Unit 2- Section 7 Evolving Antibiotic Resistance Flashcards
What is osmotic lysis and how does it work?
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
Describe how mutations cause antibiotic resistance
Mutations are changes in the base sequence of an organisms DNA. If a mutation occurs in the DNA of a gene it could change the protein and cause a different characteristic. Some mutations in bacterial DNA mean that the bacteria are not affected by a particular antibiotic anymore. They’ve developed antibiotic resistance
How is antibiotic resistance passed on?
One single resistance bacterium isn’t enough to cause disease or infection so the resistant gene must be passed on to other bacteria. There are two ways. Horizontal and vertical gene transmission
Describe vertical gene transmission
Vertical gene transmission is where genes are passed on during reproduction. Bacteria reproduce asexually. Each daughter cell is a clone of the parent cell- this means an exact copy of the parents cells genes, including any that give it antibiotic resistance. Genes for antibiotic resistance can be found in the bacterial chromosome or in plasmids. The chromosome and any plasmids are passed on to the daughter cell during reproduction. So antibiotic resistance is passed on from generation to generation
Describe horizontal gene transmission
Genes for resistance can also be passed on horizontally. This happens when two bacteria join together and a copy of a plasmid is passed on from one cell to the other. This process is called conjugation
Plasmids can be passed on to a number of the same species or a completely different species. The plasmid can then be passed on vertically leading to even more bacteria acquiring resistance
Describe natural selection
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, the number of indictable with the advantageous adaptations increases
- over generations this lead to evolution as the favourable adaptations become more common in the population
Explain the evolution of antibiotic resistance by natural selection
- some individuals in a population have alleles that give them resistance to an antibiotic
- the population is exposed to that antibiotic, killing bacteria without 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
If asked why species are common?
Identify the useful adaptation and explain how they have come common due to natural selection
Describe MRSA and antibiotic resistance
- became antibiotic resistant to nearly all antibiotics
- no new ones have been made
- deadly infection can cause death
- if in hospital isolated from other patients to minimise spread
- takes long time for doctor to figure out which antibiotic will work and this time could mean the patient dies
Describe tuberculosis and antibiotic resistance
- used to be deadly until correct antibiotic was invented
- now they are starting to mutate so have to take a mixture of antibiotics over a course of 6 months
- harder and harder to treat as natural selection is taking place
- could go back to being deadly
How do you use scientific knowledge to make decisions about antibiotic resistance?
Bacteria will develop antibiotic resistance by natural selection, it’s nature. But scientific research has shown that certain things can be done to slow down the natural process. People working in the public health sector, together with patients, have to be made aware of recent scientific findings so they can act upon them. For example washing hands
What are the ethical issues surrounding the use of antibiotics?
Antibiotics should only be used on life threatening situations to reduce the increase in resistantance. Opposition is people would spread the disease more
Animal testing
Terminally I’ll people shouldn’t have them
What are antibiotics used for?
Treat bacterial diseases. They are chemicals that either kill or inhibit the growth of bacteria. Different types of antibiotics kill or inhibit the growth of bacteria in different ways. Some prevent growing bacterial cells from forming the bacterial cell wall, which usually gives the cell structure and support. This can lead to osmotic lysis
