Exam 2: X Chromosomes and Dosage Compensation Flashcards Preview

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Flashcards in Exam 2: X Chromosomes and Dosage Compensation Deck (12)
1

the number of copies of a gene usually corresponds to...

the amount of gene expression

2

does gene "dosage" matter?

yes, more is not better

3

male mammals get how many doses of the x chromosome?

a single dose (copy)

4

female mammals get how many doses of the x chromosome?

a double dose (two copies)

5

is the double dose of X in females a problem?

it would be if we didn't have dosage compensation

6

dosage compensation

shut down one copy of the x chromosome in females so both sexes only have one active X

equalizes effect of x-linked genes in males/females

7

in placental mammals when does random x-inactivation occur in females?

early in development

8

what happens in random x-inactivation?

one or the other of the two X chromosomes is shut down and becomes a barr body

9

barr body

an X chromosome that is high condensed, inactivated, and late-replicating

10

is x-inactivation in females a way of shutting off bad genes?

no, it is a random process

11

female mammals have ____ due to sex-linked genes

mixed phenotypes

every female mammal is an "x-chromosome expression mosaic"

12

dosage compensation in fruit flies

doubling output of the x in males equalizes the effect of x-linked genes in males/females