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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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More
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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