43 Questions
What is the function of the TATA box in eukaryotic gene regulation?
It serves as a binding site for RNA polymerase.
How do transcription factors influence gene expression?
By binding to sequences in the regulatory regions of eukaryotic genes.
What is one possible reason eukaryotic gene regulation is more complex?
Eukaryotes express genes in different specialized cells.
What role do RNA-binding proteins play in gene expression?
They block access to genes.
Why is cell specialization important in multicellular organisms?
It enables the differentiation of cells to perform various functions.
What molecule binds to the operator to prevent transcription of the lac operon genes?
Lac repressor
What happens to the lac repressor when lactose is present?
It falls off the operator
Which of the following is the function of the lac operon in E. coli?
Transporting lactose and breaking it down into glucose and galactose
Where does RNA polymerase bind to begin transcription?
Promoter
Why is it important for E. coli to switch the lac genes on and off?
To save energy when lactose is not available
What is the role of the repressor protein in the absence of lactose?
It binds to the operator preventing transcription
Which compound is necessary for the lac repressor to change its shape and fall off the operator?
Lactose
Which of the following molecules is directly responsible for initiating transcription of the lac operon genes?
RNA polymerase
What role do DNA-binding proteins play in prokaryotic gene regulation?
They regulate genes by controlling transcription
Why is it beneficial for bacteria to regulate gene expression?
To conserve energy and resources
What is an operon in the context of prokaryotic gene regulation?
A group of genes regulated together
What molecule must E. coli break apart to utilize as food, as illustrated by the lac operon?
Lactose
What would be wasteful for a bacterium to produce if it can obtain the molecule from its environment?
Enzymes to make a molecule
What are the three genes involved in the lac operon of E. coli responsible for?
Breaking apart lactose
How does E. coli decide which genes to express at any given time?
By using DNA-binding proteins that control transcription
Which of the following statements about master control genes is correct?
They can trigger patterns of development and differentiation in cells.
What is the primary function of the lac operon in E. coli?
To control the breakdown of lactose
How do cells regulate gene expression through chromatin state?
By attaching chemical groups to DNA and histone proteins.
What impact does the attachment of methyl groups have on chromatin?
It condenses chromatin, shutting down gene expression.
Which of the following is an example of epigenetic regulation?
Chemical marks on chromatin
What effect does the attachment of acetyl groups have on gene expression?
It opens chromatin up for transcription and enhances gene expression.
Which of the following accurately describes epigenetic marks?
They influence gene expression without changing DNA sequences.
Which of these statements is true about the development stages of a caterpillar, pupa, and butterfly?
They have the same genes but different epigenetic marks regulating gene expression at each stage.
What is the role of nucleosomes in gene expression?
Nucleosomes form chromatin, which can either block or allow gene expression based on its packing.
What do homeotic genes regulate?
The organs that develop in specific parts of the body
Which type of genes code for transcription factors that activate other genes important in cell development?
Homeobox genes
What did Edward B. Lewis demonstrate regarding homeotic genes?
They control the identities of body parts in fruit fly embryos
What is the function of Hox genes in humans?
To tell cells how to differentiate as the body grows
What sequence do molecular studies show is shared by homeotic genes?
A 180-base DNA sequence
How are Hox genes arranged in the DNA of animals?
From head to tail
What does the process of differentiation in an embryo lead to?
Specialized tissues and organs
Which genes determine the identities of each segment of a fly’s body?
Hox genes
Which factor does not impact gene expression?
pH level
In E. coli, when is the lac operon switched on?
When lactose is the sole food source
At what temperature range does the gene controlling fur color in Himalayan rabbits produce black fur?
Between 15°C and 25°C
At what temperature is the gene controlling fur color in Himalayan rabbits inactive across the entire body?
Above 30°C
Which of the following is not a mechanism by which transcription factors regulate eukaryotic gene expression?
Inhibiting protein synthesis directly
How do master control genes contribute to organism development?
They control the expression of other genes
Study Notes
Gene Regulation and Expression
- Gene regulation is essential for cells to conserve energy and resources by controlling which genes are expressed.
Prokaryotic Gene Regulation
- Prokaryotes regulate genes by controlling transcription using DNA-binding proteins that switch genes on or off.
- The lac operon in E. coli is an example of a group of genes regulated together.
- The lac operon is turned on or off by the lac repressor protein, which binds to the operator region.
The Lac Operon
- The lac operon consists of three genes that code for proteins involved in lactose breakdown.
- The lac operon is turned off when the lac repressor binds to the operator region, preventing RNA polymerase from transcribing the genes.
- The presence of lactose changes the shape of the lac repressor, allowing RNA polymerase to bind and transcribe the genes.
Master Control Genes and Epigenetics
- Master control genes are switches that trigger patterns of development and differentiation in cells and tissues.
- Epigenetic mechanisms control gene expression by adding chemical marks to chromatin, which can compact or open up chromatin structure.
- Chromatin compactness affects gene expression, with compact chromatin blocking gene expression and open chromatin enhancing gene expression.
Environmental Influences
- Environmental factors such as temperature, salinity, and nutrient availability influence gene expression.
- The lac operon is switched on only when lactose is the sole food source in E. coli's environment.
Hox Genes and Body Development
- Homeotic genes, including Hox genes, regulate the identities of body parts in embryos.
- Hox genes code for transcription factors that activate genes important in cell development and differentiation.
- Hox genes are arranged in a specific order in the genome, corresponding to their expression from anterior to posterior in the body.
Homeobox Genes
- Homeobox genes share a similar 180-base DNA sequence, known as the homeobox.
- Homeobox genes code for transcription factors that regulate cell development and differentiation.
Genetic Control of Development
- Regulating gene expression is crucial during development to control cell differentiation and organ formation.
Explore how genes are regulated in prokaryotic and eukaryotic cells, and how they control development in multicellular organisms. Learn key terms like operon, operator, differentiation, and homeotic genes.
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