Mitochondria, chloroplasts, microtubules

1. Mitochondria
These are 0.5 -1.5 µm x 3-10µm
They can be seen under a good light microscope
Mitochondria are the site of aerobic respiration
They are found in all cells
There are
high numbers
In Metabolically
active cells

2. They are surrounded by a
double membrane
The outer membrane is
smooth and the inner is
folded into cristae
These folds increase the
surface area for the
enzymes involved in ATP
synthesis

3. The matrix contains enzymes
used in the Krebs cycle of
respiration
In the matrix are 70S
ribosomes and circular
strands of DNA

5. The ATPsynthse enzymes are called
stalked particles because they look like
stalks

7. Vacuoles
• These are only
found in plant cells
• They are membrane
bound and filled
with cell sap
• The membrane is
called the
tonoplast

9. • Cell sap contains water, ions, waste,
pigments, and hydrolytic enzymes
• Younger cells have many smaller
vacuoles
• In older cells these fuse to form a
large, permanent, central vacuole
• Animal cells have small, temporary
vesicles

10. Chloroplasts
These are the site of
photosynthesis
They are 4-10 x 2-3µm
They are a type of
Plastid, that is an
organelle containing
pigment

11. They are biconvex discs
There is a double membrane

12. The inner membrane is formed into
ling flat sacks called thylakoids

13. Some of these form stacks called
granum thylakoids
Plural = grana

14. Those going between the grana are
called stroma or inter-lammelae
thylakoids
The thylakoids contain the photosystems made of
chlorophyll pigments – light energy is trapped here

15. The fluid filled centre is the stroma
The stroma contains the enzymes needed for the Calvin Cycle which
converts carbon dioxide into a carbohydrate

16. There are 70S ribosomes

17. And circular DNA

18. Sometime there are starch granules
or lipid droplets

20. Microtubules
• These are hollow cylinders made of
protein
• They are 24nm in diameter

21. They occur throughout the cytoplasm and
bring about movement of cell contents,
such as lysosomes

22. • Microtubules are also found in cilia
and flagella and centrioles
• Misrotubules in the cytoplasm form the
structure of the cell, they are said to
from the cytoskeleton

23. Microfilaments
These are single stranded proteins
They are involved in cytoplasmic
movement

24. Centrioles
• These are only found in animal cells
• They consist of two hollow cylinders at right
angles
• They are about 0.3-0.5µm long and 0.2 µm
wide
• Centrioles contain microtubules in the same
structure as seen in cilia and flagella basal
bodies
• The Centrioles move to opposite poles
during cell division

25. Centrioles• These are only found in animal cells
• They consist of two hollow cylinders at right
angles

26. • They are about 0.3-0.5µm long and 0.2 µm
wide
• Centrioles contain microtubules in the same
structure as seen in cilia and flagella basal
bodies
• The Centrioles move to opposite poles during
cell division

27. Cilia and Flagella
Cilia are many short cytoplasmic projections
Flagella are one or a few much longer
cytoplasmic projections

28. In cross section under the
EM they are seen to
contain 9 peripheral
pairs of microtubules
and 2 central
microtubules (9+2)

29. These are connected to a different system
of microtubules inside the cytoplasm,
the basal body
The microtubules slide over each other to
bring about movement