This is an allele whose phenotypic effect is not observed in a heterozygote.
recessive allele
100
The phenotype most commonly observed in natural populations.
wild type
100
DNA polymerase adds nucleotides to the ______ ends of the leading strands and to the _______ ends of the lagging strands (Okazaki fragments).
3' and 3'
100
A nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary nucleotide triplet on an mRNA molecule.
anticodon
100
This type of bond holds tRNA molecules in their correct three-dimensional shape.
hydrogen bonds
200
This is an organism that is heterozygous with respect to two genes of interest.
dihybrid
200
A dense object lying along the inside of the nuclear envelope inside the cells of female mammals, representing a highly condensed, inactivated X chromosome.
Barr body
200
This enzyme 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 (such as a growing DNA chain).
DNA ligase
200
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
200
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
300
Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype.
test cross
300
A phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.
genomic imprinting
300
This enzyme removes RNA primers from Okazaki fragments and replaces them with DNA nucleotides. (Be specific.)
DNA polymerase I
300
This one of a ribosome's three binding sites for tRNA during translation holds the tRNA carrying the growing polypeptide chain.
P site
300
This type of RNA can play a structural or catalytic role and is the most abundant type of RNA.
ribosomal RNA (rRNA)
400
The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.
incomplete dominance
400
A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
aneuploidy
400
An enzyme that cuts DNA or RNA, either removing one or a few bases, and is involved in DNA excision repair.
nuclease
400
During mRNA processing, ________ are cut out of the primary transcript, and the resulting ________ are spliced together.
introns ... exons
400
This occurs when the number of nucleotides inserted or deleted from a gene is not a multiple of three, resulting in the improper grouping of subsequent nucleotides into codons.
frameshift mutation
500
A type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene.
epistasis
500
An offspring whose phenotype differs from the true-breeding P generation parents.
recombinant type
500
This enzyme breaks, swivels, and rejoins DNA strands to relieve strain in the double helix ahead of the replication fork.
topoisomerase
500
This is the term for groups of ribosomes translating the same mRNA in prokaryotes.