Evolving Antibiotic Resistance

Question 1

What are antibiotics used for?

Answer 1

To treat bacterial diseases.

Question 2

What are antibiotics?

Answer 2

Chemicals that either kill or inhibit the growth of bacteria.

Question 3

How does osmotic lysis work?

Answer 3

• The antibiotics inhibit enzymes that are needed to make the chemical bonds in the cell wall.
• This prevents the cell from growing properly and weakens the cell wall.
• Water moves into the cell by osmosis.
• This causes the cell contents to expand, increasing the pressure on the cell wall.
• The weakened cell wall can’t withstand the increase in pressure and bursts.

Question 4

What is antibiotic resistance?

Answer 4

Some mutations in bacterial DNA mean that the bacteria are not affected by a particular antibiotic anymore.

Question 5

What are the two ways resistance can be passed on?

Answer 5

Vertical gene transmission

Horizontal gene transmission

Question 6

What is vertical gene transmission?

Answer 6

Where genes are passed on during reproduction to subsequent generations.

Question 7

How do bacteria reproduce?

Answer 7

Asexually- in other words, a single parent cell divides to produce two genetically identical daughter cells- it’s a clone- the same- including antibiotic resistance.

Question 8

What is horizontal gene transmission?

Answer 8

When two bacteria join together and a copy of a plasmid is passed from one cell to the other without need for reproduction- a process could conjugation.

Question 9

What is an adaptation?

Answer 9

A characteristic that enhances an organism’s chance of survival, e.g antibiotic resistance.

Question 10

How does natural selection work?

Answer 10

Individuals within a population show variation in their characteristics.
Predation, disease and competition create a struggle for survival.
Individuals with better adaptations are more likely to survive, reproduce and pass on their alleles that cause the adaptations to their offspring.
Over time, the number of individuals with the advantageous adaptations increases.
Over generations this leads to evolution.

Question 11

Give three similar categories of adaptations that increase chance of survival and why.

Answer 11

Streamlined body, camouflage, larger paws for running quicker etc- help to escape from predators.

Streamlined body, camouflage, larger paws for running quicker, larger claws etc- help to catch prey/get food.

Shorter/longer hairs, large ears, increased water storage capacity etc- they make the animal more suited to the climate.

Question 12

What is MRSA?

Answer 12

A strain of the S. aureus bacterium that has evolved to be resistant to a number of commonly used antibiotics, including methicillin.

Question 13

What is tuberculosis?

Answer 13

A lung disease caused by bacteria.

Question 14

What does MRSA stand for?

Answer 14

Methicillin-resistant Staphylococcus aureus.

Question 15

What illnesses can MRSA cause?

Answer 15

A range of illnesses from minor skin infections to life-threatening diseases such as meningitis and septicaemia.

Question 16

Describe the clinical problems associated with treating cases of MRSA infection.

Answer 16

Some strains are resistant to nearly all antibiotics.
Also, it can take a long time to determine if any antibiotics will kill the strain.
During this time the patient may become very ill or even die.

Question 17

Why did the number of patients dying from TB decrease in the UK?

Answer 17

The number of patients dying from TB decreased due to specific antibodies that killed the bacterium, and a vaccine that reduced the number of people catching TB.

Question 18

Describe the recent problems regarding the treatment of TB and the current solutions.

Answer 18

More recently some strains of TB have become resistant to antibiotics, so treatment has become more difficult, often involving a combination of antibiotics taken for about 6 months.
Also, multidrug-resistant strains are evolving quicker than drug companies can develop new antibiotics.