Week6: gene regulation

DNA in bacteria

contains single circular chromosome and there are also structures known as plasmids which can be tranferred between bacteria and contain DNA

Gene expression

General process in which genetic information encoded within a gene is used to create functional products (e.g. Genes)

Promoter

a region on the gene located upstream (before) the start of the gene that serves as a binding for RNA polymerase and other transcription factors - it initiates transcription which is the first step in gene expression

operon

unit of genetic function. it consists of a coordinately regulated cluster of genes with a related function. they often consist of a promoter, an operator (on/off switch) and genes for proteins that work together - operons mainly occur in bacteria but may also be in eukaryotes

Operator

region on an operon where correspondinf regulatory proteins bind. This regulator-operatoer complex can ‘turn a gene on/off’. It turns off the gene by creating a reppressor protein.

repressor

enzyme that inhibits the expression of a certain gene by bondiing to a operator and not allowing RNA polymerase to complete transcription by blocking it - this is formed by the operator

How is transcriptions and translation different in bacteria?

bacteria have no nuclei, so transcription and translation can occur in the same space

What need to bind with the Tryptophan repressor in order to make the repressor active?

A trp molecule itself

Chromatin regulation (in eukaryotes)

cells can modify the histone around which DNA is wrapped so that it can open or close the histone structure which changes its ability to be expressed. Histone Acetylation - acetyl groups bond to histones and this makes the DNA more accessible and leads to active chromatin. Histone Methylation - usually turns gene off. methyl group bonds and blocks transcription machinery

transcriptional regulation in eukaryotes

Basal Promoter - requiref for binding of general transcription factors - initiates transcription - found before the transcriptions starting site of the gene. Enhancers and Distal promoters - enhance transcription by recruiting more transcription factors - often located far away from the gene or basal promoter

WHat are the main components of viruses

Nucleic Acid and a Capsid Protein

Acronym to rememebr virus lifecyrle?

APUTGAR

Lytic Viral replication`

Virus takes over the cells functions (all the organelles) and begins reproducing more viral cells - eventually the cell membrane bursts due to there being so many viruses and then the virus cells that are released from this bursting of the cell are like a virus army and can go and infect surrounding cells

Lysogenic Viral replication

Usually occurs when there are no other host cells nearby and there is no reason to kill of the existing host cell. the virus combines with the cells genetic information. Repressor genes on the virus stop it’s genes from being expressed - it is sitting there silently. The host cell continues replicating, and thus creates more copies of the virus as well.