Ch. 2 Chromosomes and Cell Reproduction Flashcards
prokaryote
unicellular organism with a simple cell structure; prokaryotes include bacteria (eubacteria) and archaea
eukaryotes
one of the three primary divisions of life, consisting of organisms whose cells have a complex structure including a nuclear envelope and membrane-bounded organelles; eukaryotes include unicellular and multicellular forms
bacteria
one of the three primary divisions of life, consisting of prokaryotic unicellular organisms; also called eubacteria
archaea
one of the three primary divisions of life, consisting of unicellular organisms with prokaryotic cell structure
nucleus
compartment in eukaryotic cells that is enclosed by the nuclear envelope and contains the chromosomes
histone
low-molecular-weight protein found in eukaryotes that complexes with DNA to form chromosomes
chromatin
material found in the eukaryotic nucleus; consists of DNA and proteins
virus
noncellular replicating structure consisting of nucleic acid surrounded by a protein coat; can replicate only within a host cell
origin of replication
site where DNA synthesis is initiated
homologous pair
a pair of chromosomes that are alike in structure and size and that carry genetic information for the same set of hereditary characteristics; one chromosome of a homologous pair is inherited from the male pedant and the other is inherited from the female parent
diploid
possessing two sets of chromosomes
haploid
possessing a single set of chromosomes
polyploidy
possession of more than two sets of chromosomes
centromere
constricted region on a chromosomes that stains less strongly than the rest of the chromosome; serves as the attachment point for spindle microtubules
telomere
stable end of a eukaryotic chromosome
sister chromatids
two copies of a chromosome that are held together at the centromere; each chromatid consists of a single DNA molecule
cell cycle
stages through which a cell passes from one cell division to the next
checkpoint
a key transition point at which progression to the next stage in the cell cycle is regulated
cytokinesis
process by which the cytoplasm of a cell divides
mitosis
process by which the nucleus of a eukaryotic cell divides
interphase
major phase of the cell cycle between cell divisions; in interphase, the cell grows, develops, and prepares for cell division
condensins
a group of proteins that bind to chromosomes as a cell enters prophase, causing the chromosomes to become more compact and visible under a light microscope
prophase
stage of mitosis in which the chromosomes contract and become visible, the cytoskeleton breaks down, and the mitotic spindle begins to form
prometaphase
stage of mitosis in which the nuclear membrane breaks down and the spindle microtubules attach to the chromosomes
metaphase
stage of mitosis in which chromosomes align in the center of the cell
anaphase
stage of mitosis in which chromatids separate and move toward the spindle poles
amphidiploidy
type of allopolyploidy in which two different diploid genomes are combined such that every chromosome has one and only one homologous partner and the genome is functionally diploid
telophase
stage of mitosis in which the chromosomes arrive at the spindle poles, the nuclear membrane re-forms, and the chromosomes relax and lengthen
double fertilization
fertilization in plants; includes the fusion of a sperm cell with an egg cell to form a zygote and the fusion of a second sperm cell with the polar nuclei to form an endosperm
meiosis
process by which the chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells; consists of two divisions: meiosis I and meiosis II
tetrad
see bivalent
bivalent
a synapsed pair of homologous chromosomes consisting of four chromatids; also called a tetrad
synapsis
close pairing of homologous chromosomes
prophase I
stage of meiosis I in which chromosomes condense and pair, crossing over takes place, the nuclear membrane breaks down, and the mitotic spindle forms
crossing over
exchange of genetic material between homologous but nonsister chromatids
telophase I
stage of meiosis in which chromosomes arrive at the spindle poles
metaphase I
stage of meiosis I in which homologous pairs of chromosomes align in the center of the cell
anaphase I
stage of meiosis I in which homologous chromosomes separate and move toward the spindle poles
metaphase II
stage of meiosis II in which individual chromosomes align in the center of the cell
prophase II
stage of meiosis after interkinesis in which chromosomes condense, the nuclear membrane breaks down, and the spindle forms. some cells skip this stage
interkinesis
period between meiosis I and meiosis II
telophase II
stage of meiosis II in which chromosomes arrive at the spindle poles
anaphase II
stage of meiosis II in which chromatids separate and move toward the spindle poles
homologous recombination
exchange of genetic information between homologous DNA molecules
cohesin
molecule that holds two sister chromatids of a chromosome together; the breakdown of cohesin at the centromeres enables the chromatids to separate in anaphase of mitosis and anaphase II of meiosis
spermatid
immediate product of meiosis II in spermatogenesis; matures to sperm
secondary spermatocyte
product of meiosis I in male animals
primary spermatocyte
spermatogonium that has entered prophase I
spermatogenesis
sperm production in animals
spermatogonium
diploid cell in the testis; capable of undergoing meiosis to produce a sperm
primary oocyte
oogonium that has entered prophase I
oogenesis
egg production in animals
second polar body
one of the products of meiosis II in oogenesis; contains a set of chromosomes but little of the cytoplasm
ovum
final product of oogenesis
first polar body
one of the products of meiosis I in oogenesis; contains half the chromosomes but little of the cytoplasm
secondary oocyte
one of the products of meiosis I in oogenesis; receives most of the cytoplasm
microspore
haploid product of meiosis in plants
