1. Organelles: Structure and Function
Recognise cell structures under the electron microscope
Outline the function of the different cell organelles

2. CELL ORGANELLES 1 Surrounded by membranes 2 Without membranes Nucleus
Endoplastic reticulum
Golgi apparatus
Mitochondria
Chloroplasts (plants only)
Lysosomes
2 Without membranes
Ribosomes
Centrioles
Cytoskeleton

3. THE NUCLEUS Structure Largest organelle Spherical
Dark patches=chromatin
Surrounded by nuclear envelope – double membrane
Has nuclear pore - allows large molecules through
Nucleolus inside
Function
Contains genetic material
Chromatin consists of DNA and proteins
Contains instructions for making proteins
When cells divide, chromatin condenses into visible chromosomes
Nucleolus makes RNA and ribosomes.
THE NUCLEUS

4. ENDOPLASMIC RETICULUM
Structure:
Consists of flattened membrane-bound sacs - cisternae which are continuous with the outer nuclear membrane.
RER- Ribosomes
Smooth ER- no Ribosomes
ENDOPLASMIC RETICULUM
Function:
Smooth ER- Involved in making Lipids
RER- Transports proteins made on attached ribosomes

5. GOLGI APPARATUS Structure: Stack of membrane-bound, flattened sacs
Function:
Receives proteins from the ER
Modifies them, adding other chemicals
Packages proteins into vesicles to be transported inside cytoplasm or to the outside

6. MITOCHONDRIA Function
Structure:
2 membranes separated by a fluid filled space
Inner membrane is folded to form cristae
Central part is the matrix.
Function
Site where ATP is produced during cell respiration

7. CHLOROPLASTS Structure: 2 membranes separated by fluid filled space
Inner membrane surrounds a network of thylakoids
A stack of thylakoids is called a granum
Chlorophyll molecules are present on these membranes.
CHLOROPLASTS
Function:
Site of photosynthesis
Light energy is used to make carbohydrate molecules from carbon dioxide and water

8. Function:
Contain digestive enzymes which break down materials
e.g. specialised lysosome (acrosome) in head of sperm cells helps it penetrate the egg.
Structure:
Spherical sacs surrounded by a single membrane

9. Organelles NOT surrounded by membranes
Ribosomes
Centrioles

10. RIBOSOMES
Structure
Very small organelles. Free in the cytoplasm, or bound to rough ER, or in mitochondria and chloroplasts.
Consist of 2 subunits.
Function:
Where the instructions (mRNA) from the nucleus are turned into proteins – protein synthesis

11. CENTRIOLES
Structure
Small microtubules made of protein. Mother and daughter centrioles with a very characteristic design.
Function:
Form fibres in cell division known as spindles which separate chromosomes.

12. CYTOSKELETON Structure
Microtubules and microfibrils in the cytoplasm, made of protein.
Function:
Give cells shape and structure
Help cells move or change shape