17.2 Monohybrid inheritance Flashcards
How would you draw a genetic cross diagram when you are given the symbols to be used. Eg if a single letter represents each characteristic
Eg if G is green and g is yellow
. The higher case letter represents the dominant feature, and the lower case letter is the recessive one
So G is green and g is yellow
. Represent the parents with the appropriate pairs of letters, so eg GG parent (green pod) with gg parent (yellow pod)
.State the gametes produced by each parent
So G G and g g are the 4 gametes
Make the table and put the gametes at the top and the side then find the combinations
The result should be 4 Gg offspring so they will all be green and heterozygous
What is monohybrid inheritance
It is the inheritance of a single gene, so the characteristic controlled by this
What did Gregor Mendel do
He studied monohybrid inheritance through looking at the colour of the pods of pea plants
These come in two colours, green and yellow
What would happen if pea plants with green pods were bred repeatedly together
. If they are repeatedly bred together they will consistently give rise to plants with green pods, so are pure breeding for the character of green pods
Pure bred strains can be bred for almost any character, so the organisms are homozygous (so they have two alleles that are the same) for that gene
What was the law of genetics that Mendel came up with
. In diploid organisms, characteristics are determined by alleles that occur in pairs.
Only one of each pair of alleles can be expressed in a single gamete
What happens if pure bred green-pod plants are crossed with pure bred yellow pod plants
(What mendel was researching)
All the offspring will produce green pods, so the allele for green pods must be dominant to the allele for yellow pods
Then, when the heterozygous offspring are crossed with one another, the offspring of those will always have the ratio 3:1 which is green : yellow
