Chapter 13

Question 1

SEQ morgens experiment (Traits were associated with specific chromosomes)

Answer 1

Used fruit flies: Many offspring and Wild type

P Gen: X^w+ X^w+ by X^w Y
F1 Gen: All Offpsring had Red Eyes (w+)
F2 Gen: Same as 3:1 Ratio, but all white eye flies were males

Males can’t carry recessive

Question 2

CC, HD sex chromosomes, sex linked traits (2)

Answer 2

Autosome
Sex Chromsome

Question 3

Autosome

Answer 3

Not sex chromo
22 Pairs of HC
Homo-morphic (same shape)

Question 4

Sex Chromosome

Answer 4

Determines Sex
Only one pair
Hetero-morphic (different shape)

Male = heterogametic
XY genotype

Female = homogametic
XX genotype

Question 5

Linked Gene vs X Inactivation

Answer 5

X Linked Gene

Males: carry only one X = hemizygous hemi=half
All alleles on X are expressed

Female: carry two X = homozygous
Recessive alleles cannot be masked.

X Inactivation

Barr Body
1 X randomly inactivated during embryonic development
Inactive x condenses → Inactivation involves DNA methylation and histone proteins

If a female cat is heterozygous (XAXa)
In some cells: XA is active
In others, Xa is active

Question 6

Violations of Independent Assortment

Answer 6

Linked Genes
Linked genes: are on the same chromosome
Linkage: genes being inherited together

Basically they don’t cross unlike in LOIA