1.1.2 - 1.1.4

Question 1

What is nucleosome

Answer 1

DNA + histone octamers

Question 2

How many core proteins and histones, what type, how many of each

Answer 2

4 core proteins, 8 core histones + 1 linker histone, core histone types: H2A, H2B, H3, H4, 2 of each type of core histone, H1 or H5 linker histone

Question 3

How can histones be modified to regulate DNA expression

Answer 3

Methylation, acetylation, phosphorylation to regulate DNA expression when RNA polymerase binds onto DNA

Question 4

DNA order?

Answer 4

DNA>beads on a string>30nm fiber>loop (75000bp)>Rosette (6 loops)>Coil (30 rosettes)> Chromatids (x2) (2 coils each)

Question 5

Regulation of gene expression by transcription factors?

Answer 5

1) transcription factors expressed > 2) Transcription factors bind to particular DNA sequences within promoter region of DNA >3) transcription factors determine if gene is expressed or not OR whether RNA polymerase will bind to form proteins

Question 6

Uses for DNA methylation? How is the effect of methylation on different sequences?

Answer 6

silencing retroviral elements, regulating tissue-specific gene expression, genomic imprinting, X-chromosome inactivation, different depending on gene sequence (but mainly silences genes)

Question 7

How can methylation promote gene expression

Answer 7

Methylation to C nucleotide of DNA > prevents CTCF (a protein) from binding to insulator sequence > turns insulator off > allows enhancers to bind to promoter

Question 8

How does mediator control gene expression? Its effect?

Answer 8

Brings together several transcription factors which directly bind to mediator protein > Mediator binds to RNA controlling gene transcription, can be enhancer or silencer