Gene regulation is the process that controls the timing, amount, and location of gene expression. It involves a variety of mechanisms, including regulatory proteins that bind to DNA and modify gene transcription. Key examples of gene regulation discussed in the document include the lac operon in E. coli, which regulates lactose metabolism genes in response to glucose availability, and the heat shock response in fruit flies, which induces heat shock protein expression under stress. Gene regulation occurs at multiple levels, including chromatin modification, transcription, post-transcriptional modification, mRNA transport, translation, and mRNA degradation.

1. GENE REGULATION
BY
KHADEEJA
ROLL#21017114-053

2. GENE REGULATION
Gene regulation is the process used to control the timing, location
and amount in which genes are expressed
Gene expression is the process by which the instructions present in
our DNA are converted into a functional product, such as a protein
 Gene regulation carried out by a variety of mechanisms, including
through regulatory proteins and chemical modification of DNA
One of the fundamental processes that a cell carries out in order to
produce the transcripts that will lead to the proteins

3. GENE REGULATION
A list of stages where gene expression is regulated
Signal transduction
Chromatin, chromatin remodeling, chromatin
domains
Transcription
Post-transcriptional modification
mRNA transport
Translation
mRNA degradation
The most extensively utilized point is transcription
initiation, the first stage in transcription

4. GENE REGULATION
Barbara McClintock showed interaction between two genetic loci:
Activator (Ac)
Dissociator (Ds) in the color formation of maize seeds
 The first discovery of a gene regulation system is widely considered to be the
identification in 1961 of the lac operon
Discovered by François Jacob and Jacques Monod, in which some enzymes
involved in lactose metabolism are expressed by E. coli only in the presence of
lactose and absence of glucose

5. GENE REGULATION
MODIFICATION OF DNA
Octameric protein complexes called histones together with a
segment of DNA wound around the eight histone proteins (together
referred to as a nucleosome) are responsible for the amount of
supercoiling of DNA, and these complexes can be temporarily
modified by processes such as phosphorylation or more
permanently modified by processes such as methylation
 Such modifications are considered to be responsible for more or
less permanent changes in gene expression levels

6. GENE REGULATION
REGULATION OF TRANSCRIPTION
Promoters indicate where transcription
begins
In addition genes have additional
regulatory sequences
Regulatory sequences are bound tightly
and specifically by transcriptional
regulators, proteins that can recognize
DNA sequences and bind to them
The binding of such proteins to the
DNA can regulate transcription by
preventing or increasing transcription
from a particular promoter

7. GENE REGULATION
REGULATION OF TRANSCRIPTION (PROKARYOTES)
Bacterial cells generally prefer to use glucose for their energy needs, but if
glucose is unavailable, and lactose is present, the bacteria will take up lactose
and break it down for energy
 Since the proteins for taking up and breaking down lactose are only needed
when glucose is absent and lactose is available, the bacterial cells need a way to
express the genes of the lac operon only under those conditions
 At times when lactose is absent, the cells do not need to express these genes

8. GENE REGULATION

9. GENE REGULATION
POST-TRANSCRIPTIONAL REGULATION
After the DNA is transcribed and mRNA is formed there must be some sort of
regulation on how much the mRNA is translated into proteins
 Cells do this by modulating the capping, splicing, addition of a Poly(A) Tail, the
sequence-specific nuclear export rates, and, in several contexts, sequestration of
the RNA transcript
These processes occur in eukaryotes but not in prokaryotes
This modulation is a result of a protein or transcript that, in turn, is regulated
and may have an affinity for certain sequences

10. GENE REGULATION
REGULATION OF TRANSLATION
The translation of mRNA can also be controlled by a number of mechanisms,
mostly at the level of initiation
Recruitment of the small ribosomal subunit can indeed be modulated by
mRNA secondary structure, antisense RNA binding, or protein binding
In both prokaryotes and eukaryotes, a large number of RNA binding proteins
exist, which often are directed to their target sequence by the secondary
structure of the transcript, which may change depending on certain conditions,
such as temperature or presence of a ligand (aptamer)
Some transcripts act as ribozymes and self-regulate their expression

11. GENE REGULATION
EXAMPLES OF GENE REGULATION
The Lac operon is an interesting example of how gene expression
can be regulated
The induction of heat shock proteins in the fruit fly Drosophila
melanogaster

12. THANK YOU