B2. Cell Division Flashcards
What are the stages in the cell cycle?
The cells grow, increase in mass and carry out normal cell activities. At the end of stage 1 the cells replicate their DNA to make two copies of every chromosome. They also make more sub cellular structures such as mitochondria, ribosomes and chloroplasts
In the process one set of chromosomes is pulled to each end of the dividing cell and the nucleus divides
The cytoplasm and cell membrane divide to form two jew identical cells
Why is mitosis important?
It’s important in the growth, repair and development of multicellular organisms
What are stem cells?
Undifferentiated cells with the potential to form a wide variety of different cell types
When do most animal cells differentiate?
Early in development and cell division is mainly for repair and replacement
What happens if some differentiated cells cannot divide?
They are replaced by adult stem cells
When do plant cells differentiate?
Plant cells can differentiate throughout life of the plant as it continues to grow. Actively dividing plant tissues are called meristems, found at the growing point of plants. The cells produced by mitosis in the meristem then elongate and differentiate
Why is it easier to clone a plant compared to an animal cell?
Plants are easy to clone because the cells can become unspecialised, divide by mitosis and then differentiate into the various types of plant cells. It is difficult to clone animals because once the cells are differentiated they cannot become unspecialised again.
Why are embryonic stem cells more useful for helping medical conditions?
Embryonic stem cells are pluripotent meaning they have the ability to develop into any type of cell in the body. Adult stem cells are multipotent, meaning they can only develop into certain type of cells
What are the problems with stem cells in medicine
It requires embryonic stem cells because they are the only ones able to differentiate to any type of cells
Limited supply of embryonic stem cells + some ethical issues
Patient’s immune system may reject the stem cells and try to destroy them however the risk can be reduced by giving the patient medication however this doesn’t always work
What is the process of therapeutic cloning organism?
Therapeutic cloning produces stem cells which are genetically identical to the parent cell. Nucleus is removed and discarded from the donor egg cell. Nucleus is removed from the patient’s cell. This nucleus is transferred to the donor egg cell and fused by electricity. The cell is stimulated to divide. Cell develops into an embryo. Stem cells are removed after 4-5 days.
