The process of making an RNA copy of a gene is called transcription.
Missing Word
transcription
Transcription is the process where an RNA molecule is synthesized from a DNA template. This process is essential for gene expression, as it allows the genetic information encoded in DNA to be used to create proteins.
Question 2
A cell’s genotype remains constant whereas its phenotype changes in response to environmental influences.
Missing Word
genotype
A cell's genotype, the genetic makeup, is relatively stable, while the phenotype, the observable characteristics, can change. Environmental factors can influence gene expression, leading to alterations in the phenotype without changing the underlying genotype.
Question 3
The enzyme responsible for relaxing supercoiled DNA to allow for the initiation of replication is called DNA gyrase.
Missing Word
DNA gyrase
DNA gyrase, also known as topoisomerase II, is crucial for DNA replication. It relieves the torsional stress created by the unwinding of DNA by introducing negative supercoils, allowing the replication fork to proceed.
Question 4
Unidirectional replication of a circular DNA molecule like a plasmid that involves nicking one DNA strand and displacing it while synthesizing a new strand is called rolling circle replication.
Missing Word
rolling circle replication
Rolling circle replication is a specific type of DNA replication commonly used by plasmids and some viruses. It involves a nick in one strand, which then serves as a primer for continuous DNA synthesis, displacing the original strand.
Question 5
A polycistronic mRNA is one that codes for multiple polypeptides.
Missing Word
polycistronic
Polycistronic mRNA is characteristic of prokaryotes and contains coding sequences for multiple genes. This allows for the coordinated expression of related proteins from a single mRNA molecule.
Question 6
The protein complex responsible for removing intron-encoded RNA sequences from primary transcripts in eukaryotes is called the Spliceosome.
Missing Word
Spliceosome
The spliceosome is a large RNA-protein complex that catalyzes the removal of introns from pre-mRNA in eukaryotes. This process is essential for producing mature mRNA that can be translated into functional proteins.
Question 7
The third position within a codon, in which changes often result in the incorporation of the same amino acid into the growing polypeptide, is called the wobble position.
Missing Word
wobble position
The wobble position refers to the third nucleotide in a codon, where less stringent base pairing with the tRNA anticodon is tolerated. This degeneracy in the genetic code allows for some mutations to occur without altering the amino acid sequence of the protein.
Question 8
The enzyme that adds an amino acid to a tRNA molecule is called aminoacyl-tRNA synthetase.
Missing Word
aminoacyl-tRNA synthetase
Aminoacyl-tRNA synthetases are a family of enzymes that catalyze the attachment of the correct amino acid to its corresponding tRNA molecule. This is a critical step in translation, ensuring that the correct amino acid is incorporated into the growing polypeptide chain.
Question 9
A chemical mutagen that is structurally similar to a nucleotide but has different base-pairing rules is called a nucleoside analog.
Missing Words
nucleoside, analog
Nucleoside analogs are mutagenic chemicals that resemble normal nucleotides but have altered base-pairing properties. Their incorporation into DNA during replication can lead to mutations due to incorrect base pairing.
Question 10
The enzyme used in light repair to split thymine dimers is called photolyase.
Missing Word
photolyase
Photolyase is an enzyme that uses light energy to repair thymine dimers, a common type of DNA damage caused by UV radiation. This process, called photoreactivation, directly reverses the damage without removing any bases.
Question 11
The phenotype of an organism that is most commonly observed in nature is called the wild type.
Missing Word
wild type
The wild type phenotype represents the standard, non-mutated form of a trait commonly found in natural populations. It serves as a baseline for comparison when studying genetic variations and mutations.
Question 12
A small DNA molecule that has the ability to independently excise from one location in a larger DNA molecule and integrate into the DNA elsewhere is called a transposon.
Missing Word
transposon
Transposons, also known as transposable elements, are mobile genetic elements that can move within a genome. Their ability to excise and integrate into different DNA locations contributes to genetic diversity and genome evolution.
Question 13
Horizontal gene transfer is a group of mechanisms that allow for the introduction of genetic material from one organism to another organism within the same generation.
Missing Word
Horizontal gene transfer
Horizontal gene transfer (HGT) allows for the rapid spread of genetic information between organisms, unlike vertical gene transfer which occurs from parent to offspring. HGT mechanisms like conjugation, transduction, and transformation contribute significantly to bacterial evolution and adaptation.
Question 14
The DNA sequence, to which repressors may bind, that lies between the promoter and the first structural gene is called the operator.
Missing Word
operator
The operator is a DNA sequence located downstream of the promoter that controls gene expression. Repressor proteins bind to the operator, physically blocking RNA polymerase from transcribing the structural genes of the operon.
Question 15
The prevention of expression of operons encoding substrate use pathways for substrates other than glucose when glucose is present is called catabolite repression.
Missing Words
catabolite, repression
Catabolite repression is a regulatory mechanism that prioritizes the use of glucose over other carbon sources. This ensures that the cell utilizes the most efficient energy source first, conserving resources and optimizing growth.