B1.2 Proteins

Question 1

What is the generalised structure of an amino acid?

Answer 1

All amino acids have the same structure in terms of an amine group and carboxyl group

BUT different variable groups (R groups)

Question 2

draw the generalised structure of an amino acid + label the amine group, carboxyl group, and R group

Answer 2

Question 3

what is a dipeptide?

Answer 3

a peptide made up of two monomers

OR
a molecule consisting of two amino acids joined by a single peptide bond.

Question 4

what is a oligopeptide?

Answer 4

An oligomer of amino acid units joined by peptide linkages and whose molecules contain a relatively small number of amino-acid residues

(a short chain of amino acids)

Question 5

what is a polypeptide?

Answer 5

a peptide made up of many monomers

OR
long chains of covalently bonded amino acids

Question 6

draw peptide bond formation in a condensation reaction between two amino acids

Answer 6

• two amino acids are joined in a condensation reaction via the carboxyl group of one amino acid and amine group of other, creating a peptide bond and water

Question 7

where in the cell does polypeptide formation occur?

Answer 7

a polypeptide is made on a ribosome via translation. they are formed when amino acids are joined together

Question 8

Compare the source of amino acids by plant and animal cells

Answer 8

Plants get it from photosynthesis while animals from consuming plants or other animals

Question 9

Define “essential” and “non-essential” as related to dietary amino acids

Answer 9

• Essential can’t be synthesized from the body; it gets it through diet
• Non essential can produce it on its own

Question 10

why do vegan diets require attention to food combinations to ensure essential amino acids are consumed?

Answer 10

Because some plants lack specific amino acids, so they must create a balanced diet by giving more attention to food combinations

Question 11

there is _____ of DNA base sequences

Answer 11

there is a limitless diversity of DNA base sequences

Question 12

why is there a limitless diversity of DNA base sequences?

Answer 12

The infinite variety of possible peptide chains arises from the ability to combine the 20 different amino acids in any sequence

This allows for creation of an almost limitless number of unique proteins with different structures and functions

Question 13

the structure of protein has ___ levels. what are they?

Answer 13

it has 4 levels:

• primary
• secondary
• tertiary
• quaternary

Question 14

what makes a substance acidic?

Answer 14

Hydrogen (H+) ions

Question 15

What makes a substance alkaline?

Answer 15

Hydroxide (OH-) ions

Question 16

Each of the 20 amino acids consists of?

Answer 16

an alpha carbon atom attached to an amine group, carboxyl group, H atom and an R-group

Question 17

Each of the 20 amino acids has a ____ R-group, providing it with ____

Answer 17

Each of the 20 amino acids has a unique R-group, providing it with its unique structure

Question 18

Amino acids join together to make a protein through _______

When amino acids join together, ____ are formed.

Answer 18

Amino acids join together to make a protein through condensation reactions

When amino acids join together, peptide bonds are formed

Question 19

Essential amino acids are amino acids that your body _____ while non-essential amino acids ______

Answer 19

Essential amino acids are amino acids that your body cannot synthesise while non-essential amino acids can be produced by the body from other amino acids or by the breakdown of protein

Question 20

the genetic code serves ____

Answer 20

the genetic code serves as a universal language for all living organisms and provides the instructions for protein synthesis

Question 21

what is denaturation?

Answer 21

it is when extreme pH and temperature causes the breaking of bonds, causing the protein to lose its 3D conformation.

it is a process modifying the molecular structure of a protein, damaging / changing the active site

Question 22

glycine is?

Answer 22

the simplest amino acid, with a hydrogen atom forming its R group

Question 23

Name the monomer of proteins and draw its general structure

Answer 23

Amino acids.

Question 24

1. Name the reaction that takes place in the formation of a dipeptide
2. name the bond formed.

Answer 24

1. a condensation reaction
2. a peptide bond

Question 25

What is the primary structure of a protein?

Answer 25

The sequence of amino acids in the polypeptide chain.

Question 26

Name two features of the secondary structure of a protein.

Answer 26

Alpha helices and beta pleated sheets.

Question 27

Name three types of bond that stabilize the tertiary structure of a protein

Answer 27

Hydrogen bonds, ionic bonds, and disulfide bridges

Question 28

Haemoglobin has a quaternary structure. What does this mean?

Answer 28

It consists of more than one polypeptide chain.

Question 29

Name a biochemical test for proteins.

Answer 29

Biuret test.

Question 30

What is a prosthetic group? Why are they important in some proteins?

Answer 30

It is a non-protein part of the molecule which helps the functioning of the protein.

Question 31

explain the effect of pH on temperature on protein structure and function

Answer 31

Extreme pH and temperature can cause the denaturation of a protein as it causes the breaking of bonds, causing the protein to lose its 3D conformation
–> it cannot carry out its function