.2 Proteins

Question 1

Protein facts

Answer 1

• make up 50% of organic material in cell
• Made of carbon, oxygen, hydrogen and nitrogen (sulphur=some)

-used in many structural reasons
-used as carriers
used as enzymes
-used s hormones
-used as antibodies

Question 2

collagen

Answer 2

-used in skin and ligaments

Question 3

keratin

Answer 3

found in nails

Question 4

monomers of proteins

Answer 4

amino acids

Question 5

amino acid structure

Answer 5

• amine group which is NH2
• carboxyl group which is COOH
• C in centre and H

-variable R group- different for each amino acid- make it what it is

Question 6

condensation reaction in proteins

Answer 6

• 2 molecules join together
• create a new bond called a peptide bond
• release water

Question 7

peptide bond

primary structure

Answer 7

made out of OH group of a carboxyl group and H of an Amine group

Question 8

primary structure

Answer 8

the specific sequence of amino acids in a protein

Question 9

hydrolysis

Answer 9

-water is added and bond is broken

Question 10

secondary structure

Answer 10

the coiling and pleating of parts of the polypeptide make alpha helixes and beta-pleated sheets

-this occurs because of hydrogen bonds

Question 11

tertiary structure

Answer 11

the overall 3D structure of the protein

Question 12

4 types of bonding affecting shape of protein (tertiary structure

Answer 12

• Disulphide bonds/bridges
• hydrogen bonds
• Ionic bonds
• hydrophilic/hydrophobic interactions

Question 13

Disulphide bonds/bridges

Answer 13

• occurs between amine groups that have sulphur in (e.g. cysteine)
• double bond between 2 sulfurs

Question 14

hydrogen bonds

Answer 14

-between delta negative and delta positive R’s

Question 15

Ionic bonds

Answer 15

-between completely ionic R groups

Question 16

difference between hydrophobic and hydrophilic

Answer 16

• hydrophobic away from water

- hydrophilic towards water

Question 17

globular proteins

Answer 17

• rolled into balls
• usually soluble
• metabolic roles
• Enzymes, antibodies, haemoglobin

Question 18

fibrous proteins

Answer 18

• Form fibres
• usually insoluble
• structural roles
• Collagen, Keratin

Question 19

Quaternary structure

Answer 19

• proteins made of more than one polypeptide

- (e.g. haemoglobin, collagen)

Question 20

haemoglobin

Answer 20

• globular
• Soluble
• Many amino acids
• Prosthetic group (haem)
• alpha helix

-2 alpha 2 beta polypeptide chains

Question 21

collagen

Answer 21

• fibrous
• insoluble
• 35% glycine
• no prosthetic group
• left-handed helix structures

Question 22

prosthetic group

Answer 22

-group that helps the molecule work
-non-protein element
protein can function without it

Question 23

haem

Answer 23

• prosthetic group in haemoglobin

- conatisn iron which binds with oxygen as haemoglobin carries oxygen

Question 24

collagen structure

Answer 24

• 3 polypeptide chains coiled
• provides tensile strength
• hydrogen bonds form between them
• covalent cross links between different collagen molecules
• flexible

Question 25

fibril

Answer 25

lots of protein molecules covalently bonded together

Question 26

how 2 amino acids join together?

Answer 26

peptide bonds form between H (from amine) and OH from a different carboxyl group in a condensation reaction where water is released

Question 27

how R groups interact to form tertiary structure of a protein?

Answer 27

-Some R groups attract/repel

• Disulphide bonds (S=S) between cysteine
• Hydrogen bonds
• Ionic bonds
• Hydrophobic R groups, inside
• Hydrophilic R groups, outside

Question 28

properties of collagen that make it suitable for its purpose

Answer 28

• high tensile strength
• not elastic
• insoluble
• flexible

Question 29

cations:

Answer 29

• calcium ions (Ca2+)
• sodium ions (Na+)
• potassium ions (K+)
• hydrogen ions (H+)
• ammonium ions (NH4+)

Question 30

anions:

Answer 30

• nitrate (NO3–)
• hydrogencarbonate (HCO3–)
• chloride (Cl –)
• phosphate (PO43–)
• hydroxide (OH–)