Cell Division Flashcards
What are chromosomes made up of?
Chromosomes consist of DNA molecules combined with proteins. They contain genes that provide the instructions
What is a gene?
A section of DNA that codes for a protein
How many chromosomes are found in the nucleus of human body cells?
46
What are the three main stages of the cell cycle?
- Replication of DNA and synthesis of organelles
- Mitosis
- Division of cell
Why is mitosis important?
Produces identical cells that all have the same genetic information
Produces additional cells for growth and repair
Describe the first stage of the cell cycle
Cells grow and increase in mass, replicate DNA, and synthesize more organelles
Describe the second stage of the cell cycle
Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides.
Describe the third stage of the cell cycle
The cytoplasm and cell membrane divide - two identical daughter cells are produced
What is a stem cell?
An unspecialized cell which is capable of differentiating into other cell types
What is the function of stem cells in embryos?
Embryonic stem cells can replicate themselves and differentiate into many other types of cells. Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells
What is the function of stem cells in adult bone marrow?
Adult stem cells can differentiate into several cell types to replace dead or damaged tissues. For example, bone marrow stem cells can form many different types of blood cell
What is the function of stem cells in plant meristems?
Meristem stem cells retain the ability to differentiate into any type of plant cell
What is therapeutic cloning?
A cloning method where an embryo is produced with the same genetic makeup as the patient. The stem cell will not be rejected by the patient’s immune system, so can be used to treat certain medical conditions.
What are the advantages of cloning plants using meristem stem cells?
Can prevent rare plants from becoming extinct.
Can produce large numbers of plants with a
favorable characteristics.
What issues are associated with the use of stem cells?
Many embryonic stem cells are sourced from aborted embryos - some people have an ethical/religious objection
The development of stem cell therapies is slow, expensive, and difficult
Adult stem cells infected with viruses could transfer infections to
patient
If donor stem cells do not have a similar genetic makeup to the
patient, an immune response could be triggered
