ch. 11-14 Flashcards
(143 cards)
1
Q
euchromatin
A
the less condensed form of eukaryotic chromatin that is available for transcription
2
Q
linkage map
A
a genetic map based on the frequencies of recombination between markers during the crossing over of homologous chromosomes
3
Q
heterozygote
A
an organism that has two different alleles for a gene (encoding a character)
4
Q
deletion
A
(1) a deficiency in chromosomes resulting from the loss of a fragment through breakage. (2) a mutational loss of one or more nucleotide pairs from a gene.
5
Q
primase
A
an enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA strand as a template
6
Q
codominance
A
the situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways
7
Q
gene drive
A
a process that biases inheritance such that a particular allele is more likely to be inherited than the other alleles, causing the favored allele to spread through the populations
8
Q
gene expression
A
the process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs
9
Q
missense mutation
A
a nucleotide-pair substitution that results in a codon that codes for different amino acid
10
Q
origins of replication
A
site where the replication of a DNA molecule beings, consisting of a specific sequence of nucleotides
11
Q
telomere
A
the tandemly repetitive DNA at the end of a eukaryotic chromosome’s DNA molecule. telomeres protect the organism’s genes from being eroded during successive rounds of replication
12
Q
5’ cap
A
a modified form of guanine nucleotide added onto the end of a pre-mRNA molecule
13
Q
terminator
A
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
14
Q
topoisomerase
A
a protein that breaks, swivels, and rejoins DNA strands. during DNA replication, topoisomerase helps to relieve strain in the double helix ahead of the replication fork
15
Q
signal peptide
A
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
16
Q
semiconservative model
A
type of DNA replication in which the replicated double helix consists of one strand, derived from the parental molecule, and one newly made strand
17
Q
wobble
A
flexibility in the base-pairing rules in which the nucleotide at the 59 end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (39 ends) of a codon
18
Q
Huntington’s disease
A
human genetic disease cause by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms
19
Q
spliceosome
A
a large complex made up of proteins and RNA molecules that splice RNA by interacting with the ends of an RNA intron, releasing the intron, and joining the two adjacent exons
20
Q
DNA ligase
A
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 (such as a growing DNA chain)
21
Q
inversion
A
an aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated
22
Q
punnet square
A
diagram used in the study of inheritance to show the predicted genotype of random fertilization in genetic crosses between individuals of known genotype
23
Q
nucleotide-pair substitution
A
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
24
Q
transcription initiation complex
A
the completed assembly of transcription factors and RNA polymerase bound to a promoter
25
character
an observable heritable feature that may very among individuals
26
map unit
a unit of measurement of the distance between genes. one map unit is equivalent to a 1% recombination frequency
27
TATA box
a DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
28
ribozyme
an RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing
29
genetic recombination
general term for the production of offspring with combinations of traits that differ from those found in either parents
30
crossing over
the reciprocal exchange of genetic material between non-sister chromatids during prophase 1 or meiosis
31
hemophilia
human genetic disease caused by a sex-linked recessive allele, resulting in the absence of one or more blood-clotting proteins; characterized by excessive bleeding following injury
32
pedigree
diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations
33
intron
a noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; also refers to the region of DNA from which this sequence was transcribed
34
codon
a three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code
35
nonsense mutation
a mutation that changes an amino acid codon to one of the three-stop codons, resulting in a shorter and usually nonfunctional protein
36
law of segregation
mendel's first law, starting that the two alleles in a pair segregated (separate from each other) into different gametes during gamete formation
37
duplication
an aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated
38
template strand
the DNA strand that provides the pattern, or template, for ordering by complementary base pairing, the sequence of nucleotides in an RNA transcript
39
aminoacyl-tRNA synthetase
an enzyme that joins each amino acid to the appropriate tRNA
40
transfer RNA (tRNA)
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
41
multifactorial
referring to phenotypic character that is influences by multiple genes and environmental factors
42
nucleosome
the basic, beadlike unit of DNA packing in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone
43
P site
one ribosome's three binding sites for tRNA during translation. the P site holds the tRNA carrying the growing polypeptide chain (P stand for peptidyl tRNA)
44
nondisjunction
an error in meiosis or mitosis in which members of a pair of homologous chromosomes or sister chromatids fail to separate properly from each other
45
gel electrophoresis
technique separating nucleic acids or proteins on the basis of their size and electrical charge, both of which affect their rate of movement through an electric field in a gel made of agarose or another polymer
46
mutagen
a chemical or physical agent that interacts with DNA and can cause a mutation
47
nucleic acid hybridization
the process of base pairing between a gene and a complementary sequence on another nucleic acid molecule
48
primary transcript
an initial RNA transcript from any gene, also called pre-mRNA, when transcribed from a protein-coding gene
49
restriction site
a specific sequence on a DNA strand that is recognized and cut by a restriction enzyme
50
messenger RNA (mRNA)
a type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein. (in eukaryotes, the primary RNA transcript must undergo RNA processing to become mRNA)
51
testcross
breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. the ratio of phenotypes in the offspring reveals the unknown genotype
52
P generation
true-breeding (homozygous) parent individuals from which F1 hybrid offspring are derived in studies on inheritance. (P stands for parental)
53
DNA Cloning
production of multiple copies of a specific DNA segment
54
single-strand binding protein
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
55
homozygous
having two identical alleles for a given gene (HH)
56
chromatin
the complex of DNA and proteins that make up eukaryotic chromosomes. when the cell is not dividing, chromatin exists in its dispersed form, a mass of very long, thin fibers that are not visible with a light microscope
57
RNA splicing
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)
58
monohybrid cross
cross between two organisms that are heterozygous for the character being followed (or the self-pollination of heterozygous plant)
59
genetic engineering
the direct manipulation of genes for practical purposes
60
RNA processing
modification of RNA primary transcripts, including splicing out of introns, joining together of exons, and alteration of the 5' and 3' ends
61
transcription unit
region of DNA that is transcribed into an RNA molecule
62
helicase
enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands
63
histones
small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in chromatin structure
64
mismatch repair
cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides
65
frameshift mutation
mutation occurs 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
66
virus
infectious particle incapable of replicating outside of a cell, consisting of RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope
67
genetic map
an ordered list of genetic loci (genes or other genetic markers) along a chromosome
68
promoter
specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place
69
transcription factor
regulatory protein that binds to DNA and affects transcription of specific genes
70
ribosome
a complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; it consists of a large subunit and a small subunit. in eukaryotic cells, a search subunit is assembled in the nucleolus
71
start point
in transcription, the nucleotide position on the promoter where RNA polymerase beings synthesis of RNA
72
transformation
a change in genotype and phenotype due to the assimilation of external DNA by a cell. when the external DNA is from a member of a different species, transformation results in horizontal gene transfer
73
nucleotide excision repair
repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide
74
trisomic
referring to a diploid cell that has three copies of a particular chromosome instead of the normal two
75
polygenic inheritance
an additive effect of two or more genes on a single phenotypic character
76
sickle-cell disease
recessively inherited human blood disorder in which a single nucleotide change in the globin genes causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms in afflicted individuals
77
Okazaki fragment
short segment of DNA synthesized away from the replication fork on a template strand during DNA replication. many such segments are joined together to make up the lagging strand of newly synthesized DNA
78
A site
one of a ribosome's three binding sites for tRNA during translation. the A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain. (A stands for aminoacyl tRNA)
79
aneuploidy
chromosomal aberration, in which one or more chromosomes are present in extra copies or are deficient in a number
80
lagging strand
a discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' S 3' direction away from the replication fork
81
trait
one of two or more detectable variants in a genetic character
82
law of independent assortment
mendel's second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two character are located on different pairs of homologous chromosome to behave as though they are on different chromosomes
83
antiparallel
referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5' S 3' directions)
84
heterozygous
having two different alleles for a given gene (Hh)
85
genotype
the genetic makeup, or set of alleles, of an organism
86
parental type
an offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotype itself
87
incomplete dominance
the situation in which the phenotype of heterozygotes is intermediate between the phenotype of individuals homozygous for either allele
88
chromosome theory of inheritance
the basic principle in biology states that genes are located at specific positions (loci) on the chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns
89
point mutation
a change in a single nucleotide pair of a gene
90
wild type
phenotype most commonly observed in natural populations; also refers to the individual with that phenotype
91
recessive allele
an allele whose phenotypic effect is not observed in heterozygote
92
polyploidy
chromosomal alteration in which the organism possesses more than two complete chromosome sets. it is the result of an accident of cell division
93
DNA polymerase
enzyme that catalyzes the elongation of new DNA by the addition of nucleotides to the 3' end of an existing chain. there are several different DNA polymerases; DNA polymerase III and DNA polymerase I play major roles in DNA replication in E. coli
94
complete domiance
situation in which the phenotypes of heterozygote and dominant homozygote are indistinguishable
95
dihybrid
an organism that is heterozygous with respect to two genes of interest. all the offspring from a cross between parents double homozygous for different alleles are dihybrids. for ex., parents of genotypes AABB and aabb produce a dihybrid of genotype AaBb
96
carrier
in genetics, an individual who is heterozygous at a given genetic locus for a recessively inherited disorder. the heterozygote is generally phenotypically normal for the disorder but can pass on the recessive allele to offspring
97
alternative RNA splicing
type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produces from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
98
triplet code
genetic information system in which a series of three-nucleotide-long words specifies a sequence of amino acids for a polypeptide chain
99
transcription
the synthesis of RNA using a DNA template
100
silent mutation
a nucleotide-pair substitution that has no observable effect on the phenotype; ex., within a gene, a mutation that results in a codon that codes for the same amino acid
101
linked genes
genes located close together on a chromosome that they tend to be inherited together
102
recombinant types
an offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself
103
translation
synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. there is a change of language from nucleotides to amino acids
104
restriction fragment
DNA segment that results from the cutting of DNA by a restriction enzyme
105
phenotype
the observable physical and physiological traits of an organism, which are determines by its genetic makeup
106
quantitative character
a heritable feature that varies continuously over a range rather than in an either-or fashion
107
anticodon
a nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule
108
sex-linked gene
a gene located on either sex chromosome. most sex-linked genes are on the X chromosome and show distinctive patterns of inheritance
109
exon
sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed
110
monosomic
referring to a diploid cell that has only one copy of a particular chromosome instead of the normal two
111
barr body
a dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromsome
112
allele
any of the alternative versions of a gene that may produce distinguishable phenotype effects
113
monohybrid
an organism that is heterozygous with respect to a single gene of interest. all the offspring from a cross between parents homozygous for different alleles are monohybrids. ex., parents of genotypes AA and aa produce a monohybrid of genotype Aa
114
nuclease
enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides
115
heterochromatin
eukaryotic chromatic that remains highly compacted during interphase and is generally not transcribed
116
replication fork
a Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized
117
reading frame
on an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis
118
double helix
the form of native DNA< referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape
119
ribosomal RNAs (rRNAs)
RNA molecules that, together with proteins, make up ribosomes; the most abundant type of RNA
120
epistasis
a type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene
121
E site
one of a ribosome's three binding sites for tRNA during translation. the E site is the place where discharged tRNAs leave the ribosome
122
leading strand
the new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5' S 3' direction
123
DNA sequencing
determining the order of nucleotide bases in a gene or DNA fragment
124
primer
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
125
pleiotropy
the ability of a single gene to have multiple effects
126
recombinant DNA molecule
DNA molecule made in vitro with segments from different sources
127
signal-recognition particle (SRP)
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
128
DNA replication
process by which a DNA molecule is copies; also called DNA synthesis
129
true-breeding
referring to organisms that produce offspring of the same variety over many generations of self-pollination
130
X-linked gene
a gene located on the X chromosome; such genes show a distinctive pattern of inheritance
131
dihybrid cross
cross between two organisms that are each heterozygous for both of the characters being followed
132
F1 genertation
the first filial, hybrid (heterozygous) offspring arising from a parental (P generation) cross
133
translocation
during protein synthesis, the third stage in the elongation cycle, when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome
134
nucleoid
non-membrane-enclose region in a prokaryotic cell where its chromosome is located
135
F2 generation
the offspring resulting from interbreeding (or self-pollination) of the hybrid F1 generation
136
hybridization
in genetics, the mating, or crossing, of two true-breeding varieties
137
mutation
a change in the nucleotide sequence of an organism's DNA or in the DNA or RNA of a virus
138
poly-A tail
a sequence of 50-250 adenine nucleotides added onto the 39 end of a pre-mRNA molecule
139
dominant allele
an allele that is fully expressed in the phenotype of a heterozygote
140
restriction enzyme
an endonuclease that recognizes and cutes DNA molecules foreign to a bacterium. the enzyme cute specific nucleotide sequences
141
RNA polymerase
an enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand
142
polymerase chain reaction (PCR)
a technique for amplifying DNA in vitro by incubating it with specific primers, a heat-resistant DNA polymerase, and nucleotides
143
homozygote
an organism that has a pair of identical alleles for a gene
