2.2 All Cells Arise From Other Cells Flashcards
Which type of cell has the ability to divide?
Eukaryotic
When in the cell cycle does DNA replication occur?
Interphase
What is mitosis?
Eukaryotic cell divides to produce two daughter cells with an exact copy of the DNA of the parent cell
In what way are daughter cells similar?
They have identical copies of DNA produced by the parent cell
What is the order of the cell cycle?
Interphase Prophase Metaphase Anaphase Telophase (Cytokinesis)
What is cytokinesis?
Division of the cytoplasm
Produces two new cells
What can uncontrolled cell division lead to?
Formation of tumours and cancers
What’s the main objective of most cancer treatments?
Prevent DNA from replicating
by inhibiting the metaphase stage of mitosis by interfering with spindle formation
By what process do prokaryotic cells divide?
Binary fission
What does binary fission involve?
Replication of the circular DNA and of plasmids
Cell membrane begins to grow between the DNA molecules and punches inwards, dividing the cytoplasm
What is produced by cytokinesis in prokaryotic cells?
Two daughter cells with a single copy of the circular DNA
A variable number of plasmids
Why don’t viruses undergo cell division?
They are non-living
How do viruses replicate?
Attach to the host cell with the attachment proteins on their surface
Inject nucleic acid into the host cell
The genetic information of the injected viral nucleic acid provides the instructions for the host cell to start procuring the viral components, nucleic acid, enzymes and structural proteins
These are then assembled into new viruses
What is interphase?
Cell is actively synthesising
Chromatids not visible
What is prophase?
First stage of mitosis
Chromatids visible as they get shorter and more dense and so darker
The nucleolus disappears
The nuclear envelope breaks down
Chromosomes left free in the cytoplasm are drawn towards the equator of the cell by spindle fibres attached to the centromere
What is metaphase?
Second stage of mitosis
Chromosome are seen to be made up of two chromatids (joined by centromere)
Spindle fibres pull chromosome (attached to centromere) to arrange across the equator of the cell
What is anaphase?
Third stage of mitosis
Where chromosomes move apart and so the number of chromosomes is doubled
Spindle fibres pull them towards the poles
The energy for this is provided by mitochondria which gather around the poles
What is telophase?
The last stage of mitosis
Nuclear membrane reforms as two cells are formed
The chromosomes are no longer visible, leaving only widely spread chromatin
What is a benign tumour?
Enclose in a capsule
Grown in centre
Do not invade surrounding tissue
What is a malignant tumour?
Grow at the edges
Invade surrounding tissues and organs
(metastasis can occur)
What is metastasis?
Where cells may break off and set up secondary tumours elsewhere
What is a tumour?
Mass of cells formed by uncontrolled cell division
What is a chromosome?
A thread like structure of nucleic acids
can be / or X