The Cell Cycle Flashcards
what is the cell cycle?
Is an ordered sequence of events that take place in a cell from the time a cell is formed until the duplication of its DNA and division of cytoplasm and organelles to produce two daughter cells
what are the 2 broad stages of the cell cycle? what generally happens during these stages?
- Interphase = growing stage
2. M phase = cell division stage (mitosis or meiosis)
what are the 3 sub-phases of the interphase stage?
- G1 and G2 = cell grows by producing all of the organelles, proteins, etc. found within the cell
- S phase = genetic information duplicated
what are the 2 parts of the m phase?
the cell divides
- division of genetic material by Mitosis or Meiosis
- division of cell = Cytokinesis
in which stage does a cell spend most of its time?
interphase stage
what are the 2 types of cell division in eukaryotic cells?
- Mitosis
2. Meiosis
what is mitosis? what kind of cells does mitosis occur in? what are the 3 functions of mitosis?
it is when a cell divides to produce two cells that are
genetically identical to the original cell (parent cell)
-mitosis occurs in haploid and diploid cells
1. Asexual reproduction
2. Growth in multicellular organisms
3. Cell replacement in multicellular organisms
what is meiosis? what kinds of organisms does this occur in? what is the function of meiosis?
it is when a diploid cell divides to produce genetically unique haploid cells
-occurs in sexually reproducing organisms only
-the function is to reduce the chromosome number by
half so when gamete fuse during fertilization a diploid zygote is formed
what is a diploid cell? what is a haploid cell? what kinds of organism are humans? what kinds of cells are their gametes?
Diploid (2n) = any cell with two sets of chromosomes
Haploid (n) = any cell with one set of chromosomes
-humans are diploids, gametes (eggs/sperms) are haploids
what are microtulules?
long proteins that attach to chromosomes and allow them to be moved inside the cell
what are centrosomes?
structures that organize the microtubules into a ‘spindle’ shape, enabling separation of the chromosomes during M phase
what are kinetochores?
protein complexes that attach a microtubule to the centromere of a chromosome
what are the 4 stages of mitosis? what always precedes mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
-interphase always precedes mitosis
what is the function of interphase?
- Cell growth during G1 and G2
- DNA synthesis during S phase
what happens in early prophase stage?
- Chromatin condenses into visible chromosomes
- Mitotic spindle begins to form
- Centrosomes separate
- Nucleoli disappear
what happens during late prophase? what else is this called?
- Nuclear envelope breaks down
- Microtubules attach to chromosomes at kinetochore
- Mitotic spindle is formed
-also called prometaphase
what happens during metaphase?
- Chromosomes line up along metaphase plate
2. Sister chromatids attached to microtubules from opposite poles of spindle
what happens during anaphase?
- Sister chromatids separate
2. Chromosomes move towards opposite poles of the spindle
what happens during telephase?
- Two daughter nuclei form
- Chromosomes decondense
- Nuclear envelopes reform
- Nucleoli reappear
what is the mitotic spindle composed of? how is it organized, where is this found? how are chromosomes attached?
- Composed of microtubules
- Organized by the centrosome
- Centrosome is found at each pole of the spindle
- Microtubules attach to each chromosome at the kinetochore
how are chromatids pulled apart during anaphase?
pulled apart by microtubles from opposite poles that are attached to kinetochores on chromosomes
what is cytokinesis? what does it divide? when does it occur?
the division of a cell into two
-Divides the cytoplasm and everything within it
-occurs after division of the nucleus (separation of
the chromosomes); late anaphase or telophase
what is cytokinesis in animal cells called? what happens during this?
is called cleavage
-During cleavage a ring of protein filaments contracts
until the cell divides into two new cells
what happens during cytokinesis in plants cells?
- a cell wall is formed between the two new nuclei
- vesicles form cell plate, which fuses to cell wall of parent cell and divides the two daughter cells