cell division Flashcards
why do cells go through mitosis?
growth, replacement of cells, differentiation
what is the order of the cell cycle events?
interphase, m-phase, cytokinesis
what happens in G0?
G0 is the resting state, where the cell does its cell job
what is chromatin?
uncoiled DNA that is invisible under the microscope, found during interphase
what is a double chromosome?
two sister chromatids made up of DNA coiled around histones, in which each sister chromatid is held together by a centromere, found during prophase and metaphase
what is a chromosome?
when the two sister chromatids separate, found during anaphase and telophase
what happens during G1 and G2 of interphase?
when the cells make the proteins, grow, and pass through checkpoints; cell part needed for division are made (centrioles)
what happens during S of interphase?
when DNA replicates in between G1 and G2
what is checked during G1?
growth factors and DNA damage
what is checked during metaphase?
whether the spindle fibers attached to the centromeres properly
what is checked during G2?
the cell size and whether the DNA replicated correctly
what is the order of mitosis?
interphase, prophase, metaphase, anaphase, telophase (IPMAT)
what happens during prophase?
chromatin coils up, condensing into double chromosomes; the nuclear envelope disappears; the centrioles migrate towards the poles; the spindle begins to form and the fibers attach to the centromeres of the sister chromatids
what happens during metaphase?
the doubled chromosomes line up at the equator of the cell moved by the spindle fibers attached to their centromere
what happens during anaphase?
the centromeres split, separating the sister chromatids; the spindle fibers pull the identical chromosomes towards the opposite poles
what happens during telophase?
opposite of prophase: the chromosomes uncoil; the nuclear envelopes reappear, the spindle fibers break down, disappearing; the cytoplasm begins to divide
what happens during cytokinesis?
division of the cytoplasm: in animal cells, the plasma membrane pinches causing a cleavage furrow; in plant cells, a cell plate develops and secretes a new cell wall
what are proto-oncogenes?
genes that produce proteins that promote cell division; when mutated, will overwork and lead to cancer (like a foot on the accelerator)
what are suppressor proteins?
an example is p53; it prevents cells with DNA problems to replicate; when mutated, it will not stop cells even if there is damaged DNA, and will lead to cancer (like removing the brakes)
which nucleotides are purines?
Adenine and Guanine (AG)
which nucleotides are pyrimidines?
Cytosine and Thymine (CT)
which end of the DNA has a phosphate?
the 5’ side
which end of the DNA has a deoxyribose?
the 3’ side
how many hydrogen bonds are between A and T?
2
how many hydrogen bonds are between C and G?
3
when does DNA replication occur?
the S phase of interphase (before mitosis)
which enzyme unzips the DNA?
helicase (helio=sun=unzip)
which enzyme builds the new DNA strands?
DNA polymerase
which enzyme glues the Okazaki fragments back together?
ligase (liga=ligament=connectors)
what direction do nucleotides get added?
5’ to 3’
