5.1 and 5.2 Cell Division/in Sexual Reproduction Flashcards
What is mitosis?
Cell division that produces identical new cells from the original cell
Explain the process of mitosis
- All of the organelles in a cell replicate
- All of the DNA replicates
- All of the enzymes needed for cell division are produced by the cell
- Prophase, metaphase, anaphase and telophase
What do chromosomes contain?
Alleles in the genes which must be passed on to each new cell
What are the names of unspecialised cells in plant and animal embryos?
Stem cells
What is cell division mostly for in animals?
Replacement and repair, because most animal cells differentiate early in development
What is cell division mostly for in plants?
Growth, because plant cells can differentiate throughout the life of the plant
What are cells of offspring made by asexual reproduction produced by?
Mitosis, so they contain the same alleles as their parents
Which type of cell division produces two identical cells from the original cell?
Mitosis
How to remember mitosis?…
MITosis = Making Identical Two
Name the 4 stages in the mitosis checkpoint stage of the mitosis cycle
- prophase
- metaphase
- anaphase
- telophase
PMAT
What happens in the prophase stage?
The chromosomes condense, the centrioles move to opposite poles, the spindle apparatus spreads (ready to force apart) and the nuclear membrane dissolves
What happens in the metaphase stage?
All chromosomes are aligned to the equator of each cell
What happens in the anaphase stage?
The proteins that hold the sister chromatids together degrade so all of the chromosomes are pulled to each pole
What happens in the telophase stage?
Once the chromosomes are separated, the cell splits into 2 separate cells
Which process splits the cells in two in mitosis?
Cytokinesis
What are sister chromotids?
Individual chromosomes that make a pair of chromosomes
Explain the stages of meiosis
- Replicate the pairs of chromosomes in a cell
- The cells split similarly to mitosis, with a set of each pair of chromosomes, called a diploid
- The cells split again without replicating the chromosomes so each cell only has one pair of chromosomes, called a haploid
How do cells in reproductive organs divide?
Meiosis, to form gametes
What are the gametes in humans?
Sperm and ova
Why does sexual reproduction lead to variation?
The different chromosomes from each parents fuse so half the genetic info comes from father, other half from mother
When the gametes join at fertilisation which process carries on with developing the embryo?
Mitosis splits the cells
How to remember meiosis?…
MEiosis = Making Eggs
What is cell division necessary for?
The growth of an organism and the repair of damaged tissue
Why does uncontrolled mitosis lead to the formation of tumours?
As the cells divide uncontrollably, tumours form
Normal cells usually die after going through mitosis around 50 times (depending on the type of cell) but cancer cells are often immortal. Why can this be a problem?
The cancer cells can spread around the body and take away resources from the organs, eventually causing the organs to stop working
Explain why a malignant tumour is more dangerous than a benign tumour
The malignant tumours have their own blood supply
Name the 3 types of treatment for cancer
- removal of tumour by surgery
- chemotherapy
- radiotherapy
Which 2 treatments of cancer are more suited for targeting tumours in one specific area and why?
- radiotherapy, because you only aim the X-rays at one area of the body
- removal of tumours by surgery because they will only operate on the targeted area
Which treatment is necessary for cancer that has spread around the body?
Chemotherapy because it is a drug in your bloodstream that travels the body and kills the cancerous cells
Why can’t chemotherapy be used on pregnant women?
Chemotherapy relies on a drug that travels in your bloodstream and kills cells that are dividing, and the cells of the embryo in the uterus are dividing
