CH 12 Flashcards
Cell division
-The continuity of life is based on the reproduction of cells
Genome
can consist of a single DNA molecule or a number of DNA molecules
Chromosomes
-a cellular structure consisting of one DNA molecule and associated protein molecules
Chromatin
-a complex of DNA and protein that condenses during cell division
Somatic cells
-nonreproductive cells
-have two sets of chromosomes
Gametes
-reproductive cells–sperm and egg
-have half as many chromosomes as somatic cells
Sister chromatids
-joined copies of the original chromosome
Centromere
-the narrow “waist” of the duplicated chromosome, where the two chromatids are most closly attached
Mitosis
-the division of the genetic material in the nucleus
Cytokinesis
-division of the cytoplasm
Miotic (M) phase
-mitosis and cytokinesis
Interphase
-cell growth and copying of chromosomes in preparation for cell division
Interphase three phases
-G1 phase (“first gap”)
-S phase (“synthesis”)
-G2 phase (“second gap”)
5 phases of mitosis
-prophase
-prometaphase
-metaphase
-anaphase
-telophase
Mitotic spindle
-structure made of microtubules that controls chromosome movement during mitosis
Centrosome
-microtubule-organizing center
-replicates during interphase
Kinetochores
-protein complexes associated with centromeres
Metaphase plate
-a plane midway between the spindle’s two poles
Cleavage
-process of cytokinesis in animal cells
Cleavage furrow
-a shallow grove on the cells surface
Cell plate
-formed during cytokinesis
Binary fission
-a type of cell division where prokaryotes (bacteria and archaea) reproduce
Origin of replication
-site where the replication of a DNA molecule begins
Cell cycle control system
-directs the sequential events of the cell cycle
-like a clock
Checkpoints
-cell cycle stops until a go-ahead signal is received
Cyclins & Cyclin-dependent kinases (Cdks)
-regulatory protein involved in cell cycle control
MPF (maturation-promoting factor)
-a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
G0 phase
-If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state
Growth factors
-released by certain cells and stimulate other cells to divide
Density-dependent inhibition
-crowded cells will stop dividing
Anchorage dependence
-the requirement that a cell must be attached to a substratum in order to initiate cell division
Transformation
-process by which a cell acquires the ability to divide indefinitely
Benign tumor
-when abnormal cells remain only at the original cite and forms a lump
Malignant tumor
-invades surrounding tissues and spreads
Metastasis
-the spread of cancer cells to locations distant from their original sites
