Bio 220 Exam 3 UNC

3 levels o f gene expression regulation- prokaryotes

Transcriptional control Translational control Post-translational control

8 levels of gene expression regulation in eukaryotes

Regulation of chromatin remodeling Regulation at the transcriptional level Regulation of splicing and processing Regulation of transport Degradation of mRNA Translation regulation Protein modification

CREs

cis-regulatory elements

ex of cis regulatory elements

silencers

When histone tails are acetylated

does transcription increase or decrease? Explain

difference between nucleosomes and histones

Nucleosomes are multiple histones plus the chromatin

2 ways in which chromatin can be remodeled

acting on nucleosomes or DNA

where are transcriptionally active genes located

histones

Mediators

help decide how genes bend

three examples of three different levels of expression regulation that take place at the post-transcriptional level

1. Modification of nuclear RNA trancripts 

2. Splicing 

1. Protein modification

dosage compensation

genetic mechanism that equalizes the levels of expression at loci on the X chromosome. 

Barr Body

a body of inactive sexual dna typically X. when x is inactivated it will be confined to a barr body.  

True or False & Explain: Both XCI and parent-of-origin imprinting are examples of monoallelic expression

True XCl is inactivation of an X chromosome and parent of origin is slidenting specific autosomal cells based on which parent they came fromexpression of one of the alleles while suppressing the other based on genomic imprinting.

gene construct

an artificially designed piece of DNA that is made of specific gene elements like

a promoter and coding sequence that can be used to control how a gene is expressed like where it

is located and when it will be expressed in vitro.

Why is GFP used to assist in protein localization studies

GFP glows under specific light so then when it is attached to a protein, researchers can visually track where the protein is located in the cell

restriction enzyme recognition site

a short DNA sequence that a restriction enzyme binds

to. It cuts DNA at the site, which produces fragments.

what does a restriction enzyme recognize

double stranded DNA

mitotic inheritence

Transmission of genetic material from one cell division to the next, within a single organism (e.g. a person growing

meiotic inheritence

Transmission of genetic material from one organism to the next (transgenerational) via sexual reproduction

5’-CpG-3’ Methylation

5’-CpG-3’ methylation involves the addition of a methyl group to the cytosine base of a CpG dinucleotide at the 5' end of a DNA sequence. This epigenetic modification regulates gene expression by often repressing transcription, as it inhibits binding of transcription factors and promotes chromatin condensation. Abnormal methylation patterns can lead to diseases like cancer, where tumor suppressor genes may become hypermethylated and inactive.

hemimethylated

a state where one strand of double-stranded DNA is methylated at certain cytosine bases (typically within a CpG dinucleotide) while the complementary strand remains unmethylated.

CpG islands

CpG islands are regions of DNA that have a high frequency of c and gnucleotides, connected by a phosphate bond (CpG).

- located near or within the promoter regions of genes and are generally unmethylated in normal tissues, allowing for active transcription.

- play a crucial role in the regulation of gene expression. Methylation of CpG dinucleotides in these islands can lead to gene silencing, which is significant in processes such as development, genomic imprinting, and cancer

PGC

Primordial germ cells- specilized embryonic cells that are the least methylated due to being germ cells

Pancreas 3 types of tissues

Alpha cells, beta cells, exocrine cells

Alpha cells

synthesis and secretion of glucagon (hormone)

miRNA

micro RNA; a class of functional RNA that regulates the amount of protein produced by a eukaryotic gene (regulates gene expression)

CpG islands prevent __________ from binding to DNA

activators

Beta Cells

synthesis and secretion of insulin (hormone)

synthesis and secretion of digestive enzymes

In which cells would you expect to find methylation of the insulin promoter?

Alpha and Exocrine

2 mode of RNA interference

• dependent on degree of complementarity between miRNA and Target sequence

  • incomplete complementarity- translational repression

  • perfect complementarity- mRNA cleavage

drosha

processes pri-miRNA to 70nt a precursor to miRNA

Ago

Argonoaut protein- separates the double stranded miRNA

Dicer

recongnizes dsRNA and cleaves off terminal loop to about 22 nt

steps in making miRNA

guide miRNA

transgenic

an organism or cell whose genome has been altered by the introduction of one or more forgein dna sequences by artificial means

orthologs

genes in different species that evolved by common ancestor

3 R’s of model organisms

replacement, reduction, refinement

paralogs

genes within same genome that evolved throuigh gene duplication event

forward genetics

from phenotype to genotype

reverse genetics

genotype to phenotype,

delete a gene see what happens

recombinant DNA

produced by joining segment from two two or more Dna molecs

what type of enzymes does recombinant dna rely on

restriction endonucleases and ligase

Histone acetlytransferases (HATs)

add acetyl groups to histoene neautralizes positive charge and reducing the electrostaic interection between the histone proteins and dna