Chapter 3.5: Proteins and DNA

Question 1

What is the structure of an amino acid?

Answer 1

1 Nitrogen, 4 Hydrogen, 2 Oxygen and a variable group (R)

Question 2

What bonds are used in amino acids?

Answer 2

Peptide bonds

Question 3

What reaction is used to join amino acids?

Answer 3

Condensation reaction

Question 4

What are numerous amino acids joined together called?

Answer 4

Polypeptide bonds

Question 5

What practical can be used to separate proteins?

Answer 5

Chromatography practical

Question 6

What are the 4 types of protein structure?

Answer 6

Primary, secondary, tertiary and quarternary

Question 7

Equation for Rf value?

Answer 7

Distance travelled by component divided by distance travelled by solvent

Question 8

What is a primary structure?

Answer 8

A sequence of amino acids. Only bonds involved are peptide bonds

Question 9

What is a secondary structure?

Answer 9

Two types - alpha helix and beta pleated sheet
Held together with hydrogen bonds and polypeptide chains. The shape is determined by where the hydrogen bonds form

Question 10

What is a tertiary structure?

Answer 10

The folding of a protein into its final shape. Forms hydrogen and ionic bonds. Also disulphide bridges are made (strongest of the bonds) Produces a variety of complex-shaped proteinsWh

Question 11

What is a quaternary structure?

Answer 11

Two or more subunits (individual proteins) joining together.

Question 12

Globular proteins properties?

Answer 12

Water soluble, compact, globe shaped. Used for muscles contraction and immunity

Question 13

Example of a globular protein?

Answer 13

Insulin

Question 14

What are globular proteins?

Answer 14

Globular proteins that contain a non-protein component called a prosthetic group. Proteins without this are called simple proteins

Question 15

Haemoglobin, what is it?

Answer 15

Red, oxygen carrying pigment found in red blood cells. It is a quaternary protein made up of four polypeptides ( 2 alpha, 2 beta)

Question 16

What is catalase?

Answer 16

An enzyme and a quaternary protein. Catalyses reactions

Question 17

Explain fibrous proteins?

Answer 17

They’re formed from long, insoluble molecules. Repetitive amino acid sequence which leads to very organised structures

Question 18

What is keratin?

Answer 18

A fibrous protein present in hair, nails and skin. Very strong disulphide bridges making it very strong.

Question 19

What is elastin?

Answer 19

A fibrous protein present in walls of blood vessels and alveoli. It gives these structures the flexibility to expand when needed and also return to their original size.

Question 20

What is collagen?

Answer 20

Another fibrous protein. A connective tissue found in skin, tendons and the nervous system. Has lots of flexibility.

Question 21

What 3 things make up a nucleotide?

Answer 21

Phosphate, sugar and a base

Question 22

What sugar is present in DNA?

Answer 22

Deoxyribose

Question 23

How are nucleotides linked together?

Answer 23

Condensation reactions that forms phosphodiester bonds

Question 24

What are the 4 types of base?

Answer 24

Thymine (T), Adenine (A), Guanine (G) and Cytosine (C)

Question 25

Which base changes in RNA

Answer 25

Thymine becomes Uracil (U)

Question 26

What are pyrimidines and which bases are they?

Answer 26

Smaller bases which contain a single carbon ring.
Thymine, Cytosine and Uracil

Question 27

What are purines and which bases are they?

Answer 27

Larger bases which contain a double carbon ring.
Adenine and Guanine

Question 28

Shape and direction of DNA?

Answer 28

Double helix and antiparallel

Question 29

How do the complementary base pairs bond/

Answer 29

A -> T is two hydrogen bonds
C -> G is three hydrogen bonds

Question 30

How are DNA and RNA different?

Answer 30

Ribose sugar instead of deoxyribose. Thymine is replaced by Uracil

Question 31

What enzyme ‘unzips’ DNA?

Answer 31

DNA helicase

Question 32

How does helicase work?

Answer 32

Travels along DNA backbone catalysing reactions to break hydrogen bonds between complementary base pairings

Question 33

What do the nucleotides do after being unzipped?

Answer 33

Free nucleotides pair with newly exposed bases on the template strand

Question 34

What does DNA polymerase do?

Answer 34

Catalyses the formation of phosphodiester bonds between the molecules