B1.2 What happens in Cells

Question 1

State the role of DNA in the body

Answer 1

DNA is the substance that contains all the instructions that determine your characteristics

Question 2

What is a chromosome? How many do humans have?

Answer 2

A long molecule of DNA

46

Question 3

§What are genes?

Answer 3

Short sections of DNA that code for a characteristic, such as eye colour

Question 4

How many strands is DNA made up of? What shape is DNA using the strands

Answer 4

2 strands

The 2 strands are twisted together to form a double helix

Question 5

What are the 4 base pairings? Which base links with the other?

Answer 5

Adenine, Thymine, Guanine, Cytosine

Adenine links with Thymine : Guanine links with Cytosine

Question 6

What is each nucleotide made up of?

Answer 6

sugar molecules (deoxyribose)
Phosphate
1 base

Question 7

Why is DNA a polymer?

Answer 7

The small units of nucleotides are joined together

Question 8

What are enzymes made of?

Answer 8

Protein

Question 9

Enzymes are biological catalysts. What does this mean?

Answer 9

Biological catalysts speed up a reaction without being used up themselves.Oncea reaction is finished they can be used to catalyse the same type of reaction again.

Question 10

What do enzymes do? (2)

Answer 10

Build larger molecules from smaller ones, such as protein synthesis.
Break down large molecules into smaller ones, such as in digestion.

Question 11

What is an ‘active site’

Answer 11

An active site is part of an enzyme that binds to the substrate. It has a specific shape which is formed by the way its amino acids are folded togther within the protein.

Question 12

Can enzymes bind to all molecules? Explain why/why not?

Answer 12

No as enzymes are highly specific.

This means they can only bind to one type of substrate molecule.

The substrate must fit exactly into the active site.If it does not, the molecule cannot bind.

Question 13

What is formed when a substrate binds to an enzyme?

Answer 13

enzyme-substrate complex

Question 14

What 2 factors affect enzymes?

Answer 14

pH and temperature

Question 15

How does temperature affect enzyme reactions?

Answer 15

Higher temperature will increase the movement of enzyme and substrate molecules which will collide more often allowing the enzyme to react quicker.

If temperatures are too high then an enzyme will denature (stop working)

Question 16

how does pH affect enzyme reactions?

Answer 16

Different enzymes work quicker in more acidic or more alkaline parts of the body

Question 17

how does substrate or enzyme concentration affect enzyme reactions?

Answer 17

The higher the substrate concentration is, the faster the rate of reaction.
At a certain concentration, all enzyme molecules, are bound to substrate molecules and the rate of reaction will be at its maximum.
Any further increase in the number of substrate molecules will not increase the rate of the reaction as there are no enzymes for them to bind to

Question 18

|
| ___ -What is this direct drop
| / |
| / |
| / |
|/______________

Answer 18

Substarate used up

Question 19

Rate | What does this point mean?
Of | /
Reaction | ___________
| /
| /
|/_______________

                    Substarte concentration

Answer 19

Point of saturation

Question 20

Place in size order: gene, chromosome, genome, DNA, nucleus, cell, nucleotide

Answer 20

Nucleotide (smallest)

Gene

DNA

Chromosome

Genome

Nucleus

Cell (largest)

Question 21

What is DNA?

Answer 21

DNA is deoxyribose nucleic acid, the genetic material found within the nucleus of every one of your cells.

Question 22

Name the protein that DNA coils around in the formation of a chromosome

Answer 22

Histone proteins

Question 23

Who produced the first ever photograph of DNA, ‘photo 51’, that led to the discover of DNA’s structure.

Answer 23

Rosalind Franklin

Question 24

What is the name of the weak bonds formed between bases of opposing strands of DNA?

Answer 24

Hydrogen bonds

Question 25

Name the two main stages of protein synthesis

Answer 25

Transcription

Translation

Question 26

Where does protein synthesis take place

Answer 26

Transcription - starts in the nucleus, and ends when the mRNA strand leaves through the nuclear pore to towards the ribosomes

Translation - In the cytoplasm with the assistance of ribosomes