Chapter 18; Epigenetics and Non-Mendelian Inheritance

Brooker et al. Biology Textbook McGraw Hill

Epigenetics

genes passed to offspring are altered not as a change in gene sequence, but as a change in gene expression (breaks rule #1)

vernalization

plants require exposure to cold temperatures to be able to flower

DNA methylation

methyl groups may be attached to cytosine or adenine bases in DNA, prevents expression of gene, regions of chromatin, or entire chromosomes by physically inhibiting their expression

genomic imprinting

segment of DNA is marked and the mark is retained and recognized throughout that organism’s life. Their eggs will have the mark, their sperm will not.

histone modification

condensed histones silences genes (methylation). open histones activates genes (acetylation)

honeybees royal jelly

inhibits DNA methylation, creates the queen

DNA methylation may be passed down across generations

true

Genomic Imprinting Expresses

Either mom or dad’s gene, but not both

X-chromosome inactivation

in embryonic development, one X chromosome is randomly inactivated in every cell to silence most of its genes

which gene is marked in mice, with only paternal gene expressed

Insulin-like growth factor 2

calico cats

depending on which X-chromosome is inactivated, the skin cells will be a different color

is a female is heterozygous for a gene on the X-chromosome, how will she present?

with the dominant phenotype

what is the small X-chromosome called

Barr body

what do the cells count to ensure there is only 1 X-chromosome?

X-inactivation centers

Which X-chromosome does the embryonic placenta express?

The maternal, lower risk of immune rejection of the embryo

What changes the color of the agouti mice?

Methylation of the agouti gene with diet of B vitamins

BPA

disrupts normal methylation patterns, may increase methylation in some regions and decrease in others.

Do mitochondria and chloroplasts rely on nucleus?

Yes, they need some of the genes made form the nuclear genes.

In Four O’Clock plants, who do they inherit their chloroplast genes from?

Maternal

where does the mitochondria get its DNA?

Maternally

In-vitro fertilization with three parents

one dad, mom 1 provides nucleus, mom 2 provides mitochondria

gene linkage

two genes that are close together on a chromosome are transmitted as a unit

linkage group

genes that usually stay together during meiosis

genetic mapping

the study of the arrangement of genes in a species’ genome

nonrecombinants

show combinations of traits observed in parental generation

recombinants

show combinations of traits not found in the parents

Thomas Hunt Morgan

studied linkage in flies

reciprocal cross

cross where sexes and phenotypes are reversed