Cell Structure - Part I

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Cell Structure - Part I
Chapter 3 Unit A
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Cytology the science of studying the cell,
became possible with the invention of the
compound/light microscope.
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Cytology reached new levels with the invention
and use of the Electron Microscope.
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You do not need to do math conversions, but it is
important that you have some idea of the units
used to measure cells and cell structures.
Scientists often measure in micrometers, there
are 1000 micrometers in a single millimeter.
Sometimes micrometers are too large, so
scientists measure in nanometers. There are 1000
nanometers in a single micrometer.
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Cells are limited in their size. They need to
maintain themselves by getting rid of wastes and
taking in nutrients throught their cell membrane.
As a cell gets bigger, its volume goes up much
faster than its surface area, the cell membrane
would no longer be able to keep up with the
demands of the cell and the cell would die.
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Prokaryotic vs Eukaryotic
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Prokaryotic VS. Eukaryotic
Prokaryotic Before Nucleus Much smaller cell
(10-100 X smaller) No membrane bound
organelles No true nucleus Use different
ribosomes Only life forms that use this cell are
bacteria
Eukaryotic True Nucleus Much larger
size Various membrane-bound organelles A true
membrane-bound Nucleus Much more metabolically
efficient Used by all other life forms, Protists,
Fungi, Plants and Animals.
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Plant Cell vs. Animal Cell
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This can be identified as being a Plant Cell in
that it possesses the following 1. Cell Wall 2.
Large Central Vacuole 3. Chloroplasts
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Fig. 3.2a
ANIMAL CELL
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THE CELL MEMBRANE
Consists primarily of a double layer of
phospholipids. Acts as a gate-keeper to
determine what will enter and exit the cell.
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Fig. 3.2b
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THE NUCLEUS
Acts as the control center for the cell. Stores
the DNA in the form of Chromatin. This DNA has
all the blue prints to build all the crucial
structural and functional proteins of the cell.
These proteins build the cell and run the cell.
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Recall that membrane consists of a double layer
of phospholipids. The nucleus is enclosed with a
double membrane (Nuclear Envelope), therefore
having four layers of phospholipids. Nuclear
pores tunnel through.
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Endoplasmic Reticulum
Branching out from the nuclear envelope is a
series of membranous folds that form a network of
channels (Endoplasmic Reticulum). These
membranous channels act like roadways to
transport materials.
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Rough E.R. vs. Smooth E.R.
Rough E.R. Is studded with Ribosomes. These
Ribosomes translate mRNA to make proteins which
then enter the inside of the Rough E.R.
Smooth E.R. Lacks ribosomes. It is responsible
for producing sterol lipid hormones (Ex.
Testosterone) and for housing detoxifying enzymes.
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ROUGH ER Function To build and transport
proteins.
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SMOOTH ER
SMOOTH ER Function To help form Sterol Lipids as
well as key Detoxifying Enzymes and then
transport them.