3.2.2 all cells arise from other cells Flashcards
1
Q
Describe how viruses with DNA replicate
A
- Virus attaches to a receptor on host cell using its complementary attachment proteins
- Viral DNA injected into host cell
- Viral DNA gets incorporated into host’s DNA
- Viral DNA copied: gets transcribed into viral mRNA and translated into viral proteins (eg capsid or attachment proteins)
- Virus copies itself using host cell and assembles new virus particles
- Cell bursts and new viruses released
2
Q
What happens during the telophase of mitosis?
A
- Chromosomes/chromatids reach opposite poles
- Spindle fibres disperse
- Nuclear membranes reform around each set of chromatids
- Nucleolus reforms
3
Q
Describe replication in bacteria (binary fission)
A
- Replication of circular DNA
- Replication of plasmids
- Division of cell wall and plasma membrane
- To produce 2 daughter cells with:
- A single copy of circular DNA
- Variable number of plasmid copies
4
Q
What happens during the prophase of mitosis?
A
- Chromosomes condense and become visible
- Centrioles move to opposite poles of the cell
- Nucleolus disappears
- Nuclear membrane breaks down
5
Q
What happens during anaphase of mitosis?
A
- Spindle fibres contract and centromeres split allowing sister chromatids to separate
- Chromatids move apart towards opposite poles of the cell
6
Q
What happens during the metaphase of mitosis?
A
- Spindle fibres attach to the chromosomes via their centromeres
- Chromosomes align along the equator of the cell
7
Q
Describe how a retrovirus replicates inside a host cell
A
- Reverse transcriptase enzyme
- Uses viral RNA to make viral DNA copy
- Viral DNA is inserted into host DNA
- Uses viral DNA at host ribosomes
- To make viral proteins
- And makes viral RNA
- Host cell assembles new viruses
- Budding off viruses wrapped in cell membrane
8
Q
What happens during the s-phase of interphase?
A
- DNA replication
- by semi - conservative replication
(Chromatid becomes sister chromatid joined by centromere)
9
Q
Name all stages of the cell cycle
A
INTERPHASE
* G1
* S - phase
* G2
MITOSIS
* Prophase
* Metaphase
* Anaphase
* Telophase
CYTOKINESIS
10
Q
What is the role of spindle fibres during mitosis
A
- (Spindle fibres made by centrioles)
- Attach to sister chromatids at the centromere
- Contract causing the centromere to split and they pull the sister chromatids to the opposite poles of the cell
11
Q
What is a malignant tumour
A
- a mass of undifferentiated cells
- that undergo uncontrolled cell divison
- break off and spread to other parts of body, form new tumours (metastasis)
