Cell cycle Flashcards
what is the spindle made from ?
microtubules
what is the order of mitosis?
Interphase (G1, S, G2) - prophase - meta phase - anaphase - telophase - (cytokinesis)
Describe the chromosomes in interphase
uncoiled and invisible
Describe G1
Longest stage of cell cycle, highly metabolically active, cell grows, chromosomes consist of one chromatid
Describe S
DNA replicates so chromosomes contain 2 identical sister chromatids
Describe G2
Further intense cellular activity, mitochondrion divide, ATP stores increase
Describe prophase
Chromosomes coil (spiralisation) making them visible, spindle forms, nucleolus disappears
Describe metaphase
Chromosomes move to the equator of spindle and attach to spindle fibres by their centromeres, lined up
Describe anaphase
Centromere splits, spindle fibres pull chromatids by centromere to opposite poles
Chromosomes now only 1 chromatid, so cell is 4n
Describe telophase
Chromosomes uncoil and become invisible, nuclear envelopes from around two groups of chromosomes, new nucleoli forms, spindle breaks down, (centrioles replicate in animals)
Describe cytokinesis
Cell divides into 2 identical diploid daughter cells (2n)
Describe animal cytokinesis
micro tubules constrict the cell around the equator, pinching the cell into two
Describe plant cytokinesis
cell plate forms along equator, from which cell wall forms, diving the cell into two
what are stem cells ?
unspecialized cells that develop to become specialized cells by the process of differentiation
what is the difference between embryo stem cells and adult stem cells ?
embryo stem cells are pluripotent, adult stem cells are multipotent
where are most adult stem cells in humans ?
bone marrow - to produce erythrocytes and neutrophils
define homologous pair
Pair of chromosomes, one maternal and one paternal, that carry the same genes at same loci, although may have different alleles. They pair at meiosis to form bivalent
how are phloem sieve tubes developed ?
stem cells of the vascular cambium divide and differentiate into them
how can stem cells be used for Alzheimer’s ?
Use them to grow and replace dead nerve cells in the brain
how can stem cells be used for Parkinson’s ?
Transplanted stem cells may help regenerate dopamine- producing cells (that controls movement)
What is difference between squamous epithelial / epithelium ?
epithelial - cell
epithelium - tissue
what are the three things in meiosis that gives variation ?
- crossing over
- recombination
- independent assortment
Describe prophase I
- chromosomes condense (visible)
- chromosomes arrange in homologous pairs and crossing over occurs
- nuclear envelop breaks down
Describe metaphase I
homologous pairs line across center and attach to spindle fibres by centromeres
Describe anaphase I
spindles contract, separating chromosome pairs
Describe telophase I
nuclear envelop forms around each group of chromosomes
Describe cytokinesis I
two haploid daughter cells produced
name the differences between prophase I and II
- 1 has and interphase before, 2 doesn’t
- 1 has crossing over and recombination, 2 doesn’t
- 1 has homologous pairs, 2 doesn’t
Describe anaphase II
pair of sister chromatids separate
what is crossing - over ?
bit of chromatids swap in the homologous pairs, mixing the combination of alleles
what is a bivalent ?
two homologous chromosomes who have come together
what is chiasma ?
the cross - shaped link between the chromosomes in crossing over
what is the function of the xylem ?
transports water and supports plant
what is the function of the phloem ?
transports sugas around the plant
where are most stem cells in plants ?
meristems - parts which grow (so roots and shoots)
define multi cellular organisms
organisms made up form many different cell types that are specialized for a function
what are bones ?
living organs containing nerves and blood vessels
describe specialised structure of neutrophil
- flexible shape allows them to engulf foreign pathogens
- lysosomes in cytoplasm contain digestive enzymes, break down particles
describe specialised structure of erythrocytes
- biconcave disc shape provides large SA (gas exchange)
- no nucleus for more haemoglobin
describe specialised structure of epithelial cells
- cilia (move substances)
- squamous are thin
describe specialised structure of sperm
- flagellum to swim
- lots of mitochondrion for energy
- acrosome contains digestive enzymes to penetrate egg
describe specialised structure of RHC
- large SA
- thin permeable wall
- cytoplasm has extra mitochondrion for active transport
