Genetics Quiz 5

Exon

the part of the sequence that gets left behind and spliced together

Intron

the part of the sequence that gets spliced out

Consensus site for splicing

conserved DNA or RNA sequences at the boundaries of introns that signal where splicing occurs

Self-splicing

introns that splice themselves, happens because RNA acts as a ribozyme and splices itself out

1. 3’ splice site mutation → exon is skipped

2. 5’ splice site mutation → splicing won’t begin, intron retention

3. New splice site (frameshift mutation) → splicing begins at the wrong spot

Name 3 effects that mutations could have on splicing

• Familial growth hormone deficiancy (dwarfism)

• Retinitis pigmentosa

Give two examples of diseases that involve splicing

TFIID

Which protein binds the TATA box in eukaryotes?

The TATA box recruits RNA polymerase 2 and the GTFs

What happens after the protein binds the TATA box in eukaryotes?

released after the open complex forms and most of the GTFs fall off

How is the RNA Polymerase released in eukaryotes?

Silencer

regions of DNA that bind repressors

Enhancer

regions of DNA that bind activators

TFIID

the protein in eukaryotes that binds to the TATA box

Eukaryotic mediator

interacts with regulatory factors and mediates these reactions

1. Binding of a small effector molecule

2. Protein-protein interactions

3. Covalent modification

Name 3 ways that transcriptional regulators (activators and repressors) can be
controlled

Cortisol

Give an example of hormonal regulation in eukaryotes

Change in position of histones

displaced from the DNA template by RNA polymerase II (Pol II) to allow the polymerase to pass through the nucleosome

Addition/removal of histones

regulates gene expression and other DNA-based processes by altering the interaction between DNA and histones

CHIP-seq

uses a specific antibody to isolate DNA fragments bound to a target protein, such as a transcription factor or modified histone, from a cell

Acetylated histone

binds DNA loosely since it has an acetyl group attached

Deacetylated histone

bind DNA tightly since there is no acetyl group attached

1. Prevents proteins from binding to the promoter, causes less gene expression

2. Prevents repressors from binding, causes high gene expression

Name two ways methylation affects gene expression

Combinatorial control

Each cell has multiple ways to be expressed