Test 3

anaphase

Stage of mitosis during which sister chromatids are separated from each other.

binary fission

Prokaryotic cell division process.

cell cycle

Ordered series of events involving cell growth and division that produces two new daughter cells.

cell plate

Structure formed during plant cell cytokinesis that leads to the formation of cell walls separating two daughter cells.

cell-cycle checkpoint

Mechanism that monitors the preparedness of a eukaryotic cell to advance through various cell-cycle stages.

centriole

Rod-like structure constructed of microtubules at the center of each animal cell centrosome.

centromere

Region at which sister chromatids are bound together in condensed chromosomes.

chromatid

Single DNA molecule of two strands of duplicated DNA held together at the centromere.

cleavage furrow

Constriction formed by an actin ring during cytokinesis in animal cells.

condensin

Proteins that help sister chromatids coil during prophase.

cyclin

Group of proteins that act with cyclin-dependent kinases to help regulate the cell cycle.

cyclin-dependent kinase (Cdk)

Group of protein kinases that help to regulate the cell cycle when bound to cyclin.

cytokinesis

Division of the cytoplasm following mitosis that forms two daughter cells.

diploid

Cell, nucleus, or organism containing two sets of chromosomes (2n).

FtsZ

Tubulin-like protein component of the prokaryotic cytoskeleton that is important in cytokinesis.

G0 phase

Distinct from the G1 phase; a cell in G0 is not preparing to divide.

G1 phase

First phase of interphase centered on cell growth during mitosis.

G2 phase

Third phase of interphase during which the cell undergoes final preparations for mitosis.

gamete

Haploid reproductive cell or sex cell (sperm, pollen grain, or egg).

gene

Physical and functional unit of heredity, a sequence of DNA that codes for a protein.

genome

Total genetic information of a cell or organism.

haploid

Cell, nucleus, or organism containing one set of chromosomes (n).

histone

Basic proteins found in the chromatin of all eukaryotic cells; associates with DNA to form nucleosomes.

homologous chromosomes

Chromosomes of the same morphology with genes in the same location.

interphase

Period of the cell cycle leading up to mitosis, including G1, S, and G2 phases.

karyokinesis

Mitotic nuclear division.

kinetochore

Protein structure associated with the centromere that attracts and binds spindle microtubules.

locus

Position of a gene on a chromosome.

metaphase

Stage of mitosis when chromosomes are aligned at the metaphase plate.

metaphase plate

Equatorial plane where chromosomes align during metaphase.

mitosis

Period of the cell cycle where duplicated chromosomes are separated into identical nuclei.

mitotic phase

Period during which duplicated chromosomes are distributed into two nuclei and cytoplasmic contents are divided.

mitotic spindle

Apparatus composed of microtubules that orchestrates the movement of chromosomes during mitosis.

nucleosome

Subunit of chromatin composed of DNA wrapped around histone proteins.

oncogene

Mutated version of a normal gene involved in the positive regulation of the cell cycle.

origin

Region of the prokaryotic chromosome where replication begins.

p21

Cell-cycle regulatory protein that inhibits the cell cycle.

p53

Regulatory protein that monitors DNA damage and may induce apoptosis.

prometaphase

Stage of mitosis when the nuclear membrane breaks down and spindle fibers attach to kinetochores.

prophase

Stage of mitosis when chromosomes condense and the mitotic spindle begins to form.

proto-oncogene

Normal gene that when mutated becomes an oncogene.

quiescent

Refers to a cell performing normal functions and not preparing for division.

retinoblastoma protein (Rb)

Regulatory molecule affecting the cell cycle by interacting with a transcription factor.

S phase

Stage of interphase during which DNA replication occurs.

septum

Structure formed in a bacterial cell as a precursor to the separation of the cell.

telophase

Stage of mitosis when chromosomes arrive at opposite poles and decondense.

tumor suppressor gene

Segment of DNA that codes for proteins that prevent uncontrolled division.

alternation of generations

Life-cycle type where the diploid and haploid stages alternate.

chiasmata

Structure that forms at the crossover points after genetic exchange.

cohesin

Proteins that seal sister chromatids together at centromeres until anaphase II.

crossover

Exchange of genetic material between nonsister chromatids.

fertilization

Union of two haploid cells from two organisms.

gametophyte

Multicellular haploid life-cycle stage that produces gametes.

germ cells

Specialized cells that produce gametes, like eggs or sperm.

interkinesis

Brief rest between meiosis I and meiosis II.

life cycle

Sequence of events in the development of an organism producing offspring.

meiosis

Nuclear division process resulting in four haploid cells.

meiosis I

First round of meiotic cell division where ploidy level is reduced.

meiosis II

Second round of meiotic division separating sister chromatids, producing four unique haploid cells.

recombination nodules

Protein assemblies that mark crossover events and mediate genetic recombination.

reduction division

Nuclear division producing daughter nuclei with half as many chromosome sets.

somatic cell

Cells of a multicellular organism except the gametes.

spore

Haploid cell that can produce a haploid multicellular organism or fuse with another spore.

sporophyte

Multicellular diploid life-cycle stage that produces haploid spores.

synapsis

Close association of homologous chromosomes during prophase I.

synaptonemal complex

Protein lattice between homologous chromosomes during prophase I.

tetrad

Two duplicated homologous chromosomes bound together by chiasmata.

allele

Gene variations arising by mutation at the same location on homologous chromosomes.

autosomes

Non-sex chromosomes.

blending theory of inheritance

Hypothetical inheritance pattern where parental traits blend in offspring.

codominance

Complete and simultaneous expression of both alleles in a heterozygote.

continuous variation

Inheritance pattern showing a range of trait values with small gradations.

dihybrid

Cross between two true-breeding parents differing in two characteristics.

discontinuous variation

Inheritance pattern where traits are distinct and transmitted independently.

dominant

Trait appearing the same whether homozygous or heterozygous.

dominant lethal

Inheritance where an allele is lethal in both homozygotes and heterozygotes.

epistasis

Interaction between genes wherein one gene masks the expression of another.

F1

First filial generation in a cross between parents.

F2

Second filial generation produced when F1 individuals are self-crossed.

genotype

Underlying genetic makeup of an organism.

hemizygous

Presence of only one allele for a characteristic.

heterozygous

Having two different alleles for a gene on homologous chromosomes.

homozygous

Having two identical alleles for a gene on homologous chromosomes.

hybridization

Mating of two individuals differing to achieve specific traits in offspring.

incomplete dominance

Expression of two contrasting alleles in a heterozygote resulting in an intermediate phenotype.

law of dominance

In heterozygotes, one trait conceals another for the same characteristic.

law of independent assortment

Alleles segregate independently during gamete formation.

law of segregation

Genes segregate equally into gametes.

linkage

Phenomenon where alleles close together on the same chromosome are inherited together.

model system

Species used to study specific biological phenomena applicable to others.

monohybrid

Cross between two true-breeding parents differing in one characteristic.

P0

Parental generation in a cross.

phenotype

Observable traits expressed by an organism.

product rule

Probability of two independent events occurring simultaneously.

Punnett square

Visual representation of a cross showing possible zygotic genotypes.

recessive

Trait appearing latent when alongside a dominant trait, expressed only in homozygous form.

recessive lethal

Allele lethal only in homozygous form; heterozygote may be normal or altered.

reciprocal cross

Paired cross where respective traits switch between male and female.

sex-linked

Any gene on a sex chromosome.

sum rule

Probability of occurrence of at least one of two mutually exclusive events.