Upgrade to remove ads
CH 18 Raven notes
Terms in this set (24)
What is meant by the phrase "control of gene expression
It explains the way DNA is synthesized into proteins
What is the value of controlling gene expression for a prokaryote (a single-celled organism)
They need to control the amount of proteins that they produce so that they are not wasting resources
What is the value of controlling gene expression for a multi-celled eukaryote?
We are able to make a lot more proteins that have lots of different functions. Introns and exon make us very complex and give us the ability to make more proteins
Explain the different evolutionary forces that have caused the development of distinctly different systems of regulation for the control of gene expression in prokaryotes
They don't have nuclear membranes and a division between transcription and translation. Don't have introns and exons to make complex amount of proteins. They are simple and only produce like 20 proteins.
Explain the different evolutionary forces that have caused the development of distinctly different systems of regulation for the control of gene expression in eukaryotes.
They have nuclear membranes, so they have more control over regulation between transcription and translation. They are able to have exon and introns. they have alternative splicing that makes a lot more proteins
What is a gene's promoter? What role does it serve in regulating transcription?
The DNA sequence where the RNA polymerase attaches and begins transcription
Prokaryotes use a regulatory system called an operon. Explain what an operon is
An operon is The operator, the promoter, and the genes they control. It is a stretch of DNA. It controls RNA polymerases access to the genes. (turns transcription on and off)
and identify the function of the following components: promoter, operator, repressor.
Promoter: The DNA sequence where RNA pol begins transcription
Operator: Controls access of RNA pol to the genes. Switches genes on and off
Repressor: Active repressor bind to the operon and restricts access to the DNA for RNA pol
a straightforward representation of the tryptophan (trp) operon system. explain how this system regulates the synthesis of tryptophan in a bacterium.
This is The TRP operon system. The repressor is produced by a stretch of DNA with its own promoter. This gene creates an inactive repressor for tryptophan to bind to.
In the operon: The promoter consists of RNA pol and the operator. With an inactive repressor, the DNA pol is able to work, and makes mRNA that codes for tryptophan synthesis. If the repressor is activated by an inducer, it binds to the operator and restricts DNA pol from transcribing the DNA
Describe how the trp operon is an example of a repressible operon.
It is usually being transcribed, but if needed it can be repressed by the binding of tryptophan to the repressor, which activates it and attaches to the promoter to stop transcription
Label the diagram and use it to explain how this system regulates the digestion of lactose in a bacterium.
The repressor is produced by a stretch of genes upstream with its own promoter. It is normally active, and attached to the Operator, restricting RNA pol
Operon: When there is a presence of lactose, allactose (the inducer) attaches to the Repressor and inactivates it. the repressor moves off of the operator and allows RNA pol to transcribe lactose metabolizing genes
Does the diagram represent the condition for the absence or presence of lactose?
It represents presence of lactose. When lactose is present, allactose (the inducer) attaches to the repressor and causes the transcription of genes that metabolize the lactose that is present
Describe what happens in an operon when lactose is absent
The repressor is active and attached to the operator. Transcription of the lactose metabolizing genes is paused
Describe how the lac operon is an example of an inducible operon.
It is normally not transcribing, but then if allactose is present, the transcription process can be induced
Summarize how the presence and absence of glucose influences the lac operon.
The presence of glucose causes the operator to be inactivated, and RNA pol is free to transcribe. The absence causes an active repressor that is attached to the operator and restricts RNA pol
Briefly outline why control of transcription is more complex in eukaryotes than in prokaryotes.
Eukaryotes are much more complex, and there are lots more proteins to switch on and off.
Explain the general function of transcription factors.
Transcription factors are a group of proteins and other molecules that help to bind RNA pol and start the process of transcription
Briefly distinguish between the functions of basal transcription factors and specific transcription factors (activators).
Basal: very general, do not lead to much transcription but are helpful
Specific/activators: can be located farther away, activate more transcription
explain the coordinated functions of the enhancer and the promoter regions of the DNA.
The enhancer can be found far upstream, but there are special DNA bending proteins that cause the activators bound to the enhancers to bind to the transcription factors
Briefly describe the organization of DNA in the eukaryotic nucleus.
Heterochromatin is tightly condensed and unreadable
Euchromatin is Loose and readable
Briefly described the effect on transcription of DNA methylation
Addition of methyl groups to the histones or DNA creates a condensed DNA that is less readable and less subject to transcription
Briefly described the effect on transcription of histone acetylation.
Histone acetylation is when histones are chemically modified so that the structure of chromatin and looser and more readable
RNA interference is an exciting new area of research in molecular biology. Make some brief notes about the roles of small RNA molecules (siRNAs and miRNAs) in gene control
They are able to turn off, degrade mRNA to their complementary strands, or block translation. They seem to be very relevant in the translation process
How does alternative RNA splicing affect gene expression?
It creates a much bigger ability to make many more proteins.
You might also like...
Chapter 16-Control of Gene Expression
Essential Cell Biology Chapter 8: Control of Gene…
Chapter 16 Control of Gene Expression
Other sets by this creator
AP bio ch 39
AP Bio population ecology
Other Quizlet sets
The Anti-Torque Rotor CPL(H) Aerodynamics
Module 9 US Study Guide