Cell Division Flashcards
What parallel cycles comprise the cell cycle?
- Chromosome cycle
2. Cytoplasmic cycle
What are the parts of the chromosome portion of the cell cycle?
DNA synthesis: duplication of chromosomes
Karyokinesis: separation of chromosomes into 2 nuclei (for daughter cells)
What are the component parts of the cytoplasmic cycle?
Cell growth: cell doubles in size
Cytokinesis: division of the cell by mitosis into two daughter cells
What are the two major stages of the cell cycle?
Interphase and mitosis
What generally happens during interphase?
Cell increases in size and content and replicates genetic material.
What are the stages of interphase and what happens in each?
- Gap 1: Growth and protein synthesis
- Synthesis: DNA synthesis/genome duplication. Autosomal cell goes from 2n–>4n
Centrosome duplicated - Gap 2 (resting phase): RNA, tubulin, other proteins and energy required for mitosis synthesized in this phase
What happens during mitosis?
Cell divides nucleus and cytoplasm, giving rise to two daughter cells.
What provides molecular control of the cell cycle?
Cyclins: proteins that regulate activity of cyclin-dependent kinases
What are the cyclins involved in the cell cycle, and which phases are each associated with?
Cyclins D and E: passage past restriction point to push G1 into Synthesis
Cyclin A: Synthesis to G2
Cyclin B: G2 to Mitosis
What are the stages of mitosis?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
What happens during prophase?
- Chromosomes condense
- Kinetochores assemble on centromeres
- Centrosomes (MTOCs) migrate to poles
- Spindle begins to form
What happens during prometaphase?
- Nuclear envelope breaks down
- Microtubules attach to kinetochores
- Chromosomes begin to migrate
What happens during metaphase?
Chromosomes maximally condensed and lined up on metaphase plate.
What happens during anaphase?
- Sister chromatids separate
- Cleavage furrow begins to form at late anaphase
What happens during telophase?
- Spindle microtubules begin to depolymerize
- Nuclear envelope forms around daughter nuclei
- Chromosomes begin to decondense and nuclei form
- Cleavage furrow deepens
What happens during cytokinesis?
Cell divides
What do an increase in the number of mitotic figures and diversity of nuclear morphology signal?
Malignant cancer
How do anti-cancer drugs work?
- Disrupt mitotic spindle formation (can’t go through cell division without spindles)
- Inhibit DNA synthesis (deprive cell of all material it needs to divide)
How is meiosis different from mitosis?
Meiosis is 2 rounds of cell division WITHOUT intervening round of chromosome duplication; results in 4 heterozygous daughter cells with 1/2 as much chromosomal material.
What are the stages of Meiosis I?
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
What are the stages of Meiosis II?
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2
What are the stages of meiotic prophase I?
- Leptotene: chromosomal condensation
- Zygotene: homologous chromosomes pair up through formation of synaptonemal complex forming a tetrad or bivalent
- Pachytene: chromosomes condense; chiasmata form as random exchange of genetic material occurs between homologous chromosomes
- Diplotene: chromosomes condense to reveal ciasmata; areas of decondensation allow RNA synthesis
- Diakinesis: chromosomes at max condensation; nucleolus and nuclear envelope disappear.
What are the 4 types of centromere placement?
- Metacentric (middle)
- Submetacentric (slightly off center)
- Acrocentric (long: short arms)
- Telocentric (abnormal: only 2 arms with centromere at end)
How does Down’s Syndrome develop?
Trisomy 21: extra chromosome at 21
What are double minute chromosomes?
Fragments of chromosomal material that break off, form circular plasmids that can self-replicate.
- harbor extra copies of oncogenes and genes involved in drug resistance
- manifestation of gene amplification during tumor development
- replicate in nucleus of cell during cell division
What stain allows us to see chromosome banding?
Giemsa stain allows us to view unique banding patterns of chromosomes - can see organization of genes in each chromosome.
What happens in chronic myelogenous leukemia?
DNA from chromosome 9 and 22 gets swapped. Results in abnormal 22, which controls cell division: presents as missing regulatory domain so that signaling domain goes rampant–>wild replication in bone marrow.
