Transcript Welcome to BIO201

Welcome to BIO201
Dr. Maura Parker
[email protected]
The Course….
• Cell Biology – Cell Anatomy and
Function
• Cell Biology – Energy and
Metabolism
• Genetics – DNA, Chromosomes and
Inheritance
• Genetics – Gene Expression and
Technology
Grading
• 4 exams – 52%
• Quizzes – 14%
• Lab Reports – 24% (8 labs x 3% each)
• Independent Research – 10%
Student Expectations
• Read before class - quizzes are not
announced
• Be prepared with questions – every
question is a good question – especially
during Review sessions
• Prepare for lab sessions – you have lots to
do and 3 hours is not a lot of time!
• DO NOT COPY OTHER STUDENTS’ LAB
REPORTS
Expectations for me
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To provide you with the materials to learn
Be at class prepared
Be at lab sessions prepared
Answer questions
Note: Please send me e-mails and make
appointments if you need to see me
Lecture #1 – Introduction to
Cell Biology
• Text – Chapter 6 – pages 94-101
• Note: tomorrow is Ch. 6 – pp 102-111
The Cell is the Fundamental Unit
of Life
• all living things are composed of cells
• multicellular and unicellular
organisms
• prokaryotes and eukaryotes
The size range of cells
10 m
Human height
Length of some
nerve and
muscle cells
Unaided eye
1m
0.1 m
Chicken egg
1 cm
Frog egg
Most plant and
animal cells
10 µm
nucleus
Most bacteria
1 µm
100 nm
Mitochondrion
Smallest bacteria
Viruses
Ribosomes
10 nm
Nucleus
Most bacteria
Electron microscope
100 µm
Light microscope
1 mm
Proteins
Lipids
1 nm
0.1 nm
Small molecules
Atoms
Measurements
1 centimeter (cm) = 102 meter (m) = 0.4 inch
1 millimeter (mm) = 10–3 m
1 micrometer (µm) = 10–3 mm = 106 m
1 nanometer (nm) = 10–3 µm = 10 9 m
Light Microscopes – Cells
can be Seen!
• magnification: image size/object size
• resolution: the minimum distance 2
points can be separated and still
distinguished as 2 points
• typically 1000x magnification and 0.2
mm resolution
(a) Brightfield (unstained specimen).
Passes light directly through specimen.
Unless cell is naturally pigmented or
artificially stained, image has little
contrast. [Parts (a)–(d) show a
human cheek epithelial cell.]
50 µm
(b) Brightfield (stained specimen). Staining
with various dyes enhances contrast, but
most staining procedures require that cells
be fixed (preserved).
(c) Phase-contrast. Enhances contrast
in unstained cells by amplifying
variations in density within specimen;
especially useful for examining living,
unpigmented cells.
(d) Differential-interference-contrast (Nomarski).
Like phase-contrast microscopy, it uses optical
modifications to exaggerate differences in
density, making the image appear almost 3D.
(e) Fluorescence. Shows the locations of specific
molecules in the cell by tagging the molecules
with fluorescent dyes or antibodies. These
fluorescent substances absorb ultraviolet
radiation and emit visible light, as shown
here in a cell from an artery.
50 µm
(f) Confocal. Uses lasers and special optics for
“optical sectioning” of fluorescently-stained
specimens. Only a single plane of focus is
illuminated; out-of-focus fluorescence above
and below the plane is subtracted by a computer.
A sharp image results, as seen in stained nervous
tissue (top), where nerve cells are green, support
cells are red, and regions of overlap are yellow. A
standard fluorescence micrograph (bottom) of this
relatively thick tissue is blurry.
50 µm
Electron Microscopes - What is
inside the cell?
(a) Scanning electron microscopy (SEM). Micrographs taken
with a scanning electron microscope show a 3D image of the
surface of a specimen. This SEM
shows the surface of a cell from a
rabbit trachea (windpipe) covered
with motile organelles called cilia.
Beating of the cilia helps move
inhaled debris upward toward
the throat.
Cilia
Longitudinal
section of
cilium
(b) Transmission electron microscopy (TEM). A transmission electron
microscope profiles a thin section of a
specimen. Here we see a section through
a tracheal cell, revealing its ultrastructure.
In preparing the TEM, some cilia were cut
along their lengths, creating longitudinal
sections, while other cilia were cut straight
across, creating cross sections.
1 µm
Cross section
of cilium
1 µm
What do the parts inside the cell do?
Cell Fractionation
Homogenization
Tissue
cells
1000 g
Homogenate
(1000 times the
force of gravity)
Differential centrifugation
10 min
Supernatant poured
into next tube
20,000 g
20 min
Pellet rich in
nuclei and
cellular debris
80,000 g
60 min
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloroplasts if cells
are from a Pellet rich in
plant)
“microsomes”
(pieces of
plasma membranes and
Pellet rich in
cells’ internal ribosomes
membranes)
Prokaryotes vs. Eukaryotes
• bacteria and archaea – prokaryotes
• both have plasma membrane, cytoplasm,
chromosomes and ribosomes
• eukaryotes have a membrane-enclosed
nucleus
• prokaryotic DNA is in the nucleoid region
A Typical Prokaryotic Cell
Pili: attachment structures on
the surface of some prokaryotes
Nucleoid: region where
the cell’s DNA is located (not
enclosed by a membrane)
Ribosomes: organelles that
synthesize proteins
Plasma membrane: membrane
enclosing the cytoplasm
Cell wall: rigid structure outside
the plasma membrane
Capsule: jelly-like outer coating
of many prokaryotes
0.5 µm
(a) A typical
rod-shaped bacterium
Flagella: locomotion
organelles of
some bacteria
(b) A thin section through the
bacterium Bacillus coagulans
(TEM)
Eukaryotic Cells
ENDOPLASMIC RETICULUM (ER)
Rough ER
Smooth ER
Nuclear envelope
Nucleolus
NUCLEUS
Chromatin
Flagelium
Plasma membrane
Centrosome
CYTOSKELETON
Microfilaments
Intermediate filaments
Ribosomes
Microtubules
Microvilli
Golgi apparatus
Peroxisome
Mitochondrion
Lysosome
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
The Plasma Membrane
Outside of cell
Carbohydrate side chain
Hydrophilic
region
Inside of cell
0.1 µm
Hydrophobic
region
(a) TEM of a plasma
membrane. The
plasma membrane,
here in a red blood
cell, appears as a
pair of dark bands
separated by a
light band.
Hydrophilic
region
Phospholipid
Proteins
(b) Structure of the plasma membrane
Tomorrow…..
• Chapter 6 – pp 102-111
• Cellular Anatomy – nucleus,
ribosomes, ER, Golgi, lysomsomes,
peroxisomes, mitochondria and
chloroplasts