B2 Flashcards
What is differentiation?
Differentiation is the process in which cells differentiate to form specialised cells.
When can plants and animals differentiate?
Most animal cells can differentiate only in the early stages but plant cells retain the ability to differentiate their whole lives.
Where are chromosomes found?
Chromosomes are found in the nucleus and are long strands of DNA
How many chromosomes are there in a nucleus?
46 chromosomes (23 pairs)
What is the cell cycle?
A series of stages in which a cell splits and produces two genetically identical daughter cells.
What is the first stage of the cell cycle?
The cell grows and increases the amount of organelles such as the mitochondria or ribosomes. The DNA replicates to form two copies of each chromosome.
What is the second stage of the cell cycle?
The nucleus divides and one set of chromosomes is pulled to each side of the cell, the duplicates on one and the originals on the other.
What is the third stage of the cell cycle?
The cytoplasm divides and then the cell membrane divides to form two identical daughter cells with full sets of chromsomes. This is called cytokinesis
What is a stem cell?
An undifferentiated cell that can differentiate into other specialised cells. It can replicate.
Why is cell division important?
Cell division is important for growth, repair and the development of multicellular organisms.
What is the function of stem cells in embryos?
Stem cells in embryos can differentiate into almost many different types of human cells. This allows the embryo to develop and become a human.
What is the function of stem cells in adult animals?
Stem cells in adults are produced in the bone marrow and can differentiate into various specialised cells but not as many as embryonic stem cells. They are used for growth and repair.
What is the function of the meristem in plants?
The meristem tissue can differentiate into any type of plant cell. The meristem is found at the tips and roots of plants.
What conditions can stem cells help cure?
Stem cells can help cure paralysis and diabetes.
What are the risks of using stem cells in medicine?
Using stem cells in treatments can lead to the transfer of viral infections. The stem cells might also mutate.
Why might some people object to the use of stem cells?
Some people have ethical issues against this use whilst others might have religious obligations that prevent them from supporting the use of stem cells.
What is therapeutic cloning?
Therapeutic cloning is the process in which an embryo is created and formed using a donor’s egg and a healthy patient cell. This embryo is genetically identical to the patient and it’s embryonic stem cells won’t be rejected and can be used to treat certain conditions.
How can stem cells from meristems in plants be used?
These stem cells can be used to clone plants, this allows rare species to be protected from extinction and allows crops that have resistances to be cloned and used in farms so less die.
