Unit 3.2.10 - Genetic Variation in Bacteria

Question 1

What does DNA contain and what does that code for in bacteria?

Answer 1

It contains genes which code for proteins

Question 2

How can a bacteria become resistant to antibiotics?

Answer 2

Mutations means there are changes in the base sequence of DNA, if this mutation occurs in a gene it can alter which protein it codes for, leading to new characteristics, this new characteristic may mean the bacteria isn’t affected by antibiotics and so is antibiotic resistant

Question 3

What two ways can genes for antibiotic resistance be passed on?

Answer 3

Vertical gene transmission and horizontal gene transmission

Question 4

What is horizontal gene transmission also called?

Answer 4

Conjugation

Question 5

Where would the genes for antibiotic resistance be found in a bacterial cell?

Answer 5

In the bacterial chromosomes or in plasmids

Question 6

Describe what happens during vertical gene transmission?

Answer 6

The bacteria produce by binary fission, producing two genetically identical daughter cells, which each have an exact copy of the parent cells genes including any antibiotic resistance it may have

Question 7

What are the four steps in horizontal gene transmission?

Answer 7

1. ) The plasmid containing the antibiotic resistance gets copied
2. ) A tiny thread of cytoplasm called a pilus connects two bacterial cells
3. ) One of the plasmid copies is passed to the other bacteria
4. ) This means both of the bacterial cells now have the antibiotic resistant gene

Question 8

Name one way antibiotics can treat bacterial diseases?

Answer 8

By preventing the formation of bacterial cell walls - leading to osmotic lysis

Question 9

Give the five steps that antibiotics lead to osmotic lysis?

Answer 9

1. ) antibiotics inhibit enzymes that are needed to make chemical bonds in the cell wall
2. ) This weakens the cell wall
3. ) Water moves into the cell by osmosis
4. ) Causing the cell to expand increasing the pressure on the cell wall
5. ) The weakened cell wall can’t withstand the increase in pressure and bursts.

Question 10

Can horizontal or vertical gene transmission be done inbetween species?

Answer 10

Horizontal

Question 11

Give an example of a bacteria that has developed a resistance to antibiotics

Answer 11

MRSA

Question 12

Why is MRSA resistant to antibiotics?

Answer 12

It contains a mutated gene which produces an altered enzyme which the methylcillin no longer recognises and so can’t inhibit, the bacterial cell wall can form a normal wall and so isn’t affect by osmotic lysis

Question 13

Why are patients with MRSA isolated from other patients?

Answer 13

So it can’t spread in a hospital

Question 14

Give two diseases MRSA can cause

Answer 14

Meningitis and skin infections

Question 15

How do health workers prevent the spread of MRSA?

Answer 15

Wash their hands with antiseptic gel

Question 16

How do doctors prevent MRSA?

Answer 16

Only prescribe antibiotics when necessary so the bacteria doesn’t become resistant to all types of antibiotics

Question 17

Other than MRSA what other bacteria has recently become resistant to antibiotics?

Answer 17

TB

Question 18

Give three steps during natural selection?

Answer 18

1. ) Individuals within a population show variation in their characteristics due to gene mutations
2. ) Individuals with better adaptations are more likely to survive, reproduce and pass on the alleles
3. ) Over time the allele frequency within the population increases - this is evolution.

Question 19

What is an adaptation?

Answer 19

A characteristic that increases an organisms chance of survival

Question 20

What is an example of natural selection?

Answer 20

Antibiotic resistance

Question 21

Give the four steps in how antibiotic resistance bacteria can show natural selection.

Answer 21

1. ) Individuals within a population show variation in their characteristics due to gene mutations
2. ) The mutation may mean the allele gives them resitance to antibiotics
3. ) If the population is exposed to the antibiotic only the resistant bacteria will survive and reproduce passing on the allele
4. ) This increases the allele frequency for the antibiotic resistance.

Question 22

Give three reasons why an adaptation can increase an organisms chance of survival?

Answer 22

1. ) can escape from predators better
2. ) can catch prey better
3. ) more suited to a climate

Question 23

Give four steps in an experiment that tests the effectiveness of an antibiotic?

Answer 23

1. ) grow a sample of bacteria on the agar plate
2. ) soak paper disk in different samples of antibiotics and one in sterile water (for a control) and place onto the plate
3. ) allow the bacteria to grow and the measure the size of the inhibition zone
4. ) the larger the zone the more effective the antibiotic

Question 24

What is the inhibition zone?

Answer 24

The clear patch where the bacteria hasn’t grown

Question 25

Give a reason for and against only using antibiotics in life threatening situations?

Answer 25

For - reduces the risk of resistance

Against - more people will get ill have to take more time off work reducing peoples standard of living

Question 26

Give a reason for and against giving antibiotics to people with dementia?

Answer 26

For- every has the right to medication

Against - they could forget to take them increasing the risk of resistance

Question 27

Give a reason for and against antibiotics to animals?

Answer 27

For - stops unnecessary suffering to animals

Against - increased risk of resistance