Cell Reproduction part 2: mitosis and the cell cycle – Flashcards
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it helps with all forms of growth. it rings the DNA of the first cell exactly to ALL daughter cells. this is how life works!
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why is mitosis important?
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exact copying of cells; division of the nucleus
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mitosis
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cell has exactly one copy of all of its DNA.
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haploid
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N = x
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haploid equation
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cell has 2 copies of each chromosome
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diploid
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2N = N * # of different chromosomes
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diploid equation
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haploid. N = 23
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sperm and egg are haploid or diploid? equation?
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1000s
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each chromosome has how many genes?
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interphase
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longest phase of the cell cycle
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when they wear out
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when do cells copy?
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protein waistband that holds the 2 sister chromatids together. doesn't have genes
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centromere
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after synthesis
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when do chromosomes look like: X?
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it's folded and twisted into chromosomes
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where is DNA?
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proteins
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loose DNA makes...
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chromosomes, so it can copy itself.
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what does DNA form itself into? why?
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- nucleolus disappears - chromatin condenses into chromosomes (X) - centrosomes move to opposite sides of the cell - spindles form on centrosomes
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prophase
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- nuclear envelope disassembles - each chromosome forms 2 kinetochores @ the centromere - microtubules start to attach to chromosomes - spindles and chromosomes meet in the middle of the cell - chromosomes line up on metaphase plate
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metaphase
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pacman-shaped. on the inside of the chromosome @ the centromere. the spindle fibers attach to the kinetichores on either side of the chromosome during metaphase
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kinetochore
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chromatids move apart; separate toward opposing poles - the exact same genetic material is on each side of the cell - spindle fibers are taken apart
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anaphase
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- 2 new nuclear envelopes form - chromosomes unfold back into chromatin - 2 new nucleoli show up - cell gets bigger and elongates - nucleus has divided!
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telophase
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cytoplasm splits; into 2 daughter cells - chromatids unwind into long stringy DNA
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cytokinesis
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similar to mitosis, but thy build a cell plate in the middle of the cell to form 2 cells
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plant cell division
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the cell wall
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what does the cell plate become?
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cancer-suppressing genes
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what do DNA mutations suppress?
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travel through the body and activate other cells to become cancerous
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what can cancer cells do?
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a group of cells actively growing out of control
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tumor
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discovered mitosis. he stained cells and called the colored bodies chromosomes, in 1879
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walther flemming
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single-celled; no nucleus. bacteria, yeast
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prokaryote
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one circular chromosome in the nucleoid region
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what do prokaryotes have as DNA?
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division process of prokaryotes. the cell copies its one chromosome and splits in half
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binary fission
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asexual. it's very quick bc it's so simple
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what kind of reproduction is binary fission? how fast is it, and why?
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is more complex (mitosis)
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eukaryote division
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sexual
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what kind of reproduction is meiosis?
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a fertilized egg
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zygote
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interphase, cytokinesis, mitosis
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3 main stages of cell cycle
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G1, S, G2
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substages of interphase
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growth. cellular contents, excluding chromosomes, are duplicated
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G1
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each of the 46 chromosomes is duplicated by the cell
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S
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the cell "double checks" the duplicated chromosomes for error, making repairs if needed - proteins that will form microtubules are synthesized - membranes for daughter cells are produced
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G2
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cytokinesis
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at what stage does one cell become 2 distinct ones?
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G0
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a cell that isn't going to divide enters...
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its cells grow in size and amount
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how does the cell cycle help growth?
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mitosis is way faster than gap1, because gap1 is slow growth
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time spent in mitosis vs. time spent in gap1
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it's doubled, bc each chromosome is copied
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how does the amount of DNA change after synthesis?
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the DNA is divided, so each set goes into one of the 2 cells produced
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other than the splitting of the cytoplasm, what else happens in mitosis?
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2
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if a culture starts with one human cell, how many will there be after 24 hours?
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no. it will continue to divide; it is a product of previous mitosis
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does the original cell die or disappear after mitosis?
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nerve cells
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what human cells are in G0?
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after they grow in G1 but before they replicate DNA in S.
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when do some cells go into G0?
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DNA could not be copied
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how might mutation affect synthesis?
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it would be pased on to the daughter cells, causing a buildup of mutations (even cancer)
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if apoptosis doesn't occur, how would DNA damage affect the rest of the cell cycle?
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there they can't divide and wouldn't pass their mutations on to other cells
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why is it beneficial for damaged cells to enter G0?
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proteins and organelles could be mutated
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possible problems in G2
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radiation = damaged DNA = damaged cell. it stops division of bad cells.
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why might it be beneficial to irradiate cancer cells?
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cytokinesis. if it were to split, it'd have less nuclei and be smaller
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in the formation of a multinucleated cell, what part of the cell cycle is skipped?
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at any given time, some cells in roots are undergoing mitosis, bc they continue to grow as they search for water and nutrients
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why are root cells good for studying stages of the cell cycle?
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cell performs its duty as part of tissue. DNA duplicates, preparing for mitosis. Chromosomes are bunched up; nucleolus is visible
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interphase
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plants = cell plate animals = cleavage furrow
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what do plant and animals cells have in the middle right before dividing?
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highly folded DNA. genetic info found in the nucleus, along with proteins. become visible as chromosomes when the cell divides.
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chromatin
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class of proteins in the nucleus where the DNA of chromatin is wrapped around ("beads on a string")
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histone
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G1; it has the option of later going into G0
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most variable phase of the cell cycle, why?
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regulates cell division and growth with the help of control enzymes
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cell cycle does what?
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after G1 and after S
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cell cycle 'checkpoints'
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prior to S and M
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when does p53 do checks?
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major control switch for the cell cycle; causes cell to move from G1 to S or G2 to M
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CDk
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includes CDk and cyclins, which trigger progression. regulates cell's passage from G2 to M. checks that everything is correct, then allows M to happen.
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MPF
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lung
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p53 is associated with which cancer?
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protein that blocks the cell cycle if the cell's DNA is damaged. causes apoptosis if the damage is severe
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p53
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breast
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p27 - which cancer?
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protein that binds to CDk and cyclins, blocking entry into S
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p27
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its function is impaired. reduced levels of it predict a poor outcome for patients
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what happens to p27 in cancer patients?
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so the cell has enough DNA to give to each daugher cell
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why is DNA made during S?
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prophase
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in which mitosis phase do spindle fibers form?
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telophase
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in which phase have the spindle fibers disappeared?
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telophase
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at what point in mitosis does the nuclear membrane reform?
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it would be very hard to divide long, floppy threads of DNA. small, compact chromosomes make it easier
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why does DNA coil up into chromosomes before it divides?
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death or mutation of cells bc of uneven chromosome disribution
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if sister chromatids don't line up correctly during metaphase, what happens?
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growth and repair in eukaryotic organisms
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what is mitosis used for, and in what type of organism?
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asexual reproduction/binary fission
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how do prokaryotic organisms reproduce?
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2 identical daughter cells
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what does asexual reproduction result in?
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it doesn't require energy, there is no need to find a mate, you can have numerous offspring in a short amount of time, and if the mother cell is adapted to her environment then the daughter cells are too
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advantages of binary fission
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if the environment changes, it would be difficult for the cells to adapt to the new environment quickly
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disadvantages of binary fission
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gametes
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sexual reproduction results in...
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energy and a mate
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what does sexual reproduction require?
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increases genetic variability of offspring so that they can colonize new environments: the offspring can adapt to new environments and survive
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advantages of sexual reproduction
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in the body, not the nervous or reproductive systems
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somatic cells are...
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4; no.
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how many gametes result in meiosis? are they identical to each other and the mother?
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23
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how many homologous pairs of chromosomes do humans have?
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have the same genes in the same order
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homologous chromosomes
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a sex cell; egg or sperm
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gamete
