genetics

Question 1

what is F1

Answer 1

First Filial (F1) generation - offspring resulting from the monohybrid cross

Question 2

what is F2

Answer 2

Second Filial (F2) generation – offspring resulting from the self-fertilisation of the F1 generation

Question 3

How would you determine whether the mutation in each strain is dominant or recessive?

Answer 3

-cross each mutation fly with the wild-type, red strain (normal) fly and observe the phenotypes of the progeny (offspring)
-a dominant mutation is one that appears in a heterozygote
-If the progeny shows red eyes, the mutation is recessive (the mutated brown eyes did not show up and is therefore recessive to normal red eyes)
-if the progeny shows brown eyes, then the mutation is dominant over wild type

Question 4

How would you determine how many different genes are affected in the six mutant strains?

Answer 4

• Mutations in the same gene will produce brown-eyed (mutant) progeny and belong to the same complementation group (when crossed they have brown eyes which shows that both parents had the mutation in the same gene so they can be grouped into one complementation group)
• Mutations in different genes will produce red-eyed progeny and will belong to different complementation groups (if two brown eyed fly’s make a red eyed fly then the mutations are in different places and are in 2 complimentary groups)
  If progeny comes out wild type it shows mutations on different gene, if progeny comes out mutated then mutations in both parents is on the same gene

Question 5

How would you determine which mutants if any, are allelic?

Answer 5

Allelic mutations are those that are members of the same complementation group

Question 6

How would you determine whether any of these mutants are alleles of genes already known to affect eye colour?

Answer 6

Cross each mutant fly to known mutant flys of eye colour genes and test for complementation

Question 7

How would you determine how many different genes are affected in the six mutant strains?

Answer 7

• We perform a complementation test
• Make pairwise crosses and observe eye colour phenotype of F1s

Remember
* Mutations in the same gene: will produce brown-eyed (mutant) progeny
* Mutations in different genes: will produce red-eyed (wild type)

• We make groups based on the crosses that don’t give complementation
• Flies in a group carry same gene mutation e.g., flies A, F, D
• The number of different complementation groups = the number of genes affected!

Question 8

what is polygenic inheritance?

Answer 8

Polygenic inheritance: interaction between genes

Question 9

what is a factor?

Answer 9

a gene

Question 10

what is cytogenetics?

Answer 10

study of chromosomes

Question 11

what was morgans first prediction?

Answer 11

1st prediction = genes are on the same chromosome and linked

Question 12

when is linkage established?

Answer 12

when heterozygote is test crossed and deviation from 1:1:1:1 ratio

Question 13

what is oogenesis?

Answer 13

Oogenesis = growth process in which the primary egg cell (or ovum) becomes a mature ovum

Question 14

what is cytoplasmic inheritance?

Answer 14

Cytoplasmic inheritance = The inheritance of traits controlled by genes found in the cell cytoplasm rather than by genes on the chromosomes in the cell nucleus