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Lab Exercise # 2
Zoo- 103
Lab Exercise # 2
• Cells were discovered in
1665 by a British
scientist named
Robert Hooke.
• He was able to observe
the cell with the use of
the microscope.
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Lab Exercise # 2
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Definition of Cell
A cell is the smallest unit that is capable of
performing life functions.
Cells are the basic unit of life
All organisms are made up of cells
All cells come from pre-existing cells
Lab Exercise # 2
The Cells
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Basic structural and functional unit of life
The Tissues
Cells group together to form tissues
The Organ
Different tissues combine together to form an organ
The System
Different organs combine together to form a system
The Body
Different systems combine together to form an
animal or organism
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Some cells are capable to live independent which called single celled
or unicellular organisms like the protozoa.
Classification of the cell
1- Prokaryotic cell: they are devoid of the true nucleus.
2- Eukaryotic cell: they have true nucleus (surround by nuclear
membrane).
Structure of the cell: the true cell consist of three parts
1- The Central part (nucleus).
2- The Peripheral part (cytoplasm).
3- The Cell membrane encases both of these parts.
Lab Exercise # 2
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• Contain nucleus and organelles surrounded by membranes
• Most living organisms, example: humans
• Usually larger than prokaryotic cells
Plant
Animal
CELL DIVISION
Amitosis
Mitosis
Amitosis
Direct cell division
It is simple division
It occurs in lower animals such as amoeba
Meiosis
Mitosis
The term mitosis (mitos= threads, sis= process)
It occurs in somatic cells of the body
Mother cell gives two daughter cells each one contains diploid
number of chromosomes (2n)
This type of cell division : responsible for growth of the
organism and repair of damaged tissues.
Mitosis can be divided into stages
• Prophase
• Metaphase
• Anaphase
• Telophase
Prophase stage- mitosis cell division
Chromosome become visible
Centriole divides in two halves
Nuclear membrane disappears
Each pair of centrioles move to one pole of dividing cell
Metaphase stage- mitosis cell division
Each chromosome divides in two chromatids
The chromosomes are align at the equatorial (middle) plate of the cell
Spindle fibres attaches the chromosomes at centromere
Anaphase stage- mitosis cell division
Halves of the chromosomes go to the opposite poles
Two paws of the chromosomes are formed
Telophase stage- mitosis cell division
Two daughter nuclei are formed
Chromosomes in the nuclei disappeared
Nuclear membrane and nucleolus reappear
Daughter nuclei are identical and copy of their mother cell
Lab Exercise # 2
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HISTOLOGY is the branch of Biology that studies
the microscopic structure of the tissues, organs
and systems under the microscope
Type of Tissues
Epithelial
Tissue
Muscular
Tissue
Skeletal
Muscle
Compound
Neuron
Cardiac
Muscle
Hyaline Cartilage
Simple
Nervous
Tissue
Connective
tissue
Blood
Simple epithelial
Compound Epithelial
Single layer of cells
more than one layer of cell
Fibrous connective tissue is characterized by an abundance of fibres with fewer
cells.
It is called fibrous or collagenous connective tissue because of the abundance
of collagen (collagenous) fibres.
Little intercellular substance is present.
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The Connective Tissue
Hyaline Cartilage
• Hyaline cartilage is covered externally by a fibrous membrane, called the
perichondrium.
• The chondrocytes cells are round or oval in shape and are located in group of two or
four in each cavity, Lacunae.
• It contains lots of empty spaces in between the cells. The matter that support the cells
and cavities is thick and is called the matrix.
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The Muscular Tissue
Striated Muscle
Skeletal muscle
 Skeletal muscle is made up of individual components known as muscle fibers.
 Each muscle fiber is formed of still finer fibers, myofibrils.
 The identifying features of these muscles are haphazard distribution of nuclei among the
muscle fibers.
 The fibers are also transversely marked with lines or striations, dark and light bands.
 Each muscle fiber is encased in a membrane, myolemma.
What is blood made up of?
An adult human has about 4–6 liters of blood
circulating in the body.
Blood consists of several types of cells floating
around in a fluid called plasma.
The red blood cells (RBCs) contain
haemoglobin, a protein that binds oxygen. RBCs
transport oxygen to, and remove carbon dioxide
from the tissues.
The white blood cells fight infection.
The platelets help the blood to clot, if you get
a wound for example.
Lab Exercise # 2
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The Nervous Tissue
Neurons
Nucleus
Dendrites
• These are unit of Nervous Tissue and are specialized in function and shape.
• The neurons or the nerve cells are star shaped bodies with few microns in diameter.
• The sharp protrusions of these cells are named as dendrites and the number of such
spine like extensions varies from 5 to 7.
• Centrally, the star shaped mass is loaded with a small nucleus and cytoplasm around
the nucleus