Tag: biology

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Multiple choice expression of gene inherited changes biology

Wild type Escherichia coli growing on medium having glucose is transferred to lactose containing medium. Which change occurs?

  1. Lac operon is induced

  2. Lac operon is suppressed

  3. All operons are induced

  4. The bacterium stops dividing
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When E. coli is moved from glucose to a lactose-containing medium, the lac operon is induced to produce enzymes necessary for lactose metabolism.

Multiple choice expression of gene inherited changes biology

In repressible or negative operon

  1. Corepressor binds with inducer

  2. Corepressor binds with aporepressor

  3. Corepressor does not bind with repressor

  4. cAMP has negative effect
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a repressible operon, the corepressor binds to the inactive aporepressor to form an active repressor complex that can bind to the operator.

Multiple choice expression of gene inherited changes biology

In lac-operon, repressor protein binds to

  1. Regulator gene

  2. Operator gene

  3. Promoter gene

  4. Structural gene
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the lac operon, the active repressor protein binds to the operator site, physically blocking RNA polymerase from transcribing the structural genes.

Multiple choice expression of gene inherited changes biology

Operon contains

  1. Operator and regulator genes

  2. Operator and structural genes

  3. Operator and regulator genes, and repressor

  4. Operator gene, regulator gene, repressor, structural genes and promoter gene
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An operon system typically includes the regulator gene, promoter, operator, and the structural genes it controls.

Multiple choice expression of gene inherited changes biology

Telomere of eucaryotic chromosome possesses short segments of

  1. Guanine rich repeats

  2. Thymine rich repeats

  3. Cytosine rich repeats

  4. Adenine rich repeats
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Telomeres, the ends of eukaryotic chromosomes, consist of repetitive DNA sequences that are typically rich in guanine.

Multiple choice expression of gene inherited changes biology

Lac operon is

  1. Arabinose operon

  2. Repressible operon

  3. Inducible operon

  4. Overlapping genes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The lac operon is a classic example of an inducible operon, meaning it is typically turned off but can be activated (induced) by the presence of lactose. Repressible operons, by contrast, are typically on and turned off by the presence of a product.

Multiple choice expression of gene inherited changes biology

Eucaryotic genome differs from procaryotic genome in

  1. DNA is circular arid single-stranded in procaryotes

  2. Intervening sequences are present in eucaryotic DNA

  3. DNA is coinplexed with histones in procaryotes

  4. DNA is organised into operons in eucaryotes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Eukaryotic genes are characterized by split gene organization, meaning they contain non-coding intervening sequences called introns that are removed during RNA processing. Prokaryotic genomes generally lack these introns.

Multiple choice expression of gene inherited changes biology

Operon is

  1. Sequence of three nitrogen bases determining a single amino acid

  2. A set of closely placed genes regulating a metabolic pathway in procaryotes

  3. Segment of DNA specifying a polypeptide

  4. Gene responsible for switching on and switching off of other genes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An operon is a functional unit of DNA in prokaryotes consisting of a cluster of genes under the control of a single promoter and operator, allowing for the coordinated regulation of a metabolic pathway.

Multiple choice expression of gene inherited changes biology

In eukaryotes transcription occurs in

  1. Cytoplasm

  2. Nucleus

  3. Cytosol

  4. Matrix
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In eukaryotic cells, the DNA is contained within the nucleus, which is where the process of transcription (DNA to RNA) occurs. Translation then takes place in the cytoplasm.

Multiple choice expression of gene inherited changes biology

In an inducible operon, the genes are

  1. Usually expressed unless a signal turns them "off

  2. Never expressed

  3. Always expressed

  4. Usually not expressed unless a signal turns them on
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Inducible operons are typically in an 'off' state due to the presence of a repressor protein bound to the operator. They are turned 'on' only when an inducer molecule binds to the repressor, preventing it from binding to the DNA.