Protiens

Question 1

What are amino acids

Answer 1

Monomer units of a proteins, 20 different r groups make up the 20 amino acids

Question 2

Diepeptide

Answer 2

2 amino acids joined by a peptide bond
OH from carboxyl group combine with H from amine group to make a h20 molecule
Condensation reaction

Question 3

primary structure

Answer 3

Polypeptide chains

Chains of 3 or more amino acids

Question 4

Secondary structure

Answer 4

A- helix : polypeptide chain coiled into cylindrical shape , h bonds

B- pleated sheet, different polypeptide chains become linked in Parallel flat sheets

Question 5

Tertiary structure

Answer 5

Further folding of the secondary structure of proteins involving interactions between r groups
Each protein has a unique tertiary structure, which is responsible for properties and functions
Held together by bonds between r groups

Question 6

Types of interactions of r groups in tertiary structure

Answer 6

Hydrophobic interaction 
Polypeptide backbone 
H bonds 
Disulphides bridge
Ionic bonds

Question 7

Quaternary structure

Answer 7

The association of 2 or more protein subunits

Same interaction as in the tertiary but between different proteins

Question 8

structure of haemoglobin

Answer 8

red oxygen carrying pigment
polypeptide chain of amino acids linked by peptide bonds
secondary structure - alpha helix and beta pleated sheets linked by h bonds
tertiary - folding on secondary structure leading to more interactions hydrophobic/hydrophilic/ionic, r groups move depending on whether they are hydrophobic/phillic
quaternary - 4 polypeptide chains 2 alpha 2 beta become linked, each contain a haem group which has fe2+ present

Question 9

What chemical elements can make up a protein

Answer 9

Carbon , hydrogen, oxygen, nitrogen , sulphur

Question 10

General structure of an amino acid

Answer 10

Amine group (h-n-h)
R group-c-h
Carboxyl group (o=c-o-h)

Question 11

Importance of hydrophobic/hydrophilic interactions

Answer 11

Depending on wether the r group is hydrophilic or hydrophobic , dictates the way the protein will fold

Question 12

Breakdown of peptides

Answer 12

Protease enzymes catalyse the reaction
Turning peptides back into amino acids
Water molecule is needed to break peptide bond in hydrolysis reaction
Amine and carboxylic acid groups are reformed

Question 13

Example of prosthetic group

Answer 13

Haem groups contains fe2+

Question 14

Conjugated proteins

Answer 14

gobular proteins that contain a non-protein component called a prosthetic group

Question 15

Insulin

Answer 15

Globular protein
Hormone that Regulates blood glucose concentration
Hormones are transported in the bloodstream need to be soluble
Must have precise shapes to fit into specific receptors on cell surface membranes

Question 16

Catalase

Answer 16

In an enzyme
Catalyse is a quaternary protein contains 4 haem prosthetic groups
Catalyses the breakdown of hydrogen peroxide due to fe2+ presence
Hydrogen peroxide -> oxygen and water

Question 17

3 fibrous proteins

Answer 17

Keratin- group of fibrous proteins present in hair, skin, nails, creates disulphide bonds ( determining flexibility
elastin- found in elastic fibres, present in walls of blood vessels and in the lungs- they give these structures flexibility
collagen - connective tissue found in : skin, tendons, ligaments, and nervous system

Question 18

Cations

Answer 18

Calcium ca2+
Sodium Na+
Potassium k+
Hydrogen h+
ammonium NH4*+

Question 19

Anions

Answer 19

Nitrate NO3*-
Hydrogencarbonate HCO3*-
Chloride Cl- 
Phosphate PO4*3- 
Hydroxide OH-

Question 20

Differences between globular and fibrous proteins

Answer 20

Fibrous proteins are long and insoluble, have structural roles
Globular proteins are compact and soluble and have metabolic roles

Question 21

Structure and properties of collagen

Answer 21

Peptide bonds between amino acids
Left handed helix
twisting of 3 polypeptide chain allowing molecule to be tight
Many H bonds between
Every third amino acids is glycine which is very small allowing a closely packed triple helix
Insoluble
Fibril molecule
Flexible, not elastic, strong
In some tissues multiple fibers of clooagen combine into large bundle forming tendons - ligemnts which are resistant to tearing

Question 22

Bonds between amino acids

Answer 22

Peptide

Question 23

property of collagen that makes it useful as a component of blood vessels

Answer 23

Strength

Insoluble

Question 24

Fiberous protiens properties

Answer 24

Formed from long insouble molecules
High proportion of amino acids with hydrophobic r groups in their primary structres
Very organised and repetitive amino acid sequnce and therefore organised structure
Not folded into 3 dimesional shapes like gobular protiens

Question 25

Structure and properties of elastin

Answer 25

Linking many tropoelastin protien molecules to make a very large, insousble, stable cross linked structre
Linked by hydrophobic interactions and covelant bonds
Tropelastin moleces are able to strech and recoil without breaking

Question 26

Role of polypeptides

Answer 26

Enzymes that catalyse reactions
Hormones
Receptor protiens
Strucutral proteins - collagen, keratin, actin

Question 27

How do R group interaction detriment tertiary structure

Answer 27

H bonds 
Ionic bonds between opposing charges 
Some R groups atract/repel 
If R group is hydrophobic/hydrophilic it will face inwards/outwards from the cell
Disulphide bridges

Question 28

Meaning of primary structure

Answer 28

Sequence of amino acids