Proteins

Question 1

Protein chemical composition

Answer 1

H2NCHRCOOH

Question 2

What are proteins made up from

Answer 2

monomers of amino acids (polypeptide chain)

Question 3

What do all amino acids possess

Answer 3

Amino group -NH2
Carboxylic group - COOH
R group - sidechain (different in each amino acid)

Question 4

What does the r group determine?

Answer 4

The name and properties of each amino acid.

Question 5

Why is the position of NH2 group and COOH important in amino acids?

Answer 5

They link and are the points of attachment that bond amino acids together.
Creating a dipeptide (double amino acid) gradually crating a polypeptide.

Question 6

What is the bond between amino acids called

Answer 6

Peptide bond

Question 7

Monomers of proteins

Answer 7

Amino acids (20 amino acids in total

Question 8

4 structures of proteins

Answer 8

Complex and varied structure.
Primary
Secondary
Tertiary
Quaternary

Question 9

Function of proteins

M M I G B P S S

Answer 9

Movement - fibres form that lengthens and shorten depending on stimulation

Membrane transport channel and carrier proteins. (haemoglobin and membrane carrier proteins)

Immunology - Immune system protection - antibodies
Chemical communication for hormones

Genes that code for proteins are important for structure and function in the body.

Biochemical reactions - Enzymes (catabolic reactions)
Receptor proteins - signal change in a cell if chemical messenger binds to it.

Physical structure / support (Hair / nails / muscles) In plants - keratin / collagen structural support

Signalling - some proteins are released to signal a change in other cells.

Storage - can be used to store chemicals needed incase of a shortfall. (Haemoglobin could be classed as a storage cell as it stores oxygen to be released into the bloodstream.

Question 10

Subclasses of protein (group and examples e.g. defence - immunoglobulins)

Answer 10

Enzymes - Digestive =  Amylase, lipase, pepsin, trypsin
Transport - Hemoglobin, albumin
Hormones - Insulin, thyroxine
Antibodies -Defence, Immunoglobulins
Contractile - Actin, myosin
Structural
Storage 
Transport proteins

Question 11

Why does a protein need to be formed in its correct shape / structure?

Answer 11

Carry out its function properly.

e.g enzyme needs to be in its tertiary structure to enable substrates to attach and catabolic process to occur.

Question 12

Describe the primary structure of a protein (5 points)

Clue SSPPG

Answer 12

1. Sequence of amino acids in a polypeptide chain held together by peptide bonds
2. Sequence of amino acids is critical to structure and function - the order of amino acids determines the primary structure shape and properties of the protein.
3. Polypeptide chain via protein synthesis
4. Proteins made up of 1 or more polypeptide chains
5. Genes made of DNA determine the order of amino acids.

Question 13

Describe the secondary structure of a protein

CLUE: HIT

Answer 13

1. Hydrogen bond to an oxygen on another amino acid
2. Initial folding of a polypeptide chain
   either in an ALPHA HELIX or BETA PLEATED SHEET
3. Type of folding dependent on the amino acid arrangement.

Question 14

Alpha helix structure process

CLUE = BTA

Answer 14

1. Bonds between hydrogen atoms at the side of chains
   pulling together as they turn back around
2. Turn…..Individual peptides turn when connected so a secondary structure like a spiral staircase
3. Atoms at the side of the backbone are pressed together forming a helix

Question 15

Beta pleated sheet structure

Answer 15

Polypeptide chains adjacent to each other and held together via hydrogen bonds between the backbone.

Chains can run parallel or anti-parralell.

R-Groups alternate pointing above and below the sheet.

H-bonds are perpendicular to the direction of the polypeptides.

Fold back on themselves pressing oxygen and hydrogen together

Forms the support framework prevents structure unwinding.

Polypeptide chains can turn sharply in any direction – allows reverse turns and loops

Question 16

Tertiary structure

Answer 16

FOLDING IN THE 3D SHAPE OF A SINGLE MAJOR POLYPEPTIDE CHAIN.

FOLDS TO BE A FUNCTIONAL PROTEIN – DUE TO R GROUPS AKA SIDE CHAINS

No symmetry

Shape dependant on amino acid sequences – how the different amino acids cross-link with other agents or amino acids close in structure.

Enzymes functional in tertiary formation with an indentation for the active site.

Stabilized by hydrophobic bonds and ionic bonds

R-GROUP VARIES in amino acids – makes amino acids behave a certain way.

E.G. Some R groups like water (hydrophilic) some don’t (hydrophobic)

Amino acids with hydrophilic acids may be present on the outside – hydrophobic groups are on the inside.

Question 17

Describe Quaternary structure

Answer 17

More than one plypeptide chain

Question 18

Why are structure and shape so important for proteins?

Answer 18

When some substances are added to a protein, the bonds can be broken or changed

Changing the proteins nature; usually, resulting in the protein being unable to carry out its role

Hence why shape is critical to function.

Question 19

What is a damaged protein referred to as?

Answer 19

denaturing protein

Question 20

What is Denaturing?

Answer 20

A protein whose bonds have been broken or changed by chemicals or temperature, changing the structure and function.
Denaturing usually means the function of a protein is stopped

n.b Some proteins can rearrange themselves to regain function, some changes are permanent meaning not able to function.

Question 21

Structure of haemoglobin

Answer 21

Haemoglobin is a quaternary structure, made up of 4 sub-units, each created from a polypeptide chain containing an ion component.

Question 22

Haemoglobin function

Answer 22

Combines oxygen with red blood cells and enables respiratory cells to be equipped with oxygen for use in aerobic respiration.

Transports oxygen around the body in the bloodstream to equip respiring cells with oxygen during respiration.