Pedigrees & Mitosis (unfinished)

In an X-linked dominant inheritance pattern, affected males will pass the trait to 50% of their daughters. True or False?

False!

1. Daughters must get an X chromosome from their father and mother

2. If the trait is X-linked dominant, the daughter will have the trait

In an autosomal recessive disorder, males and females are affected in roughly equal numbers. True or False?

True!

1. autosomal - body cells

2. gender is irrelevant

If the trait in the pedigree presented shows an autosomal recessive mode of inheritance, what is the genotype of individual 1?

Could the trait presented in the pedigree shown be caused by an X-linked recessive allele? Why or why not?

Yes, all individuals fit the X-linked recessive inheritance pattern

1. If it was X-linked dom., 8 and 9 would have it from #3

2. if it was autosomal dom. #8, #9 and #10 would have it as well as #1 and #2

3. If it was autosomal rec.,

In the pedigree shown, the indicated trait is most likely caused by what type of allele?

X-linked dominant

1. first clue is if the parent has it, all the daughters have it

Tunas have an XY genetic sex determination system. If there are 24 chromosomes in a tuna gamete, how many autosomes are there in each somatic cell of a female tuna?

46!

1. gamete = sex cell = haploid therefore haploid # = n = 24

2. autosomes = non-sex related chromosomes (X/Y)

3. total somatic chromosomes = 2n = 48

4. 48 - autosomes = 48 - 2 = 46

In a diploid cell where 2n = 12, how many chromatids would you expect in a cell during metaphase of mitosis?

24!

1. diploid = replicated chromosomes = (X shaped chromosomes)

Suppose this is a karyotype of one individual human. What is unusual here?

This individual has 2 extra sex chromosomes

In Drosophila flies, which combinations of sex chromosomes would result in a male fly?

• Y chromosome only

Which of the following does not happen during mitosis?

1. chromosomes replicate

2. the nuclear membrane re-forms

3. chromosomes align on the metaphase plate

4. the nuclear membrane breaks down

1. chromosomes replicate

• this happens in interphase

• do not confuse for the chromosome condensation in prophase I

Which one is part of the chromosome?

1. centriole

2. centrosome

3. centromere

centromere