Mitosis Flashcards
Types of tumour
Malignant
Benign
What is mitosis usually used for
1) increase size of tissue during development
2) replace dead and worn out cells
Interphase
First stage
Cell grows
DNA replicates
Normal condition of cell
Prophase
Second stage
DNA supercoils
Chromosomes condense
Nuclear membrane breaks down
Centrioles migrate to poles
Spindle fibres form
Metaphase
Third stage
Chromosomes line up centrosomes on equator of cell
Centromeres attach to spindle fibres
Anaphase
Fourth stage
Centromeres breaks down
Sister chromatids pulled to opposite poles
Spindle fibres shorten
Telophase and cytokinesis
Fifth stage
Telophase = nuclear membrane reform, chromosomes disperse, cytokinesis begins
Cytokinesis = cytoplasm divides
Mitosis in prokaryotic cells name
Binary fission
Binary fission in bacteria
Replication of DNA
Replication of plasmids
Division of cytoplasm
What phase does DNA replication occur
Interphase
Cytokinesis is what
Division of cytoplasm to produce two identical daughter cells
What does binary fission involve
Replication of circular DNA and plasmids
Division of cytoplasm to produce two daughter cells, each with one copy of circular DNA and many plasmids
Virus cell division
Non-living things don’t undergo cell division
Infected host replicated virus particles
Mitosis importance
Growth = haploid cells fuse to form diploid cell, cells grow from original cell so they are identical.
Repair = damaged or die new cells produced to replace those lost
Reproduction = single-celled organisms divide by mitosis to form new organism
Method of required practical
1) Garlic root grow by suspending on water for a week or two
2) 1M of HCL acid in boiling tube, placing in 60C water both for 10 mins
3) Remove tips of rots and place in warm HCL acid for 5 mins
4) Rinse tips with cold water using pipette, blot to dry with paper towel
5) Cut 2mm off tip and place on microscope slide
6) Add drop of warm acetic orcein to stain purple
7) Gently squash root tip on glass slide using mounting needle
8) View and count cells undergoing mitosis on microscope
How to calculate mitotic index
No. of cells with chromosomes / total no. of cells
Meiosis prophase 1
DNA condenses and becomes visible as chromosomes
Homologous pairs pair up
Crossing over occurs
Centrioles migrate to opposite poles
Spindle is formed
Nuclear envelope breaks down
Meiosis metaphase 1
Homologous pairs line up at equator
Spindle fibres attach to centromeres
Meiosis Anaphase 1
Chromosomes/homologous pairs are separated and pulled to opposite poles by spindle fibres
Meiosis telophase 1
Chromosomes reach poles
Spindle fibres start to break down
metaphase 2
Chromosomes line up in single file at the equator
anaphase 2
chromatids and separated by spindle fibres and pulled to opposite poles
Centromeres divide
telophase 2
chromosomes reach poles
Nuclear envelopes form
meiosis cytokinesis
Cytoplasm divides
produces 4 gametes with half the number of chromosomes the parent cell had
How does variation occur
Homologous pairs cross over
chromatids break
chromatids join the other chromosomes in the homologous pairs
Describe binary fission in bacteria.
Replication of (circular) DNA
Replication of plasmids
Division of cytoplasm
Where does growth in plants occur
Root tip meristem
Mitosis practical method
1) remove garlic tips of roots and place in ethanolic alcohol
2) place tips ni warm dilute hydrochloric acid
3) Place on microscope slide
4) Add suitable stain using pipette
5) place coverslip on top of root tip and press down firmly using paper towel
Mitotic index equation
mitotic index = number of cells with visible chromosomes ÷ total number of cells
What are carcinogens
Agents that may cause cancer
Stages in development of cancer
1) Oncogenes (mutated genes that cause cancer) arise due to carcinogens
2) Cancerous cell does not respond to signals from other cells so continues to divide
3) Mitosis
4) Cancerous cells not removed by immune system
5) rapid mitosis
6) Tumour gets larger
7) Tumour supplied with blood and lymph vessels. If it is a malignant tumour, tumour cells spread in bloo and lymph to other parts of the body
8) Metastasis, tumour cells invade other tissues formign other cancers
CAncer treatments
Methotrexate = inhibits synthesis of DNA nucleotides in cells
Vincritstine and taxol = prevent formation og mitotic spindke
What is a virus
Non cellular infectious particles that straffle the boundary between living and non living
Viral replication by injecting nucleic acid into a host cell process
1) Virus uses attachment proteins on its surface to bind to complementary receptor proteins on surface of a host cell
2) Virus injects DNA or RNA into host cell
3) Host cell uses nucleic acid and protein building machinery to produce new viral particles
Process of viral replication
1) Attachment = virus attaches to surface of host cell
2) entry = viral DNA/RNA enters hsot cell
3) Replication = viral DNA/RNA replicates and new viral proteins are made
4) Assembly = new viral particles are assembled
5) release = host cell lyses (bursts) releasing newly made viruses
Label the cell cycle circle
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/01/The-cell-cycle.png
Label the cell cycle circle
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/01/The-cell-cycle.png
What are the three stages of the cell cycle
Interphase
Nuclear division (mitosis)
Cell division (cytokinesis)
What is the cell cycle definition
Regulated sequence of events that occurs between one cell division and the next
What variable does the length of the cell cycle depend on
Environmental conditions
Cell type
Organism
What are cyclins
Movement from one phase to another is triggered by chemical signals called cyclins
What occurs during interphase
Cell increases mass and size
Protein synthesis
Replicated DNA
What phase is interpahse
G1 phase
S phase
G2 phase
What does G1 phase do
Cell grows and receives signal to divide
Protein synthesis
Production of organelles
Produces RNA
Monitors cellular environment to see if it can enter S phase
What does the S phase do
DNA synthesis
Relatively short
WHat happens during G2 phase
Further cell grwoth
Error checking of newly synthesised DNA
E.g. Tubulin protein produced to make spingle fibres
What phase is nuclear division
M phase
Cell growth stops
What occurs during cytokinesis
Cell divides and one nucleus moves into each cell to create two geneticall identical daughter cells
Constriction of cytoplasm
