Antibiotic Action And Resistance UNIT 2

Question 0

What are antibiotics

Answer 0

Chemicals that either kill or inhibit the growth of bacteria

Question 1

What are antibiotics used for

Answer 1

Treating bacterial diseases

Question 2

Example of how an antibiotic can work

Answer 2

Prevent growing bacterial cells from forming the bacterial cell wall, which usually gives the cell structure and support. This can lead to osmotic lysis

Question 3

What are the steps involved osmotic lysis

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 cell wall

Water moves into the cell by osmosis

The weakened cell wall can’t withstand the increase in pressure so bursts

Question 4

Mutations in bacterial DNA can cause…..

Answer 4

Antibiotic resistance

Question 5

The genetic material in bacteria is the same as…..

Answer 5

Most other organisms

Question 6

What are mutations

Answer 6

Changes in the base sequence of an organisms DNA

Question 7

What happens if a mutation occurs in the DNA of a gene

Answer 7

It could change the protein and cause a different characteristic

Question 8

The DNA of an organism contains….

Answer 8

Genes that carry the instructions for different proteins. These proteins determine the organisms characteristics

Question 9

Some mutations in bacterial DNA mean that bacteria are not affected by…..

Answer 9

A particular antibiotic anymore so they have developed antibiotic resistance

Question 10

What is methicillin

Answer 10

An antibiotic that inhibits an enzyme involved in cell wall formation. Some bacteria have developed resistance to methicillin, eg MRSA. Usually, resistance to methicillin occurs because the gene for the target enzyme of methicillin has mutated. The mutated gene produces an altered enzyme that methicillin no longer recognises, and so can’t inhibit.

Question 11

Antibiotic resistance can be passed on….

Answer 11

Vertically or horizontally

Question 12

Describe how resistance to an antibiotic arises in bacteria

Answer 12

A mutation occurs in the DNA of a bacterium. If the mutation occurs in a gene it may alter the protein that gene codes for, which may make the bacteria resistant to an antibiotic

Question 13

Describe how resistance to antibiotics is spread between two bacteria

Answer 13

By horizontal gene transmission. The 2 bacteria join together by a process called conjugation and a copy of a plasmid carrying a gene for antibiotic resistance is transferred from one cell to the other

Question 14

Penicillin is a cell wall inhibitor antibiotic. Explain how penicillin kills bacteria.

Answer 14

Penicillin inhibits an enzyme involved in making the bacterial cell wall. This prevents cell wall formation in growing bacteria and weakens the wall. Water moves into the cell by osmosis. The weakened cell wall can’t withstand the increased pressure so bursts, killing the bacterium

Question 15

What is horizontal gene transmission

Answer 15

Genes for resistance passed horizontally. Two bacteria join together in a process called conjugation and a copy of the plasmid is passed from one cell to the other. Plasmids can be passed on to a member of the same or different species

Question 16

What is vertical gene transmission

Answer 16

Bacteria produces daughter cells that are identical to parents. Means each daughter cell has an exact copy of parents cell’s genes, including any that give it antibiotic resistance. Genes for antibiotic resistance can be found in bacterial chromosome or in plasmids. The chromosome and any plasmids are passed on to the daughter cells

Question 17

What is a plasmid

Answer 17

A small ring of DNA found in bacterial cells

Question 18

Bacterial populations evolve antibiotic resistance by….

Answer 18

Natural selection

Question 19

Adaptations are caused by…

Answer 19

Gene mutations

Question 20

What does natural selection cause

Answer 20

An adaptation (like antibiotic resistance) to become more common in a population

Question 21

Explain natural selection

Answer 21

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 the alleles that cause the adaptations to their offspring. Over time, number of individuals with advantageous adaptations increases. Over generations this leads to evolution as the favourable adaptations become more common in the population

Question 22

How do populations of antibiotic resistant bacteria evolve by natural selection

Answer 22

Some individuals in population have alleles that give them resistance to an antibiotic

The population is exposed to that antibiotic, killing bacteria without the antibiotic resistance allele

The resistant bacteria survive and reproduce without competition, passing on the allele that gives antibiotic resistance to their offspring

After some time most organisms in the population will carry the antibiotic resistance allele.

Question 23

Antibiotic resistance makes it difficult to treat…..

Answer 23

Some diseases

Question 24

Diseases caused by bacteria are treated using ……….. Because bacteria are becoming ……….. to different antibiotics through ………………. it’s becoming more difficult to treat some bacterial infections such as ……….. and ………..

Answer 24

Antibiotics

Resistant

Natural selection

TB

MRSA

Question 25

Info on TB due to antibiotic resistance

Answer 25

TB is lung disease caused by bacteria, was once a major killer in UK but numbers of people dying from it has decreased with development of specific antibiotics that killed the bacterium. Also dropped due to vaccine. More recently, some populations of TB bacteria have evolved resistance of the most effective antibiotics. Natural selection has led to populations that are resistant to a range of different antibiotics- the populations are multidrug resistant. To try to combat this a combination of antibiotics are taken over 6 months. TB becoming harder to treat as multidrug resistant strains are evolving quicker than drug companies can develop new antibiotics

Question 26

Info on MRSA due to antibiotic resistance

Answer 26

Evolved to become resistant to number of commonly used antibiotics including methicillin. Causes minor skin infections to life threatening diseases such as meningitis. Major problem is that Some strains are resistant to nearly all the antibiotics that are available. Also can take a long time for clinicians to determine which antibiotics, if any, will kill the strain each individual is infected with. During this time the patient may become very ill or even die. Drug companies are trying to develop alternative ways of treating MRSA to try to combust the emergence of resistance

Question 27

A bat has a very long tongue. This enables the bat to feed on the nectar inside flowers. Describe how natural selection can explain the evolution of such a long tongue

Answer 27

Some bats in the population will carry a mutation for a longer tongue. The bats with longer tongues will be able to feed from the flowers and so will be more likely to survive, reproduce and pass on their alleles. Over time, this feature will become common in the population

Question 28

Ethical issues surrounding the use of antibiotics

Answer 28

Some argue they should only be used in life threatening situations to reduce the increase in resistance. Others argue against this as people would take more time off work for illness, reduce people’s standard of living, could increase incidence of disease, could cause unnecessary suffering.

Argue doctors shouldn’t prescribe antibiotics to those suffering from dementia, as they may forget to take them, increasing chance of resistance developing. Some argue all patients have right to medication

Some argue terminally ill shouldn’t receive antibiotics as they’re going to die. But withholding them from patients could reduce their length of survival and quality of life.

Argue animals shouldn’t be given antibiotics, as increases antibiotic resistance . Others say could causes unnecessary suffering to animals