Chapter 16b - Eukaryotic Regulation

In prokaryotes, expression of

many genes is __ by default,

until something turns it __

on, off

In Eukaryotes, expression of

most genes is __ by default,

until something turns it __

off, on

Each of our cells carry the exact same DNA with the exact same genomic sequence.

So how do we get such different properties?

Genomic Regulation

Eukaryotes have a variety of ways to regulate.

1. At the structural level (has to do with tightly wound around histones our linear DNA molecules are)

2. At the transcription level (combinatorial action of many different transcriptions factors and sometimes ncRNA)

3. At the translation level (has to do with the pace at which mRNA molecules degrade and how translation initiates)

If DNA is in heterochromatin state, expression of

genes in that area is __ . But if it is in the euchromatin state, expression in that area is __

repressed, possible

Eukaryotic cells shift

different regions of DNA

between euchromatin and

heterochromatin as a

__ strategy

regulatory

Acetylation makes nucleosomes bind DNA less ___

tightly

Epigenetics = the study of how gene expression is

changed by chemical modifications to chromatin that

__ gene sequence

do not impact

Regulation at Transcription Level:

Transcription factors participate in __ intermolecular _ with DNA. This is x

weak, interaction, non-covalent

Some transcription factors __ gene expression. They do this by recruiting _ to the promoter region.

active, RNA Polymerase

Other transcription factors act like traffic cones, __ gene expression.

silencing

Tryptophan Operon (TRP) is a transcription factor that __ transaction.

represses

CAP is a transcription factor that activates when there isn’t any glucose around. It is an __ transcription factor.

activating

There are approximately ~___ different transcription

factors in the human body that we know of

1,600

Eukaryotes do not have __

Each Eukaryotic gene has its own promoter and

polyadenylation signal.

operons

Eukaryotes employ ____ of

transcription factors to regulate how __

transcription __

complex combinations, often, initiates

Each colorful circle is a ___ transcription factor (TF)

These have nothing to do with regulation, they must be

__ every time RNAPII initiates transcription.

general, recruited

Don’t forget. Similar combinatorial schemes to combinational TF-based regulation also exist for gene ___.

repression

Hormone cascades coordinate regulation of related

genes via TFs. This will assist in turning on all __ genes throughout the _.

related, geonome

Long noncoding RNA (lncRNA) does not carry gene sequence, and carries out diverse regulation. Here, long RNA means RNA greater than __ bases in length. They can act like transcription factors. They can bind to _ themselves and prevent or promote translation.

200, mRNA

Translation Level:

Manipulation of UTRs, caps, and tails of

mRNA all present opportunities for post-

transcriptional regulation

3’ UTR and polyA tail largely influence mRNA half-life. Often, longer poly(A) tails = more stable mRNA molecule. The lengths and motifs of sequence contained in 3’ UTRs can either increase or decrease mRNA half-life.

Rates of initiation is another post-transactional regulatory strategy