Lecture notes - Cell And Molecular Biology (DNA - Genes) - Using Becker's World of the Cell, Global Edition
7 views 0 purchase
Course
Cell And Molecular Biology
Institution
Manchester Metropolitan University (MMU)
Book
Becker\'s World of the Cell, Global Edition
If you're studying a life science (e.g. - biomed, bioscience, physiology, sports science, sports physiology etc), then this detailed set of lecture notes on DNA and Genes will help you smash your first set of exams on cell/molecular biology!
Try using this set of notes along with my other notes ...
Test Bank for Becker's World of the Cell 10th edition by Jeff Hardin & James Lodolce Chapters 1-26 , ISBN: 9780135832011 |All Chapters Verified| Guide A+
Test Bank - Becker's World of the Cell, 10th Edition by Jeff Hardin, All Chapter 1-26 | Complete Guide A+
Lecture notes - Cell And Molecular Biology (Cilia and Mitochondria)- Using Becker's World of the Cell, Global Edition
All for this textbook (9)
Written for
Manchester Metropolitan University (MMU)
Unknown
Cell And Molecular Biology
All documents for this subject (17)
Seller
Follow
jaz2
Content preview
Gene Regulation 21/10/19
- Gene regulation allows us to adapt to environmental change
All organisms must regulate which genes are expressed at a given time
Genes = turned off/on when responding to signals – from internal/ext. env.
Gene regulation = essential for cell specialization for multicellular organisms
Regulation differs in Bacterial cells and Eukaryotes
Bacterial regulation:
Bacterial cell that conserves energy/resources = advantage over one that can’t
- E.g. = E. coli – lives in Colon
- Needs AA tryptophan to survive
- If host person ≠ intake said AA – E. coli actives metabolic pathway – makes AA trypt. from
another compound
- If host person intakes trypt. – E. coli ≠ produce trypt. – stops using resources for metabolism
Metabolic pathway = controlled on 2 levels:
- Cells adjust activity of enzymes (catabolic enzyme activity = dependent on ‘chemical cues’)
- Activity of 1st enzyme in pathway = inhibited by pathway’s end product (trypt.)
- Accumulation of trypt. = inhibition of enzyme = no more trypt. production
- Process = feedback inhibition – lets cell adapt to short-term fluctuations of substance
- Cells adjust production of enzymes – regulate expression of genes coding for enzyme
- If trypt. ≠ needed – cell prevents production of enzymes catalysing synthesis of trypt.
- Process occurs at transcription level
Allosteric = Protein with structure altered reversibly by small molecule – modifying function
Many bacterial genes = switched on/off by metabolic changes in a cell
Operon model = basic mech. of gene expression control
, Operons:
Operon = cluster of functionally related genes – co-ordinately controlled by single ‘on/off switch’
- One promoter = sufficient for all 5 operon genes coding for enzymes for metabolic pathway
- One long mRNA strand = produced – all code for pp for enzymes
- Translation = separate due to presence of start/stop codons
Enzymes = simultaneously synthesised due to on/off switch
- On/off switch = segment of DNA (Operator)
- Controls access of RNA Polymerase to said genes
Operator, Promotor and genes being controlled = Operon
Operon = switched off by Repressor
- Binds to operator – blocks attachment of RNA pol. to promotor region
- Transcription of genes ≠ occur
- Rep. protein = specific for operator of certain operon
- Active or inactive form – determined by presence of other molecules
Rep. Protein = encoded by regulatory gene
- Expressed continuously (at low rate)
- Binding of repressors = reversible
- Operator = in 2 states – repressor bound and repressor unbound
- Repressor = allosteric – 2 shapes - active and inactive
- Inactive version = synthesized – low affinity for operator
Tryptophan = corepressor
- Small mol – binds to allosteric site of repressor – activates it
- More trypt. = more assoc. with repressor – less transcription of operon genes = less enzyme
- Less trypt. = less assoc. with repressor – more transcription of operon genes = more enzyme
Enzymes = repressible enzymes
Inducible Operons:
Inducible operons = usually off – stimulated/induced to be on when small molecule interacts with
different regulatory protein
- E.g. = lac operon (lactose)
Lac operon = genes coding for enzymes for hydrolysis & metabolism of lactose
- Lactose = available for E. coli – if host has milk
- Metabolism = hydrolysis of lactose to glucose and galactose
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 jaz2. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.51. You're not tied to anything after your purchase.