A.S Biology Unit 2.16.2 Antibiotics

aimee1234's version from 2015-04-11 09:46


Question Answer
What are antibiotics, what do they do and how do they do it?Anitbiotics 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.
Process of osmotic lysis?1.The antibiotics inhibit enzymes that are needed to make the chemical bonds in the cell wall. 2.This prevents the cell from growing properly and weakens the cell wall. 3.Water moves into the cells by osmosis. 4.The weakened cell wall can't withstand the increase in pressure and bursts (lyses).
How can mutations in bacterial DNA lead to antibiotic resistance?1.The genetic material in bacteria is the same as in most other organisms - DNA. 2.The DNA of an organism contains genes that carry the instructions for different proteins. These proteins determine the organism's characteristics. 3.Mutations are changes in the base sequence of an organism's DNA. 4.If a mutation occurs in the DNA of a gene it could change the protein and cause a different characteristic. 5.Some mutations in bacterial DNA mean that the bacteria are not affected by a particular antibiotic any more - they've developed antibiotic resistance.
What is methicillin and what is the problem with it?Methicillin is an antibiotic that inhibits an enzyme involved in cell wall formation. Some bacteria have developed resistance to methicillin, e.g. 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.
Describe the process of vertical gene transmissionVertical Gene Transmission is where genes are passed on during reproduction. 1.Bacteria reproduce asexually, so each daughter cell is an exact copy of the parent. 2.This means that each daughter cell has an exact copy of the parent cell's genes, including any that give it antibiotic resistance. 3.Genes for antibiotic resistance can be found in the bacterial chromosome or in plasmids (small rings of DNA found in bacterial cells) 4.The chromosome and any plasmids are passed on to the daughter cells during reproduction.

Recent badges