B1.2 Cell structure

Question 1

Describe the structure of DNA

Answer 1

• It is a polymer made of many
  nucleotide monomers
• It is made of 2 strands in the shape of
  a double helix

Question 2

Describe the structure of a nucleotide

Answer 2

A nucleotide contains a 5 carbon sugar,

phosphate group and nitrogenous base

Question 3

Name the 4 bases in DNA

Answer 3

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

Question 4

How do the bases in DNA pair up

Answer 4

Adenine pairs with Thymine (A with T)

Cytosine pairs with Guanine (C with G)

Question 5

Describe transcription (Higher)

Answer 5

1) DNA unzipped
2) Complementary mRNA nucleotides bind
and are joined together
3) mRNA detaches and leaves the nucleus

Question 6

Describe translation (Higher)

Answer 6

1) mRNA travels to a ribosome
2) Carrier molecules carry amino acids to
the ribosome based on the mRNA
sequence
3) The amino acids are joined together

Question 7

How does the sequence of DNA affect
the protein made in protein synthesis?
(Higher)

Answer 7

DNA is a triplet code where 3 bases
code for one amino acid and the order of
amino acids determine the protein
produced

Question 8

What are enzymes?

Answer 8

Enzymes are biological catalysts that

speed up the rate of metabolic reactions

Question 9

Describe the structure of enzymes

Answer 9

Enzymes are proteins that contain an

active site that fits a specific substrate

Question 10

Describe the lock and key hypothesis

Answer 10

A substrate that fits the specific active
site of the enzyme binds, a reaction
occurs (catalysed by the enzyme) and
then the products are released

Question 11

State 4 factors that affect enzyme function

Answer 11

• Temperature
• pH
• Substrate concentration
• Enzyme concentration

Question 12

Describe the effect of temperature on the

rate of an enzyme-controlled reaction

Answer 12

• As the temperature increases, so does the rate of reaction
• Once the temperature exceeds the optimum, the enzyme
  denatures and the rate of reaction decreases