Chapter 3
Why are cells small
• Surface area to volume ratio
• The larger the cell  the smaller the ratio
• The smaller the cell  the larger the ratio
10 units
1 unit
10 units
Volume = 1000
units3
Surface Area =600
Ratio
3:5
units2
Volume = 1 units3
Surface Area = 6 units2
Ratio
6:1
• This means that a small cell can get more food
for its size than a larger cell
• A small cell can get rid of its waste more easily
than a larger cell
The parts of a Cell
• The parts of a cell are called Organelles
• The first organelle is the cell membrane or the
plasma membrane
Work Sheet
• Use your book to answer the worksheet.
• Label the Animal cell
Work Sheet Answers
1. Nucleolus
2. Nucleus
3. Ribosome
4. Vesicle
5. Rough Endoplasmic reticulum
6. Golgi apparatus (Golgi body)
7. Cytoskeleton
8. Smooth endoplasmic reticulum
9. Mitochondrion
10.Vacuole
11.Cytoplasm
12.Lysosome
13.Centriole
Label Pictures
Ribosomes
• This is where proteins are made ( Amino acids
are put together to make proteins)
• Ribosomes made of 2 sub-units, composed of
rRNA and protein
• Found on the Rough Endoplasmic Reticulum
When free
ribosomes are in
groups they are
called
polyribosomes
Endoplasmic Reticulum
• Also called the ER
• It is attached and is continuous with the
nuclear envelope
• Rough ER  has ribosomes all over it
• Proteins are made then go into the ER to be
transported
• Smooth ER  does not have any ribosomes
• Makes phospholipids used in the cell membrane and
makes steroids
Golgi Apparatus
• Packaging and distributes materials to the rest
of the cell
• Import and Export Centre
• Export
– Modifies Proteins for export out of the cell
– Forms secretory vesicles
– Exocytosis of
• Proteins
• Lipids
• Waste products
Lysosome
• Lyse  to break up or to break apart
• Some  body
• Lysosome  is an organelle the breaks up
things. It can break up and digest food. Or it
can break up parts of the cell
• Lysosomes use digestive enzymes to break up
things
• They are made by the Golgi Body
Chloroplasts
• These are responsible for photosynthesis in
plants (makes food)
Mitochondria
• In both plants and animals
• Does Cell Respiration (Turns food into energy)
Cytoskeleton
• Made of Microtubules and Microfilaments
• The are Filamentous Protein structures that
help the cell:
– Keep its shape
– Keep organelles where they are, or
– Help the organelles move
Vacuole
•
•
•
•
Occur in both plant and animal cells
Very large central vacuole in plant cells
Stores water-soluble compounds
Helps maintain cells shape
– When a plant does not have water the leaves
droop
Cytoplasm
• The liquid that all the organelles float in
Cell Wall
• Cell Wall is only in Plant cells
• It provides structural support
• It is made of Cellulose and cannot be digested
by humans
Cell Wall
Located
outside of
the cell
membrane
On a test
• You will be asked to identify organelles from a
TEM (Transmission Electron Micrograph)
picture.
Review
• Mr. Lum is going to tape the name of a cell
organelle onto your back
• You will walk around the class asking people
questions
• The questions can only be a “yes” or a “no”
question
• You can only ask one question to one person