2.2 Proteins

Question 1

what is a protein

Answer 1

large polymer comprised with long chain of amino acids

Question 2

what are 3 roles of proteins

Answer 2

1 they form structural components of animals e.g muscle, tendons, bones

2 they adapt specific shapes as enzymes

3 membranes have proteins constituents that’s act as corner + pores for active transport across membranes + facilitated diffusion

Question 3

what elements does it contain

Answer 3

Each amino acid contains C,H,N,O and S sometimes

Question 4

what is the structure of an amino acid

Answer 4

• All protein chains of amino acid contain amine group (NH3) at one and + carboxyl group (-COOH) at the other

-The R group can vary by size polarity and charge

Question 5

what is a peptide bond

Answer 5

A covalent bond formed when two amino acids are joined together in a condensation reaction

Question 6

what does protease enzyme do

Answer 6

Protease enzymes break down protein peptides bond in digestion

Question 7

what is a dipeptide

Answer 7

When two amino acids join they are a dipeptide

Question 8

what is a polypeptide

Answer 8

Polypeptide is when many amino acids join together

Question 9

what is the primary structure

Answer 9

It is the sequence of amino acid in the polypeptide chain.

Question 10

why is primary structure important

Answer 10

The function of protein depends on the structure, which depends on the amino acid order.

Question 11

what is the secondary structure

Answer 11

The coiling or folding of the amino acid chains to form either an a-helix or B pleated sheet. This is due to H bonds. (Between C equals O And H in the amine a group) to hold the structure.

Question 12

what is the tertiary structure

Answer 12

Further folding of a secondary structure which forms 3D unique shape and is held by; Iconic, Hydrogen, disulphide Bonds.

The iconic + sulphide Form between R groups of different amino acids.

disulphide bonds only sometimes occur as there must be sulphur in R- group.

Question 13

what is the quaternary structure

Answer 13

Where proteins consist of more than one polypeptide chain bonded together.

Question 14

what is hydrogen bond in the tertiary structure

Answer 14

Form between C = O in carboxyl groups and H in an amine group.

Question 15

what is the ionic bond between tertiary structure

Answer 15

Form between carboxyl + amine groups that are part of R groups

Question 16

what are the hydrophobic and hydrophilic interactions in the tertiary structure

Answer 16

R groups are hydrophobic + tend to stay in the middle of polypeptide to stay away from H2O.

The hydrophilic parts are found at edge to be close to water.

Hydrophobic + Hydrophilic interactions cause twisting of amino acids which charge shape of the protein.

These interactions can be especially Important influence given that most protein are tube found surrounded by H2O inside a living Organism.

Question 17

what are disulphide bonds

Answer 17

Bond formed Between 2 sulphurs in R group and forms a bridge.

These are strong covalent bonds.

Made from Cysteine amino acid (They contain s)

Question 18

What are fibrous proteins

Answer 18

They are long thin protein that is insoluble in water.

They are made from repeating sequences of amino acids and are metabolically inactive leading them to have structural roles in an organism

Question 19

3 types of fibrous proteins and their uses & structure

Answer 19

Collagen
Keratin
Elastin

Question 20

Collagen

Answer 20

Found in the artery wall and a layer of collagen prevents the artery from bursting when withstanding HP

Tendons are made from collagen and connect muscle to bones allowing them to pull bones

Cartilages + Connective tissue are made from collagen

Bones are made from collagen + then reinforced with calcium phosphate which makes them hard

Question 21

Keratin

Answer 21

Is found in body parts that need to be hard to provide mechanical protection as well as acting as an impermeable barrier to infection being waterproof and preventing entry of Waterbourne pollutants

Keratin can be found in nails, claws, hooves, horns, and scales

They are rich in cystine which means they have many disulphide bridges in its polypeptide as well as having many H-bonds to provide additional strength

Question 22

Elastin

Answer 22

Due to coiling and cross linking of the elastin molecules its long and extensible (stretchy)

Skin can stretch around bones and muscles due to elastin

Elastin in lungs allow them to deflate and inflate

They are also found in the bladder to help it expand to store urine

Elastin also helps our blood vessels widen and stretch + recoil as blood is pumped through them helping maintain the pressure wave of blood as it passes through

Question 23

Globular Proteins

Answer 23

Type of 3d protein that is spherical and soluble in water and having metabolic roles

They have Hydrophobic R groups on the inside the hydrophilic R groups on the outside

Question 24

3 types of Globular proteins , their roles and structure

Answer 24

Haemoglobin
Insulin
Catalase

Question 25

Haemoglobin

Answer 25

A globular protein that is found in red blood cells

Made from 4 polypeptide chains making it have a quaternary structure (2 Alpha Globin chains + 2 Beta Globin chains)

At each polypeptide group there is a prosthetic group attached (a non-protein component that forms a permanent part of a functioning protein molecule) making a conjugated protein (protein which has another chemical group)

The 4 prosthetic group in haemoglobin are called haem groups and contain iron ion (Fe2+)

One O2 molecule binds to each haem group allowing for each haemoglobin to transplant 4 O2 molecules

Question 26

Insulin

Answer 26

Made from 2 polypeptide chains – the A chain has an alpha helix while the Beta chain has a Beta-pleated sheet

The 2 chains are linked by disulphide links

Amino acids with hydrophilic R groups are on the outside of molecule making it soluble in water

The shape of insulin allows for it to bind to glycoprotein receptor on the outside of muscle + fat cells to increase its uptake of glucose from blood and to increase the rate of glucose consumption making a lower blood glucose concentration

Since its soluble it dissolves in blood + easily transported around body

Question 27

Catalase

Answer 27

• Quaternary protein consisting of 4 haem prosthetic groups
• Presence of Fe2+ ion in the prosthetic group & allow it to interact & break down Hydrogen peroxide
• Hydrogen Peroxide is a by product of metabolism and is harmful to cells if it accumulates