B2 - Genetic Variation Flashcards
Why is the fact that everyone has different DNA useful?
We can identify people with DNA traces
An example of this is in a crime scene
What is a genetic fingerprint?
The pattern in the traces of our DNA which is identified at a crime scene
What is an allele?
The different variations that you can have of 1 gene
For example, an allele of the gene for eye colour could be brown eyes
What does dominant mean?
If a dominant allele is present, the result will be that allele
What does recessive mean?
Both alleles have to be recessive if the result is going to be recessive
What is the difference between homozygous and heterozygous?
Someone who is homozygous has two of the same allele (bb for example)
Someone who is heterozygous has 2 different alleles for one gene (Bb for example)
What is the 23rd pair of chromosomes?
Sex chromosomes
They decide your sex
What are the sex chromosomes that make a boy or girl?
Boy has XY
Girl has XX
What is a Punnett square?
A table that shows every possible outcome of alleles
Similar to genetic diagrams
Why do we have DNA?
It contains code for specific proteins to be made
What did Mendel do?
He crossed 2 purple flowered plants until he was sure he had a pure-breeding purple plant
He did the same with white flowered plants
When he crossed a purple flowered plant and a white flowered plant, all the plants that came from this cross had purple flowers
When he allowed these plants to self-pollinate, white flowered plants reappeared at a 1:3 ratio
What 3 things did Mendel conclude from his results?
Characteristics in plants are determined by hereditary units (what we call genes)
Hereditary units are passed on from both parents with one unit from each
Hereditary units can be dominant or recessive and if an individual has a dominant and a recessive together, the dominant characteristic will be expressed
What is monohybrid inheritance?
Where a characteristic of a living thing is only decided by one gene
What is pure-breeding?
When the 2 parents have characteristic in common and this characteristic is passed to the offspring
