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Lecture 4

BIOL 1201 Lecture Notes - Lecture 4: Intron, Corepressor, Lac Operon

Biological Sciences
Course Code
BIOL 1201

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Coplete geoe DNA seuee ko: huas, hips, flies, os, eeds… ad ay
bacteria and viruses
Exact AGCT base order is known
Genes are known
Functions are being figures out
We know abt genes
We know where they are
We do’t ko hat they all do
Human genome: 3 billion base pairs of DNA
o 23 types chromosomes
o 1 cope from each parent 46 chromosomes total in each cell
Each chromosome is one DNA molecule
o 22,000 genes spread out on the 23 different types of chromosomes for humans (14,000
genes in flies)
Human genome
o Genes are at set locations on the chromosomes
o Only ~5000 different genes expressed in each cell type
o Of those 5, ~ ae housekeepig gees
Gene regulation
o If all cells have the same 22,000 genes in them, but only 5000 are being expressed at a
time, that means some genes are turned on and off depending on gene regulation
o Other proteins regulate when and where that expression occurs
o Transcription factors
o All genes encode RNA
o Mode RNAs eode poteis soe RNAs ad tRNAs do’t code for proteins)
Eukaryotic Gene Regulation
Prokaryotic gene regulation occurs at the level of transcription
Eukaryotic gene regulation occurs at many levels
Levels of Regulation (below)
Regulated at the chromosomal level
o DNA packing (so the ribosomes a’t oe aoud the
o DNA methylation (methyl or some sht is added and the backbones are twisted all weird
and are essentially turned off -the ezyes a’t id oetly
o Gene amplification (if you add more of the same gene, more of its product will be made)
Regulated transcriptionally
o Promoters** where the RNA polymerase is gonna bind
o Enhancers** located nearby
o Regulatory proteins** have to bind to all of this before RNA polymerase is attached
to begin transcription
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