Biology 211 Intro Molecular and Cell Biology
Lectures 10 and 11 "Cell Structure"
Reading: Chap. 7 Campbell
Outline:
1. Prokaryotic vs. eukaryotic cells
2. Tools for observing cells
3. Cell structure and function
Lecture:
Cell Theory: All organisms are composed of cells; the cell is the basic unit of life.
1. Prokaryotes vs. eukaryotes
The simplest organisms are made up of a single cell. Single celled
organisms include: bacteria and blue-green algae (prokaryotes), yeast and
protozoans (eukaryotes).
pro karyote
before for karyon, referring to the nucleus
Features of a prokaryotic cell
 No nucleus
 Genetic material concentrated in region called a nucleoid, not bound by
membrane
 Lack internal membrane bound organelles found in eukaryotes
 Usually very small, 1-10 M diameter
eu karyote
true from karyon, nucleus
Features of a eukaryotic cell
 Membrane bound nucleus contains genetic material
 Usually contain many other membrane-bound organelles
 Major compartments: nucleus, cytoplasm (made of cytosol and
organelles)
2. Tools for observing cells
a. Cells first observed through the light microscope (up to 1000x magnification)
b. Improve contrast using stains and specific probes, new optics
c. Electron microscope


Scanning EM
Transmission EM
d. Other tools allow fractionation of cells (centrifugation) and isolation of
particular cell components (protein purification).
3. Cell structure and function: Focus on eukaryotic cells
Structure
Plasma membrane
Nucleus
Ribosomes
Endoplasmic Reticulum
(ER)
Golgi Apparatus
Lysosomes
Vacuoles
Definition
The lipid bilayer that
forms the boundary of all
cells, prokaryotic or
eukaryotic
The large central
organelle of eukaryotic
cells that contain the
chromosomes
RNA protein complexes
in the cell that serve as
the site of protein
synthesis
Extensive membranous
network in the cytoplasm
extending from nucleus
to plasma membrane
Organelle made up of
stacked membranes that
modify proteins from the
ER to prepare them for
secretion
A membrane bound sac
containing enzymes that
break down
macromolecules.
Membrane bound sacs
that may function in food
storage or water balance.
Function
Selective barrier; allows
nutrients, oxygen to enter
and wastes to leave
Stores the genetic
material (DNA), copy
DNA (replication), make
RNA copies of genes
(transcription)
Make proteins from
amino acids. May be free
or membrane bound.
Process and modify
secreted protein.
Processing steps occur in
different locations.
Smooth ER lacks
ribosomes is involved in
drug detoxification.
Rough ER is site of
protein synthesis for
secreted proteins.
Adds carbohydrate
groups to proteins.
Works after the ER and
before the protein is
secreted via vesicles.
Breakdown of proteins,
polysaccharides, fats and
nucleic acids. Acidic
compartment (pH ~5).
Recycles old organelles
in the cell.
Storage by vacuoles of
phagocytic cells or plant
cells. Water balance by
Mitochondria
Chloroplasts
Peroxisomes
Cytoskeleton
Organelles that are the
sites of cellular
respiration. Extract
energy from breakdown
of sugars to make ATP.
Organelles in plants that
capture light energy from
the sun and use it to
synthesize sugars.
Small membrane bound
organelle involved in
some metabolic
reactions.
Network of fibers
extending through the
cytoplasm.
contractile vacuole.
Carry out the Krebs cycle
and oxidative
phosphorylation. Also
crucial for cell death
pathways.
Carry out the light
reactions and dark
reactions (Calvin cycle)
of photosynthesis.
Produces and breaks
down hydrogen peroxide,
a toxic byproduct of
metabolism.
Provides structural
support and is involved in
cell motility.