lecture 13 - mitosis Flashcards
Where is genetic information in viruses stored?
Acellular RNA
Where is genetic information stored in bacteria (prokaryotic cells)?
Circular, single copy, double stranded DNA.
How is genetic information stored in eukaryotes?
Histone bound DNA (double helix)
How many base pairs fit into a 1µm section?
3000 bp
How many genes are in a human DNA strand?
21000 genes
What is a karyotype?
An ordered visual representation of the chromosomes in a cell, showing the pairs of homologous chromosomes. In metaphase, each chromosome will be duplicated, so the karyotype will have sister chromatids.
What are the two overall phases of the cell cycle in terms of mitosis?
Interphase, mitosis phase (M phase)
What are the 3 phases of interphase in the cell cycle?
G1 (gap 1), S (synthesis), G2 (gap 2)
What occurs in the G1 phase of the cell cycle?
Organelles, cytoplasmic components and the centrioles replicate inside the cell.
What occurs in the S phase of the cell cycle?
DNA is synthesised, replicating the chromosomes to form sister chromatids
What occurs in the G2 phase of interphase in the cell cycle?
Enzymes that aid in cell division are produced as the cell prepares for mitosis
What kind of cells are centrioles found in?
Animal cells
What is a centriole?
A cylindrical organelle made of tubulin that organises spindle fibres during mitosis and meiosis
What is a centrosome?
A structure made up of two perpendicular centrioles, which regulates the progression of the cell cycle by organising microtubule arrangement (the spindle)
Where are sister chromatids attached?
Centromeres
What are the 5 phases of mitosis?
Prophase, Prometaphase, Metaphase, Anaphase, Telophase & cytokinesis.
How are chromosomes ordered in the nucleus in G2 of interphase in the cell cycle?
They are disordered
What occurs at prophase in mitosis?
Chromosomes become visible, mitosis spindles form at asters and begin to migrate, cytoskeleton disassembles
What are asters?
A component in prophase of mitosis. Made up of the centrosome and the microtubules it radiates
What occurs at the propmetaphase of mitosis?
Nuclear envelope disintegrates, centromeres of sister chromatids are attached to the poles via mitotic spindles (kinetochore and nonkinetochore microtubules)
What are kinetochore microtubules?
A part of the mitotic spindle that attach the kinetochore of sister chromatids to the centrosomes
What are nonkinetochore microtubules?
A component of the mitotic spindle that connect the centrosomes at opposite poles of the cell, but do not interact with the sister chromatids
What occurs in the metaphase of mitosis?
Sister chromatids are lined up long ways in the centre of the cell along the metaphase plate, due to equal and opposite forces applied by the kinetochore microtubules.
What is the ‘equator’ of a cell in metaphase called?
The metaphase plate
What occurs during Anaphase of mitosis?
Sister chromatids are pulled apart as the kinetochore microtubules shorten and the nonkinetochore microtubules lengthen. Each pair of sister chromatids splits into two daughter chromosomes.
What occurs in the telophase and cytokinesis phases of mitosis?
Spindle apparatus disassembled and microtubules broken down in tubulin for forming new cytoskeleton in daughter cells. chromosomes cluster at poles and nuclear envelope forms around them. Cleavage furrow forms, key organelles reappear in each cell.
How does the cleavage furrow split the parent cell in cytokinesis of mitosis/meiosis?
A constricting belt of actin filaments forms around the equator of the cell and tightens to split the cell.
What are the the cell cycle checkpoints? (3)
G1/S, G2/M, spindle checkpoint
What is the primary checkpoint in the cell cycle?
G1/S checkpoint
What is the function of the G2/M cell cycle checkpoint?
Allows cells that have successfully completed the phases of interphase to begin mitosis
What occurs at the spindle checkpoint in the cell cycle?
Checkpoint ensures all chromosomes have attached to spindles for anaphase to proceed.
What is the gene copy number?
The number of copies of a particular gene in the genotype of an individual. (AKA copy number variation - CNVs)
What is the chromatid number?
The number of chromatids in a cell, with two for every duplicated chromosome.
What is the diploid chromosome number?
The number of chromosomes in a cell, with two for every homologous pair. There are 46 chromosomes in a normal cell.
What is the haploid number?
Symbol is n. The number of chromosomes in a haploid cell or gamete, which is equal to the number of homologous pairs in a diploid cell.
