Biology 30 - UNIT C

Cell Cycle

• lead to cell division and replication

• life span of a cell

• regulates cellular growth, replication, and division

• ending with mitosis

5 Stages of Mitosis

(PMATC) prophase, metaphase, anaphase, telophase, cytokinesis

Interphase

prepares cell for mitosis/cell division

Parts of Interphase

Gap 1, Gap 2, Synthesis

Mitosis

division of non-sex cells in the body (somatic cells)

• asexual reproduction

Synthesis

the phase where DNA is replicated before cell division

Gap 1

the first phase of interphase where the cell grows and performs normal functions.

• prepare cell by rapid growth

Gap 2

the final phase of interphase where the cell prepares for mitosis, including further growth and protein synthesis.

Meiosis

a type of cell division that reduces the chromosome number by half, resulting in four genetically diverse daughter cells

• sexual reproduction

Prophase

the first stage of mitosis where the chromatin condenses into chromosomes and the nuclear envelope breaks down.

Metaphase

the second stage of mitosis where chromosomes align at the cell's equatorial plane, ensuring proper segregation during the next phase.

Anaphase

the third stage of mitosis where sister chromatids are pulled apart to opposite poles of the cell by spindle fibers.

Chromatids

The replicated forms of a chromosome, joined together at a centromere, that separate during cell division.

Telophase

the final stage of mitosis where chromosomes de-condense, nuclear envelopes reform around each set of chromosomes, and the cell prepares to divide.

Cytokinesis

The process that follows mitosis where the cytoplasm of a parental cell is divided into two daughter cells, completing cell division.

• CELL DIVISION

Chromosome

A thread-like structure made of DNA and proteins that carries genetic information. Each chromosome is made up of two sister chromatids joined at the centromere before cell division.

Chromatin

The complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells, existing in a relaxed state during interphase.

Diploid

A cell or organism that has two complete sets of chromosomes, one from each parent, typical of somatic cells in humans.

Haploid

A cell or organism that has a single set of chromosomes, typically found in gametes (sperm and egg cells) in humans.

Stem Cell

An undifferentiated cell that can give rise to specialized cell types through differentiation. Stem cells have the ability to self-renew and can develop into various cell lineages.

Telomere

The protective end caps of chromosomes that prevent DNA degradation and maintain chromosomal stability during cell division.

Synapsis

The process during meiosis where homologous chromosomes pair up and exchange genetic material, facilitating genetic diversity.

Homologous Chromosomes

Chromosomes that are paired during meiosis, containing the same genes but possibly different alleles. They are critical for genetic recombination and ensuring proper segregation during cell division.

Tetrad

A structure formed during meiosis that consists of a pair of homologous chromosomes, each made up of two sister chromatids, allowing for genetic recombination.

Crossing-over

The exchange of genetic material between homologous chromosomes during tetrad formation in meiosis, increasing genetic variation in offspring.

During what stage of meiosis I does segregation occur?

Segregation occurs during anaphase I of meiosis I, where homologous chromosomes are pulled apart to opposite poles.

What happens to the 2 haploid cells during meiosis II?

They undergo another division to produce four haploid daughter cells, each with a unique set of chromosomes.

nondisjunction

is the failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to gametes with an abnormal number of chromosomes.

gametophyte

is the haploid phase of the plant life cycle that produces gametes through mitosis, leading to fertilization.

gametogenesis

is the process of forming gametes through meiosis in organisms, resulting in haploid cells that can participate in fertilization.

difference between the ootid and polar body

The ootid is a haploid cell that develops into an ovum after fertilization, while the polar body is a small cell that results from uneven cell division during oogenesis and typically does not develop into a viable gamete.

autosomes vs sex chromosomes

Autosomes are chromosomes that do not determine sex, while sex chromosomes determine the sex of an organism and are involved in sex-linked traits.

trisomy

is a genetic condition where an individual has three copies of a chromosome instead of the usual two, often leading to developmental and physical abnormalities.

monosomy

is a genetic condition where an individual has only one copy of a chromosome instead of the usual two, often causing significant developmental challenges.