Lecture 6: Cell Replication Flashcards
bacterial cell division
- aka
- occurs in
- how
- aka fission
- prokaryotes
- chromosomes replicate and are pushed apart by a ring of contractive proteins that squeeze and fold cell wall
- meiosis
- mitosis
- meiosis: produces reproductive cells called gametes
- mitosis: produces all other cell types (somatic cells)
chromosomes
- made how
- double helix binds to histones which package and order DNA into structural units called nucleosomes
- eventually become highly condensed during cell division into x shaped chromosomes
can you label the parts on a chromosome? (2)
- sister chromatids
- centromere
microtubules
- structure
- function
- metaphase:
- anaphase:
- polymers of tubulin
- alpha and beta tubulin dimers
- attach to centrosome and chromosome at kinetochore (see notes)
- in the metaphase they grow and move centrosomes apart
- shorten at the positive end during anaphase
centrosome
- made up of microtubules and centrioles
- microtubule organizing centre
interphase
occurs before mitosis; cell growth; DNA duplicates and the nucleus and organelles are duplicated and separated
list all the stages of mitosis in order (6)
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
briefly describe: prophase
chromosomes condense; spindles form
briefly describe: prometaphase
- nuclear envelope breaks down
- microtubules contact chromosome in the centre
briefly describe: metaphase
- chromosomes move to the middle of the cell
briefly describe: anaphase
- sister chromatids separate; daughter chromosomes are pulled apart
briefly describe: telophase
- nuclear envelope forms and chromosomes decondense
briefly describe: cytokinesis
- cell division begins
- actin/ myosin ring contracts
in plant cells, how does cytokinesis differ?
- microtubules move vesicles in place to form a new membrane
List the key proteins in mitosis and their jobs (5)
- cohesins: hold sister chromatids together
- condensins: compact DNA
- nuclear lamins: stabilize nucleus
- microtubules (tubulin): move chromosomes to opposite poles
- kinetochore proteins: attach microtubules to DNA
control of cell cycle
- what are the 4 stages?
- where are the 3 checkpoints? what do each of them check for (1st stage: 4 things, 2nd stage: 2 things, 4th stage: 2 things)
- interphase stages: G1, S, G2, M
- end of G1: checks for appropriate cell size, nutrient sufficient, DNA undamaged, and social signals (prevents liver growing in the brain)
- end of G2: replication finished; DNA undamaged
- M checkpoint: are chromosomes attached to spindle? Have chromosomes segregated?
- note: mature cells do not go through checkpoint 1 and just go to G(o)
apoptosis
cell death
Why do cancer cells divide uncontrollably?
They ignore social signals
Everytime a cell divides, what increases?
the chance of mutation
