B1.2

Question 1

What is a chromosome?

Answer 1

Long strands of DNA in the nucleus

Question 2

What are genes?

Answer 2

Sequence of bases that codes for a sequence of amino acids that produce a protein
Determine characteristics

Question 3

What is the structure of DNA?

Answer 3

Made of 2 strands
Joined together by bases
Forms a double helix

Question 4

What is DNA made of?

Answer 4

Nucleotides which make up the polymer DNA

Question 5

What are nucleotides made of?

Answer 5

Sugar (deoxyribose)(pentagon)
Phosphate group (circle)
4 different bases (rectangle) (C,G,A,T)

Question 6

How do the bases bond?

Answer 6

Complementary base pairings are formed
C - G
A - T

Question 7

What is DNA?

Answer 7

Genetic material, that determines the characteristics of all living organisms
Contained in chromosomes

Question 8

What is protein synthesis?

Answer 8

How proteins are made
Proteins are made of amino acids

Question 9

What is transcription?

Answer 9

DNA cannot leave the nucleus as it’s too big so a copy of DNA is made called mRNA which a single strand of DNA

Question 10

How is mRNA made?

Answer 10

1) DNA unzips and one strand acts as a template
2) Complementary bases attach to the template to form mRNA
3) Uracil (U) replaces thymine (T)
4) When the mRNA is complete it detaches from the DNA template and the DNA zips back up

Question 11

What is the process of translation?

Answer 11

Where proteins are made
1) mRNA attaches to a ribosome which ‘read’ the nucleotides on the mRNA in groups of 3 (codons)
2) each codon codes for a different amino acid
3) as the amino acids are read they join together in a chain which is a protein

Question 12

How are proteins differentiated?

Answer 12

Sequence of amino acids determines how the protein folds
Each protein has a specific shape

Question 13

What are enzymes?

Answer 13

Made of proteins
Biological catalysts (speed up reactions without being used up)

Question 14

How do enzymes bind?

Answer 14

Substrate binds to the active site of the enzyme to form an enzyme-substrate complex
Only one type of substrate can bind to one type of enzyme

Question 15

What is the lock and key hypothesis?

Answer 15

Enzyme is a lock and substrate is the key
Only one key works

Question 16

What are some roles of enzymes?

Answer 16

Build larger molecules from smaller ones
Break down larger molecules into smaller ones

Question 17

What factors affect enzymes?

Answer 17

Temperature
pH
Concentration of enzymes and substrates

Question 18

How does temperature affect enzyme-controlled reactions?

Answer 18

At lower temperatures the enzymes work slower
Rate of reaction increases with increase in temperature
Optimum temperature is when the reaction works as fast as possible
Temperatures above the optimum mean the enzyme denatures (shape of active sit changes) and the reaction stops (substrate can’t bind to active site)

Question 19

How does pH affect enzyme-controlled reactions?

Answer 19

Change in pH affects the interactions between the amino acids in a chain
Enzyme may unfold or shape of active site may change (enzyme denatures)

Question 20

How does substrate concentration affect enzyme-controlled reactions?

Answer 20

Higher substrate concentration = faster rate initially
When all the substrate are bound to the enzymes that is the maximum rate
At the point of saturation the graph plateaus

Question 21

How does enzyme concentration affect enzyme-controlled reactions?

Answer 21

Higher enzyme concentration = faster rate of reaction
But substrate concentration becomes a limiting factor