Lecture #1 Mitosis Flashcards
Why does cell division occur? (4 main reasons)
Growth
Cell replacement
Healing
Reproduction
In what cell does mitosis occur?
Stem cells
How is mitosis different in eukaryotes vs. prokaryotes?
Eukaryotes: the genome is large and linear, DNA is in the nucleus
Prokaryotes: the genome is small and circular, DNA is in the cytoplasm
What are the main stages of the cell cycle?
G1 phase (gap 1): growth, cellular metabolism
S phase (synthesis): DNA replication (chromosome duplication)
G2 phase (gap 2): preparation for mitosis
M phase(mitosis): chromosomal separation and cytokinesis
Interphase: the time between successive mitoses ( G1 + S + G2)
G0 phase: cells is inactive in cell cycle and may exit the cycle
What are homologous chromosomes?
2 paired chromosomes, one from mom and one from dad
What are each of the stages in mitosis? What happens in each of them?
Prophase: chromosomes condense. Centrosomes move to opposite ends of the cell and make microtubules
Prometaphase: microtubules (spindle fibres) attach to chromosomes. Nuclear membrane starts to break down
Metaphase: chromosomes align in the centre of the cell
Anaphase: sister chromatids are separated and move to opposite ends of the cell
Telophase: nuclear envelope re-forms and chromosomes decondense
What are kinetochores?
Proteins on the ends of microtubules that help them attach to chromosomes and split them apart in anaphase
What is ploidy?
The number of complete sets of chromosomes in a cell
Diploid (ex. Somatic cell)
Haploid (ex. Sperm cell or egg)
What does haploid(n) mean?
1 unique chromosome from mom or dad
What does diploid(2n) mean?
2 unique chromosomes
What occurs in cytokinesis in animal cells?
Chromosomes decondense
Contractile ring forms
Nucleus reforms
How long does it take for the cell cycle to complete?
24 hours
What occurs in cytokinesis for plant cells?
Chromosomes decondense
Cell plate forms
Nucleus reforms
Does DNA and ploidy level change in mitosis
DNA changes
Ploidy levels DONT
How does DNA change in a diploid vs haploid cell
A haploid cell has twice as much DNA than the diploid cell
