Chapter 9 vocab

cell cycle

an ordered sequence of events in eukaryotes that involves cell growth and nuclear division; consists of stages G1, S, G2, and M

interphase

stages of the cell cycle (G1, S, G2) during which growth and DNA synthesis occur when the nucleus is not actively dividing

chromatid

following replication, a chromosome consists of a pair of sister chromatids, held together at the centromere; each chromatid is comprised of a single DNA helix.

sister chromatid

one of the two genetically identical chromosome units that are the result of DNA replication and are attached to each other at the centromere

mitosis

the stage of cellular reproduction in which nuclear division occurs; process in which a parent nucleus produces two daughter nuclei, each having the name number and kinds of chromosomes as the parent nucleus

mitotic spindle

a complex of microtubules and associated proteins that assist in separating the chromatids during cell division

cytokinesis

division of the cytoplasm following mitosis or meiosis

signal

a molecule that stimulates of inhibits and event in the cell

growth factor

a hormone or chemical, secreted by one cell, that may stimulate or inhibit growth of another cell or cells.

cyclin

protein that cycles in quantity as the cell cycle progresses; combines with and activates the kinases that promote the events of the cycle.

caspases

a family of protease enzymes essential for programmed cell death (apoptosis) and inflammation

nucleosome

1. a structural unit of a eukaryotic chromosome, consisting of a length of DNA coiled around a core of histones.

euchromatin

chromatin with a lower level of compaction and therefore accessible for transcription

heterochromatin

highly compacyted chromatin that is not accessible for transcription

diploid (2n)

cell condition in which two of each type of chromosomes are present

haploid (n)

cell condition in which only one type of chromosomes is present

centromere

constriction where sister chromatids of a chromosome are held together

centrosome

central microtubule-organising center of cells, in animal cells, It contains two centrioles

centriole

cell structure, existing in pairs, that occurs in the centrosome and may help organize a mitotic spindle for chromosome movement during animal cell division

asters

a radiating array of microtubules associated with a centrosome in a dividing cell.

kinetochore

an assembly of proteins that attaches to the centromere of a chromosome during mitosis

metaphase plate

an imaginary plane located in the center of a dividing cell, equidistant from the two spindle poles, where chromosomes align during the metaphase stage of mitosis and meiosis

polar spindle fibers

non-kinetochore microtubules that extend from centrosomes toward the cell center, overlapping in the middle without attaching to chromosomes

cleavage furrow

indentation in the plasma membrane of animal cells during cell division; formation marks the start of cytokinesis

cell plate

structure across a dividing plant cell that signals the location of new plasma membranes and cell walls

therapeutic cloning

used to create mature cells of various cell types. facilitated study of specialization of cells and provides cells and tissue to treat human illness

reproductive cloning

used to create an organism that is genetically identical to the original individual

benign

mass of cells derived from a single mutated cell that has repeatedly undergone cell division but has remained at the site of origin

malignant

the power to threaten life; cancerous

cancer

malignant tumor whose non differentiated cells exhibit loss of contact inhibition, uncontrolled growth, and the ability to invade tissue an metastasize

tumors

cells derived from a single mutated cell that has repeatedly undergone cell division; benign tumors remain at the site of origin, while malignant tumors metastasize

metastasis

spread of cancer from the place of origin throughout the body; caused by the ability of cancer cells to migrate and invade tissues

angiogenesis

formation of new blood vessels; rapid angiogenesis is a characteristic of cancer cells

oncogenes

cancer-causing gene formed by a mutation in a proto-oncogene; codes for proteins that stimulate the cell cycle and inhibit apoptosis

proto-oncogenes

gene that promotes the cell cycle and prevents apoptosis; may become an oncogene through mutation

tumor suppressor genes

gene that codes for a protein the ordinarily suppresses the cell cycle; inactivity due to a mutation can lead to a tumor

stimulatory pathway

a series of molecular signals, initiated by the binding of a molecule to a cell receptor, that activates, increases, or perpetuates a specific cellular response or function. These pathways are critical for transmitting external signals (such as hormones, growth factors, or antigens) from the cell surface to the nucleus or cytoplasm, resulting in actions like cell growth, differentiation, or increased metabolism.

telomeres

tip of the end of a chromosome that shortens with each cell division and may thereby regulate the number of times a cell can divide

nucleoid

region of prokaryotic cells where DNA is located; it is not bound by nuclear envelope

binary fission

splitting of a parent cell into two daughter cells; serves as an asexual form of reproduction in bacteria.