Cell Structure

Microscopes (Light Microscope)

Uses 2 lenses.

Magnification = Powe of eyepiece lens x Objective lens

Light Microscope (Diagram)

Microscope (Electron Microscope)

Electron instead of light

Transmission electron microscope: A beam of electrons passes through a thin specimen to show the internal structure.

Scanning electron microscope: Shows the surface structure.

Cell structure (Plant cell Diagram) under (light) microscope

Cell Structure (Animal cell Diagram) under (light) microscope

Cell Ultrastructure

The detailed structure as seen using an electron microscope

Cell Components (7)

1. Cell membrane

2. Nucleus

3. Cytoplasm

4. Mitochondria

5. Ribosomes

6. Cell wall (Plant Only)

7. Chloroplasts (Plants Only)

Cell Membrane (plasma)

Composed of phospholipid bilayer and proteins.

Phospholipids have a water loving (hydrophilic) and a water hating (hydrophobic) lipid group.

Functions:

Retain the cell contents.

Some support.

Control what enters and exits the cell.

Nucleus

made up of a double membrane.

The nucleolus contains RNA, DNA and proteins and makes ribosomes.

Chromatin = elongated chromosome

Cytoplasm

= The jelly-like liquid that surrounds the nucleus.

Mitochondria

= Where respiration occurs

Ribosomes

= Tiny structures made of RNA and protein

Function: protein synthesis - combine amino acids to make proteins.

Cell wall (Plants Only)

Made of cellulose

Function: Strength and support

Chloroplasts (Plants Only)

Double membrane. contain a green pigment

Function: Photosynthesis

Differences between plant and animal cell

Has a cell wall - does not have a cell wall

May have chloroplasts - Do not have chloroplasts

Has a large vacuole - Does not have a large vacuole

Prokaryotic Cell

Do not have a nucleus or membrane enclosed organelles. e.g. bacteria.

Eukaryotic Cell

Have a nucleus and a membrane. e.g. plants, animals and fungi.

Prokaryotic + Eukaryotic Diagrams

To prepare and examine plant cells using the light microscope.

Step 1: Use a forceps to pull a thin, transparent strip of onions epidermis between from between the onion leaves.

Step 2: Place strip on a glass slide.

Step 3: Add a few drops of iodine.

Step 4: Lower coverslip at an angle to prevent air bubbles.

Step 5: Blot off excess iodine.

Step 6: Examine and draw results.

(Check Booklet for Diagram)

To prepare and examine animal cells using the light microscope.

Step 1: Rinse your mouth out with water.

Step 2: Scrape the inside of your cheek gently with a cotton swap.

Step 3: Spread the smear of cells thinly onto a glass slide.

Step 4: Add a few drops of methylene blue (Stains nucleus dark blue).

Step 5: Add a cover slip at an angle to avoid air bubbles.

Step 6: Blot off excess stain.

Step 7: Examine under low and high power and draw a labelled diagram of results.

(Check booklet for diagram)