cell division 2 Flashcards
(33 cards)
In multicellular organisms, can specialised cells divide?
No
What cells cannot divide?
Specialised cells
What occurs during G1 phase of the cell cycle?
Growth as cell increases in size
New organelles made
What occurs during S phase of the cell cycle?
DNA replication
Chromatids produced
Chromatids join at centromere to form a chromosome
What occurs during the G2 phase of the cell cycle?
Growth as cell increases in size
New organelles made
What happens during the M phase of the cell cycle?
Mitosis + Cytokinesis
Describe what occurs in prophase of mitosis.
DNA coils and condenses to form visible chromosomes
They are two sister chromatids joined at the centromere
Spindle fibres begin to form
Describe what occurs during metaphase of mitosis.
Chromosomes line up at the equator of the cell
Spindle fibres attach to centromere
Describe what occurs during anaphase of mitosis.
Chromosomes are pulled apart
Centromere splits
A chromatid from each pair is pulled to opposite poles of the cell
As spindle fibres contract and shorten
Describe what occurs during telophase of mitosis.
Chromosomes uncoil and uncondense
Two diploid nuclei form at cell poles
Spindle fibres break down
Describe the process of cytokinesis in mitosis.
Cytoplasm divides
2 genetically identical daughter cells form
What is the difference in the process of cancer cells dividing, and regular cells dividing?
Mitosis is a controlled process
What ensures that DNA has been copied correctly during the cell cycle, and what happens if this fails?
Checks occur
If they fail, uncontrolled cell division occurs
Uncontrolled cell division can lead to tumours and cancer
How do cancer treatments work?
Slow the rate of cell division, or destroy rapidly dividing cells
Describe the process of binary fission.
Circular DNA and plasmids replicate (circular DNA replicates once, plasmids can be replicated many times).
Cytoplasm expands (cell gets bigger) as each DNA molecule moves to opposite poles of the cell.
Cell membrane grows between two DNA molecules.
Cytoplasm divides and new cell wall forms.
2 daughter cells formed, each with a single copy of DNA and a variable number of plasmids
Why don’t viruses undergo cell division?
They are non-living
Describe the process of viral replication.
Attachment proteins on virus attach to cell receptors
Virus injects nucleic acid into host cell
Reverse transcriptase makes DNA from RNA
The cell replicates the nucleic acids
Cell produces viral proteins, capsids and enzymes
The virus is assembled and released from the cell by budding or cell lysis
RP2: Why roots placed in warm HCl?
Break down cell walls
Stop mitosis
RP2: Why end of root used?
Where most mitosis is occurring
RP2: Why squash sample, and why not too hard?
Single layer of cells
Allowing light’s long wavelength to pass through
Not pushed too hard, as to not break the chromosomes
RP2: Why stain used?
To distinguish chromosomes
RP2: Why different mitotic indices obtained from different samples?
Roots different ages
Different species of garlic
Different parts of root tip
Undergo mitosis at different rates
What is a chromosome during mitosis?
2 chromatids attached by a centromere.
What does mitosis produce?
A
2 genetically-identical daughter cells.
