biology 12 Word Scramble

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Question	Answer
what distinguishes living things from nonliving matter	the ability of organisms to produce more of their own kind
cell division	the continuity of life is based on the reproduction of cells
in unicellular organism	division of one cell reproduces the entire organism
multicellular organisms depend on cell division for	development from a fertilized cell, growth, and repair
cell division is an	integral part of the cell cycle
cell cycle	the life of a cell from formation to its own division
cell division results in	daughter cells with identical genetic information, dna. with the exception of meiosis
meiosis	special type of divison that can produce sperm and egg cells
genome	all the dna in a cell
genome can consist of	a single dna molecule (prokaryotic cells) or a number of DNA molecules (eukaryotic cells)
chromosomes	packaged dna molecules
chromatin	complex of dna and protein that condenses during cell division in eukaryotic chromosomes
eukaryotic species have a	characteristic number of chromosomes in each cell nucleus
somatic cells	nonreproductive cells which have 2 sets of chromosomes
gametes	reproductive cells: sperm and eggs which have half as many chromosomes as somatic cells
in preparation for cell division	dna is replicated and chromosomes condense
each duplicated chromomses have	2 sister chromatids (joined copies of original chromosome) which separate during cell division
centromere	the narrow waist of the duplicated chromosome where two chromatids are most closely attached
the 2 sister chromatids during cell division	separate and move into two nuclei, once separate the chromatids are called chromosomes
eukaryotic cell division consist of	mitosis and cytokinesis
mitosis	the division of the gentic material in the nucleus
cytokinesis	the division of the cytoplasm
gametes are produced by	meiosis which yields nonidentical daughter cells that have only one set of chromosmes and half as many as the parent cell
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cell cycle consists of	mitotic phase (mitosis and cytokinesis) and interphase (cell growth and copying of chromosomes in preparation for cell division)
interphase	90% of the cycle
subphases of interphase	G1 phase (first gap) S phase (synthesis) and G2 phase second gap
cell in subphases of interphase	grow in all three phases but chromsomes are duplicated only during the S phase
5 phases of mitosis	prophase, prometaphase, metaphase, anaphase, telophse with the latter stages being overlapped by cytokinesis
mitotic spindle	structure made of microtubules that controls chromosome movement during mitosis
centrosome	microtubule organizing center, where assembly of spindle microtubules begins
during interphase centrosomes	replicat e, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase
aster	a radial array of short microtubules which extends from each centrosomes
the mitotic spindle includes	centrosomes, the spindle microtubules and the asters
during prometaphase	some spindle microtubules attach to the kinetochores of chromoes and begin to move the chromosmes
kinetochores	protein complexes associated with centromeres
at metaphase	the chromosoems are all lined up at the metaphase plate
metaphase plate	imaginary structure at the midway point between the spindles two poles
in anaphase	sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell, the microtubules shorten by depolymerizing at the kinethochore ends
nonkinetochore microtubules in anaphase	from opposite poles overlap and push against each other elongating the cell
telophase	genetically identical daughter nuclei fom at opposite ends of the cell
cytokinesis begins	during anaphase or telophase and the spindle eventually disassembles
cytokinesis occurs by	a process known as cleavage forming a cleavage furrow
in plants,	cell plate froms during cytokinesis
binary fision	a cell division which prokaryotes (bacteria and acrhaea) reproduce by
during binary fission	the chromosomes replicates ( beginning at the origin of replication) and the two daughter chromsomes actively move apart, the plasma membrane piches inward dividing the cell into two
because prokaryotes evolved before eukaryotes	mitosis probably evolved from binary fission
certain protists exhibit	types of cell division that seem intermediate between binary fission and mitosis
frequency of cell divison varies with	the type of cell which result from regulation at the molecular level
cancer cells manage	to espcape the usual controls on the cell cycle
the cell cycle is driven by	specific chemical signals present in the cytoplasm, evidence comes from experiments of cultured mammalian cells at different phases of the cell cycle were fused to form a single cell with 2 nuclei
cell cycle control system	similar to a clock, direct sequential events of the cell cycle
cell cycle control system is regulated by	both internal and external controls
the clock has	specific checkpoints wehere the cell cycle stops until a go ahead signal is received
G1 check point	the most important, if cell revieves go ahead signal here, it completes the S and G2 and M phases and divide
if cell does not receive go ahead signal	it will exit the cycle switching into a nondividing state called the G0 phase
types of regulatory proteins invoved in cell cycle control	cyclins and cyclin dependent kinases (Cdks)
Cdks	acitivty fulucates during the cell cycle because it is controlled by cylcins so named because their concentrations vary with the cell cycle
Maturation promoting factor (MPF)	a cyclin Cdk complex that triggers a cells passage past te G2 checkpoint into M phase
example of an interal signal	kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase
external signals are	growth factors, proteins released by cetain cells that stimulate other cells to divide
ex of growth factor	platelet derived growth factor which stimulates the division of human fibroblst cells in culture
ex of external signals	density dependent inhibitions wher crowded cells stop dividing
anchorage dependence	in animal cells, where they must be attached to a substratum in order to divide
cancer cells do not	exhbit desity dependent inhibition nor anchorage dependence
cancer cells do not need	growth factors to grow and divide, they make their own growth factor, convey its singal w/o presence of it, and may have an absnormal cell cycle control system
transformation	when a normal cell is convereted to a cancerous cell
cancer cells that are not eliminated by	the immune system from tumors, masses of abnormal cells within otherwise normal tissue
benign tumor	a lump where abnormal cells remain only at the original site
malignant tumors	invade surrounding tissues and can metastasize
metastasize	exporting cancer cells to other parts of the body where they may form additional tumors
advances in understanding cell cycle and cell signaling have led to	advances in cancer treatment

Created by: newmee32