Test 4 Flashcards
The process by which a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells.
Transformation
A virus that infects bacteria; also called a phage.
Bacteriophages
An infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope.
Virus
The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.
Double helix
Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix
Antiparallel
Type of DNA replication in which the replicated double helix consists of one old strand, derived from the parental molecule, and one newly made strand.
Semiconservative model
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
Origins of replication
A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized.
Replication fork
An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands.
Helicase
A protein that binds to the unpaired DNA strands during DNA replication, stabilizing them and holding them apart while they serve as templates for the synthesis of complementary strands of DNA.
Single-strand binding protein
A protein that breaks, swivels, and rejoins DNA strands.
Topoisomerase
A short polynucleotide with a free 3′ end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication.
Primer
An enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA strand as a template.
Primase
An enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3′ end of an existing chain.
DNA polymerase
The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5′→3′ direction.
Leading strand
A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5′→3′ direction away from the replication fork.
Lagging strand
A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication.
Okazaki fragment
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3′ end of one DNA fragment (such as an Okazaki fragment) to the 5′ end of another DNA fragment
DNA ligase
The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides.
Mismatch repair
An enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides.
Nuclease
The tandemly repetitive DNA at the end of a eukaryotic chromosome’s DNA molecule.
Telomere
The complex of DNA and proteins that makes up eukaryotic chromosomes.
Chromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.
Heterochromatin
The less condensed form of eukaryotic chromatin that is available for transcription.
Euchromatin
The synthesis of RNA using a DNA template.
Transcription
A type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.
Messenger rna
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of “language” from nucleotides to amino acids.
Translation
A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit.
Ribosome
An initial RNA transcript from any gene; also called pre-mRNA when transcribed from a protein-coding gene.
Primary transcript
A genetic information system in which a series of three-nucleotide-long words specifies a sequence of amino acids for a polypeptide chain.
Triplet code
The DNA strand that provides the pattern, or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript.
Template strand
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal
Codon
Nontemplate strand of DNA, which has the same sequence as the mRNA except it has thymine (T) instead of uracil (U).
Coding strand
On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis.
Reading frame
An enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand.
RNA polymerase
A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.
Promoter
In bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA.
Terminator
A region of DNA that is transcribed into an RNA molecule.
Transcription unit
In transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA.
Start point
A regulatory protein that binds to DNA and affects transcription of specific genes.
Transcription factor
The completed assembly of transcription factors and RNA polymerase bound to a promoter.
Transcription initiation complex
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.
TATA box
Modification of RNA primary transcripts, including splicing out of introns, joining together of exons, and alteration of the 5′ and 3′ ends.
RNA processing
A modified form of guanine nucleotide added onto the 5′ end of a pre-mRNA molecule.
5’ cap
A sequence of 50–250 adenine nucleotides added onto the 3′ end of a pre-mRNA molecule.
Poly-A tail
After synthesis of a eukaryotic primary RNA transcript, the removal of portions of the transcript (introns) that will not be included in the mRNA and the joining together of the remaining portions (exons).
RNA splicing
A noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing
Intron
A sequence within a primary transcript that remains in the RNA after RNA processing
Exon
A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons.
Spliceosome
An RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing.
Ribozyme
A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns.
Alternative RNA splicing
An RNA molecule that functions as a translator between nucleic acid and protein languages by picking up a specific amino acid and carrying it to the ribosome, where the tRNA recognizes the appropriate codon in the mRNA.
Transfer rna
A nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule.
Anticodon
An enzyme that joins each amino acid to the appropriate tRNA.
Aminoacetyl-tRNA synthetase
Flexibility in the base-pairing rules in which the nucleotide at the 5′ end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3′ end) of a codon.
Wobble
RNA molecules that, together with proteins, make up ribosomes
Ribosomsl rna
One of a ribosome’s three binding sites for tRNA during translation.
P site
One of a ribosome’s three binding sites for tRNA during translation.
A site
One of a ribosome’s three binding sites for tRNA during translation.
E site
A sequence of about 20 amino acids at or near the leading (amino) end of a polypeptide that targets it to the endoplasmic reticulum or other organelles in a eukaryotic cell.
Signal peptide
A protein-RNA complex that recognizes a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum (ER) by binding to a receptor protein on the ER.
Signal-recognition particle
A group of several ribosomes attached to, and translating, the same messenger RNA molecule.
Polyribosome
A change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus.
Mutations
A change in a single nucleotide pair of a gene
Point mutation
A type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides.
Nucleotide-pair substitution
silent mutation
A nucleotide-pair substitution that has no observable effect on the phenotype
Silent mutation
A nucleotide-pair substitution that results in a codon that codes for a different amino acid.
Missense mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
Nonsense mutation
A mutation involving the addition of one or more nucleotide pairs to a gene.
Insertion
A deficiency in a chromosome resulting from the loss of a fragment through breakage.
Deletion
A mutation occurring when nucleotides are inserted in or deleted from a gene and the number inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.
Frameshift mutation
A chemical or physical agent that interacts with DNA and can cause a mutation.
Mutagen
In bacterial and phage DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach.
Operator
A unit of genetic function found in bacteria and phages, consisting of a promoter, an operator, and a coordinately regulated cluster of genes whose products function in a common pathway.
Operon
A protein that inhibits gene transcription. In prokaryotes, repressors bind to the DNA in or near the promoter
Repressor
A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
Regulatory gene
A small molecule that binds to a bacterial repressor protein and changes the protein’s shape, allowing it to bind to the operator and switch an operon off.
Corepressor
A specific small molecule that binds to a bacterial repressor protein and changes the repressor’s shape so that it cannot bind to an operator, thus switching an operon on.
Inducer
Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells.
Cyclic AMP
The expression of different sets of genes by cells with the same genome.
Differential gene expression.
The attachment of acetyl groups to certain amino acids of histone proteins.
His tone acetylation
The presence of methyl groups on the DNA bases (usually cytosine) of plants, animals, and fungi.
DNA methylation
Inheritance of traits transmitted by mechanisms that do not involve the nucleotide sequence.
Epigenetic inheritence
A segment of noncoding DNA that helps regulate transcription of a gene by serving as a binding site for a transcription factor.
Control element
A segment of eukaryotic DNA containing multiple control elements, usually located far from the gene whose transcription it regulates
Enhancer
A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns.
Alternative RNA splicing
A small, single-stranded RNA molecule, generated from a double-stranded RNA precursor.
MicroRNA
One of multiple small, single-stranded RNA molecules generated by cellular machinery from a long, linear, double-stranded RNA molecule.
small Interfering rna
A mechanism for silencing the expression of specific genes.
RNA interference
An RNA between 200 and hundreds of thousands of nucleotides in length that does not code for protein but is expressed at significant levels.
Long noncoding rna
The process by which a cell or group of cells becomes specialized in structure and function.
Differentiation
The development of the form of an organism and its structures.
Morphogenesis
A maternal substance, such as a protein or RNA, that when placed into an egg influences the course of early development by regulating the expression of genes that affect the developmental fate of cells.
Cytoplasmic determinant
A process in which a group of cells or tissues influences the development of another group through close-range interactions.
Induction
The progressive restriction of developmental potential in which the possible fate of each cell becomes more limited as an embryo develops.
Determination
The development of a multicellular organism’s spatial organization, the arrangement of organs and tissues in their characteristic places in three-dimensional space.
Pattern formation
Molecular cues that control pattern formation in an animal or plant embryonic structure by indicating a cell’s location relative to the organism’s body axes.
Positional formation
Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells.
Homeotic gene
A mutation with a phenotype leading to death of an embryo or larva.
Embryonic lethal
A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the offspring’s genotype.
Maternal effect gene
A maternal effect gene that codes for a protein responsible for specifying the anterior end in Drosophila melanogaster.
Bicoid
A substance, such as Bicoid protein in Drosophila, that provides positional information in the form of a concentration gradient along an embryonic axis.
Morphogen
A gene found in viral or cellular genomes that is involved in triggering molecular events that can lead to cancer.
Oncogene
A normal cellular gene that has the potential to become an oncogene.
Proto-oncogene
A gene whose protein product inhibits cell division, thereby preventing the uncontrolled cell growth that contributes to cancer.
Tumor suppressor gene
A gene that codes for Ras, a G protein that relays a growth signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases, ultimately resulting in stimulation of the cell cycle.
Rae gene
A tumor-suppressor gene that codes for a specific transcription factor that promotes the synthesis of proteins that inhibit the cell cycle.
P53 gene
