B2.7.2+3 Genetic variation and disorders Flashcards
Why does sexual reproduction give rise to variation?
When gametes fuse, one of each pair of alleles comes from each parent
What are the male and female sex chromosomes?
- Male is XY
- Female is XX
Define an allele
A version of a gene
What is a gene?
A small section of DNA
What does each gene code for?
A particular combination of amino acids which make a specific protein
“Everyone has unique DNA, including identical twins” True or False
False; everyone has unique DNA apart from identical twins
What physical features would a person with polydactyly have and is it recessive or dominant?
- Extra fingers or toes
- Dominant
What is cystic fibrosis a disorder of and is it recessive or dominant?
- A disorder of cell membranes
- Recessive
How can we find out if a baby will have a genetic disorder?
Embryo screening
Give three advantages of embryo screening
- Reduce number of people with the inherited disease
- Reduce health care costs
- Allows for the decision of termination
Give three disadvantages of embryo screening
- Possible risk to embryo
- Possible risk to mother
- Unethical or could go against religious beliefs
Why was the importance of Gregor Mendel’s discovery not recognised until after his death?
- He was not believed because he was a monk
- His findings were published in a journal that was not widely read by scientists
What was the idea that Mendel proposed and what was the experiment that he carried out?
- SEPARATELY INHERITED FACTORS
- He cross pollinated pea plants and recorded the results to work out which gene for colour was dominant
What did Mendel’s results prove?
That characteristics don’t blend
e.g. a red crossed with a white flower does not produce pink offspring
Mendel’s work preceded the work by other scientists. What did they do with the new information?
They linked the idea of inherited factors with chromosomes
