Chapter 18 Flashcards
When genes are altered because of epigenetics, is the DNA sequence changed?
This alteration does not change the DNA sequence of a gene but, instead, alters the structure of chromatin and thereby affects the gene’s expression.
One definition of epigenetics:
The study of mechanisms that lead to changes in gene expression that can be passed from cell to cell and are reversible, but do not involve a change in the sequence of DNA.
epigenetic inheritance:
An epigenetic change that is passed from parent to offspring. An example is genomic imprinting.
genomic imprinting:
A phenomenon in which a segment of DNA is imprinted, or marked, during egg or sperm formation in a way that affects gene expression throughout the life of the individual who inherits that DNA.
X-chromosome inactivation (XCI):
A process that causes an X chromosome to become highly compacted and silences the genes that it carries.
What is a Barr body?
A highly condensed X chromosome present in the cells of female mammals.
extranuclear inheritance:
In eukaryotes, the transmission of genes that are located outside the cell nucleus.
maternal inheritance:
A phenomenon in which offspring inherit particular genes only from the female parent (through the egg).
Do all epigenetic changes get passed on to offspring?
Epigenetics is the study of mechanisms that lead to changes in gene expression that can be passed from cell to cell and are reversible, but do not involve a change in the sequence of DNA. Not all epigenetic changes are passed from parent to offspring. For example, a cigarette smoker could acquire an epigenetic change in a lung cell; this change would not be passed to offspring.
