Cell Biology - Topic 1

?
  • Created by: Riya.b123
  • Created on: 10-02-19 13:11

Prokaryotes & Eukaryotes

- Prokaryotic cells are smaller & simpler.

- e.g. Bacteria

- single-celled organism

- Eukaryotic cells are complex 

- include animal & plant cells

1 of 15

Animal Cells & Plant Cells

- Nucleus - controls activity of cells ( genetic material)

- Mitochondria - where aerobic respiration takes place

- Cytoplasm - where chemical reactions take place

- Cell Membrane - holds cell together

- Ribosomes - where proteins are made

- Plants also contain :

- Cell Wall - made of cellulose - supports & strengthens cell

- Chloroplasts - where photosynthesis takes place (chlorophyll)

- Permanent Vacuole - contains cell sap

2 of 15

Bacteria Cell

- Are prokaryotes

- No nucleus, chloroplasts or mitochondria

- Circular strand of DNA - floats freely in cytoplasm

- Small rings of DNA called plasmids

 

3 of 15

Light Microscope & Electron Microscope

- Light miscroscopes use light & lenses to form image of specimen.

- see individual structures & large subcellular structures

- Electron microscopes use electrons to form an image

- Higher magnification & higher resolution than light microscopes

- See small things in detail (internal structures)

4 of 15

Microscopy - Required Practical

 - Prepare slide

- Add drop of water to clean slide

- Using tweezers peel of epidermal tissue from onion & place on slide

- Add drop of iodine to stain

- Place coverslip & clip to stage on microscope

- Select lowest powered objective lens & look using the eyepiece with coarse adjustment knob to focus

- Adjust fine adjustment knob until clear image seen

 

5 of 15

Cell Differentiation

- Cells develop different subcelleluar structures & turn into different types of cells

- Most animals ability to differentiate lost at early stage

- Plants don't lose ability

- In mature animals used for repairing & replacing cells

- Undifferentiated cells called stem cells 

6 of 15

Examples of Specialised Cells

Sperm Cells - specialised for reprodcution (Male DNA to Female DNA) - long tail & streamlined head to swim - Mitochondria - Enzymes.

Nerve Cells - carry electrical signals to parts of the body - long - branched connections

Muscle Cells - contract quickly - long - lots of mitochondria - energy

Root Hair Cells - absorbing water & minerals - on surface if plant roots - big surface area

Phloem & Xylem - transporting substances (food & water)

7 of 15

Stem Cells

- Divide to produce more undifferentiated cells

- Found in early human embryos - ability to turn into any cell

- Found in bone marrow in humans

- Used in medicine or research

- To replace faulty cells

- Therapeutic cloning - embryo made to have same genetic info as patient - not rejected

- Risks involve contamination with virus

- Some against it for religous & ethical reasons

- Can produce identical plants - meristem

8 of 15

Chromosomes & Mitosis & The Cell Cycle

- Coiled up DNA - contains genes

- Body cells divide 

- Multicellular organisms use mitosis to grow, develop & replace cells.

- Cell increases amount of subcellular structures & DNA duplicated - chromosomes pulled apart - nucleus divides - produces 2 new identical daughter cells.

9 of 15

Diffusion

- Particles moving from area of higher concentration to low concentration

- In solutions & gases

- Bigger the concentration gradient, faster rate of diffusion

- Larger the surface area of the membrane - faster rate of diffusion - more particles mass through at once. 

10 of 15

Osmosis

- Movement of water particles from higher water concentration to lower water concentration. 

- Water molecules move randomly 

- Passive Movement

 

11 of 15

Osmosis Required Practical

- Cut potato into cyclinders 

- Have beakers with different concentrated sugar solutions & one with water in it

- Measure mass of cylinders & add each one to a beaker

- Leave for 24 hours

- Dry them & measure mass again

- if drawn in water - increase in mass

- if water drawn out - decrease in mass

12 of 15

Active Transport

- Low to high concentration 

- Root hair cells take in minerals using active transport

- Used in gut when there is low concentration of nutrients in the gut but higher concentration of nutrients in the blood

13 of 15

Exchanging Substances

- Larger the organism the smaller its surface area compared to its volume

- Thin Membrane - short distance to diffuse

- Large surface area 

- Lots of blood vessels in animals

- Ventilated 

14 of 15

Examples of Exchange Substances

Gas Exchange in Lungs - transfer oxygen to blood & remove CO2 - contain alveoli - maximise diffusion - large surface area - moist lining - thin walls - good blood supply

Villi - large surface area - inside small intestine - digested food absorbed quickly - single layer of surface cells - good blood supply. 

Structure of Leaves - Stomata (exchange surface) - CO2 diffuses in - O2 diffuses out - size of stomata controlled by guard cells - flat shape of leaf increases area

Gills - Large SA - lamallae - blood capillaries to speed up diffusion - thin surface layer - less distance

15 of 15

Comments

No comments have yet been made

Similar Science resources:

See all Science resources »See all Biology resources »