Download CELL STRUCTURE AND FUNCTION

CELL STRUCTURE AND FUNCTION
Lab 3
Objectives
• Be able to make a wet mount of any cellular material
provided and focus on a cell.
• Be able to stain cells with either Lugol’s solution or
methylene blue.
• Be able to determine the length and width of cells in
micrometers and/or millimeters.
• Be able to diagram any cell observed through the
microscope.
• Be able to locate the following structures in an onion cell:
• cell wall
• vacuole
• nucleus
• cytoplasm
• cell membrane.
THE CELL
• The cell concept is basic to understanding
the activities and characteristics of
organisms.
• Cells are the units of structure and
function of an organism.
• As units, they reflect the abilities of the
organism as a whole. Cells are of interest
because of their variety and also because
of their similarities.
• In this exercise, we will examine the cell. We
will try to determine the three-dimensional
shape of theses cells and identify some of
their structures.
• The cell is compose by three principal
compartiment:
1.- Plasmatic membrane
2.- Cytoplasm (organelles)
3.- Nucleous
Plasma Membrane
Figure 3.3
Cytoplasma
• It is the specialized living material of cells
• It lies between the plasma membrane and
the nucleus
• Numerous small structure (organelles) are
part of the cytoplasma, along with the fluid
that serves as the interior
environment of each cell
Organelles
•
•
•
•
•
•
Ribosomes
Endoplasmic reticulum
Golgi apparatus
Mitocondria
Lysosomes
Centrioles
Nucleus
• Contains nuclear envelope, nucleoli,
chromatin, and distinct compartments rich in
specific protein sets
• Gene-containing control center of the cell
• Contains the genetic library with blueprints
for nearly all cellular proteins
• Dictates the kinds and amounts of proteins
to be synthesized
Nucleoli
• Dark-staining spherical bodies within the
nucleus
• Site of ribosome production
Nucleus
Figure 3.28a
CELL PART
STRUCTURE
FUNCTION(S)
Plasma
Membrane
Phospholipid bilayer
studded with proteins
Serves as the boundary
of the cell. P and C
(outer surface) perform
various functions (Ex.
markers and receptor)
Ribosomes
Tiny particles each
made up of rRNA
subunits
Synthesize proteins; a
cell’s “protein factories”
Endoplasmic
Reticulum
(ER)
Membranous network
of interconnected
canals and sacs, some
with ribosome (rough
ER) and some without
(smooth ER)
Rough ER receives and
transports synthesized
proteins
Smooth ER synthesizes
lipids and carbohydrates
CELL PART
Golgi
apparatus
STRUCTURE
Stack of flattened,
membranous sacs
Mitochondria Membranous capsule
containing a large,
folded membrane
encrusted with
enzyme
Lysosomes
“Bubble” of enzymes
encased by membrane
FUNCTION(S)
Chemically processes,
then packages
substances from ER
ATP synthesis; a cell’s
“powerhouse”
A cell’s “digestive
system”
CELL PART
STRUCTURE
FUNCTION(S)
Nucleus
Double-membrane,
spherical envelope
containing DNA
strands
Dictates protein
synthesis, thereby
playing and essential
role in other cell
activities, namely active
transport, metabolism,
growth and heredity
Nucleolus
Dense region of the Plays an essential role
nucleus
in the formation of
ribosomes
• During this lab exercise you can:
• Prepare sections of onion membrane, make a
temporary wet mount, and view the specimen
through a microscope.
• Prepare sections of onion membrane, make a
stained temporary wet mount, view through a
microscope, and sketch a generalized cell.
• Collect cheek epithelial cells, make a stained
temporary wet mount, view through a
microscope, and make drawing of the structure
of a generalized cheek cell.
• Make a temporary wet mount of Elodea, view it
through a microscope and make drawing of the
structure of a generalized cheek cell.
• Locate the following structures:
• cell wall (thick, clear band which surrounds the
cell)
• cytoplasm (granular material in the cell next to
the cell wall)
• nucleus (football-shaped object in the cell)
• vacuole (large, central, nongranular space)
• cell membrane (thin membrane just inside the
cell wall. If you place a drop of 5% salt solution
on the onion tissue, the size of the cell will shrink
and the cell membrane will pull away from the
cell wall revealing the cell wall and the cell
membrane are separate structures).