Flashcards in Chapters 12-15 Deck (63)
Gap 1 Phase
growth of cell and synthesis of cytoplasmic organelle
DNA replication (DNA replication is the only replication not involved in G1)
Gap 2 Phase
synthesis of structures involved in cell division. (Ex. microtubules)
Mitosis (M) = Karyokinesis
"chromosome splitting" chromosomes condense and separate into 2 nuclei
"Cell splitting" the cytoplasm separates into 2 cells
Gap 1, Synthesis and Gap 2 are collectively called this. The cell is very biologically active at this time.
how much time do cells spend in mitosis?
5-15% of lifetime but varies among organs.
how long do blood marrow cells spend in mitosis?
Divide rapidly to replace worn out blood cells (120 days = life of a red blood cell)
How long do neurons (nerve cells) spend in mitosis?
neurons divide very slowly, or not at all in adults. Cycle stops in gap 1 stage (at the Gap 1 checkpoint) and exits the cell cycle into G0 phase.
how long do liver cells spend in mitosis?
liver cells divide rapidly to replace missing tissue but slowly otherwise
a strand of DNA that has wound up tightly causing it to be visible in the microscope
constricted region of the chromosome with associated proteins
2 identical copies of the same chromosome
chromosomes that are the same length, have centromeres in the same location, and carry genes for the same traits (e.g. eye color or blood type). One comes from your father, the other comes from your mother.
how do you count the number of chromosomes?
count the number of centromeres
Interphase role in Mitotic Division
no condensation of chromatin
cant tell the number of chromosomes through a microscope
nuclear envelope present
nucleolus present at nucleolar organizer region
centrosomes paired side-by-side (not found in plants)
chromatin condenses into chromosomes
chromosomes massed in center of cell
nuclear envelope disappears
spindle fibers, made of microtubules attached end-to-end, form between the migrating centrioles and attach to kinetochores of each sister chromatid.
disk-shaped proteins found on the centromere of the chromosome. allows spindle fibers to push and pull the chromosomes into place.
chromosomes are fully condensed
chromosomes line up at metaphase plate by the spindle fibers in a 1X1 pattern
spindle fibers push and pull sister chromatids to separate poles of the cell.
two nuclei are now forming
chromosomes unwind into chromatin
nuclear envelope reappears
spindle fibers break down
where the animal cell pinches off in cytokinesis. made of contractile ring of microfilaments that work like a draw string.
cytokinesis of plant cells
1. vesicles form
2. vesicles fuse into cell plate
3. cell plate fuses with cell wall
nuclear division that produces 4 daughter cells that have half the number of chromosomes as the original parent cell.
egg or sperm. result of meiosis and are haploid.
another name for Meiosis
reduction-division because chromosome numbers are reuced by half during Meiosis I, then sister chromatids are separated in Meiosis II.
homologous chromosomes (mom and dad) pair up during a process called synapsis
during synapsis some homologous chromosomes break and swap places. this is called recombination
location where homologous chromosomes touch. this is where recombination is occuring
homologous chromosomes line up at metaphase plate 2-by-2. these sets of homologous chromosomes are called tetrads.