Gene Regulation (3.3) Flashcards
Describe gene regulation
Process that controls gene expression, turning genes on or off
Describe gene expression
Process that leads to the transformation of the information stored in a gene into a functional gene product
State whether or not gene regulation is tightly controlled in both prokaryotes and eukaryotes. True/False.
True. Gene regulation is tightly controlled in both prokaryotes and eukaryotes.
Compare and contrast gene regulation in both eukaryotic and prokaryotic cells
Gene expression is more complex in eukaryotes and therefore occurs in a greater number of stages than in prokaryotes
Describe gene regulation in eukaryotes
Gene expression - transcription, RNA processing and translation
- highly regulated (all stages)
Describe gene regulation in prokaryotes
Gene expression - transcription and translation
- regulated during (transcription stage)
Describe constitutive genes
Always switched on and are transcribed continually
State two types of gene expression
- induced
- repressed
Describe regulatory genes
Genes that code for transcription factors
Describe transcription factors
Proteins that control gene expression at the transcription stage
Describe structural genes
Genes that code for proteins and RNA that are not involved in gene regulation
Describe the lac Operon
Contains genes which code for three proteins involved in the metabolism of lactose in E Coli.
Describe the operon in prokaryotes
Unit of DNA under the regulation of a single promoter that codes for several proteins
What can the lac operon be classified as?
Inducible operon
Describe an inducible operon
Can be switched on/off
State what the lac operon codes for
Three structural genes that code for three enzymes
What do the enzymes produced by the lac operon break down?
Lactose -> glucose and galactose
Provide a reason why these enzymes are not produced constantly
Misuse of energy as these enzymes are only required for the breakdown of lactose
State what the lac operon consists of:
- Promoter
- Operator
- Three structural genes
Describe the operator
Binding site of the transcription factor
State the three structural genes
- lacZ
- lacY
3 lacA
State what gene is adjacent to the lac Operon
lacI
Describe what the lacI gene codes for
Transcription factor called the lac repressor
State whether or not the lac repressor is always present
Yes. Always present.
Describe the process that occurs in the lac operon model in the presence of lactose
Lactose binds to the lac repressor, inhibiting the transcription factors from binding to the operator. This enables RNA polymerase to attach to the promoter in the lac operon and transcribe the the three structural genes.
Describe the process that occurs in the lac operon model in the absence of lactose
Transcription factors binds to the operator in the lac operon, blocking the RNA polymerase from binding to and transcribing the structural genes in the lac operon,
Compare and contrast chromosome number in prokaryotes and eukaryotes
Prokaryotes = singule Eukaryotes = multiple
Compare and contrast chromosomal structure in prokaryotes and eukaryotes
Prokaryotes = circular chromosomes Eukaryotes = linear chromosomes
Compare and contrast plasmid presence in prokaryotes and eukaryotes
Prokaryotes = contain plasmids Eukaryotes = no plasmids (however have mitochondrial and chloroplast DNA)
Compare and contrast gene arrangement in prokaryotes and eukaryotes
Prokaryotes = genes cluster in operon regions Eukaryotes = gene do not cluster in operon regions
Describe nucleosome
The basic structural unit of chromatin, and is made up of a coil of DNA wound around a histone core
Describe histone
Water-soluble protein in nucleus which DNA tightly coils around to form the nucleosome
Describe chromatin
Complex of nucleic acids which condense to form a chromosome during cell division
Describe what structure binds to the lac repressor in the lac operon model
Allolactose
Describe gene induction
The increase in gene expression due to the presence of an inducer molecule
Describe gene repression
The decrease in gene expression due to the activity of a repressor molecule
Describe operator
A DNA sequence that acts as an on-off switch when interacting with a repressor molecule
Describe operon
Section of prokaryotic DNA consisting of a cluster of related structural genes, a promoter and operator
Describe promoter
DNA sequence that marks the binding site of RNA polymerase
Describe regulatory gene
Gene involved in substance production which regulates gene expression
Describe structural gene
A gene coding for the production of a specific protein involved in regulation
Describe TATA box
A highly conserved region of the promoter to which the first transcription factor binds prior to transcription
Describe transcription factors
Regulatory proteins that bind to DNA sequences to control transcription
Compare and contrast structural and regulatory genes
Structural genes code for proteins required for cell structure or function whereas regulatory genes code for proteins that turn other genes on or off.
