B1.2 What Happens In Cells

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

Answer 5

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

Question 6

Describe translation

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?

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