Biology 3201 Cell Reproduction and Continuity of Human Life

Chromosome

A length of DNA and associated protein; condensed form of genetic material.

Sex chromosome

X or Y chromosome; determines genetic sex.

Autosome

Chromosome other than sex chromosome.

Chromatin

Non-condensed form of genetic material that predominates for most of the life cycle of the cell.

DNA (deoxyribonucleic acid)

A molecule that governs the expression of a trait.

Gene

Geverns expression of a trait

allele

One of the different forms of the same gene.

Cell cycle

Life cycle of a cell

Somatic cell

Body cell.

Diploid

Cell with two pairs of homologous chromosomes (2n)

Homologous Chromosomes

Chromosomes with the same gene sequence.

Interphase

Growth stage of cell cycle.

G1 phase

The cell grows quickly during this phase, making many new cell molecules (except DNA)

S phase

The DNA in the chromatin replicates to create an identical copy of DNA.

Sister chromatid

One of two chromosomes that are genetically identical and held together at the centromere.

The Centromere

The specialized DNA sequence of a chromosome that links a pair of sister chromatids.

G2 phase

This second growth stage lets the cell rebuild its reserves of energy to prepare for division. As well, the cell manufactures proteins and other molecules to make structures required for division of the nucleus and cell.

Mitosis

Division of genetic material and the cells nuleus.

Cytokinesis

Separation of the cytoplasm and organelles to form two separate daughter cells.

Prophase

The chromatin condenses into tightly packed chromosomes. The nuclear membrane breaks down, releasing chromosomes into the cytoplasm. The nucleolus disappears. One pair of cylindrical organelles, called, centrioles, moves apart to opposite poles of the cell.

Centriole

A cylindrical Organelle near the nucleus in animal cells, occuring in pairs and involved in the development of spindle fibers in cell division.

Metaphase

The spindle fibres guide the chromosomes to the equator, or centre line, of the cell. The spindle fibres from opposite poles attach to the centromere of each chromosome.

Anaphase

Each centromere splits apart and the sister chromatids separate from one another. The spindle fibres that link the centromeres to the poles of the cell shorten. As these fibres shorten, sister chromatids are pulled to opposite poles. At the same time, other microtubules in the spindle apparatus lengthen and force the poles of the cell away form one another.

Telophase

Telophase begins when the chromatids have reached the opposite poles of the cell. The chromatids begin to unwind into the longer and less visible strands of chromatin. The spindle fibres break down. A nuclear membrane forms around each new set of chromosomes, and a nucleolus forms within each new nucleus.

Cleavage Furrow

AN indentation that appears in a cells surface when the cell is preparing to divide.

Cytokinesis (Plants)

A membrane called a cell plate forms between the two daughter nuclei.

Cancer

Uncontrolled cell division.

Surgery

A type of cancer therapy which removes the tumor and nearby tissue during an operation.

Radiation Therapy

A type of cancer therapy that uses high doses of radiation to kill cancer cells and shrink tumors.

Chemotherapy

A drug cancer treatment that uses powerful chemicals to kill fast-growing cells in your body.

Targeted therapy

A cancer treatment that uses drugs to target specific genes and proteins that are involved in the growth and survival of cancer cells.

Hormone therapy

A cancer treatment that slows or stops the growth of cancer that uses hormones to grow.

Stem cell transplant

A type of cancer treatment when healthy stem cells are placed in your body to help you bone marrow start to work properly. The new stem cells make healthy blood cells.

Haploid

Cell with half the number of chromosomes

Meiosis

Cell division that produces haploid gametes form a germ cell.

Germ cell

Gamete producing cell.

Gametes

AN organisms reproductive cells. Also reffered to as sex cells.

Recombination

The products of meiosis have different combinations of genes. Genetic recombination gives rise to offspring that are genetically distinct from one another and their parents.

Prophase 1

Each pair of homologous chromosomes align side by side.

Synapsis

Aligning of homologous chromosomes in prophase 1.

Non-sister chromtids

Chromatids in a tetrad that do not belong to the same chromosome.

Chromatid

Is one of two strands of a copied chromosome.

Tetrad

Homologous chromosome pair; contains four chromatids.

Meiosis 1- Metaphase 1

A spindle fibre attaches to the centromere of each chromosome. A spindle fibre from one pole attaches to one pair of sister chromatids in the tetrad, and a spindle fibre from the opposite pole attaches to the other pair of sister chromatids. The spindle fibres guide each tetrad to the equator of the cell. The chromosomes, however, do not line up in single file as they do in mitosis. Instead they line up as homologous pairs. In each pair, one homologous chromosome is positioned on one side of the cellś equator, and the other homologous chromosome is positioned on the other side of the cellś equator.

Meiosis 1- Anaphase 1

During this phase, the spindle fibres shorten. This causes the homologous chromosomes to separate from one another. The Homologues move to opposite poles of the centromeres do not split as they do in mitosis. The result is that a single chromosome (made up of two sister chromatids) from each homologous pair moves to each pole of the cell.

Meiosis 1- Telophase 1

Some cells move directly from anaphase 1 to meiosis 2, other cells go through this phase. In this phase, the homologous chromosomes begin to uncoiled the spindle fibres disappear. The cytoplasm is divided, the nuclear membrane forms around each group of homologous chromosomes, and two cells are formed. Each of these new cells contains one set of sister chromatids and is now haploid. Chromosome replication does not take place before the next phase of meiosis.

Meiosis 1- Cytokinesis 1

It involves the division of the cytoplasm to produce two individual daughter cells. Result of Meiosis 1.

Meiosis 2- Prophase 2

The nuclear membrane initiates to break down, and the spindle fibres appear again. Each centriole divides, forming two pairs of centrioles. Chromosomes do not replicate any further in this phase of meiosis and begin migration towards the centre of the cell.

Meiosis 2- Metaphase 2

Chromosomes arrange on the equator of the cell with the help of spindle fibers. The centrioles are now at opposite poles in each of the daughter cells. Centromere divides, producing two sister chromatids, now known as daughter chromosomes, with the spindle fibers attached to each chromosome.

Meiosis 2- Anaphase 2

The daughter chromosomes are pulled towards the opposite poles of the cells with the help of the spindle fibers. At the end of this stage, each end of the cell contains a complete set of chromosomes.

Meiosis 2- Telophase 2

The nuclear membrane forms around each chromosome with the disappearance of the spindle fibers. Nucleolus reappears as the cell prepares for the second round of cytoplasmic division.

Cytokenisis 2

This step is identical to cytokinesis 1, involving the second cytoplasm division, resulting in the formation of two individual daughter cells. The end result of meiosis.

Independant Assortment

The creation of gametes that carry different combinations of maternal and paternal chromosomes.

Crossing Over

The exchange of genetic material between maternal and paternal chromosomes.

Spermatogenesis

Process of male gamete production

Spermatogonium

Diploid germ cell from which sperm are produced.

Sperm Cell

Male gamete.

Oogenesis

Process of female gamete production.

Oogonium

Diploid germ cell from which ova are produced. Each oogonium undergoes mitosis to form two primary oocytes.

Primary oocytes

The oocyte that arises from the oogonium.

Polar body

A small haploid cell that is formed at the same time as an egg cell during oogenesis, but generally does not have the ability to be fertilized.

Ovum

A mature ovum is a non-motile, sphere-shaped cell approximatly 0.1 mm in diameter (that is, over 20 times larger than the head of a sperm cell.)

Asexual Reproduction

Reproduction that requires only one parent.

Sexual Reproduction

Reproduction involving fertilization of gametes.

Binary fission

Asexual form of reproduction in prokaryotes (bacteria) that produces two identical cells.

Budding

A new organism develops from an outgrowth of the parent. The new organism then separates to become an independant organism.

Vegetative reproduction

Growth of a new plant from a modified stem.

Fragmentation

A new organism forms from a part of a parent.

Parthenogenisis

Development of an adult organism from an unfertilized egg.

Spore

Reproductive cell able to develop into a new organism.

The lytic cycle

Involves the reproduction of viruses using a host cell to manufacture more viruses; The viruses then burst out of the cell.

The Lysogenic cycle

Involves the incorporation of the viral genome into the host cell genome, infecting it from within.

Stamen

The male reproductive organ in flowering plants.

Filament

supports the anther

Anther

Contains cells that undergo meiosis and mitotic cell divisions to form pollen grains.

Pistil

The female reproductive organ in flowering plant.

Stigma

The tip of the pistil and is the place where pollination takes place

Style

Connects the stigma to the ovary, which contains one or more ovules.