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Organelles (little organ) tiny structures
inside a cell that perform specific functions for
a cell. Example: mitochondria, lysosome and
chloroplast.
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THE UNIQUENESS OF THE CELL
A cell is unique:
Specialisation Division of labour
Coordination and integration
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Living components of cell is called as
PROTOPLASM (cytoplasm + nucleus)
The cytoplasms contains ORGANELLES
- Perform specific functions which enable the
cell to function as a unit of life
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NUCLEUS
contains the genetic material
regulates and controls the activities of the cell
an organelle bounded by double (2)
layers of nuclear membrane with poresand selectivelypermeable
responsible forall cellular structure, chemical functions, growth and reproduction
separates the genetic materials (chromatin)from cytoplasm
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NUCLEOLUS
spherical structure within the nucleus
consists of DNA (deoxyribonucleic acid)
and RNA (ribonucleic acid) and proteins
visible when the cell is not dividing
synthesis RNA which is needed to
make ribosomes
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NUCLEOPLASM
fluid contained within the nucleus
highly viscous solid
made up of the chromatin and the nucleolus
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CHROMOSOMES
thread-like structures (consists of genetic
material)
appears as chromatin spread throughout the
nucleus in the form of tiny granules
chromatin condenses into chromosomes
(during cell division)
carry genetic information in its DNA
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ENDOPLASMIC RETICULUM(ER)
connected to the nuclear membrane
synthesises proteins, steroids and lipids
collects, stores and distributes protein, steroids andlipids
exists as rough ER and smooth ER
Rough ER: covered with ribosomes, flat sealed sacwhich continued from the nuclear membrane,transports protein, and have a large surface area for
chemical reactions. Smooth ER: does not have ribosomes, transports lipids
and presents in large amounts of cells.
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PLASMA MEMBRANE
cell membrane
thin membrane surround the cytoplasm of a
cell
selectively permeable / semi permeable
a protective and selective outer barrier
consistsof phospholipids and protein molecules
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GOLGI APPARATUS
bound sacs
processes, packages and transport moleculessynthesised in the cell
forms lysosomes
transports and stores lipids
synthesis of carbohydrate from hormone
changes protein into glycoprotein
excretes waste products out of the cell
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CYTOPLASM
aqueous solution (except nucleus)
stores water, enzymes, nutrient, salts and
dissolved gases
provided support, shape and protects the cell
organelles
medium for metabolic reactions
provides substances
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LYSOSOME (ac)
sac-like organelle with one membrane
digest proteins, lipids and carbohydrates
removes undigested materials releases enzymes to digest external materials
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CENTRIOLE (ac)
are paired cylindrical organelles
nine tubes with three tubules each
produces spindle during cell division (mitosisand meiosis)
migrate to the opposite poles of the cell
(during cell division will be discussed in
Chapter 5 Cell Division)
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CELL WALL (ac)
rigid and tough cellulose layer surrounding the
plasma membrane (cell membrane)
protects and supports the cell
maintains the shape
prevents the cell from busting (excessive
intake of water)
allows substances to move freely through the
cell wall
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CHLOROPLAST (pc)
disc / lens-shaped organelle
have two membranes: inner and outer
membrane
contains chlorophyll in the grana to trap
sunlight energy
carry out photosynthesis in the chlorophyll
storage of food and pigments
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CELL ORGANISATION
Unicellular
A single cell performs all thebasic life process. Example:Amoebasp.,Paramecium sp., Chlamydomonas, Bacteria
and Euglena. MulticellularAn organism consists of more
than one cell. Each group of cell specialized tocarry our life processes. Example: Homosapien (human), animals and plants. It has fivelevels of organisation
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Cells: basic units of structure and function.Example: Red blood cells and xylem vessel cells.
Tissues: made up of cells with similar in structure andfunction.Example: Epithelial tissues and vascular tissues.
Organs: made up of tissues that perform a specificfunction.Example: Heart and flower.
System: two of more organs that perform a specificfunction.Example: Digestive system and root system.
Organisms: whole living thing that carry out all thebasic life processes.Example: Human and durian tree.
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CELL ORGANISATION in Amoeba sp.
Cell structure
Amoeba sp.: plasma membrane, food vacuole,
contractile vacuole, pseudopodium, nucleus,
ectoplasma, endoplasm.
Locomotion
Amoeba sp.: Pseudopodium (false foot) helps
it to move forward slowly and it is known
asamoeboid movement.
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Feeding
Amoeba sp.: Omnivore. Eat bacteria, plantcells, algae and other microscopic organisms.
Entrapment extend pseudopodium.
Engulfment
engulf tiny food (phagocytosis)
with its pseudopodia.
Digestion food enclosed in food vacuole
Absorption
enzyme digests the bacteria
Egesting expel indigestible material.
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Reproduction
Amoeba sp.: two types of reproduction. Binary Fission nucleus divides (favourable
condition) and then follows by division of
cytoplasm. Two daughter cells are formed(mitotic division).
Spore Formation spores form (bad
condition) and germinate into new amoeba
under favourable condition.
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Osmoregulation
Amoeba sp.: water moves into the cell by
osmosis and prevention of bursting, it has a
contractile vacuole.
Respiration
exchange gases throughout the whole cell
membrane
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Excretion
waste products are ammonia and carbon
dioxide by diffusion. Solid waste in
paramecium is expelled through its anal pore.