CELL BIOLOGY INTRO.ppt

7/27/2019 CELL BIOLOGY INTRO.ppt

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CELL BIOLOGY


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Modern cell theories

All living matter is composed of cells

All new cells arise from other cells

All metabolic reactions of an organismtake place in cells

Cells contain the hereditary information

of the organisms of which they are apart, and this is passed from parent todaughter cell


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Other information

All cells are similar in comprisinga self-contained and more orless self-sufficient unit,

surrounded by a cell membraneand having a nucleus at somestage of their existence.

At the same time cells show a

remarkable biodiversity ofstructure and function.


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Cells are basically spherical in shape, althoughmodification to suit function leads to a degreeof diversity

In size, they mostly range from 10-30m indiameter

Their size is restricted by:

The surface area to volume ration, which must belarge to allow exchange of metabolic substances

The capacity of the nucleus to exercise control overthe rest of the cells


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THE DISCOVERY OF CELLS

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MICROSCOPE

To observe the dramatic properties of asingle cell

Visible parts of the cell

Light microscope - achieve magnifications ofup to 1500

Electron microscope- over 500,000 times

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Comparison of light and electron microscopes

Light microscope Electron microscope

Advantages

Cheap to purchase and

operate

Small and portableUnaffected by magnetic

fields

Preparation of material

is relatively quick and

simpleLiving as well as dead

material may be viewed

Natural colour can be

observed

Disadvantages

Expensive to purchase

and operate

Very large and must bein special room

Affected by magnetic

field

Preparation of material

is lengthy and complexLiving material cannot

be observed

All images in black and

white


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Image by microscopes

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Electron microscopeLight microscope


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Light microscope Electron microscope

Disadvantages

Magnifies object

up to 1500x

Can resolveobjects up to 200

nm apart

The depth of field

is restricted

Advantages

Magnifies objects

up to 500,000x

Has a resolvingpower for biological

specimens of

around 1 nm

It is possible toinvestigate a greater

depth of field


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BASIC CELL POPERTIES


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Cells are highly complex and organized

Cellular activities - remarkably precise

Eg DNA duplication (error rate 1 in 10million nucleotides incorporated)

Organizations: atom, molecules, polymers,polymeric molecules, subcellularorganelles, and finally into cells

From cells into tissues, organ and system


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Cells possess a genetic program andthe means to use it

Organisms are built accoding to informationencoded in a collection of genes

A set of chromosomes that occupies th space

of a cell nucleus Genes are more than storage lockers for

information

They constitute the blueprints for constructing

cellular structure, the directions for runningcellular activities and the program for makingmore of themselves

Allows variation among individuals


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Cells are capable of producing moreof themselves

Reproduce by division, a processin which the contents of a mothercell are distributed into two

daughter cells Prior to division, genetic material

is duplicated, and each daughtercells receives complete and equalshare of genetic information

In certain cases (eg oocyte), thecells retain the cytoplasm butreceive only half of the geneticmaterial

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Cells acquire and utilize energy

Developing and maintaining complexityrequires the constant input of energy

The energy from sunlight is trapped by light-

absorbing pigments present in themembranes of photosynthetic cells

Light energy is then converted into chemicalenergy that is stored in energy-rich

carbohydratesATP is produced when breakdowns of

macromolecules occur


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Cells carry out a variety of chemicalreactions

Chemical changes which requireenzymes

The biochemical reactions - cellsmetabolism


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CELLULAR BIOCHEMISTRY ANDPHYSIOLOGY

Knowledge of the submicroscopic molecularpattern of the protoplasm is necessary tocomprehend the structure and function of cells

Biochemistry Describe and analyze the chemical changes

that occur in organisms

Investigations into the chemistry of living

systems have shown that individual cells,whether of plants, animals andmicroorganisms, are fundamentally similar infunction despite vast differences in structure


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Physiology

response of organisms and cells to theirenvironment,

mechanism of cell growth, duplication, and reproduction,

ability of cells to take up nutrients from theenvironment,

function and method of control of anorganisms metabolic machine


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CYTOLOGY

A study of cells

Two basic types -prokaryotic and eukaryoticcells

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MOLECULAR ORGANISATION


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ATOM

Smallest unit of a chemicalelement which can existindependently

It has a nucleus made up of Positively charged particles -

protons

Particles with no charge - neutrons

Around this positively chargednucleus orbit - negatively chargedparticles called electrons

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IONS

When an atom loses an electron (aprocess called oxidation), it

becomes positively charged due tothe excess of protons overelectrons

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CELL BIOLOGY INTRO.ppt

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