Cell Biology (Section 3) Flashcards
What is mitosis?
Mitosis is a stage in the cell cycle
Describe what happens during mitosis
• Chromosomes replicate
• They line up at cell equator
• The chromatids separate to opposite ends
• New nuclei forms
What sub-stages are included in the cell cycle?
• Chromosomes doubling
• Sub-Cellular structures increasing (ribosomes, mitochondria)
What are the 3 main stages of the cell cycle?
- Growth Phase
- Mitosis
- Cytokinesis
What happens during Cytokinesis?
• Cytoplasm divides
• Cell membrane divides
Why is mitosis important in human reproduction?
Allows the zygote to divide and form our embryo through repeated cell divisions
What is a stem cell?
A stem cell is an undifferentiated cell which is capable of dividing into various cell types
What are embryonic stem cells important for?
Forming tissues and organisms during development
What can animal stem cells do?
• Replace damaged cells
• Produce new cells for growth
What is special about meristem cells in plants?
They remain unspecialised. This means they can differentiate into any type of plant cell throughout its life
What is stem cell technology used for in medicine?
Repair damaged organs by growing new tissue from embryonic stem cells using patients DNA
What is therapeutic cloning?
Creating an embryo with the same genes as the patient
What does cloning plant cells from meristems do?
Protect the plants from extinction - this is considered ethical
What can stem cell treatment be used to cure in the future? (2 details)
• Diabeties
• Paralysis
What is diffusion?
Diffusion is a passive process where particles move from one area of a higher concentration to an area of a lower concentration
Where does diffusion occur in living organisms?
Cell membrane
What is special about the cell membrane (in terms of diffusion)
It is partially permeable (allowing certain substances like oxygen & CO2 whilst also blocking other substances)
What is diffusion important for?
Diffusion is important for processes such as aerobic respiration and photosynthesis (where oxygen and CO2 must diffuse into the cell)
What direction can things diffuse?
In & Out
What are the 3 factors which affect diffusion?
• Concentration Gradient
• Temperature
• Surface Area
What is the effect of concentration gradient on diffusion?
The greater the difference in concentration, the faster the rate of diffusion
What is the effect of temperature on diffusion?
The greater the temperature, the more kinetic energy there is so the particles spread quicker
What is the effect of surface area on diffusion?
The greater the surface area, the greater the rate of diffusion
What does surface area: volume ration affect?
It affects how easily substances can be exchanged between it
