B2: Cell Division Flashcards
What is a gene?
A section of DNA that codes for a particular characteristic
What is one reason the body needs to be able to make new cells?
Skin cells are continuously lost
What is the cell cycle?
The 3 stages of cell division
What happens in stage 1 of the cell cycle?
The DNA is replicated to make 2 identical chromosomes
What happens in stage 2 of the cell cycle?
Mitosis - One set of chromosomes are pulled to each end of the dividing cell and the nucleus divides
What happens in stage 3 of the cell cycle?
The cytoplasm and cell membrane divide to make 2 identical daughter cells
What stage of the the cell cycle is the longest?
Stage 1
Why are all the cells in your body not the same?
Because they divide, grow and begin to differentiate
How do you clone a plant?
1) Scrape a tissue sample from the parent plant
2) Place the tissue samples in Agar Growth medium
3) Let the samples develop into tiny plantlets
4) Plant the plantlets into compost
Where are the 2 main places that stem cells are found in animals?
Bone marrow and embryos
What are adult stem cells mainly needed for?
To replace old warn out cells
What type of cells can adult stem cells only differentiate to?
The cells of the type of tissue they are found in
What type of cells can embryonic stem cells become?
Any type of cell
What are stem cells?
Un-differentiated cells that can differentiate into any type of specialised cell
Where are embryonic stem cells stored?
In hollow balls called embryos
Where are adult stem cells found?
In bone marrows
What is therapeutic cloning?
When an embryo is produced with the same genes as a patient to help treat them
Where are stem cells found in plants?
In meristem tissues
What can stem cells in a plant do?
They can differentiate into any type of plant tissue, at any point in the life of the plant
What are 3 functions of mitosis?
- Mitosis is essential for the growth and development of multicellular organisms
- Mitosis takes place when an organism repairs itself (e.g when a broken bone heals)
- Mitosis happens during asexual reproduction
What are gametes?
Sperm or egg cells containing single chromosomes with 23 total chromosomes
What does meiosis do to the total number of chromosomes?
It halves the total number of chromosomes
What happens in stage 1 of meosis?
All of the chromosomes are replicated to make pairs of 2 identical chromosomes
What happens in stage 2 of meosis?
The cell divides into 2 new identical daughter cells
What happens in stage 3 of meosis?
Both of the new cells divide again, forming 4 gametes
Where does meiosis take place?
In reproductive organs
How many gametes are formed from one cell in meiosis?
4
Are each 4 of the gametes formed by meiosis genetically similar or different?
Genetically different - they have different alleles
