unit 5 - cellular reproduction

Mitosis

A process where a single cell divides into two identical daughter cells, each having the same number and kind of __chromosomes__ as the parent __nucleus__

Chromosome

Threadlike structures made of protein and a single molecule of DNA that serve to carry the genomic information from cell to cell

Chromatid

One of the two identical halves of a chromosome that has been replicated in preparation for cell division.

Centromere

Structure in a chromosome that holds together the two chromatids, the region where the cell's spindle fibers attach.

Telomere

Forms the end of chromosomes, protects chromosome ends from fusion and from being recognized as sites of DNA damage

Histones

A type of protein found in chromosomes. Histones bind to DNA, help give chromosomes their shape, and help control the activity of genes.

Interphase

Phase before mitotic division, the cell grows and makes a copy of its DNA, preparing for mitosis

G0 phase

A form of the resting state, cells reide here until they receive appropriate signals. The cell is not dividing nor preparing for division.

G1 phase

Cells accomplish most of their growth, they get bigger in size and make proteins and organelles needed for normal functions of DNA synthesis. Cell is preparing to divide.

S phase

Synthesis phase- replicates DNA. Genetic material is doubled before it enters mitosis.

G2 phase

A period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis. Includes a checkpoint that prevents cells from entering mitosis if DNA is damaged.

Prophase

The first stage of cell division, during which the chromosomes become visible as paired __chromatids__ and the nuclear envelope breaks down. The complex of DNA and proteins contained in the nucleus, known as chromatin, CONDENSES.

Metaphase

The stage of cell division during which the spindle fibers attach to the centromeres of the sister chromatids. Chromatids have aligned in the center of dividing cell.

Anaphase

The stage of cell division where replicated chromosomes are split into chromatids and the newly-copied chromosomes are moved to opposite poles of the cell.

Telophase

The phase of cell division in which the __chromatids__ or chromosomes move to opposite ends of the cell and nuclear membranes form around each set of DNA.

Cytokinesis

The cytoplasmic division of a cell at the end of __mitosis__ or __meiosis__, bringing about the separation into two daughter cells.

Cancer

A term for diseases in which abnormal cells divide without control and can invade nearby tissues.

Proto-oncogene

Genes that normally help cells grow and divide to make new cells, or to help cells stay alive. Mutations in this can cause the growth in cancer cells.

Tumor suppressor gene

A type of gene that makes a protein called a tumor suppressor protein that helps control cell growth. Mutations (changes in DNA) in this may lead to cancer.

Spindle fiber

Form a protein structure that divides the genetic material in a cell. This is necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis. During mitosis, these are called the mitotic spindle.

Stem cell

cells from which all other cells with specialized functions are generated.

Differentation

The process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function.

Transcription factors

Proteins involved in the process of converting, or transcribing, DNA into RNA.

Germ layers

A group of cells in an embryo. These things interact with each other as the embryo develops and will eventually give rise to all of the organism's organs and tissues.

Ectoderm

the outermost of the three germ layers, appears early in the development of an animal embryo. differentiates to form epithelial and neural tissues (spinal cord, peripheral nerves, skin, linings of the mouth, and brain).

Mesoderm

arises during gastrulation, and is present between the ectoderm, this will produce the gut and the lungs (

Endoderm

the innermost of the three germ layers, or masses of cells (lying within ectoderm and mesoderm), develops into the interior linings of two tubes in the body, the digestive and respiratory tube.

Gastrulation

an early developmental process in which an embryo transforms from a one-dimensional layer of epithelial cells (blastula) and reorganizes into a multilayered and multidimensional structure called the gastrula.

Fertilization

The union of two gametes. During this, sperm and egg fuse to form a diploid zygote to initiate prenatal development.

Zygote

fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm).

Cleavage

After fertilization, the development of a multicellular organism proceeds this process, a series of mitotic divisions whereby the enormous volume of egg cytoplasm is divided into numerous smaller, nucleated cells.

Organogenesis

the process of formation of organs from three germ layers

Totipotent

The ability of a single cell to divide and produce ALL the differentiated cells in an organism, including extraembryonic tissues.

Pluripotent

A cell that is able to develop into many different types of cells or tissues in the body. (most cells, cannot become an organism on its own)

Multipotent

A cell that is able to develop into multiple specialised cell types present in a specific tissue or organ (more limited).

Trimesters

One of the three divisions of three months each during pregnancy, in which different phases of fetal development take place.

Blastomere

type of cell produced by cell division (cleavage) of the zygote after fertilization

Cell determination

the process by which the cell commits to a certain developmental pathway and eventually produces a specialized cell

Meiosis

Special form of cell division in which each daughter cell receives half the amount of DNA as the parent cell. Occurs during formation of egg and sperm cells in mammals.

Haploid

The presence of a single set of chromosomes in an organisms cells. Sexually reproducing organisms are this.

Diploid

The presence of two complete sets of chromosomes in an organisms cells, with each parent contributing a chromosome to each pair.

DNA

The molecule inside cells that contains the genetic information responsible for the development and function of an organism.

Gene

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The basic unit of heredity passed from parent to child. Made up of DNA

Nucleotide

A molecule consisting of a nitrogen containing base, phosphate group, and a sugar. Basic building block for DNA and RNA

Somatic Cell

Any of the body cells except the reproductive cells.

Gamete

Reproductive cell of an animal or plant. Female - egg. Male - sperm.

Autosome

Having to do with any of the 22 numbered pairs of chromosomes found in most human cells (not the sex chromosomes)

Sex Chromosome

A type of chromosome involved in sex determinations. Male have one X and one Y, females have two X chromosomes.

Homologous Chromosomes

Two chromosomes in a pair - normally one inherited from the mother and one from the father. Same length and gene position, joined by a centromere.

Ploidy Level

The number of sets of chromosomes in a cell or an organism. Haploid = 1 sets. Diploid = 2 sets.

Centriole

a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

Centrosome

as division begins, the two centrosomes move to opposite ends of the cell - facilitates the organization of the spindle poles during mitosis.