Notebook Check #13

Gene Expression in Prokaryotes

E. coli takes lactose if glucose is not available

If you don’t have the protein to break down lactose then you’re lactose intolerant

When lactose is present the sugar will enter the e coli cell

Structural gene:codes for any RNA or protein product other than a regulatory factor

Regulatory genes: involved in controlling the expression of one or more genes, section of DNA that determine which transcription factors are released

Transcription factors: proteins the increase transcription or decrease expression by binding to DNA

Repressor: stops RNA polymerase from making mRNA

RNA polymerase: read DNA to make RNA, enzyme

Turn off lac gene by adding a repressor to it

How to turn on a gene:

An activator increases transcription

Removes repressor, distracts repressor

Lactose sugar sits on repressor making it unable to do its job

Regulatory genes + Structural genes = Operon

Gene expression is about if we’re going to make a protein or not.

Genes can’t be turned on all the time.

Whether a gene is being turned on or off & the abundance of it

Signs of aging: gray hair, wrinkles, bad hearing

Male pattern baldness is passed on from your mother/maternally

Lac operon: breaking down lactose to make glucose

Gene regulation in Eukaryote

  • External environment: a traumatic event that causes the production of hemoglobin to increase
    • Loss of blood would cause for more hemoglobin to be produced
  • Internal environment: estrogen, needs to be turned on and off
    • The cause of periods

Gene Expression Regulation

  1. The transcriptional level

   

  1. During mRNA production
    1. The post-transcriptional level

   

  1. After mRNA production
    1. Post translational level

   

  1. After protein production

Method 1: Turning access to DNA on/off

  • chromatin accessibility:
    • structure of chromatin, open chromatin makes gene more available for transcription

Method 2: Turning TF’s on/off:

  • Transcription factors binding sites called:
    • enhancers & silencers can turn a gene on/off in specific parts of the body
  • TF allows cells perform logic operations & combin different sources of info. to “decide” whether to express a gene

Method 3: mRNA Editing/Splicing

  • RNA processing:
    • splicing, capping, and adding poly-a-tail
    • molecule can be regulated from the same pre-mRNA by alternative splicing
  • RNA stability:
    • the lifetime of mRNA in the cytosol affects how many proteins can be made.
    • Small regulatory RNAs called miRNAs can bind to target RNAs & caused them to be chopped up

You can help allergies by turing the gene off and start using the things you’re allergic to in small amounts

miRNA = RNA destroyer

Splicing → making a copy