1.1 Cells Flashcards
The cell theory states that…
- Cells are the smallest unit of life
- All cells are made from pre-existing cells
- All living organisms are made up of cells
Exceptions to cell theory
- Striated muscle (fibres multi-nucleated)
- Gian algae (unicellular despite being large)
- Type of fungus (continuous cytoplasm, many nuclei)
Functions of life (MR H GREN)
M: Metabolism
R: Response
H: Homeostasis
G: Growth
R: Excretion
E: Reproduction
N: Nutrition
How does Paramecium carry out all functions of life?
Metabolism: reactions to cytoplasm catalyzed by enzymes
Response: moves in another direction when it touches a solid object (reacting to stimuli)
Homeostasis: keeps internal conditions within limits
Growth: grows in size by accumulating minerals from food
Excretion: CO2 diffuses out of the cell
Reproduction: asexually or sexually
Nutrition: feeds on smaller organisms (digesting in vesicles)
Explain Surface Area to Volume ratio
larger cell = smaller SA to Vol. ratio
Cell too large = not able to take in materials or excrete waste quickly enough
Cell too small: might overheat
Special cells can increase their SA by…
- Changing their shape to be long and thin
- Folds in cell membrane
Why do cells reproduce?
- for growth in multicellular organisms
- for reproduction in single-cell organisms
- to replace dead/damaged cells
What are stem cells?
cells that can turn into different specialized cells
what makes stem cells different?
- self-sustaining, can continually divide
- undifferentiated
Stem cells can be collected from…
- embryonic stem cells
- bone marrow
- liver
What is Stargardt’s disease?
genetic disease that can cause blindness in children by affecting the retina. it can be treated by injecting embryonic stem cells into the eye which can differentiate into retina cells
What are the ethical concerns of using stem cells?
The use of embryonic stem cells means that the embryo will not get to develop, so there will be no baby.
