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Biology Final Prep
Finals man
91
Biology
Not Applicable
12/30/2003

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Term
germ cell
Definition
Of animals, a cell of a lineage set aside for sexual reproduction. They give rise to gametes!
Term
sister chromatid
Definition
One of two DNA molecules of duplicated chromosome.
Term
prokaryotic fission
Definition
Division mechanism by which a bacterial cell reproduces.
Term
karyotype
Definition
for an individual, a preparation of metaphase chromosomes sorted by lengt, centromerer location, and other defining features.
Term
cell cycle
Definition
the process in which the cell doubles its mass an then divides. G1, S, G2, mitosis are all phases of cell cycle.
Term
mitosis
Definition
the phase in a cell cycle that marks the nuclear division. The subphases are prophase, metaphase, anaphase, and telaphase in order.
Term
interphase
Definition
the phase that fills the gap of cell cycle after mitosis is fill in.
This phase has three smaller phases, G1, S, and G2.
Term
G1 phase
Definition
G1 of interphase is an interval of cell growth before the onset of DNA replication. G1 begins immediately after mitosis. During G1, most of the carbohydrates, lipids, and proteins for a cell's own use and for export are assembled. During this stage, the cell almost doubles in size; it also replaces many of the cytoplasmic components that it lost in the previous
division.
Term
S phase
Definition
S is the synthesis stage. During S, the cell copies its DNA and synthesizes the proteins that will become organized into structural scaffolding for the condensed versions of chromosomes. A duplicate copy of each chromosome is then made.
Term
G2 phase
Definition
G2 is an interval between DNA replication and mitosis. It is a second period of cellular growth. During G2 the mitochondria divide, and the proteins that will drive mitosis to completion are produced. By the end of G2, the cell is ready to divide.
Term
centriole
Definition
A cylinder of triplet microtubules of cilia and flagella
Term
centromere
Definition
A small, contricted region of a chromosome with attachment sites for the mirotubules that move the chromosome during nuclear division.
Term
chromotids
Definition
one of the two chromosomes that haven't split apart yet.
Term
nuclear envelope
Definition
A double membrane that is outermost portion of a cell nucleus.
Term
cell plate
Definition
dislike structure that forms from remnants of a microtubular spindle when a plant cell divides. This thing partitions the cytoplasm.
Term
cleavage furrow
Definition
you know what it is. And it occurs only in animal cells.
Term
cytokinesis
Definition
cytoplasmic division
Term
microfilament
Definition
Thin cytoskeletal element of two
twisted polypeptide chains; it has
roles in cell movement, especially
at the cell surface, and in
producing and maintaining cell
shape.
Term
histone
Definition
Any of a class of proteins
intimately associated with
eukaryotic DNA and largely
responsible for the organization of
eukaryotic chromosomes.
Term
nucleosome
Definition
One of the organizational units of
the eukaryotic chromosome; a
stretch of DNA looped twice
around a "spool" of histone
molecules.
Term
oogenesis
Definition
Formation of a female gamete, from
a germ cell to a haploid ovum
(mature egg)
Term
ovum
Definition
Of vertebrates, the mature female
gamete (egg).
Term
polar body
Definition
One of four cells that form during
the meiotic cell division of an
oocyte but does not become the
ovum.
Term
spermatogenesis
Definition
Process by which mature sperm
form from a germ cell in males.
Term
sporophyte
Definition
Of plant life cycles, a vegetative
body that grows by way of mitosis
from a zygote and produces
spore-bearing structures.
Term
zygote
Definition
The first cell of a new individual,
formed by the fusion of a sperm
nucleus and an egg nucleus at
fertilization; also called a fertilized
egg.
Term
gametophyte
Definition
A haploid, multicelled,
gamete-producing body that forms
during the life cycle of most plants.
Term
heterozygous condition
Definition
Of a specified trait, having a pair of
nonidentical alleles at a gene locus
(on a pair of homologous
chromosomes).
Term
homozygous condition
Definition
For a specified trait, having a pair
of identical alleles at a gene locus
(on a pair of homologous
chromosomes).
Term
inheritance
Definition
The transmission, from parents to
offspring, of structural and
functional patterns that have a
genetic basis and are characteristic
of their species.
Term
locus
Definition
The particular location of a gene
along the length of a chromosome.
Term
Punnett-square method
Definition
A way to predict the probable
outcome of a genetic cross in
simple diagrammatic form.
Term
monohybrid cross
Definition
An experimental cross in which
offspring inherit a pair of
nonidentical alleles for a single trait
being studied, so that they are
heterozygous
Term
theory of segregation
Definition
A Mendelian theory that diploid
organisms inherit pairs of genes for
traits (on pairs of homologous
chromosomes) and that the two
genes segregate during meiosis
and end up in separate gametes.
Term
testcross
Definition
For an individual of unknown
genotype that shows dominance
for a trait, a type of experimental
cross that may reveal whether the
individual is homozygous
dominant or heterozygous.
Term
dihybrid cross
Definition
An experimental cross in which
true-breeding F1 offspring inherit
two gene pairs, each consisting of
two nonidentical alleles.
Term
independent assortment
Definition
By the end of meiosis in a germ
cell, each pair of homologous
chromosomes (and hence the
genes that they carry) have been
sorted for shipment into gametes
independently of how the other
pairs were sorted out.
Term
linkage group
Definition
A quantitative measure of the
relative positions of genes along
the length of a chromosome.
Term
allele
Definition
At a given gene locus on a
chromosome, one of two or more
slightly different molecular forms of
a gene that arise through mutation
and that code for different versions
of the same trait.
Term
multiple allele system
Definition
Three or more different molecular
forms of the same gene (alleles)
among individuals of a population.
Term
antibody
Definition
One of a diverse array of
antigen-binding receptors. Only B
cells make antibody molecules and
position them at their surface or
secrete them.
Term
epistasis
Definition
An interaction between gene pairs.
Two alleles of one gene mask
expression of another gene's
alleles, so expected phenotypes
may not appear.
Term
pleiotropy
Definition
As a result of expression of alleles
at a single gene locus, positive or
negative effects on two or more
traits. The effects may or may not
be manifest at the same time in the
individual.
Term
continuous variation
Definition
Of a population, a more or less
continuous range of small
differences in a given trait among
all of its individuals.
Term
autosome
Definition
any chromosome that is not a sex chromosome
Term
somatic cell
Definition
body cells that are not sex cells
Term
karyotype
Definition
For an individual (or a species), a
preparation of metaphase
chromosomes sorted by length,
centromere location, and other
defining features.
Term
gonad
Definition
Primary reproductive organ in
which animal gametes are
produced.
Term
linkage
Definition
The tendency of genes located on
the same chromosome to end up in
the same gamete. For any two of
those genes, the probability that
crossing over will disrupt the
linkage is proportional to the
distance separating them.
Term
wild-type allele
Definition
The allele that is represented most
frequently at a locus in the genome
of a species.
Term
linkage mapping
Definition
Use of crossover frequencies to
determine the arrangement and
distance between genes on a
chromosome.
Term
autosomal dominant inheritance
Definition
Condition arising from the
presence of a dominant allele on an
autosome (not a sex chromosome).
The allele is always expressed to
some extent, even in
heterozygotes.
Term
autosomal recessive inheritance
Definition
Condition arising from a recessive
allele on an autosome (not a sex
chromosome). Only recessive
homozygotes show the resulting
phenotype.
Term
genetic disorder
Definition
An inherited condition that results
in mild to severe medical problems.
Term
X-linked gene
Definition
any gene on the x-chromosome
Term
deletion
Definition
Loss of a chromosome segment.
Term
duplication
Definition
A repeat of the same linear stretch
of an individual's DNA in the same
chromosome or in a different one.
Term
inversion
Definition
A linear stretch of DNA within a
chromosome that has become
oriented in the reverse direction,
with no molecular loss.
Term
translocation
Definition
Of cells, a stretch of DNA that
physically moved to a different
location in the same chromosome,
or a different one, with no
molecular loss. Of vascular plants,
the process by which organic
compounds are distributed by way
of phloem.
Term
aneuploidy
Definition
Having one more chromosome or
one less relative to the parental
chromosome number.
Term
nondisjunction
Definition
The failure of two sister chromatids
or a pair of homologous
chromosomes to separate at
meiosis or mitosis, thus daughter
cells end up with too many or too
few chromosomes
Term
monosomy
Definition
A chromosome abnormality; the
presence of a chromosome that has
no homologue in a diploid cell.
Term
trisomy
Definition
Of cells, the presence of three
chromosomes of a given type
rather than the two characteristic of
the parental diploid chromosome
number. In humans, Down
syndrome is caused by trisomy of
chromosome 21.
Term
polyploidy
Definition
Having three or more of each type
of chromosome in the interphase
nucleus, compared to a diploid
chromosome number.
Term
bacteriophage
Definition
Category of viruses that infect
bacterial cells.
Term
adenine
Definition
[image]
Term
guanine
Definition
[image]
Term
cytosine
Definition
[image]
Term
purine
Definition
A type of nucleotide base with a
double ring structure. Examples are
adenine and guanine.
Term
pyrimidine
Definition
A type of nucleotide base with a
single ring structure. Examples are
cytosine and thymine.
Term
thymine
Definition
[image]
Term
DNA ligase
Definition
An enzyme that seals together the
new base pairings during DNA
replication; also used by
technologists to seal base pairings
between DNA fragments and cut
plasmid DNA.
Term
DNA polymerase
Definition
An enzyme that assembles a new
strand on a parent DNA strand
during replication; also takes part
in DNA repair.
Term
DNA repair
Definition
Following an alteration in the base
sequence of a DNA strand, a
process that may restore the
original sequence, as carried out by
DNA polymerases, DNA ligases,
and other enzymes.
Term
DNA replication
Definition
Of cells, the process by which
hereditary material is duplicated for
distribution to daughter nuclei.
Occurs prior to mitosis and meiosis
in eukaryotic cells and during
prokaryotic fission in bacterial
cells.
Term
semiconservative replication
Definition
How a DNA molecule duplicates
itself. A DNA double helix unzips
and a complementary strand is
assembled on the exposed base of
each strand. Each conserved
strand and its new partner wind
together into a double helix. Thus
the outcome is two Òhalf-old,
half-newÓ molecules.
Term
promoter
Definition
A short base sequence in DNA
that signals the start of a gene; the
site where RNA polymerase binds
to start transcription.
Term
transcription
Definition
The first stage of protein
synthesis, when an RNA strand is
assembled on one of the two
strands of a DNA double helix; the
base sequence of the resulting
transcript is complementary to the
DNA template.
Term
translation
Definition
The stage of protein synthesis
when the encoded sequence of
information in mRNA becomes
converted to a sequence of
particular amino acids, the outcome
being a polypeptide chain; rRNA,
tRNA, and mRNA interact to bring
this about.
Term
uracil
Definition
[image]
Term
RNA polymerase
Definition
An enzyme that catalyzes the
synthesis of RNA from a DNA
template in transcription
Term
intron
Definition
A noncoding portion of a newly
formed mRNA molecule
Term
exon
Definition
Any of the nucleotide sequences
of a pre-mRNA molecule that
become spliced together to form a
mature mRNA transcript and
ultimately get translated into
protein.
Term
codon
Definition
One of the base triplets in an
mRNA molecule, the linear
sequence of which corresponds to
a linear sequence of amino acids in
a polypeptide chain. Of sixty-four
codons, sixty-one specify different
amino acids, and three of these are
also start signals for translation;
one serves as a stop signal for
translation
Term
anticodon
Definition
A sequence of three nucleotide
bases in a tRNA molecule that can
base-pair with a codon in an mRNA
molecule.
Term
peptide bond
Definition
A covalent bond that forms
between one amino acid's amino
group and the carboxyl group of
the next amino acid.
Term
cytomembrane system
Definition
Organelles functioning as a system
to modify, package, and distribute
newly formed proteins and lipids.
Endoplasmic reticulum, Golgi
bodies, lysosomes, and a variety of
vesicles are its components.
Term
mutation rate
Definition
Of a gene, the probability of it
undergoing spontaneous mutation
during some specified interval,
such as each DNA replication
cycle
Term
transposable element
Definition
A DNA region that moves
spontaneously from one location
to another in the same DNA
molecule or a different one. Often
such regions inactivate genes into
which they become inserted and
cause changes in phenotype.
Term
hemoglobin
Definition
Iron-containing,
oxygen-transporting protein that
gives red blood cells their color.
Term
frameshift mutation
Definition
Mutation that results in an altered
reading of triplet genetic code, for
example, due to deletion.
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