Chapter 2 Flashcards
prokaryote
Unicellular organism with a simple cell structure. Prokaryotes include eubacteria and archaea.
eukaryote
Organism with a complex cell structure including a nuclear envelope and membrane-bounded organelles. One of the three primary divisions of life, eukaryotes include unicellular and multicellular forms.
eubacteria
One of the three primary divisions of life. Eubacteria consist of unicellular organisms with prokaryotic cells and include most of the common bacteria.
archaea
One of the three primary divisions of life. Archaea consist of unicellular organisms with prokaryotic cells.
nucleus
Space 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 agent consisting of nucleic acid surrounded by a protein coat; can replicate only within its host cell.
homologous pair of chromosomes
Two 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 parent and the other is inherited from the female parent.
diploid
Possessing two sets of chromosomes (two genomes).
haploid
Possessing a single set of chromosomes (one genome).
polyploid
Possession of more than two haploid sets of chromosomes.
telomere
stable end of a chromosome
origin of replication
Site where DNA synthesis is initiated.
sister chromatid
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.
interphase
Period in the cell cycle between the cell divisions. In interphase, the cell grows, develops, and prepares for cell division.
M (mitotic) phase
Period of active cell division; includes mitosis (nuclear division) and cytokinesis (cytoplasmic division).
mitosis
Process by which the nucleus of a eukaryotic cell divides.
cytokinesis
process by which the cytoplasm of a cell divides
prophase
Stage of mitosis. In prophase, the chromosomes contract and become visible, the cytoskeleton breaks down, and the mitotic spindle begins to form.
prometaphase
Stage of mitosis. In prometaphase, the nuclear membrane breaks down and the spindle microtubules attach to the chromosomes.
metaphase
Stage of mitosis. In metaphase, chromosomes align in the center of the cell.
anaphase
Stage of mitosis in which chromatids separate and move toward the spindle poles.
telophase
Stage of mitosis. In telophase, the chromosomes arrive at the spindle poles, the nuclear membrane re-forms, and the chromosomes relax and lengthen.
meiosis
Process in which chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells. Consists of two divisions: meiosis I and meiosis II.
fertilization
Fusion of gametes (sex cells) to form a zygote.
prophase 1
Stage of meiosis I. In prophase I, chromosomes condense and pair, crossing over takes place, the nuclear membrane breaks down, and the spindle forms.
synapsis
Close pairing of homologous chromosomes.
bivalent
Refers to a synapsed pair of homologous chromosomes.
tetrad
The four products of meiosis; all four chromatids of a homologous pair of chromosomes.
crossing over
Exchange of genetic material between homologous but nonsister chromatids.
metaphase 1
Stage of meiosis I. In metaphase I, homologous pairs of chromosomes align in the center of the cell.
anaphase 1
Stage of meiosis I. In anaphase I, homologous chromosomes separate and move toward the spindle poles.
telophase 1
Stage of meiosis I. In telophase I, chromosomes arrive at the spindle poles.
interkinesis
Period between meiosis I and meiosis II.
prophase 2
Stage of meiosis after interkinesis. In prophase II, chromosomes condense, the nuclear membrane breaks down, and the spindle forms. Some cells skip this stage.
metaphase 2
Stage of meiosis II. In metaphase II, individual chromosomes align on the metaphase plate.
anaphase 2
Stage of meiosis II. In anaphase II, chromatids separate and move toward the spindle poles.
telophase 2
Stage of meiosis II. In telophase II, chromosomes arrive at the spindle poles.
recombination
Process that produces new combinations of alleles.
cohesin
Molecule that holds the 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.
spermatogenesis
Sperm production in animals.
spermatogonium
Diploid cell in the testis; capable of undergoing meiosis to produce a sperm.
primary spermatocyte
Spermatogonium that has entered prophase I.
secondary spermatocyte
Product of meiosis I in male animals.
spermatid
Immediate product of meiosis II in spermatogenesis; matures to sperm.
oogenesis
Egg production in animals.
oogonium
Diploid cell in the ovary; capable of undergoing meiosis to produce an egg cell.
primary oocyte
Oogonium that has entered prophase I.
secondary oocyte
One of the products of meiosis I in female animals; receives most of the cytoplasm.
first polar body
One of the products of meiosis I in oogenesis; contains half the chromosomes but little of the cytoplasm.
ovum
Final product of oogenesis.
second polar body
One of the products of meiosis II in oogenesis; contains a set of chromosomes but little of the cytoplasm.
microsporocyte
Diploid reproductive cell in the stamen of a plant; undergoes meiosis to produce four haploid microspores.
microspore
Haploid product of meiosis in plants.
megasporocyte
In the ovary of a plant, a diploid reproductive cell that undergoes meiosis to produce haploid macrospores.
megaspore
One of the four products of meiosis in plants.
kinetochore
point of attachment for spindle microtubules
what type of chromosome is this?

acrocentric
what type of chromosome is this?

metacentric
what type of chromosome is this?

submetacentric
what type of chromosome is this?

telocentric