Unit 7 bio test 1
unicellular definition
generates complete new organism (bascteria yeast protozoa)
What is metazons
Many cell division required to generate new organism from fertilized egg
features of cell division that are universal (3)
1. prokaryotes must faithfully replicate DNA
2. yeast's replicated DNA must be accurately distributed to daughter cells
3. Animal cells also duplicate their other macromolecules and organelles and double in size before they divide
what is mitosis
division of genetic material that produces daughter cells geneticall identical to parent cell. Usually accompanied by cytokinesis, division of the cytoplasm into the two daughter cells.
what key events is cell division essential for in eukaryotes (3)
1. growth and development (human embryo)
2. Asexual reproduction (yeast)
3. Wear n tear, wound repair (epithelial cells lining intestine)
What is a eukaryotic chromosome (4)
- multiple linear chromosomes housed in nucleus
- two copies of each essential to survive
- complex packaging of DNA
- chromosomes become visible only in cells about to divide
homologous chromosomes vs sister chromtids
each parent has one homolog, the homologs are replicated and each are considered one chromosome consisting of two sister chromatids.
Cell cycle events
Interphase:
1. G1 -> 2 unreplicated chromosomes
2. S and G2 -> 2 replicated chromsomes making sister chromatids
3. Mitosis -> M phase: chromosomes become highly condensed
4. cell division: chromatids seperate into two daighter cells formed by cytokinesis
What is interphase (2)
- 90% of a proliferating cell's time
- cell grows by producing proteins and organells, copies its chromosomes and prepares for cell division
what are the 4 subdivisions in interphase
1. G1: most of cells growth
2. DNA copied chromosomes attached at centromeres, still fully extended
3. G2: cell completes preperation for mitosis, chromosomes start to condense, spindle apparatus starts to form
4. M phase: mitosis and cytokinesis, subdivided according to state of chromosomes, chromosomes finally condensed enough to become visible at prophase
what two transient cytoskeletal structures are required for cell division in eukaryotes
1. microtubules of the mitosis spindle are made of protein tubulin synthesized during G2
2. Actin and myosin filaments act on the contractile ring
difference in cytokinesis animal vs plant cell
- animal cells involve a rung of actin filaments just under plasma membrane, in association with motor proteins (myosin)
- plant cells have a new wall that must be constructed between living plant cells.
steps of cytokinesis in plant cells (3)
1. microtubules and protein define and organize the regions where new cell membrane and wall will form (anaphase)
2. vesicles mostly from golgi arrive, carrying polysaccharides glycoproteins to lay down matrix for new cell wall (telophase)
3. later cellulose fibres are laid down to complete wall. vesicles fuse to form new wall (cytokineses)
Stages of Mitosis in animals (6)
1. interphase
2. prophase: chromosome consisting of two sister chromatids
3. pro metaphase: spindle pole and kinetochore miscrotubule hold sister chromatids
4. metaphase: chromosomes migrate to equator of cell (metaphase plate)
5. Anaphase: daighter chromosomes form by sister chromosomes seperating
6. Telophase and Cytokineses: daughter cells form, nuclear envelope reforms, spindle apparatus disintegrates