Cell Division And Genetics Flashcards
What are the advantages and disadvantages of using cell length to measure growth?
It is easy to measure under a microscope.
Although, it is often irregular shape.
There is also no reference to number of cells.
What are the advantages and disadvantages of counting the number of cells?
Good indication of overall size
Organisms may contain millions of cells - hard to count
Doesn’t take account of size of cells
What are the advantages and disadvantages of using dry mass to measure growth?
Accurate indication of growth
Time consuming
Organism is killed during the process
Describe the stages of mitosis.
1) DNA condenses into chromosomes and each chromosome replicates so it contains two identical chromatids.
2) The chromosomes align in the equator of the parent cell
3) Spindle fibres attached to the centromere and contract. Pulling sister chromatids to opposite poles.
4) The cell splits in two to produce two genetically identical diploid daughter cells
When is mitosis used?
Growth
Replace worn out cells
Repair of damaged tissue.
Describe the stages of meiosis.
1) Chromosomes pair up in homologous pairs.
2) Genetic cross-over occurs ( exchange of alleles between chromatids in the homologous pair )
3) Homologous pairs of chromosomes randomly align along the equator of the parent cell ( independent assortment )
4) Spindle fibres attach to the centromere and contract, pulling chromosomes to opposite poles.
5) Each cell divides again, so each new cell only contains one chromatid from each chromosome
6) Daughter cells are haploid and not genetically identical.
What is a mutation?
Random change in DNA
How is cancer caused?
Uncontrolled cell division.
What are the two types of tumour?
Benign and and malignant.
What is a benign tumour?
They remain in one place and are an encapsulated tumour, they are surrounded by a capsule.
What is a malignant tumour?
Break off from primary tumour and spread into the blood stream to another location. No capsule and more dangerous.
What are the three treatments of cancer?
Surgery, chemotherapy, radiotherapy.
How is skin cancer caused?
UV radiation from the sun and the risk of getting it can be reduced by using sun lotion, covering up and reducing the time spent in the sun.
How is lung cancer caused?
Cigarette smoke contains a number of cancer causing chemicals collectively known as tar. This causes lung cancer.
