DNA Processes: Cell Reproduction and Differentiation Flashcards
NOTE
Every body cell in an organism must have the same number of chromosomes.
Human body cells have 46 (2n or diploid) chromosomes
Every body cell in an organism must have the same number of chromosomes.
Human body cells have 46 (2n or diploid) chromosomes
NOTE
Cell Reproduction
- The process of producing new cells from existing cells
- This is asexual reproduction (only one parent cell involved)
- New cells are genetically identical to parent cell
Why do cells divide?
- Too big
- replace damaged or dead cells
- growth and development in thh embryo
Types of Asexual Reproduction
- Binary Fission
- Budding
- Vegetative Propagation
- Regeneration
Advantages of Mitosis
- Rapid production of offspring (bacteria)
- Replacement of lost body parts
- Desirable characteristics are continually passed on
Cell Cycle
A series of events that takes place during the life of a eukaryotic cell
Interphase
Most of the cell cycle is called Interphase, a time of growth and development
M Phase
The “M” phase is Mitosis, a time when the nucleus divides
Cytokinesis
The final stage of eukaryotic cell division is when the cytoplasm divides
Animal cells: Cleavage is seen (indention in cell membrane)
Plant cells: Cell plate formation occurs
NOTE
The number of chromosomes remains constant
Mitosis
The number of chromosomes remains constant
NOTE
Mitosis
DNA Replication
- Making an exact copy each DNA molecule before mitosis
- Occurs during “S” phase of Interphase
Involves 3 easy steps
1) DNA unzips
2) Both sides of the DNA molecule
are copied
3) Two DNA molecules result,
neither one is completely new
What happens if something goes wrong in the cell cycle?
1) When a cell’s DNA is damaged or changed (mutation) the cell doesn’t grow and divide normally
2) Uncontrolled cell replication (mitosis) occurs
3) Cancer is the result
Stem cells
undergo cell reproduction (mitosis) and then differentiate to develop into other types of body cells and tissues
At four or five days old, an embryo is composed of stem cells.
As adults, stem cells can be found in bone marrow
Differentiation
The process by which a stem cell divides and the new cells specialize to become a particular type, like a skin or blood cells
Enzymes of DNA Replication
Helicase Unzips DNA
Ligase zips it back up
