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What are the three key roles of cell division?
- Reproduction
- Growth and development
- Tissue Removal
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What is meant by the cell cycle?
life of a cell from the time its first formed from a dividing parent cell until its own division into two cells
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One of the three key roles:
-- an amoeba, a single celled eukaryote divides into two cells; each new cell will be an individual organism
reproduction
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a sand dollar embryo shortly after the fertilized egg divided, forming two cells
growth and development
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the dividing bone marrow cells will give rise to new blood cells
tissue renewal
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What is a genome?
a cell's endowment of DNA; its genetic info
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Compare prokearyotic and eukaryotic genomes.
- Prokaryotic:
- --> one circular bacterial chromosome; single; no organelles; no nucleus
- Eukaryotic:
- --> # of DNA molecules; overall length- ENORMOUS; characteristic # in each cell nucleus
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How many chromosomes are in a human somatic cell?
46 (2 sets of 23)
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What is a gamete?
reproductive cell; unite during sexual reproduction (fertilization) to produce a diploid zygote; half as many chromosomes as somatic cells; one set of 23 chromosomes in humans
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Name two types of gametes.
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How many chromosomes in a human gamete?
one set of 23
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Define chromatin.
- a complex of DNA and associated protein molecules
- - called this when a cell is not dividing
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How many DNA molecules are in each somatic cell?
46
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a cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each consists of a very long DNA molecule and associated proteins; a bacterial one usually consists of a single circular DNA molecule and associated proteins found in the nucleoid region, which is not membrane bound
chromosome
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each duplicate chromosome has two asister ones that each contain an identical DNA molecule, initially attached all along their lengths by adhesive protein complexes called cohesins
chromatid
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specialized region of the chromosome where two sister chromatids are most closely attached
centromere
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COMPLEX OF dna AND PROTEINS THAT MAKE UP A EUKARYOTIC CHROMOSOME. wHEn the cell is not dividing, it exists in its dispersed replicated chromosome form, as a mass of very long, thin fibers that are not visible with a light microscope
chromatin
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What is mitosis? cytokinesis?
- division of the nucleus
- division of the cytoplasm
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What occurs in meiosis?
How is the chromosome number of daughter cells different?
- produce gametes; modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division, but only one round of DNA replication;
- yields nonidentical daughter cells that have only one set of chromosomes thus half as many chromosomes as the parent cell
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By what process are the damaged cells in a wound replaced?
mitosis
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By what process are eggs formed?
meiosis
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By what process does a zygote develop into a multicellular organism?
mitosis
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In which process are identical daughter cells produced?
mitosis
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Which process reduces chromosome # of daughter cells?
meiosis
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A cell grows/ first gap
G1
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continues to grow as it copies its chromosomes- chromosomes duplicate (synthesis)
S
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completes preparation for cell division (second gap)
G2
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What are the components of the mitotic spindle?
- centrosomes
- spindle microtubules
- asters
- (microtubules/ proteins)
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What is another name for the centrosome?
microtubule-organizing center
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What happens to the centrosome during interphase and prophase?
- Interphase: centrosomes are duplicated, resulting in two, but they remain together until prophase
- Prophase: centrosome begins to separate with microtubules forming between them
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a structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle
kinetochore
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What is the difference between kinetochore and nonkinetochore microtubules?
- kinetochore: microtubules that attach to kinetochores at the centromere of sister chromatids
- non: do not attach to kinetochores and continue elongating and overlapping
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At wich end do kinetochore microtubules shorten during anaphase?
the kinetochore ends; metaphase plate end
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Describe cytokinesis in an animal cell.
- a process called cleavage
- forms a cleavage furrow
- on cytoplasmic side of the furrow is a contractile ring of actin filaments associated with myosin molecules
- actin microfilaments interact with the myosin molecules, causing the ring to contract
- cleavage furrow deepens until the parent cell is pinched in two, producing two completely separated cells, each with its own nucleus and share of cytosol, organelles, etc.
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Describe cytokinesis in plant cells.
- no cleavage furrow
- during telophase, vesicles derived from Golgi move along microfilaments to center of cell, where they coalesce forming a cell plate. Cell wall materials carried in the vesicles collect in the cell plate as it grows
- cell plate enlarges until it fuses with membrane
- two daughter cells result,e ach with own plasma membrane
- a new cell wall arising from the chontents of the cell plate has formed between the daughter cells
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a method of asexual reproduction by division in 1/2. in prokaryotes, it does not involve mitosis, but in single-celled eukaryotes that undergo it, mitosis is part of the process
binary fission
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Difference between prokaryotic reproduction and eukaryotic.
- Prokaryotic: binary fission; one chromosome; circular DNA molecule
- Eukaryotic: mitosis: varies in amt. of chromosomes; double helix
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