Test Bank for Genetics From Genes to
Genomes
Continuous Traits - answersInherited trait that exhibits many intermediate form;
determined by segregating alleles of many different genes whose interaction with each
other and the environment produces the phenotype. Also called a quantitative trait.
Complete Dominance - answersOne of the Parents trait is shown
Epistasis - answersGene interaction in which the expression of 1 gene 'masks' the
phenotypic display of a 2nd gene
50 units - answersin order to have independent assortment the 2 genes need to be at
least 50 units apart
Product Rule - answersIf the events are independent,probability that both will occur is
the product of each single
Penetrance - answersIndicates how many members of a population with a particular
genotype show the expected phenotype
Expressivity - answersThe degree or intensity with which a particular genotype is
expressed in a phenotype
Histones - answersSmall-binding proteins with a preponderance of the basic, positively
charged amino acids lysine and arginine. Histones are the fundamental protein
components of nucleosomes
H2A, H2B, H3, H4 - answersCore histones found in the nucleosome
Nucleosome - answersThe basic repeating structural (and functional) unit of chromatin.
Contains nine histone proteins and about 166 base pairs of DNA
H1 - answersbind to the nucleosome at the entry and exit sites of DNA (locking the DNA
into place)
Hemizygous - answersmales with one copy of an X-linked gene
Holandric - answerson Y chromosome(Y-linked traits are passed from father to sone.
No interchromosomal genotype.
Monavalent - answersunpaired chromosome during meiosis
Euchromatin - answersRegion of Lightly pack chromatin.
,Chromatin - answersThe generic term for any complex of DNA and protein found in a
cell's nucleus
Heterochromatin - answersHighly condensed chromosomal regions within which genes
are usually transcriptionally inactive
Xist gene - answers"X inactivation specific transcript"; produces a single-stranded RNA
that coats the inactive X chromosome and initiates condensation.X inactivation is an
early developmental process in mammalian females that transcriptionally silences one
of the pair of X chromosomes, thus providing dosage equivalence between males and
females. Done by splicing and polyadenylation.
Nucleotides - answersOrganic molecules that serve as the monomers, or subunits, of
nucleic acids like DNA and RNA. Composed of a nitrogenous base, a five-carbon sugar
(ribose or deoxyribose), and at least one phosphate group.
Nucleoside - answersSimple base bound to a ribose or deoxyribose sugar via a beta-
glycosidic linkage. (Guanine, Cytosine, Adenine, Thymine, Uracil)
telomerase - answersA ribonucleoprotein involved in replication. A reverse transcriptase
that carries its own RNA molecule which is used as a template when it elongates
telomeres, which are shortened after each replication cycle. Adds DNA sequence
repeats to the 3' region to create telomeres to prevent the loss of DNA
Telomere - answersA region of repetitive nucleotide sequences at each end of a
chromatid , which protects the end of the chromosome from deterioration or from fusion
with neighboring chromosomes
Chromatid - answersOne of 2 copies of a chromosome that exist immediately after DNA
replication
Topoisomerase - answersEnzyme that regulates the overwinding or underwinding of
DNA during replication. It moves ahead of the replication fork, breaking covalent bonds
that connect deoxyribosenucleotides
Helicase - answersEnzyme that unwinds double stranded DNA to single Strand DNA for
replication. Creates a fork, breaks hydrogen bonds
Auxotroph - answersA mutant microorganism that can grow on minimal medium only if it
has been supplemented with one or more growth factors not required by wild type
strains
Prototroph - answersMicroorganism(usually wild type) that can grow on minimal
medium in the absence of one or more growth factors
, Forward Mutations - answersChanges wild type to a new type
Transition - answersReplacement of a purine with a purine or vice versa.
Purine - answersAdenine and Guanine (double ring)
Pyramidine - answersUracil, Thymine, Cytosine. (single ring)
Transversion - answersreplacement of pyramidine with purine or vice versa
Reversion - answersmutation that changes the mutant allele back to the wild type
Inversion - answersSegments of chromosomes that become reversed
DNA polymerase - answersmove in 5' to 3' direction, needs a primer, has proof reading,
continuous until done, faster, and has helices, synthesizes DNA
RNA polymerase - answersmove in 5' to 3' direction, doesn't need a primer, doesn't
have proof reading, has exonuclease activity, uracil base, synthesizes RNA
MutS, MutH and MutL - answers3 proteins are essential in detecting the mismatch and
directing repair machinery for methylation repair
Methylation repair mechanism - answersDNA repair mechanism that corrects mistakes
in replication, discriminating between newly synthesized and parental DNA by tagging
the parental strand with methyl groups. Exonuclease acitivity next then rejoined by
ligase.
Aminoacyl synthetase - answersenzymes that catalyze the attachment of tRNAs to their
corresponding amino acids, forming charged tRNAs -> for translation
Splice Donor Sequence - answersSite within primary transcript that is cleaved 1st
during splicing
Eukaryotic RNA polymerase I - answerstranscription of ribosomal RNA genes
Hypomorphic mutations - answersaltered gene product possesses a reduced level of
activity/ wild type gene product is expressed and at reduced level
Amorphic/null mutations - answersaltered gene product that lack molecular function of
wild type gene- (gene function doesn't work anymore)
Neomorphic mutations - answersaltered gene product possesses new or different
function that is usually dominant or semi-dominant
Genomes
Continuous Traits - answersInherited trait that exhibits many intermediate form;
determined by segregating alleles of many different genes whose interaction with each
other and the environment produces the phenotype. Also called a quantitative trait.
Complete Dominance - answersOne of the Parents trait is shown
Epistasis - answersGene interaction in which the expression of 1 gene 'masks' the
phenotypic display of a 2nd gene
50 units - answersin order to have independent assortment the 2 genes need to be at
least 50 units apart
Product Rule - answersIf the events are independent,probability that both will occur is
the product of each single
Penetrance - answersIndicates how many members of a population with a particular
genotype show the expected phenotype
Expressivity - answersThe degree or intensity with which a particular genotype is
expressed in a phenotype
Histones - answersSmall-binding proteins with a preponderance of the basic, positively
charged amino acids lysine and arginine. Histones are the fundamental protein
components of nucleosomes
H2A, H2B, H3, H4 - answersCore histones found in the nucleosome
Nucleosome - answersThe basic repeating structural (and functional) unit of chromatin.
Contains nine histone proteins and about 166 base pairs of DNA
H1 - answersbind to the nucleosome at the entry and exit sites of DNA (locking the DNA
into place)
Hemizygous - answersmales with one copy of an X-linked gene
Holandric - answerson Y chromosome(Y-linked traits are passed from father to sone.
No interchromosomal genotype.
Monavalent - answersunpaired chromosome during meiosis
Euchromatin - answersRegion of Lightly pack chromatin.
,Chromatin - answersThe generic term for any complex of DNA and protein found in a
cell's nucleus
Heterochromatin - answersHighly condensed chromosomal regions within which genes
are usually transcriptionally inactive
Xist gene - answers"X inactivation specific transcript"; produces a single-stranded RNA
that coats the inactive X chromosome and initiates condensation.X inactivation is an
early developmental process in mammalian females that transcriptionally silences one
of the pair of X chromosomes, thus providing dosage equivalence between males and
females. Done by splicing and polyadenylation.
Nucleotides - answersOrganic molecules that serve as the monomers, or subunits, of
nucleic acids like DNA and RNA. Composed of a nitrogenous base, a five-carbon sugar
(ribose or deoxyribose), and at least one phosphate group.
Nucleoside - answersSimple base bound to a ribose or deoxyribose sugar via a beta-
glycosidic linkage. (Guanine, Cytosine, Adenine, Thymine, Uracil)
telomerase - answersA ribonucleoprotein involved in replication. A reverse transcriptase
that carries its own RNA molecule which is used as a template when it elongates
telomeres, which are shortened after each replication cycle. Adds DNA sequence
repeats to the 3' region to create telomeres to prevent the loss of DNA
Telomere - answersA region of repetitive nucleotide sequences at each end of a
chromatid , which protects the end of the chromosome from deterioration or from fusion
with neighboring chromosomes
Chromatid - answersOne of 2 copies of a chromosome that exist immediately after DNA
replication
Topoisomerase - answersEnzyme that regulates the overwinding or underwinding of
DNA during replication. It moves ahead of the replication fork, breaking covalent bonds
that connect deoxyribosenucleotides
Helicase - answersEnzyme that unwinds double stranded DNA to single Strand DNA for
replication. Creates a fork, breaks hydrogen bonds
Auxotroph - answersA mutant microorganism that can grow on minimal medium only if it
has been supplemented with one or more growth factors not required by wild type
strains
Prototroph - answersMicroorganism(usually wild type) that can grow on minimal
medium in the absence of one or more growth factors
, Forward Mutations - answersChanges wild type to a new type
Transition - answersReplacement of a purine with a purine or vice versa.
Purine - answersAdenine and Guanine (double ring)
Pyramidine - answersUracil, Thymine, Cytosine. (single ring)
Transversion - answersreplacement of pyramidine with purine or vice versa
Reversion - answersmutation that changes the mutant allele back to the wild type
Inversion - answersSegments of chromosomes that become reversed
DNA polymerase - answersmove in 5' to 3' direction, needs a primer, has proof reading,
continuous until done, faster, and has helices, synthesizes DNA
RNA polymerase - answersmove in 5' to 3' direction, doesn't need a primer, doesn't
have proof reading, has exonuclease activity, uracil base, synthesizes RNA
MutS, MutH and MutL - answers3 proteins are essential in detecting the mismatch and
directing repair machinery for methylation repair
Methylation repair mechanism - answersDNA repair mechanism that corrects mistakes
in replication, discriminating between newly synthesized and parental DNA by tagging
the parental strand with methyl groups. Exonuclease acitivity next then rejoined by
ligase.
Aminoacyl synthetase - answersenzymes that catalyze the attachment of tRNAs to their
corresponding amino acids, forming charged tRNAs -> for translation
Splice Donor Sequence - answersSite within primary transcript that is cleaved 1st
during splicing
Eukaryotic RNA polymerase I - answerstranscription of ribosomal RNA genes
Hypomorphic mutations - answersaltered gene product possesses a reduced level of
activity/ wild type gene product is expressed and at reduced level
Amorphic/null mutations - answersaltered gene product that lack molecular function of
wild type gene- (gene function doesn't work anymore)
Neomorphic mutations - answersaltered gene product possesses new or different
function that is usually dominant or semi-dominant
