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cell
In 1665 Robert Hook ( an English scientist) design his own microscope and used it to examine
cork from the bark of a tree
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He called these units cells
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All living things are made up of cell and all life process are take in
cell
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The theory state that:
• all living things are composed of cell
• cell in the basic unit of structure and function in living things
• All cell are produced from other cell
• cells contains inherited information which control their activities
• All cell are basically the same in chemical composition
• All life process take place in the cell
the theory applies in all living things no matter how big or small
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Scientists can study cells to learn about
nutrition ,growth, reproduction ,respiration ,movement ,sensitivity and excretion
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Prokaryotes are
mostly single-celled organisms such as bacteria and blue-green algae

Characteristics of prokaryotics cells
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They do not have nucleus
They do not have membrane bound organelles
They are general smaller in size than eukaryotic
Some prokaryotic use flagella or pili for locomotion
Prokaryotic can be rod –shaped, spherical or spiral shape
They reproduce asexual

Eukaryotic cell
eukaryotic cells are cells which are found in organism called eukaryotes
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The cell membrane is up of two
layers of lips and protein molecules
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the cytoplasm
Is the site for chemical reactions in the cell ,cell organells such as the vacuole ,nucleus and
Mitochondria are suspended in the cytoplasm

Nucleus
This is round or oval organelle suspended in the cytoplasm
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It is surrounded by membrane called nuclear membrane
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Animal cells have temporary vacuoles
Mainly used to secrete and excrete wastes from the cell

Lysosomes
Lysosomes are spherical organelles bound by a membrane
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there are two type
endoplasmic
Reticulum ,which are smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum(RER)
• rough endoplasmic reticulum : has ribosome on it surface
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The
RER transports the protein made in ribosome
• Smooth endoplasmic reticulum: has no ribosome
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For example ,Golgi bodies transport enzymes
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mitochondria are oval-shaped organells that have
two membrane
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There organells work the same way
as in animal however ,plant cell have additional structures which serve specific roles in a plant
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the
cell wall is fully permeable
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The cell wall serves to
protect and support the cell as well as to give it definite shape

Chloroplasts
Chloroplast are oval organelles that contain the green pigment that we see in plants
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it is important in photosynthesis

Cell sap vacuole
Plant cell have a large permanent vacuole that usually occupies the central part of the cell, this
vacuole contain sap and is surrounded by tonoplast membrane
The sap causes the vacuole to exert pressure outwards
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this helps plant to retain their shape and to remain upright

Similarities and differences between plant and animal cells
Plant and animal cells are similar in that they both have :
• A cell membrane
• Cytoplasm
• A nucleus
• Cell vacuoles
• Endoplasmic reticulum
• Golgi bodies /Golgi apparatus
• Lysosomes
• Mitochondria
the following table give differences between plant and animal cells

Plant cell

animal cell

Has a cell wall

No cell wall

Regular shape

Irregular shape

Has chloroplast

Lack chloroplast

Has large permanent vacuole

Has small temporary vacuole

Nucleus is to the side

Nuclear is central position

Has tonoplast membrane

Has no tonoplast membrane

Thin layer of cytoplasm

A lot of cytoplasm

Store starch

Store glycogen

Cell differentiation

An organism which is made up of one cell is called unicellular organism, example are Bactria,
Amoeba and paramecium while those made up of more than one cell are called multicellur organism
example are animal and plant
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This is called cell differentiation
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example of animal tissues are bone,
muscle and skin ,example of plant tissue are xylem and phloem
An organ is the group of tissue that perform the same function
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example of animal system is blood
circulatory system
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Specialized cells are found in both plants and
animals
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This provides a large surface area for transporting
oxygen from the lungs to various parts of the body
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The sperm cell has
tail which enables it to swim to the egg and a pointed head with acrosome which enable it
penetrate the egg

Specialized plant cells

Root hair cell
these cell absorb water and minerals from the soil
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This makes them expand irregularly
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when they contract ,stoma opens
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Lignin is tough rigid material
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chloroplast are sites of photosynthesis
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You should able to know
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Meaning of cell
Characteristics of cell
Differentiate various types of cells
Draw and label plant and animal cells
Parts and function of plant and animal cells
Similarities and differences between plant and animal cell
Concept of cell differentiation
Importance of cell differentiation and formation of tissue, organs and body system
Differentiate cells ,tissues, organs and body system



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