Cell Division Flashcards
What are 2 extrinsic factors of cell cycle control?
nutrients, growth factors
What are the 3 stages of interphase?
G1, Synthesis, G2
What is an intrinsic factor of cell cycle control?
cell senescence, accelerated aging
What is Werner’s syndrome?
Mutation in DNA helicase (unwinds DNA). Faulty replication, faulty cell cycle.
What is Progeria (Hutchinson Gilford Syndrome)?
Mutation in lamin A (intermediate filament), prevents cell division
Which cyclin(s) push a cell from G1 to S?
Cyclin D, E. Goes from G1 to S only once Cyclin D and E passes threshold level.
Which cyclin(s) push a cell from S to G2?
Cyclin A
Which cyclin pushes a cell from G2 to M?
Cyclin B
What happens during G1? How long is this phase?
Growth and protein synthesis. Variable duration.
What happens during S phase? How long does this phase take?
DNA synthesis, genome duplication, 2n->4n. Centrosome duplicated. 8-10 hours.
What happens during G2 phase? How long does this phase last?
RNA, tubulin, other energy and proteins made. 2-4 hours.
In a metaphase chromosome, sister chromatids are connected at the _______.
Centromere.
What happens during prophase?
- Chromosomes condense,
- kinetochores assemble on centromeres,
- centromeres (MTOCs) migrate to poles,
- spindles begin to form.
What happens during prometaphase?
- Nuclear envelope begins to break down
- Microtubules attach to kinetochores
- Chromosomes begin to migrate.
What happens during metaphase?
Chromosomes maximally condense and line up on metaphase plate.
What are the three types of microtubules?
kinetochore, polar, astral
What happens during anaphase?
Sister chromatids separate, cleavage furrow begins to form
What happens during telophase?
- Spindle microtubules begin to depolymerize
- Nuclear envelope forms around daughter nuclei
- Chromosomes begin to de-condense and nucleoli form
- Cleavage furrow deepens
What happens during cytokinesis?
Cytoplasm divides.
The contractile ring involved in cytokinesis is made of _____ and _____.
Actin and myosin.
What are two cellular signs of malignancy?
An increase in the number of mitotic figures and diversity of nuclear morphology are signs of malignancy.
What are two potential processes an anticancer drug can inhibit?
- Mitotic spindle formation
2. DNA synthesis
What 3 anticancer drugs disrupt mitotic spindle formation?
Vincristine, colchicine, taxol.
What are 3 anticancer drugs that inhibit DNA synthesis?
5 fluorouracil
methotrexate
cytosine arabinoside
What happens during prophase 1 of meiosis?
Chromosomes that have been replicated condense and pair with homologues to form tetrads.
What happens during metaphase 1 of meiosis?
Tetrads held together my chiasmata. Chromosomes arrange themselves on the equator of the spindle.
What happens during anaphase 1?
Homologues separate and migrate to opposite poles of the cell.
What happens during telophase 1 of meiosis?
Separates into 2 daughter cells.
What are the 5 cell stages of meiotic prophase 1?
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis
“He lept and zigzagged, packing a dipstick and diabetes.” yea…
What happens during the leptotene stage of meiotic prophase 1?
Chromosmes condense forming long strands in nucleus.
What happens during the zygotene stage of meiotic prophase 1?
Homologous chromosomes pair up through formation of synaptonemal complex forming a tetrad or bivalent
What happens during the pachytene stage of meiotic prophase 1?
- Chromosmes continue to condense
2. Chiasmata (crossing over sites) form as random exchange of genetic material occurs between homologous chromosomes
What happens during the diplotene stage of meiotic prophase 1?
- Chromosomes continue to condenserevealing chiasmata
2. Areas of decondensation allow RNA synsthesis
What happens during the diakinesis stage of meiotic prophase 1?
Chromosomes condense maximally
Nucleolus and nuclear envelope disappear
Centromeres can be located in a variety of places in a metaphase chromosome. LIst the 4 types of chromosomes in the order of centromere distance from the middle of the chromosome.
Metacentric, submetacentric, acrocentric, telocentric.
What is the arrangement of chromosomes from largest to smallest called?
Karyotype.
What is special about the karyotype of a Down’s syndrome patient?
Trisomy 21.
How are double minute chromosomes involved in drug resistance?
These circular fragments of extracellular DNA replicate in the nucleus during cell division, gene amplify during tumor growth, and harbor extra oncogenes/drug resistance genes.
What would you use to stain the highly conserved banding patterns of a chromosome?
Giemsa stain.
What mutation causes chronic myelogenous leukemia, and what happens as a result?
Crossover of chromosomes 9 and 22, leading to uncontrollable replication.
