Summary ISE Genetics Analysis and Principles - Genetics Part 2!!
Chapter 1, overview of genetics
Complete Test Bank Genetics Analysis and Principles 7th Edition Brooker Questions & Answers with rationales (Chapter 1-29)
All for this textbook (60)
Written for
Vrije Universiteit Amsterdam (VU)
Biomedical Sciences
Genetics
All documents for this subject (120)
1
review
By: joris52 • 3 year ago
Seller
Follow
mabel46
Reviews received
Content preview
Gene regulation in bacteria
Gene Enhances efficiency in energy use. Cell does not waste energy making RNAs and proteins it does not need.
regulation Means level of gene expression can vary under different conditions.
Unregulated genes = constitutive, constantly expressed, encode proteins that are continuously necessary
for survival.
Regulated genes = encoded proteins/RNAs only produced when required.
Regulation can occur at any point in the pathway to gene expression, but most commonly at transcription
initiation level -> rate of mRNA production ; increased or decreased
Involves two Repressors: inhibit transcription; negative control
main types of Activators: increase transcription; positive control
regulatory Both bind directly or indirectly to DNA, also have two bindings sites; one for small effector molecules, one
proteins for DNA.
Small effector molecules; bind to regulatory proteins not directly to DNA
Small effector Inducers: increase transcription, gene regulation inducible
molecules Inducer bind activator and cause them to bind to DNA
Inducer bind repressor and prevent them from binding to DNA
Inhibitors: inhibit transcription
Corepressor bind to repressor and cause them to bind to DNA
Bind to activator and prevent them from binding to DNA
Enzyme Particular enzyme appears in the cell only after the cell has been exposed to the enzymes substrate. When
adaptation bacteria is not exposed to particular substance, it does not make the enzymes needed to metabolize this
substance -> E.g. lactose metabolism.
Operon A regulatory unit (group) consisting of a few structural genes under the control of one promoter. Very
common in bacteria: genes arranged together in an operon. However, not all genes in bacteria are in an
operon. In a operon there is 1 promoter.
The promoter of It encodes polycistronic (copy-ORF) mRNA: contains the coding sequence for 2/+ structural proteins.
an operon is
where transcription It allows a bacteria to co-ordinately regulate a group of genes that encode proteins involved in the same
begins. If the process/function -> expression of a gene occurs in a unit.
promoter
sequence is It contains: promoter, operator, structural genes, terminator.
deleted,
transcription will
not take place.
, Lac operon = Two distinct transcriptional units;
inducible 1. The lac operon:
regulation DNA elements/sequences involved in
transcriptional regulation (same promoter
region in Euk.
Promoter: binds RNA polymerase (LacP)
Operator: binds lac repressor protein (lacO) (3
operator sites)
CAPsite: binds Catabolite Activator Protein (CAP)
Structural genes: contain coding sequences for the enzymes
Lac Z gene: encodes B-galactosidase; enzymatically cleaves lactose and lactose analogous in
galactose and glucose. Converts lactose into allolactose (acts as small effector protein)
Lac Y gene: encodes lactose permease; membrane protein required for transport of lactose and
analogues into cytoplasm.
Lac A gene: encodes transacetylase
2. The lacl gene: codes for regulatory protein: lac repressor (homotetramer). Not considered part of
lac operon. Has its own promoter; i promoter. Constitutively expressed at fairly low levels. Only
small amount of protein is needed to repress the lac operon.
1. Inducible negative control mechanism: repressor + inducer
Negative control Involves lac repressor protein -> when bound ot lacO prevents RNA polymerase from transcribing. In
refers to
transcriptional absence of alloctose, lac repressor is bound to lacO. When inducer alloctose binds to lac repressor it
regulation by a inactivates it and prevents binding to DNA, RNA polymerase can start transcribing. Repressor does not
repressor. An
inducer is a small
effector molecule
that causes the
rate of
transcription to
increase. One way
that it does this is
to bind a repressor
and prevent it from
binding the DNA.
Therefore, an
inducible gene that
is under negative
control will be
transcribed when a
repressor and an
inducer is present.
completely inhibit trnascription; very small amount are made.
Proteins involved with lactose utilization are
fairly stable, but wille eventually be degraded.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller mabel46. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.77. You're not tied to anything after your purchase.