Chapter 21 Flashcards
(11 cards)
- Define epigenetics
Inheritance of variation that isn’t related to DNA sequences
- Describe how DNA methylation alters chromatin structure
Causes chromatin to become more tightly packed, lowering the rate of transcription
. Define CpG islands and know where these are located**
Regions with a lot of C and G nucleotides that are connected via phosphate groups, usually near promoters
Understand how DNA methylation is stably maintained through DNA replication
Once DNA strands are replixated, methyltransferase sees where methyl groups are added to template strand and fills them in on the new strand
. List 3 ways that DNA methylation represses transcription
*
Methylation inhibits binding of transcription factors
* Methylated cytosine attracts proteins that repress transcription
* Methylation attracts histone deactylases
Explain how histone modifications alter chromatin structure, specifically methylation and acetylation of
Histones
Acetylation- destabilizes chromatin structure, causing more transcription.
Methylation- Can increase or decrease transcription by adding methyl groups
- Know that histone modifications are/are not maintained across cell divisions
are
- Give an example of how RNA molecules alter chromatin structure with respect to X inactivation
It coats the inactive chromosome, which recruits proteins that methylate the chromosome, inactivating it
- Explain the statement “epigenetic changes are responsible for cell differentiation.”
Transcription factors are responsible for what type of cell a stem cell grows into
- Define genomic imprinting (Fig 21.12)
Where the expression of an allele determines on which parent it is inherited from- certain alleles may oonly be expressed if they’re from the male/female parent
- Define imprinted gene and explain how it gets imprinted
A gene whose expression depends on which parent it was ingerited from- different degrees of methylation of alleles inherited from each parent
