Biology AS AQA Unit 2 Adaption and Selection

Made these notes for my year 12 summer exam to revise and read over. There are spelling mistakes in most of my files but due to the busy exam schedule I had no time to correct them (sorry).

Most files have more information than what is needed but I feel it helps you feel more confident walking into the exam if you have a greater knowledge background and may help when having to apply knowledge to questions. Good luck :)

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  • Created by: Chelcie
  • Created on: 02-09-13 12:41
Preview of Biology AS AQA Unit 2 Adaption and Selection

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Adaptation and Selection
ADAPTATION
Organisms adjusting to suit their environment.
DIVERTSITY
Arises from changes in the DNA from genetic recombination and mutation.
MUTATIONS
Changes in DNA that result in different characteristics.
A difference in the base sequence may result in a different sequence of amino acids being coded
for.
Different amino acids will cause different polypeptides- hence a different protein or no protein at
all.
Proteins are responsible for the characteristics of an organism.
CONJUGATION
When one bacterial cell transfers DNA to another.
1. One cell produces a thin projection that meets another and forms a conjugation tube
between the two cells.
2. Donor cell replicates plasmid.
3. Circular DNA is broken to be linear to pass along the tube to recipient.
4. Recipient acquires new characteristic.
HORIZONTAL GENE TRANSMISSION
Transmission of gene from one species to another species.
VERTICAL GENE TRANSMISSION
Transmission of genes from one generation down to next in the same species.
DISCOVERING CONJUCATION...

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Each strain is unable to synthesize nutrients needed for growth.
STRAIN 1 ­ needed amino acid methionine, vitamin biotin.
STRAIN 2 ­ amino acid theromine and leucine needed.
They mixed the two strains of ecoli together with all the nutrients.
Bacteria was then removed by centrifugation and washed.
Then it was transferred to a medium without all supplements.
1/10000000 bacteria grew a colony, now having the ability to synthesise all nutrients.
HOW ANTIBIOTICS WORK
It prevents bacteria from forming cell walls.…read more

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