Bio 111 Lesson 11 Cell Division

Vocabulary flashcards covering chromosome structure, cell division, the eukaryotic cell cycle, and the stages of mitosis based on Bio 111 Lesson 11.

Cell division

Division of a parent cell into two daughter cells.

Mitosis

Cell division preserving chromosome number by creating 2 genetically identical diploid cells.

Nucleosome

DNA coiled twice around 8 histone proteins.

Linker DNA

DNA between nucleosomes.

Chromatin

DNA and its associated proteins (histones).

Chromosome

Condensed DNA composed of 1 or 2 chromatids for cell division.

Sister chromatids

Identical chromosome copies joined at the centromere by cohesion proteins.

Centromere

Attachment site of sister chromatids.

Telomere

The ends of the chromosome.

Homologous chromosomes

Chromosome pair of the same size with genes at the same locus.

Maternal chromosome

maternal half of a homologous pair

Paternal chromosome

paternal half of a homologous pair

Autosomes

The 22 pairs of non-sex chromosomes in humans.

Sex chromosomes

The 1 pair of chromosomes ($XX$ for female, $XY$ for male) in humans.

Karyotype

diagram of chromosomes from largest to smallest in order to detect abnormalities

Nucleus

Double-membrane organelle housing DNA.

Nuclear envelope

The double membrane surrounding the nucleus.

Cytoskeleton

Network of proteins that provide structure to the cell.

Centrosome

Two centrioles that organize microtubules.

Centriole

Barrel-shaped organelle located in the centrosome.

Mitotic spindle (spindle apparatus)

Set of microtubules (cytoskeleton) used in mitosis to organize the chromosomes.

Cell cycle

The ordered series of events a eukaryotic cell goes through as it grows, replicates its DNA, and eventually divides.

Interphase

Stage of the cell cycle preparing for mitosis, consisting of $G_1$, $S$, and $G_2$.

$G_1$ phase

Sub-phase of interphase where the cell grows bigger.

$S$ phase

Sub-phase of interphase where the cell synthesizes a second copy of DNA.

$G_2$ phase

Sub-phase of interphase where the cell grows and prepares for mitosis.

$G_0$ phase

Resting phase where the cell is not dividing and performs normal cell functions.

Cytokinesis

Division of the cytoplasm into two new daughter cells.

Condensin proteins

Proteins that help DNA condense during prophase.

Prophase

DNA condenses, kinetochores assemble at the centromere, the nuclear envelope breaks apart, centrioles move to opposite poles, the mitotic spindle forms, and the nucleolus disappears.

Kinetochore

Centromere structure that attaches to the mitotic spindle.

Metaphase

Chromosomes meet and line up at the equatorial plate (metaphase plate) dragged by the mitotic spindle.

Equatorial plate (metaphase plate)

The middle plane of the cell where chromosomes line up during metaphase.

Anaphase

Cohesion proteins degrade, sister chromatids separate into individual chromosomes, and the mitotic spindle pulls them toward opposite ends of the cell.

Telophase

Nuclear envelopes reform around each new identical grouping of chromosomes, the mitotic spindle breaks apart, and chromosomes decondense.

Meiosis

Cell division which reduces chromosome number by producing 4 genetically different haploid cells from one diploid cell. Goes through 2 cycles.

Prophase I

Chromosomes condense (pair up) and crossing over occurs

Prometaphase I

Nuclear envelope breaks down and microtubules attach to chromosomes

Metaphase I

Chromosome pairs randomly line along metaphase plate

Anaphase I

Homologous chromosomes separate and move to opposite poles

Telophase I

2 haploid cells form, chromosomes each have 2 sister chromatids

Prophase II

DNA condenses, kinetochores assemble at the centromere, the nuclear envelope breaks apart, centrioles move to opposite poles, the meiotic spindle forms, and the nucleolus disappears.

Metaphase II

Chromosomes meet and line up at the equatorial plate dragged by the meiotic spindle.

Anaphase II

Cohesion proteins degrade, sister chromatids separate into individual chromosomes, and the meiotic spindle pulls them toward opposite ends of the cell.

Telophase II

Nuclear envelopes reform around each new identical grouping of chromosomes, the meiotic spindle breaks apart, and chromosomes decondense.

Meiotic spindle

The microtubule structure that moves chromosomes around the cell during meiosis.

Random mutation

A change in the DNA sequence and is passed onto offspring when it occurs in a gamete (genetic variation)

Crossing over

The exchange of whole non-sister chromatids at chiasmata during prophase I, resulting in non-identical chromatids and genetically unique gametes.

Synapsis

Homologous chromosomes pair up in prophase I to exchange portions of chromosomes. (genetic variation)

Synaptonemal complex

A lattice of proteins formed between homologous chromosomes during synapsis.

Bivalent/Tetrad

A paired set of two homologous chromosomes consisting of four chromatids.

Chiasma/chiasmata

X-shaped structure representing the physical site of crossing over

Linked genes

Genes located closer together on the same chromosome which have a higher likelihood of being inherited together.

Independent assortment

The random mixing and matching of maternal and paternal chromosomes into daughter cells based on their alignment at metaphase I (genetic variation)

Haploid dominant life cycle

A life cycle found in fungi such as black bread mold (Rhizopus nigricans) where the main multicellular form is haploid, and diploid zygospores divide by meiosis into haploid spores.

Alternation of generations

Plant life cycle that alternates between a sporophyte and a gameophyte

Sporophyte

Diploid plant phase that undergoes meiosis within sporangia to produce haploid spores.

Gametophyte

Haploid plant phase developed from haploid spores via mitosis that produces haploid sperm and egg cells by mitosis.

Gregor Mendel (1822–1884)

Known as the father of genetics, renowned for studying dominant and recessive traits in pea plants and predicting offspring ratios.

Gene

A segment of DNA that codes for a specific trait

Allele

A variant form of a gene, symbolized by capital letters for dominant versions and lowercase letters for recessive versions.

Dominant trait

A characteristic that is always expressed whenever its allele is present.

Recessive trait

A trait that can be hidden by a dominant allele and is only expressed when no dominant allele is present.

Homozygous

Having 2 identical alleles for a specific trait

Heterozygous

Having 2 different alleles for a specific trait

Genotype

The specific combination of alleles

Phenotype

The observable physical characteristic or trait displayed by an organism