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Cell Structure and Function

Galileo Galilei arranged
two glass lenses within
a cylinder, and used it
to look at an insect.
 He was not a biologist
was the first to record
observations through a
microscope.
 He
took slices of
cork from a mature
tree and observed
the tiny
compartments in
the sample and gave
them the Latin
name, cellulae,
meaning small
rooms.

This later became the
term “cell.”
 Was
exceptional in
constructing
lenses.
 He began looking
at everything he
could.
 Notices
opaque
spots in cells and
named them
nucleus.
 Discovered
that
cells develop as
independent units
even though they
are part of a larger
whole.
 Studied
animal
tissues and noticed
that cells are part
of the organism,
but to some extent
have a life of their
own.
1)
2)
3)
Every organism is made of one or more
cells.
Cell is the smallest unit that has all of the
basic properties of life.
Cells come from preexisting cells.
 Prokaryotes
are simpler cells. They lack a
nucleus and other membrane bound
organelles.

They do contain ribosomes to perform protein
synthesis. Despite their simplicity, they have the
ability to survive in very diverse habitats.
 Eukaryotes

are more complex cells.
They have a nucleus and membrane bound
organelles
1)
2)
They have a plasma membrane surrounding
them made of a phospholipid bilayer. This
membrane determines what substances may
enter and leave the cell.
They have a DNA containing region.
•
•
3)
In a prokaryote cell, it is simply a circular piece of
DNA called a plasmid.
In eukaryote cells, the genetic material is
contained in a nucleus.
They have cytoplasm. Cytoplasm is the
substance between the cell membrane and the
DNA region. It is a fluid substance that contains
the organelle
Fluid Mosaic Model
 Cells
are surrounded by fluids, inside the cell
itself and around it.
 The membrane is a flexible substance that
allows the cell to move around in this fluid
environment.
 This is referred to as the fluid mosaic model
 The
membrane is made up of various
substances – phospholipids, sterols, proteins,
and glycolipids.
 All of these components are working
together for the membrane to function
properly.
 The
fluid quality comes from the ability of
the membrane to move and adapt to the
surrounding environment.
 It is not a rigid barrier, but a flexible one
Membrane Proteins: Proteins in the
surface of the cell carry out most
membrane functions.
 Enzyme
– to carry out metabolic functions
 Transport – span the bilayer to allow water
soluble substances to move through their
interior
 Receptor – bind extracellular substances that
can trigger changes in cellular activity
 Recognition
– identify cells of a certain type
(ex: recognizing “self”)
 Adhesion – help cells of the same type locate
each other and stick together and stay
positioned in proper tissues
Surface to volume ratio
 As
a growing cell expands, the volume
increases faster than the surface area.
 Cell size is limited to the surface area.
 Smaller cells can move around more easily
than larger ones
 http://www.gap-
system.org/~history/PictDisplay/Galileo.html
 http://rationalwiki.org/wiki/File:Robert_Hoo
ke_portrait.jpg
 http://www.ucmp.berkeley.edu/history/leeu
wenhoek.html
 http://www.answers.com/topic/matthiasjakob-schleiden
 http://www.nndb.com/people/357/0000960
69/