BY 101 EXAM 4

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Cell Division

Process by which one parent cell divides into two daughter cells.

Binary Fission

Prokaryotic cell division that produces two cells.

Mitosis

Eukaryotic cell division that produces somatic (body) cells.

Meiosis

Eukaryotic cell division that produces gametes (sex cells).

Somatic Cells

Diploid body cells produced by mitosis.

Gametes

Haploid sex cells produced by meiosis.

Diploid (2n)

Cell containing two copies of each chromosome.

Haploid (n)

Cell containing one copy of each chromosome.

Asexual Reproduction

Reproduction involving one parent that produces genetically identical offspring.

Sexual Reproduction

Reproduction involving two parents that produces genetically diverse offspring.

Genome

The complete set of DNA in a cell.

Histones

Proteins around which DNA wraps.

Nucleosomes

DNA wrapped around histone proteins.

Chromatin

Loosely packed DNA found in non-dividing cells.

Chromosomes

Tightly condensed DNA found in dividing cells.

DNA Replication

Process that creates an exact copy of DNA.

Sister Chromatids

Identical copies of a replicated chromosome.

Centromere

Region where sister chromatids are attached.

Cell Cycle

Series of events from cell formation until division.

Interphase

Non-dividing phase involving growth and DNA replication.

G1 Phase

Cell growth and normal cell functions.

S Phase

DNA replication phase.

G2 Phase

Preparation for mitosis.

G0 Phase

Non-dividing state where cells perform specialized functions.

M Phase

Mitosis plus cytokinesis.

Centrosome

Microtubule-organizing center that forms the mitotic spindle.

Mitotic Spindle

Microtubule structure that separates chromosomes during mitosis.

Prophase

Chromosomes condense and spindle begins forming.

Prometaphase

Nuclear envelope breaks down and spindle attaches to chromosomes.

Metaphase

Chromosomes line up at the cell's equator.

Metaphase Plate

Imaginary plane where chromosomes align during metaphase.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclear envelopes reform and chromosomes uncoil.

PMAT

Order of mitosis: Prophase, Metaphase, Anaphase, Telophase.

Cytokinesis

Division of the cytoplasm into two cells.

Cleavage Furrow

Groove formed during animal cell cytokinesis.

Cell Plate

Structure that develops into a new cell wall during plant cytokinesis.

Growth Factors

Proteins that stimulate cell division.

Cell Cycle Checkpoints

Control points that ensure proper progression through the cell cycle.

G1 Checkpoint

Checks DNA before replication.

S Checkpoint

Monitors DNA replication.

G2 Checkpoint

Ensures DNA replication is complete before mitosis.

M Checkpoint

Ensures chromosomes are attached to spindle fibers.

p53

Tumor-suppressor protein that can trigger repair or apoptosis.

Apoptosis

Programmed cell death.

Cancer

Disease characterized by uncontrolled cell division.

Tumor

Abnormal mass of cells.

Benign Tumor

Tumor that remains localized.

Malignant Tumor

Tumor that can spread to other tissues.

Proto-oncogene

Normal gene that promotes cell division.

Oncogene

Mutated gene that promotes uncontrolled cell growth.

Tumor-Suppressor Gene

Gene that inhibits cell division.

Gene

Segment of DNA that codes for a protein or trait.

Allele

Alternative version of a gene.

Cell Ploidy

Number of chromosome sets in a cell.

Karyotype

Ordered display of chromosomes in a cell.

Autosomes

Non-sex chromosomes.

Sex Chromosomes

Chromosomes that determine biological sex.

Female Sex Chromosomes

XX.

Male Sex Chromosomes

XY.

Homologous Chromosomes

Chromosome pairs carrying the same genes but possibly different alleles.

Life Cycle of Sexual Reproducers

Includes mitosis, meiosis, gamete formation, and fertilization.

Fertilization

Fusion of sperm and egg.

Zygote

First diploid cell formed after fertilization.

Germ Cell

Diploid precursor cell that undergoes meiosis.

Meiosis

Process producing four genetically diverse haploid gametes.

Meiosis I

Reductional division that separates homologous chromosomes.

Reductional Division

Division that reduces chromosome number by half.

Meiosis II

Equational division that separates sister chromatids.

Equational Division

Division that maintains chromosome number.

Metaphase I

Homologous chromosome pairs line up at the cell equator.

Anaphase I

Homologous chromosomes separate.

Telophase I

End of Meiosis I producing two haploid cells.

Metaphase II

Chromosomes align in a single row.

Anaphase II

Sister chromatids separate.

Mitosis vs. Meiosis

Mitosis produces identical cells; meiosis produces genetically diverse gametes.

Crossing Over

Exchange of DNA between homologous chromosomes.

Prophase I

Stage where crossing over occurs.

Synapsis

Pairing of homologous chromosomes during Prophase I.

Chiasma

Site where crossing over occurs.

Non-Sister Chromatids

Chromatids from homologous chromosomes involved in crossing over.

Genetic Variation

Differences in DNA among individuals.

Independent Assortment

Random alignment of homologous chromosomes during Metaphase I.

2^n Formula

Calculates possible chromosome combinations from independent assortment.

Human Independent Assortment

Produces about 8 million chromosome combinations (2^23).

Nondisjunction

Failure of chromosomes to separate properly.

Aneuploid Cell

Cell with too many or too few chromosomes.

Down Syndrome

Genetic disorder commonly caused by trisomy 21.

Homologous Chromosomes Separate During

Meiosis I.

Sister Chromatids Separate During

Mitosis and Meiosis II.

Crossing Over Occurs During

Prophase I.

Independent Assortment Occurs During

Metaphase I.

Meiosis Produces

Four genetically diverse haploid gametes.

Mitosis Produces

Two genetically identical daughter cells.

If an error is detected at a cell cycle checkpoint, what protein can trigger repair or cell death?

p53

Cells that do not continue dividing after G1 enter what phase?

G0 phase

Cancerous cells may have what characteristics?

High nucleus-to-cytoplasm ratio, multiple nuclei, and more karyokinesis than cytokinesis

Plant cytokinesis occurs in what direction?

Centrifugally (inside outward)

Animal cytokinesis occurs in what direction?

Centripetally (outside inward)