robert hook) van leeuwenhoek)

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M.A.BARAKAT 0126375561

2CHAPTER

UNIT OF STRUCTURE OF THE LIVING ORGANISM

The Cell: Is the unit of structure and function in living organism. The discovery of the cell The English scientist (Robert Hook)

He made himself a microscope and examined some plant tissue.

He observed the cork consists of tiny cavities separated by walls. These cavities ate called cells.

The German scientist (Van Leeuwenhoek) He made a microscope and used it to examine various parts

of animal tissues. The Botanist( Mathias Shleiden):

He is considered the founder of the cell theory. The zoologist (Theodor Schwann):

He concluded that animal tissues consist of cells. Rudolf Virchow:

Virchow confirmed that the cell, in addition to being a building unit of living organisms, is also a unit of function.

He also confirmed that living cells are produced from pre-existing ones

Robert Brown: He discovered the nucleus.


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The cell theory

(Schwnn- Scheiden- Virchow)

Bodies of living organisms consist of either one cell (unicellular) or more (multicellular).

All living cells are similar in their basic structures. All new cells are produced from old (pre-existing) cells as

a result of their division.


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The fine structure of the cell

The most important components of the cell are the following: A- The Nucleus

Its shape may be spherical or oval. When the nucleus was removed from an amoeba by

microsurgery, the amoeba stopped dividing and died after few days.

The nucleus is made of the following main parts : 1- the nucleus membrane :

It is very thin membrane of protoplasmic that surrounds the nucleus with tiny pores.

2- The nucleoplasm:(nuclear sap): It is very clear fluid which is jelly like.

3- The Nucleolus:

It is a spherical body that is suspended in the nucleoplasm. 4- The chromatin Reticulum:

Tiny threads that coil around each other. During cell division, the chromatin reticulum forms the chromosomes.

The chromosome is formed of one molecule of DNA. The chromosome consists of two identical halves attached

together at a point known as the centromere. The maize plant each cells has 20 chromosomes (2n). The pea plant the cells have 14 chromosomes (2n). (Diploid

number). The cells that are produced from the gonads contain half the

number of chromosomes (n) because it is haploid.


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B – The cytoplasm : It is a viscous jelly like fluid similar in texture to the white of an egg (albumin). Cytoplasmic organelle

function

Endoplasmic reticulum

* Rough E.R. stores proteins, E.R. takes part

In the formation of the cell secretions. * It is the internal transport system of

cell. * Smooth E.R. synthesizes fats and glycogen.

The ribosome Are the centers of protein synthesis. Mitochondria Are the centers of respiration (energy

production and storage in the cell) Golgi apparatus Golgi bodies secrete different secretory

substances (enzymes or hormones) Centrosomes (centerioles)

They have an important role in the cell division.

Lysosomes They contain enzymes which can digest proteins, fat and carbohydrate. Lysosome in white blood cells can break down bacteria. They can digest worn out or damaged organelles and cells.

Cell vacuoles Storage place in which excess substances and juices (solution) are stored.

Q: Give reasons for:

Mitochondria exist in large number in muscles and liver. Because they are active organs need a lot of energy.


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Types of plastids

Types Chloroplasts Chromoplasts Leucoplasts

Colour Green Red, yellow, orange and brown

Colourless.

Position They exist in green leaves and green stems

They exist in petals of flowers, in fruits, in vegetables and in some leaves, some roots such as beet and turnip.

They exist in parts of the plant away from light such as inner cabbage leaves onion leaves.

Function Photosynthesis Coloring Storage of food. They can change to chloroplasts or chromoplasts.

Properties Cell wall Cell membrane Existence In plant cell only In both plant and

animal cells Chemical Composition

Young plants cells have primary wall made of cellulose. Old plant cells have secondary wall made of cellulose. Lignin or cutin or subrin.

It appears under electron microscope as a light line of lipids between 2 dark lines of protein. (fluid mosic)

permeability Fully permeable Selectively permeable


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function Support, protect, and give the cell its final shape

Enclose and protect the cell. Control what enter and leave the cell.

1-Light microscope

Mechanical parts: 1- The base. 2- The pillar. 3- Inclination joint. 4- The stage. 5- The curved arm. 6- A revolving nose piece 7- The body tube 8- Coarse adjustment 9- fine adjustment 10- Sliding tube. Optic parts: 1- The mirror. 2- Objective lenses. 3- Eye piece. Magnification power = power of eye piece x power of the objective piece.

2-The electron microscope: Its magnification power ranges from 100.000 to 500.000. times.

Answer the questions

Q1: draw all the following: Digestive system of Bilharzia worms- the eggs of ac, haematobium an sc.mansoni - adult worms. Q2: what would happened if: 1- Man drinks water with cercaria. 2- Patient of bilharziasis urinate in dray places. 3- The cell lost its mitochondria. Q3 what is meant by : 1-Alternation of generation? 2-diploid number


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3-haploid number

Q4: compare between intermediate host of Sch. haematobium and intermediate host of Sch. mansoni. Q5: compare between chloroplasts and leucoplasts. 6-Choose: 1- ………is the founder of the cell theory which states that the cell is the building unit of living organisms. (Virchow – Schleiden – Schwann)

2- The most important center of energy production in the cells are … (The plastids – the chromosomes – the mitochondria – Golgi bodies) 3-The increase in the number of living organisms is due to ………. (Vegetative activities – absorption of raw materials – reproductive activities – digestion of food) Q7: Give reasons for:

1- The endoplasmic reticula appear smooth or granulated. 2- The white blood cells are rich in lysosomes. 3- Plastids have different color. 4- The importance of a nucleus for cell. 5- Golgi bodies are found mainly in glandular cells.

Q8:What would happened if:

1- The inner cabbage leaves are exposed to direct sunlight. 2- The number of mitochondria is reduced in the cell. 3- The centriols are damaged in animal cells. 4- Some bacteria attack the blood cells. 5- There are no plastids in the plant cell.


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Differentiation of cells And types of tissues

Meristematic tissues Permanent tissues

* are composed of small cubical cells + big nucleus. * It is devoided of cellular sap. * It is capable of mitotic division forming new cells. * Are in embryo tissue and buds.

* The cells are bigger than meristematic cells. * Its vacuolar sap is big. * It lost its capability for division. * It is developed from meristematic cells.

Permanent tissues : are ( simple or compound) Simple tissue: It is a tissue which consists of one type of cells. Compound tissue: It is a tissue which consists of several types of cells.

Simple tissues

A The parenchyma tissues: are found in the cortex and the pith. B The chlorenchyma tissues: * Its cells contain chloroplast, and found in green leaves, where photosynthesis occurs. C The collenchyma tissues: * Their walls are thickened with cellulose. * It supports the plant part such as leaf stalk. D The sclerenchyma tissues: * It is lignified walls * It support the plant against factors of pressure and pulling with the help of the collenchyma tissue


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The compound tissue Vascular tissues: (the phloem tissue and xylem tissue)

1- The phloem tissue: It consists of: sieve tubes, companion cells, parenchymatous cells and fibers. Its main function is the transport of food stuff.

2- The xylem : The xylem is concerned with the translocation of water and

salts. It consists of vessels, tracheids, parenchyma cells and

sclernchyma cells. Differentiation of animal tissues Animal tissues are divided into four main types:

1- The Epithelial tissues. 2- The connective tissues. 3- The muscular tissues. 4- The nervous tissues.


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1- the Epithelial tissues It covers the whole surface of animal in order to protect

the underlying cells against harmful bacteria and dryness.

Epithelial tissues are mostly found lining the inner walls of the alimentary canal, tracheae of the lung and also the skin.

Its cells lined adjacent to each other.

A- Surface Epithelial tissue: It covers the surface of the body and lines its internal

cavities.

B- Glandular Epithelial tissue: 1- Exocrine glands (Duct glands)

It produce substance such as sweat, mucus and digestive enzymes.

2- Endocrine glands:

They are ductless glands, they produce hormone and secrete them to the blood stream.

3- Mixed glands: such as pancreas.

C- Neuro-Epithelial tissue: There are some epithelial tissues specialized for receiving certain

external stimuli like odour, taste .., from surrounding medium and transmit them to central nervous system

Example: taste buds on the tongue.


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2-the connective tissue Its cells are few and widely spaced. Its cells are embedded in a large amount intercellular

substance (matrix). The matrix which is non-living could be solid as in bone, or

semi- solid as in cartilage, or fluid as in blood.

PROPER CONNECTIVE

TISSUE

SKELETAL CONNECTIVE

TISSUE

VASCULAR CONNECTIVE

TISSUE Matrix Semi-solid ( so

it is high elastic) Solid or semi-solid

Liquid

Types Proper Bone – cartilage

* blood * lymph

Function Connect various tissues and organs of the body together.

Supporting tissues

Transport, feed and protect different tissues and organs of the body defend the body against microbes.

Proper connective tissue: blow the skin also found in the mesentery which binds the internal organs together inside the abdominal cavity.


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Properties Cartilage Bone Matrix It has no calcium salts

( semi sold) It contain calcium salts ( sold)

Hardness More flexible than bones

Harder than cartilage.

Position and function

It found in the nose tip, ends of bones and the ear pinna.

Bone is the building material of the teeth, the skull, vertebrae and limbs

3-Muscular tissue "It is the tissue which can contract and relax and causes motion"

P.O.C Skeletal muscles

Smooth muscles Cardiac muscles

Place Attached skeleton

Walls of the alimentary canal and blood vessels

Cardiac walls

Kind of control Voluntary Involuntary Involuntary Striating Striated Non-striated Striated

Number of nuclei in fiber

Several One One

Getting fatigue and tired

Gets fatigue and tired

Does not Get fatigue and tired

Does not Get fatigue and tired


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4-Nervous tissue Functions of the nervous tissue:

Reception and transmitting sensory impulses. Co- ordinates between all body organs. Response to external and internal stimuli.

Quiz Q1: Choose the correct answer:

1- Simple, surface …………..(muscle – epithelial – connective) tissue is composed of one row of adjacent cells, which are identical in shape.

2- Shark's skeleton is………..( bony - cartilaginous – bony and cartilaginous)

3- (Blood – Cartilage – bone) cells are arranged in elongated cylindrical units called Haversian system.

4- Both …… (Skeletal and smooth – cardiac and smooth – skeletal and cardiac) muscles are not exhausted or fatigued quickly.

5- Nervous tissue can receive sensory impulse and transmit them to the …….. (Muscles – central nervous system – glands).

Give scientific term: 1- A gland that has the characters of both exocrine and exocrine

glands. 2- Animal tissue that can contract and cause motion. 3- A tissue that binds different types of animal tissues together. 4- The cytoplasm of the muscle fiber. 5- Animal tissue that line internal body cavities.


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Q3 : Give reason for:

1-Epithelial cells cover the whole surface of the animal body. 2- Tear gland is an exocrine gland. 3-Bone is harder than cartilage. 4- Cardiac muscles and smooth muscles have common characters. Q4: What would happen when : 1- A long bone is fractured. 2- The cartilage matrix contains calcium salts. 3- Neuro-epithelium of the tongue is damaged.

The cell division Mitosis (Mitotic division):

It takes place in somatic cells. It plays an important role in the reproduction the primitive

organism and many of the higher plant. Before the cell divides, it passes through a stage known as

"interphase" in which the chromosome material multiplicatio 1-The prophase:

*This is the longest phase. * Network structure of nucleus disappears. * The chromatin condenses into chromosomes.


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* In animal cell each pair of centrioles move towards one f two poles. * The nuclear membrane disappears. * Formation of spindle. 2- The Metaphase: * The paired chromatids become straightly arranged and fixed by spindle fibers with the centromeres along the midline of the cell.

Each cenromere then divides. 3-The Anaphase: This is the shortest phase. The spindle fibers contract withdraws

each of the new chromosomes towards one of the cell poles.

4- The Telophase: The chromosomes coil up into chromatin net. The nuclear membrane appears. The nucleolus appears, spindle disappear.


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Then cytoplasm divides between the two daughter cells (2n) Middle lamella develops in plant cell.

Meiosis (Meiotic division)

This division occurs only in sexual organs (the gonads).

The first meiotic division:

1-prophase 1:

It is the longest stage (in time). Homologous chromosomes then arrange in pairs, each pairs formed of four even chromatids called a tetrad. The process of chiasma formation and crossing over occurs. Centrioles divide near the end of this phase. Crossing over is renewable source of genetic variation due to

the new genetic arrangement 2- Metaphase 1: * Homologous pairs of chromosomes arrange on the midline. 3- Anaphase 1 : * The chromosomes separate from one another each chromosome move as pair chromatids (without division of centromeres) by the pull of the cell poles.


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4- Telophase 1: * Haploid chromosomes (half their original number) arrive to cell pole.

nuclear membrane appears, nucleolus appears The cytoplasm starts to divide giving two daughter cells.

The second Meiotic Division: This is similar to normal mitosis.


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Quiz

P.O.C MITOSIS MEIOSIS Occurs

* In somatic cells * The resulting cells can be repeated the division many times.

* In the gonads. * The resulting cells can't be repeated the division.

Crossing over

Doesn't occurs Occurs

Anaphase The chromatids are separated.

The whole chromosomes are separated.

Aim Each cell produces 2 diploid cells.

Each cell produces 4 haploid gametes.

Function for

1- Asexual reproduction. 2- Growth in multicellular

Sexual reproduction.


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Choose the correct answer : 1- Meiosis occurs in ………….. (Liver cells – testes –

ovaries and testes). 2- The number of chromosomes is reduced during ….(

mitosis – meiosis – fertilization). 3- The chromosomes are arranged in one row along the

equatorial plane of the cell during (Anaphase – prophase – metaphase) of mitotic division.

4- The shortest phase of mitotic division……. (Prophase – anaphase – metaphase – Telophase).

Write scientific term: 1- Attaches the two chromatids of each chromosome

together. 2- A stage of mitosis in which two chromatids of each

chromosome separate into independent chromosomes. 3- The stage where crossing over occurs during cell division. Give reasons for : 1- Prophase 1 is the longest and the most important and

complex step of meiosis. 2- Meiosis is a reduction division.


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robert hook) van leeuwenhoek)

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