Transcript What is a cell?

Cell Structure &
Organisation
Chapter Outline
(a)
identify cell structures (including organelles) of typical
plant and animal cells from diagrams,
photomicrographs and as seen under the light
microscope using prepared slides and fresh material
treated with an appropriate temporary staining
technique:
• chloroplasts
• cell membrane
• cell wall
• cytoplasm
• cell vacuoles
• nucleus
Chapter Outline
(b)
(c)
(d)
identify the following organelles from diagrams and
electronmicrographs:
• mitochondria
• ribosomes
state the functions of the organelles identified
above
compare the structure of typical animal and plant
cells
Chapter Outline
(e)
(f)
state, in simple terms, the relationship between cell
function and cell structure for the following:
• absorption – root hair cells
• conduction and support – xylem vessels
• transport of oxygen – red blood cells
differentiate cell, tissue, organ and organ system
What is a cell?
• Building blocks of life
• Simplest units of life
• Chemical reactions in the cell keeps us
alive
Cells
Red Blood Cells
White Blood Cells
Cells
Embryonic Stem Cells
Other Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Cells
What does a cell consists of?
Each living cell consists of living material called
protoplasm.
Protoplasm:
• Water makes up 70% of protoplasm
• Proteins
• Carbohydrates
• Fats
Protoplasm
1) Cell Surface Membrane
2) Cytoplasm
3) Nucleus
Cell Structures in Plant
and Animal Cells
• nucleus
• cytoplasm
• cell membrane
• cell wall
• cell vacuoles
• ribosomes
• mitochondria
• chloroplasts
Animal and Plant Cells
Animal Cell
Plant Cell
Cell Structure and Function:
http://lgfl.skoool.co.uk/keystage3.aspx?id=63
Animal Cell
Animal Cell
Cell Surface Membrane
• Surrounds the cytoplasm of the cell
• Partially permeable membrane
– Allows some substances but not all to move in
and out of the cell
Nucleus
• Surrounded by a membrane
called the nuclear
envelope
• Contains one or more
nucleoli
• Contains chromatin
Functions of the nucleus:
1. Controls cell activities such as
cell growth and the repair of
worn-out parts
2. Essential for cell division
Nucleolus
Cytoplasm
• Between the cell surface membrane and the nucleus
• Contains enzymes and organelles
Organelles in the Cytoplasm
•
•
•
•
Mitochondria
Ribosomes
Chloroplasts (only in plant cells)
Cell vacuoles
Mitochondria
• Aerobic respiration occurs in the mitochondria
• Energy production
• Energy used to perform cell activities such as
growth and reproduction
Ribosomes
• Required for protein synthesis in the cell
Vacuoles in Animal Cells
• A vacuole is a fluid-filled space
enclosed by a membrane
• Animal cells have many small
vacuoles that contain water and food
substances such as proteins and
carbohydrates
Pop Quiz!
Label and identify the diagram
D
E
A
B
F
C
Plant Cell
Plant Cells:
http://lgfl.skoool.co.uk/keystage3.aspx?id=63
Plant Cell
Differences Between Animal
and Plant Cells
Animal Cells
Plant Cells
Cell wall absent
Cell wall present
Chloroplasts absent
Chloroplasts present
Vacuoles are small,
temporary in animal cells
Vacuoles are large, sapfilled in plant cells
Cell Wall
• Surrounds the cell surface
membrane
• Cell wall is made of
cellulose
• Protects the cell from injury
• Gives the plant cell a fixed
shape
• Cell wall is fully permeable
Chloroplasts
• Found only in plant
cells
• Chloroplasts contain a
green pigment called
chlorophyll
• Chlorophyll is essential
for photosynthesis, the
process by which plants
make food
Vacuoles in Plant Cells
• Plant cells usually have
a large central vacuole
which contains a liquid
called cell sap
• Cell sap contains
dissolved substances
such as sugars, mineral
salts and amino acids
Pop Quiz!
Label and identify the diagram
A
D
B
E
C
F
Specialised Cells
Red Blood Cell
Sperm Cell
Nerve Cell
Root Hair Cell
Egg Cell
Cell Differentiation
The process by which cells develop special
structures or lose certain structures to
enable them to carry out specific functions.
Hence, cells become differentiated to form
specialised cells.
The structure of each cell is adapted to
perform the specific functions of the cell.
Cell Differentiation
How is cell structure
related to cell function?
1) Red Blood Cell
Cell Structure
Adaptation to Function
Contains haemoglobin
Haemoglobin transports
oxygen from the lungs to
all parts of the body.
No nucleus
Carry more haemoglobin
which leads to increased
transport of oxygen.
Circular biconcave shape Increased surface area
to volume ratio of the
cell. Hence, increased
transport of oxygen.
How is cell structure
related to cell function?
2) Xylem Vessel
Cell Structure
Adaptation to Function
Long hollow tubes (no
protoplasm)
Enables water to move
easily through the lumen.
Lignified walls
Lignin strengthens the
walls and prevents the
xylem vessels from
collapsing.
How is cell structure
related to cell function?
3) Root Hair Cell
Cell Structure
Long and narrow
Adaptation to Function
Increased surface area
to volume ratio of the cell
which leads to increased
absorption of water and
mineral salts from the
soil.
Specialised Plant and Animal Cells:
http://lgfl.skoool.co.uk/keystage3.aspx?id=63
How do cells
work together in
a multi-cellular
organism?
Organisation in Living Things:
http://lgfl.skoool.co.uk/keystage3.aspx?id=63
Tissue
A tissue is a group of similar cells which work together
to perform a specific function.
Examples of tissues:
• Muscle, the lining of the intestine, the lining of the
lungs, phloem, root hair tissue
Connective
Tissue
Organ
Different tissues may be combined together to form
organs.
An organ is a structure made up of different tissues
working together to perform a specific function.
Examples of organs:
• Heart, lung, brain, leaf, root
Lungs
An organ is a structure made up of different
tissues working together to perform a
specific function.
Organ System
Organs work together to
form organ systems.
Various systems work
together to make up the
entire organism.
Examples of organ systems:
• Circulatory system,
respiratory system,
digestive system,
nervous system and
reproductive system
Circulatory System
Organ Systems
Organs work together to form organ
systems.
System
Organs
Digestive
Esophagus
Stomach
Small intestine
Large intestine
Trachea
Lungs
Respiratory
Pop Quiz!
Q1. Write out the order of cell
organisation within an organism.
Q2. Give an example of an animal
system with the order of cell
organisation stated above.
Pop Quiz!
Q1. Write out the order of cell
organisation within an organism.
Organism
Pop Quiz!
Q2. Give an example of an animal
system with the order of cell
organisation stated above.
• Intestinal cell  intestinal muscle 
small intestine  digestive system 
human
• Nerve cell  nerve tissue  eye 
sensory system  bird