Lecture 5 - Gene Regulation

Regulation of transcription, Regulation of Translation

Different cells perform different jobs. What makes them different?

Different cells perform different jobs. What makes them different?

- the proteins present
- the active proteins present in a cell determine the type of cell and what it can do

How many chromosomes in the human body?

46 (23 pairs) chromosomes

Gene expression

- the transcription and translation of a gene to make an active protein product
- all cells in the same body have the same DNA BUT are expressed differently resulting in different mRNAs and proteins

Constitutive expression

gene is expressed at all times

Inducible expression

gene expression is off until actively turned on

Repressible expression

gene expression is on until actively turned off

Trans sequences

- genes for transcription factor proteins
- located anywhere in genome

- activators: increase transcription
- repressions: decrease transcription

Cis sequences

- binding sites for transcription factors
- located near gene

- enhancer: attracts activator
- silencer: attracts repressor

Chromatin remodeling

Alters chromatin structure to affect gene expression by making it more accessible or less open

Regulator

Controls the activity of genes by bringing in chromatin remodeling proteins, such as enzymes, to influence gene expression

Lac operon

Regulates the expression of genes in bacteria, particularly in E. coli, with both inducible and repressible features to manage protein production for lactose digestion

Operon

A group of multiple genes with one promoter, specifically found in prokaryotes

Diauxic shift

A pause in the growth of E. coli after consuming glucose, followed by the activation of the lac operon when lactose is available and glucose is not

Positive control

Involves the CAP protein as a transcription factor, activated when glucose levels are low and cAMP is present

Negative control

Represses the lac operon when lactose is absent, mediated by the lac repressor transcription factor

Lactose sensor

Detects lactose concentration to regulate gene expression in the lac operon

Alternative splicing

A process creating different protein variants and RNA sizes, aiding in neural connections and regulated by Dscam

Untranslated regions (UTRs)

Regulate mRNA translation by creating hairpins that block start codons, located between the promoter and polyadenylation sequence

Non-coding RNAs

Regulate gene expression and translation, including RNA interference (RNAi) and microRNA (miRNA)

RNAi

highly specific to one mRNA
double stranded RNA (dsRNA) activates systems that destroy mRNAS that are complimentary to the dsRNA
dsRNAS come from outside the cell

microRNA

regulate multiple mRNAs
produced by cellular genome to regulate gene expression and translation step

how is lac operated and what are transcription factors involved

CAP when glucose not present - activated by CAMP
glucose sensor
- low glucose


low glucose high lactose for strong expression
lac repressor - sits on operator and promoter and blocks transcription
- lactose sensor

trna role

tRNA translates the genetic code from mRNA into proteins by carrying specific amino acids to the ribosome, where they are added to the growing polypeptide chain in accordance with the sequence of codons in the mRNA.

What are the signals that control the beginning and end of transcription and translation?

transcription: promoter and termination sequennce

translation: start and stop codon

What is a reading frame, an open reading frame, and a frameshift mutation? What technique(s) would help you discover open reading frames?

next generation sequencing