Untitled Flashcards Set

Chromosome

A structure made of DNA and proteins that contains genetic information.

Chromatin

The substance found within a chromosome, consisting of DNA and proteins that condense to form chromosomes during cell division.

Centromere

The region of a chromosome where the two sister chromatids are joined.

Sister Chromatids

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

Nucleosome

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

Histone

A type of protein that helps package and organize DNA in the nucleus into nucleosomes.

Chromatin Condensation

The process by which chromatin fibers become tightly coiled and compacted to form visible chromosomes.

What processes require mitosis?

Somatic cell division, asexual reproduction, and tissue regeneration.

What are the products of mitosis?

Two genetically identical daughter cells.

Kinetochore

A protein complex that forms at the centromere during cell division and attaches to spindle fibers.

Spindles

Microtubule structures that separate sister chromatids during mitosis.

Centrioles

Cylindrical structures in the centrosome that help organize spindles during mitosis.

Centrosome

The organelle that serves as the main microtubule organizing center during cell division.

Prophase

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

Metaphase

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

Anaphase

The phase of mitosis when sister chromatids are pulled apart to opposite poles of the cell.

Telophase

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

Cytokinesis

The process of cytoplasmic division that occurs after mitosis, differing in plant and animal cells.

Interphase

The phase of the cell cycle during which the cell is not dividing, consisting of G1, S, and G2 phases.

Checkpoints

Regulatory points in the cell cycle that ensure proper division and function.

Oncogenes

Genes that have the potential to cause cancer when mutated.

Tumor Suppressor Genes

Genes that help regulate cell growth and division, preventing cancer when functioning properly.

Homologous Chromosomes

Pairs of chromosomes containing the same genes at identical loci, one inherited from each parent.

Alleles

Different forms of a gene that can exist at a specific locus.

Haploid (1n)

Cells that contain one set of chromosomes.

Diploid (2n)

Cells that contain two sets of chromosomes.

Somatic Cells

All body cells that are not involved in reproduction.

Gametes

Reproductive cells (sperm and egg) that are haploid.

What are the products of meiosis?

Four non-identical haploid cells.

What processes require meiosis?

Formation of gametes (spermatogenesis and oogenesis) for sexual reproduction.

Prophase I

The first stage of meiosis where homologous chromosomes pair and crossing over occurs.

Metaphase I

Homologous pairs align at the equatorial plane during meiosis.

Anaphase I

Homologous chromosomes are pulled apart to opposite poles during meiosis.

Telophase I

The stage of meiosis where the cell divides into two haploid cells.

Prophase II

The stage of meiosis II where chromosomes condense again if they had decondensed.

Metaphase II

The stage of meiosis II where chromosomes align at the equator of the cell.

Anaphase II

Sister chromatids are separated and pulled towards opposite poles in meiosis II.

Telophase II

The final stage of meiosis II where four haploid daughter cells are formed.

Crossing Over

The exchange of genetic material between homologous chromosomes during prophase I.

Synapsis

The pairing of homologous chromosomes during meiosis.

Tetrad

A group of four chromatids formed during synapsis in prophase I of meiosis.

Chiasma

The point at which homologous non-sister chromatids exchange genetic material during crossing over.

What happens during crossing over?

Genetic material is exchanged between homologous chromosomes, contributing to genetic variation.

Independent Assortment

The random distribution of homologous chromosomes during meiosis.

When does independent assortment occur?

During metaphase I of meiosis.

What is fertilization?

The union of sperm and egg to form a diploid zygote.

What is non-disjunction?

The failure of chromosomes to separate properly during cell division.

Results of non-disjunction in Meiosis I

Results in gametes with an abnormal number of chromosomes, leading to disorders like Down syndrome.

Results of non-disjunction in Meiosis II

Results in some gametes having two copies of a chromosome and others having none.

What is a karyotype?

A visual representation of an individual's chromosomes arranged in pairs.

Monosomy

A condition where there is only one copy of a chromosome instead of the normal two.

Trisomy

A condition where there are three copies of a chromosome instead of the normal two.

Gamete

A reproductive cell that carries genetic information.

Germ Cell

Cells that give rise to gametes through the process of meiosis.

Somatic Cell

Any cell of the body excluding gametes.

Spermatogenesis

The process of sperm cell formation through mitosis and meiosis.

Structure of Sperm

Sperm consists of an acrosome, nucleus, mitochondria, and flagellum.

Location of Spermatogenesis

Occurs in the testes, where mature sperm are released into the seminal vesicle.

Oogenesis

The process of egg cell formation through mitosis and meiosis, resulting in one egg and polar bodies.

Polar Bodies

Small cells produced during oogenesis that do not develop into eggs and assist in nutrient allocation.

Timing of Meiotic Divisions in Oogenesis

Starts before birth and resumes at puberty, completing after fertilization.

Location of Oogenesis

Occurs in the ovaries within follicles.

Where does fertilization take place?

In the fallopian tube, with implantation occurring in the uterus (endometrium).

Role of the Acrosome

To facilitate the sperm's penetration of the egg's protective layers during fertilization.

Haploid Sperm and Egg Nuclei

Unite to form a diploid zygote during fertilization.

Parthenogenesis

A form of asexual reproduction where an egg develops into an organism without fertilization.