Bio 93 Quiz 4: Cell Division: Mitosis and Meiosis Overview (more review)

Cell Division

The process by which a parent cell divides into two or more daughter cells, essential for growth, development, and repair in multicellular organisms.

Genome

The complete set of DNA, including all of its genes, present in a cell.

Chromosome

A structure composed of DNA and protein that carries genetic information; found in the nucleus of eukaryotic cells.

Chromatin

A complex of DNA and proteins that condenses to form chromosomes during cell division.

Somatic Cells

Non-reproductive cells that contain two sets of chromosomes, one from each parent.

Gametes

Reproductive cells (sperm and egg) that contain only one set of chromosomes, half the number found in somatic cells.

Nucleosome

A structural unit of chromatin consisting of a segment of DNA wrapped around a core of histone proteins.

Mitosis

The process of nuclear division that results in two genetically identical daughter cells, maintaining the same chromosome number.

Cytokinesis

The division of the cytoplasm that occurs after mitosis, resulting in two separate cells.

Meiosis

A specialized form of cell division that reduces the chromosome number by half, producing four genetically diverse haploid cells.

Interphase

The phase of the cell cycle during which the cell prepares for division, including DNA replication.

G1 Phase

The first gap phase of interphase where the cell grows and prepares for DNA replication.

S Phase

The synthesis phase of interphase where DNA is replicated.

G2 Phase

The second gap phase of interphase where the cell checks for DNA damage and prepares for mitosis.

Prophase

The first stage of mitosis where chromatin condenses into visible chromosomes and the mitotic spindle begins to form.

Metaphase

The stage of mitosis where chromosomes align at the cell's equatorial plane.

Anaphase

The phase of mitosis where sister chromatids are pulled apart toward opposite poles of the cell.

Telophase

The final stage of mitosis where chromosomes decondense and the nuclear envelope re-forms around each set of chromosomes.

Cleavage Furrow

The indentation that begins the process of cytokinesis in animal cells, leading to cell division.

Cell Plate

The structure that forms during cytokinesis in plant cells, eventually leading to the separation of the two daughter cells.

Binary Fission

A form of asexual reproduction in prokaryotes where a single cell divides into two identical daughter cells.

Cell Cycle

A series of phases that a cell goes through to grow and divide, including G1, S, G2, and M phases.

G1 Checkpoint

A critical point in the cell cycle where the cell checks for DNA damage and decides whether to proceed with division.

G0 Phase

A non-dividing state that a cell can enter if it does not receive a go-ahead signal at the G1 checkpoint.

Cyclins

Regulatory proteins whose concentrations fluctuate throughout the cell cycle, activating cyclin-dependent kinases.

Cyclin-Dependent Kinases (Cdks)

Enzymes that, when activated by cyclins, regulate the progression of the cell cycle.

Maturation-Promoting Factor (MPF)

A cyclin-Cdk complex that triggers the cell's transition from the G2 phase to the M phase.

Internal Signals

Molecular signals within a cell that can delay cell cycle progression, such as those from unattached kinetochores.

External Signals

Factors such as growth factors that stimulate cells to divide, often produced by other cells.

Density-Dependent Inhibition

A phenomenon where crowded cells stop dividing due to lack of space.

Anchorage Dependence

The requirement for cells to be attached to a substrate in order to divide.

Rb Protein

A regulatory protein that halts the cell cycle until the cell receives a signal to grow.

p53 Protein

A tumor suppressor protein that regulates the cell cycle and can trigger apoptosis if DNA damage is detected.

Hypoxia

A condition of low oxygen levels in tissues that can influence cell behavior and survival.

Cancer Cells

Cells that grow and divide uncontrollably, often bypassing normal regulatory mechanisms of the cell cycle.

Apoptosis

A programmed cell death process that eliminates damaged or unnecessary cells.

p53

A tumor suppressor protein that regulates the cell cycle and prevents the formation of tumors.

Locus

The specific physical location of a gene on a chromosome.

Karyotype

An ordered profile of an individual's chromosomes, used to examine chromosomal abnormalities.

Homologous Chromosomes

Pairs of chromosomes that are similar in shape, size, and genetic content, one inherited from each parent.

Autosomes

Chromosomes that do not determine the sex of an individual; humans have 22 pairs of these.

Diploid

A cell that contains two complete sets of chromosomes, one from each parent.

Haploid

A cell that contains only one set of chromosomes, as seen in gametes.

Zygote

The fertilized egg that results from the union of two gametes, containing genetic material from both parents.

Sporophyte

The diploid multicellular stage in the life cycle of plants and algae that produces haploid spores.

Gametophyte

The haploid multicellular stage in the life cycle of plants and algae that produces gametes.

Cloning

The process of producing genetically identical individuals from a single parent.

Chromatid

One of the two identical halves of a replicated chromosome.

Fertilization

The process in which male and female gametes fuse to form a zygote.

Meiosis I

The first division in meiosis where homologous chromosomes pair up and separate, resulting in two haploid cells.

Meiosis II

The second division in meiosis that separates sister chromatids, resulting in four haploid daughter cells.

Sex Chromosomes

Chromosomes that determine the sex of an individual; in humans, these are X and Y.

Replication

The process of copying DNA prior to cell division, ensuring each daughter cell receives an identical set of chromosomes.

Sister Chromatids

Identical copies of a chromosome connected by a centromere, formed during DNA replication.

Centromere

The region of a chromosome where sister chromatids are joined and where the spindle fibers attach during cell division.

Tetrad

A structure formed during prophase I of meiosis, consisting of a pair of homologous chromosomes, each made up of two sister chromatids.

Crossing Over

The exchange of genetic material between non-sister chromatids during prophase I, leading to genetic variation.

Chiasmata

X-shaped regions where crossing over occurs between homologous chromosomes during prophase I.

Metaphase Plate

The imaginary plane where chromosomes align during metaphase, ensuring proper separation during cell division.

Spindle Apparatus

A structure made of microtubules that segregates chromosomes into daughter cells during cell division.

Anaphase I

The stage in meiosis I where homologous chromosomes are pulled apart to opposite poles of the cell.

Telophase I

The stage in meiosis I where the chromosomes reach the poles, and the cell begins to divide into two haploid cells.

Prophase II

The stage in meiosis II where the spindle apparatus forms and chromosomes condense, preparing for the next division.

Metaphase II

The stage in meiosis II where sister chromatids align at the metaphase plate, ready for separation.

Anaphase II

The stage in meiosis II where sister chromatids are pulled apart and move toward opposite poles.

Telophase II

The final stage of meiosis where chromosomes arrive at the poles, nuclei form, and cytokinesis occurs, resulting in four haploid daughter cells.

Genetic Variation

The diversity in gene frequencies, which can result from processes such as crossing over during meiosis.

Kinetochore

A protein structure on the chromosome where the spindle fibers attach during cell division.

Mutation

A change in an organism's DNA that can create different versions of genes, known as alleles.

Allele

A variant form of a gene that can result from mutations and contributes to genetic diversity.

Independent Assortment

The process during meiosis where homologous chromosomes line up and segregate into daughter cells independently of one another.

Random Fertilization

The process by which any sperm can fertilize any egg, contributing to genetic diversity in offspring.

Gamete

A reproductive cell (sperm or egg) that is haploid and can fuse with another gamete during fertilization.

Hybridization

The process of mating two contrasting, true-breeding varieties to produce offspring with mixed traits.

P Generation

The true-breeding parental generation in Mendel's experiments.

F1 Generation

The first generation of offspring resulting from the hybridization of the P generation.

F2 Generation

The second generation of offspring produced when F1 individuals self-pollinate or cross-pollinate.

Dominant Trait

A trait that is expressed in the phenotype even when only one copy of the allele is present.

Recessive Trait

A trait that is only expressed in the phenotype when two copies of the allele are present.

Gene

A discrete unit of hereditary information that influences traits and is passed from parents to offspring.

Heritable Factor

What Mendel referred to as a gene, which is responsible for the inheritance of traits.

Trait

A specific characteristic or feature of an organism, such as flower color in pea plants.

Alleles

Alternative versions of a gene that determine specific traits.

Homozygous

An organism with two identical alleles for a particular trait.

Heterozygous

An organism that has two different alleles for a gene.

Phenotype

The observable physical characteristics of an organism.

Genotype

The genetic makeup of an organism, represented by its alleles.

Dominant Allele

An allele that expresses its trait even in the presence of a recessive allele.

Recessive Allele

An allele that only expresses its trait when two copies are present.

Law of Segregation

The principle stating that alleles for a trait separate during gamete formation.

Punnett Square

A diagram used to predict the outcome of a genetic cross.

Testcross

A breeding experiment used to determine the genotype of an individual with a dominant phenotype.

3:1 Ratio

The expected phenotypic ratio in the offspring of a monohybrid cross of heterozygous parents.