lecture 10+ 11+12 Flashcards
Difference between somatic and reproductive cell division
Somatic produces diploid, identical daughter cells whereas reproductive produces 4 haploid daughter cells.
Cell theory concept
All organisms made of cells which come from pre existing cells
Check points of cell cycle
G1, G2, M (during mitosis)
Germ line
passed onto future progeny (basically means genetic)
types of subsitutions
silent (no effect, same aa coded), missense (effect varies, different aa coded), nonsense (stop codon, truncated protein )
Maturation promoting factor (MPF) structure/function
Complex consisting of cyclin and cyclin dependent kinase (cdk), allows for mitosis by phosphorylating many other proteins. The key at G2 checkpoint.
interphase components
G1 - cellular activities, length varies depending on cell type; S phase - DNA synthesis; G2 (interphase) - prep for mitosis by producing proteins, enzymes, check correct DNA replication, centrosome replication completed
proto-oncogenes
accelerator, promote cell proliferation (e.g. Ras - a GTPase, Myc - a transcription factor)
tumour supressor gene
brakes, inhibit cell proliferation (e.g. tp53, BRCA1, BRCA2)
Prophase (mitosis)
-chromosomes condense, mitotic spindle begins to form, nuclear envelope begins to break
Metaphase (mitosis)
sister chromatids line up at the meta-plate via tug of war
Anaphase (mitosis)
Segregation of sister chromatids, start pulling away
Telophase (mitosis)
Nuclear envelope starts to reform, cleavage furrow between two forming cells
Cytokinesis (mitosis)
Splitting of into two cells, nuclear envelope reformed. Result are two diploid cells identical to parent cell
Prophase I compared to II (meiosis)
I: DNA already replicated, spindle forms, nuclear envelope shatters, homologous chromosome tetrads pair up
II: DNA not replicated, spindle forms and envelope shatters, chromatids
Metaphase I compared to II (meiosis)
I: Homologous chromosome tetrads line up at meta-plate (synapsis/cross over)
II: chromatids line up at meta-plate
Anaphase I compared to II (meiosis)
I: Homologous chromosome pairs start to pull apart
II: sister chromatids start to pull apart
Telophase/cytokinesis I compared to II (meiosis)
I: two new cells form from cleavage furrow (diploid), goes into second round of division
II: four new cells form from cleavage furrow (haploid).
Nuclear envelope reformed in both.
S phase
DNA replication by breaking of weak hydrogen bonds between nucleotides, each new strand is made from half old half new
when does crossing over occur
prophase 1 after synapsis (homologous chromosomes pair up) and joined by chiasmata (crossing over/recombination)
Cyclin fluctuation cycle
Cyclin build up when nearing M phase, forms MPF complex with cdk, degraded during M phase.