Cell divison Flashcards
What is a chromosome?
A protein found in the nucleus of eukaryotic cells, which is a coiled thread-like structure of nucleic acids (DNA)
What are genes?
Sections of DNA that contain the code for a particular protein.
In what arrangement are chromosomes found normally?
Pairs
How many chromosomes does a human have in each cell?
23 pairs OR 46 in total.
What has to happen within the cell before Mitosis? (2 steps)
- Cell organelles (e.g. mitochondria and ribosomes) have to replicate
- Chromosomes have to be replicated (copied).
How many chromosomes will be present in a cell after DNA replication?
92 OR 46 pairs.
What occurs during cytokinesis (the final stage)?
The cytoplasm and cell membranes divide. Two daughter cells are created.
Mitosis is critical for….
growth, replacement and development of an organism.
What is a stem cell?
Cells that have not undergone differentiation. aka. an undifferentiated cell.
Describe the function of stem cells in embryos.
To develop into multiple cell types. So that the embryo can develop into a mature organism.
Describe the function of stem cells in plant meristems.
To allow a plant to keep growing throughout its life (animals stop growing when mature) by specialising into any type of cell.
What is a potential use of stem cells in medicine?
To treat conditions where cells have been damaged e.g. diabetes, paralysis.
Give an advantage of therapeutic cloning.
No rejection of the new cells by the patient (as they are the patient’s own genetic make-up).
Give two potential problems with therapeutic cloning.
- Risk of viral infection
- Religious/ethical objections around the use of embryos.
How are plant stem cells used in horticulture (commercial plant growing)?
To create plant cuttings (clones of the original plant).
Give two advantages of the use of clones in horticulture.
1.Rare species can be cloned to prevent extinction
2. Crops with special adaptations (e.g. disease resistance) can be identically produced in large numbers.
What happens during mitosis?
Two sets of chromosomes are pulled to opposite ends of the cell. Nucleus divides in two.
Why does yeast grow slowly at the start?
Cells are metabolising preparing for division.
What is the difference between an embryonic stem cell and an adult stem cell?
Embryonic stem cells can differentiate into every type of cell. Whereas, adult stem cells cannot.
What are the stages of the cell cycle called?
The Interphase, Mitosis, Cytokinesis
What happens in the second stage of the cell cycle?
Mitosis - the nucleus divides
What is therapeutic cloning?
Where stem cells are produced with the same genetic make-up as the patient
What are the steps to carry out therapeutic cloning?
- Take a human egg cell from donor and discard the nucleus.
- Add the patients nucleus from their cell to the egg cell.
- The cell is stimulated to divide and will form an embryo.
- The stem cells from the embryo can then be cultured after 4-5 days.
