Chapter 16: Transmission of Genetic Information from Parents to Offspring II Flashcards
The Mendelian inheritance patterns follow three general rules. What are they?
16.1
- except in the case of rare mutations, genes are passed unaltered from cell to cell, and from generation to generation
- the genes obey Mendel’s law of segregation
- for crosses involving two or more genes, the genes obey Mendel’s law of independent assortment
Define epigenetic inheritance.
16.1
modification of a gene or chromosome during gamete formation that alters a gene’s expression but does not change the DNA sequence
Which phenomenon describes the presence of two genes very close to each other on the same chromosome, and which are transmitted together as a unit?
16.6
linkage
Epigenetics is the study of?
16.1
mechanisms that lead to changes in gene expression that can be passed from cell to cell, are reversible, but do not involve a change in the sequence of DNA
What are some common types of molecular changes that can have an epigenetic effect that alters gene expression?
16.1
DNA methylation, chromatic remodeling, covalent histone modification, and localization of histone variants
The phenomenon where offspring express a paternal or maternal allele depending on how a particular gene is marked is known as what?
16.2
genomic imprinting
T or F: A gene can be marked by females during egg formation and by males during sperm production.
16.2
false; either or, not both
Do imprinted genes follow a Mendelian pattern of inheritance?
16.2
No
What is the function of the Igf2 imprinted gene?
16.2
it encodes a growth hormone called insulin-like growth factor 2; the mutation (Igf2-) blocks the function of the hormone
Individuals may have the same genotype but very different phenotypes as a result of what?
16.2
genomic imprinting
What serves as the marking process that occcurs during the imprinting of certain genes including Igf2?
16.2
DNA methylation
Genomic imprinting refers to the:
16.2
marking of DNA so that the phenotype of the offspring depends on the parental origin of the gene
What is the function of DNA methylation in genomic imprinting?
16.2
it silences gene expression by inhibiting the initiation of transcription or by causing the chromatin in a region to become more compact
Draw a diagram of genomic imprinting via DNA methylation in both females and males! :)
16.2
A male mouse that is homozygous for the functional allel of the Igf2 gene is mated to a female that is heterozygous, carrying one functional copy and one mutant (nonfunctional) copy of the gene. What would be the expected outcome of this cross?
all normal size offspring (paternal allele is expressed)
In the somatic cells of female mammals, the genes on one fo the two copies of the X-chromosome are not expressed. This phenomenon is known as?
16.3
X-chromosome inactivation