Transcript Genetics revision for learners

Starter:
DNA
This is a chromosome and a gene. Describe
how an allele and DNA fit into this picture
Do you have this??
Cells and mitosis
Dalmations
In Dalmations black spots are dominant over brown spots.
Jordan picks up a black spotted one from the Silverdale shelter. He thinks the coat
colour is perfect and decides he could make some money breeding her. Most people
prefer black spots. How would he figure out if the dog was homozygous or
heterozygous for its black spots?
This is a test cross. Any time you get a problem like this the answer is ALWAYS the same.
Breed it with a homozygous recessive one
What is variation?
Independent Assortment Revision
Crossing Over
Explain how independent assortment and crossing over lead to an increase in variation
The answer to most variation questions
Meiosis produces gametes with half the number of chromosomes. This means that pairs of alleles
are separated at meiosis. During meiosis matching chromosomes cross over (swap sections of the
chromosome) which adds variation. Independent assortment also increases variation as the
chromosome pairs randomly line up and then separate
At fertilisation, which sperm fertilise which egg is due to chance and this results in new combinations
of alleles.
The advantage of variation to a species is that it may enable some individuals to survive if some
threatening event occurs. For example, if a new disease arrives, not all individuals will be wiped out