Transcript St. Bonaventure College and High School Form 4 Biology

St. Bonaventure College
and High School
Form 4 Biology
Bridging Course 2009-2010
Cell structure
The structures of animal
cells and plant cells
• Cell is the basic unit of life.
• There are more than 200 types of
cells in our body.
• The shape and size of cells vary, but
some features are common to all.
Electron microscope
• The first electron
microscope prototype
was built in 1931 by the
German engineers
• Electron microscopes have much
greater resolving power than light
microscopes that use
electromagnetic radiation and can
obtain much higher magnifications of
up to 2 million times, while the best
light microscopes are limited to
magnifications of 2000 times.
Micrograph
Electron micrograph
Scanning electron
micrograph
Cell membrane
• It is selectively permeable.
• It controls the movement of
substances into and out of the cell.
• Different organelles exist within the
cytoplasm.
Nucleus
• Nuclear membrane
– double layer with
many pores
– pores allow
exchange of
materials
between the
nucleus and the
cytoplasm.
Nucleus
• Chromatin
– includes coils of
DNA and
histones
Nucleus
• Nucleoplasm
– contains
chromatin,
nucleolus,
proteins,
nucleotides.
Nucleus
• Nucleolus
– synthesis of
ribosomal RNA.
Nucleus
• The nucleus contains the genetic
material DNA, which stores
information used to synthesis
proteins .
• The nucleus is surrounded by a
double membrane, called the nuclear
membrane .
• Nuclear pores serve as the pathways
for the exchange of the materials
between the nucleus and the
cytoplasm.
• Nucleoli (singular: nucleolus) are
involved in making ribosomes.
Mitochondria
• They are the places where aerobic
respiration occurs.
• Generate adenosine triphosphate
(ATP) as a immediate source of
energy.
• Mitochondria have a double
membrane.
• The inner membrane, where most
ATP is made, is highly folded. This
greatly increases the surface area
for ATP production.
Chloroplasts
• Chloroplasts are oval-shaped
organelles commonly found in plant
cells.
• Chloroplasts, like mitochondria, have
a double membrane.
• Internal membranes contain the
green photosynthetic pigment
chlorophyll, which absorbs light
energy to make food through the
process of photosynthesis.
Vacuoles
• A vacuole is a liquid-filled space
within the cytoplasm, surrounded by
a membrane called the tonoplast.
• Plant cells usually have a large central
vacuole, which stores water, other
useful substances and wastes.
Cell Wall
• It consists of cellulose fibres
embedded in a polysaccharide matrix.
• Plant cells are surrounded by cell
walls.
• Protects plant cells and gives them
shape.
Vocabularies
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organism
electron microscope
cell membrane
selectively permeable
cytoplasm
organelles
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nucleus
synthesis
proteins
reproduction
nuclear membrane
nuclear pores
chromatin
chromosomes
nucleoli
ribosome
rough endoplasmic reticulum
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mitochondria
aerobic respiration
adenosine triphosphate (ATP)
highly folded
increases the surface area
chloroplasts
pigment
chlorophyll
photosynthesis
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vacuoles
tonoplast
cell sap
mineral salts
wastes
cell walls
elastic
rigid
protects
Short questions
1. What is the basic unit of life?
2. How many different types of cells
in our body?
3. What is the advantage of electron
microscope?
4. List out five organelles which can
find in both animal and plant cells.
5. What is the function of cell
membrane?
6. Where do the chemical reactions of
most cells take place?
7. List out three organelles which can
be found in cytoplasm.
8. What is the meaning of selectively
permeable?
9. What is the genetic material inside
nucleus?
10. How does the nucleus control the
activities of cell?
11. What is the function of nucleoli?
12. Where can we find ribosome in cell?
13. Why do scientists call mitochondria
as the “powerhouse” of the cell?
14. Why is the inner membrane of
mitochondria highly folded?
15. What organelle is more abundant in
a very active animal cell?
16. What is the shape of chloroplast?
17. How many organelles have double
membrane?
18. What are the functions of
vacuole?
19. What is the permeability of cell
wall?
20.List out the organelles that can
only find in plant cells.