Key Concepts in Cell Biology and Stem Cells

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endosymbiotic theory

theory that suggests that eukaryotic cells evolved from prokaryotic cells through symbiosis and suggests chloroplasts and mitochondria arose from ancient prokaryote cells that were ingested by other prokaryote host cells

zygote

A zygote is the single-cell organism formed when a sperm fertilizes an egg

stem cell

an

unspecialised,

immature cell capable

of differentiating into a

specialised cell

totipotent stem cell

stem cell that can develop into any of the types of cells necessary for embryonic development

pluripotent stem cell

a stem cell that can develop into many, but not all, of the cell types necessary for foetal development

embryonic stem cell

a stem cell that is cultured from an embryo

multipotent stem cell

stem cell that can develop into a limited number of cell types

adult stem cell

a stem cell harvested from tissues such as bone marrow that are not part of an embryo

unipotent stem cell

a stem cell that can develop into only one type of cell

mitosis

a type of cell division in which a parent cell produces two daughter cells with exactly the same genetic material as each other and as the parent cell

cytokinesis

the process in which the parent cell's cytoplasm divides between the two daughter cells

part of interphase What happens in Gap 1?

the cell is preparing to divide

part of interphase Synthesis of S?

the dna is copied

part of interphase What happens in Gap 2?

the cell is getting organized and begins to condense

Prophase

DNA condenses and form sister chromatids, spindles begin to form and centrioles appear

Metaphase

the sister chromatids line up along the spindle’s

equator.

Anaphase

sister chromatids separate as the centromere breaks down. One copy of each chromatid, now called a chromosome, is drawn to each pole of the cell as the spindle fiber

shortens.

Telophase

Telophase – chromosomes reach the poles, decondense and the nuclear membrane reforms. These phases are followed by cytokinesis, during which the remaining organelles and cytosol also separate.