Genetics 💊 Flashcards
What does recessive mean
2 recessive alleles are required for the phenotype to be shown
What does dominant mean
Only one dominant allele is required for the phenotype to be show
What is a genome
All the possible dna in an organism
What did mendel discover
Gregor Mendel discovered the basic principles of heredity through experiments with pea plants. Mendel showed that when two varieties of purebred plants cross-breed, the offspring resembled one or other of the parents, not a blend of the two.
Why was Mendels work not accepted straight away
Because scientists couldnt see how his factors could explain the wide variation in characteristics such as eyecolour.
Nor can they see how his ideas could explain Dawin’s theory of evolution
What were the two conclusions Mendel reached
‘Factors’ are not changed when they are passed on
The fact that there are dominant and recessive alleles
What is the purpose of the human genome project
To work out to the DNA code for human life to make them accessible to futher biological study
What is genetic screening
Screening process to identify an unusual gene that may be passed on to offspring (wether someone is a carrier)
What is an advantage of genetic screening
Gives parents knowledge as to whether they are carriers of a disease and could pass it on to their children
Give one disadvantage of genetic screening
Concern is that it will result in intolerance to people with a disease
What is genetic variation
Different characteristics as a result of a mutation and sexual reproduction
What is environmental variation
Characteristics caused by an organisms environment
What is continuous variation
Involves values that can change gradually e.g. height (produces a bell shaped normal distribution)
What is discontinuous variation
Involves discrete options
How should you draw a graph showing continuous variation
All bars touch
