Transcript Tour Of The Cell

Tour Of The Cell
Microscopy
• What is the difference between
magnification and resolving power?
• Magnification is how much larger the
object can now appear.
• Resolving power is the ability to
distinguish between two points, it is
limited by the wavelength of visible light.
The different microscopes:
• Light microscope - resolving power is
limited by the wavelengths of light.
• Specimen should be stained, but can be
alive
– Compound microscope
– stereomicroscope
• Electron microscope - resolving power is
greater since wavelengths of electrons is
smaller than those of light.
– SEM - 3D image
– TEM - flat image
• electron microscopes cannot use live specimens
Cool link!!!
• http://learn.genetics.utah.edu/content/be
gin/cells/scale/
As Organisms Get Larger,
Why do They Become
Multicellular?
Reason #1:
Surface
area:volume
ratio
declines!
• Reason #2
– Distance to middle of cell increases
beyond diffusion’s ability to transport
materials efficiently
• Reason #3
– DNA limitations
Prokaryotic vs. Eukaryotic Cells
Prokaryotic cells:
• Bacteria, archaea
• genetic material not in
a nucleus
• no membrane-bound
organelles
Eukaryotic cells:
• Protists, Plants, Fungi
and Animals
• true nucleus with
genetic material
• has membrane-bound
organelles
The Prokaryotic Cell:
General Eukaryotic Cells:
Advantages of
Compartmentalization
(Eukaryotic Cells)
• Incompatible processes can happen
simultaneously
– Ex. Synthesis of fatty acids in one area,
degradation in another area
• Allows clustering of enzymes/molecules
– Ex. Those enzymes used in cell resp.
located in mitochondria
– Ex. Buildup of ionic gradient used as
energy
Two Areas of the Eukaryotic
Cell:
• What is the space between the cell
membrane and the nucleus called?
• The cytoplasm. This includes the
organelles and the cytosol.
• The cytosol is the fluid medium found in
the cytoplasm
The
nucleus
Nuclear Components:
• Envelope =
Nuclear Components:
• Envelope = double layered membrane
that has pores for molecular transport.
• Chromatin =
Nuclear Components:
• Envelope = double layered membrane
that has pores for molecular transport.
• Chromatin = DNA + protein complex of
threadlike fibers that make up the
eukaryotic chromosome.
• Chromosome =
Nuclear Components:
• Envelope = double layered membrane
that has pores for molecular transport.
• Chromatin = DNA + protein complex of
threadlike fibers that make up the
eukaryotic chromosome.
• Chromosome = Chromatin fibers
condense into visible chromosomes
during cell division.
• Nucleolus = rRNA synthesized and
formed into ribosomes
Ribosomes:
• Prokaryotic ribosomes differ from eukaryotic ribosomes
• Function =
Ribosomes:
• Prokaryotic ribosomes differ from eukaryotic ribosomes
• Function = Site of Protein synthesis
Ribosomes
• Particles made of rRNA and protein
• 2 subunits: small and large
Ribosomes
• Free ribosomes: make proteins for
cytosol
• RER ribosomes: make proteins for
export
• Cells w/protein secreting fxn – MANY
ribosomes
FORM FITS FUNCTION!
The Endomembrane system:
• Related through direct continuity or by
transfer on membrane segments
through vesicles.
• Structure of membranes is not identical
• Includes:
• Nuclear envelope --> Endoplasmic
reticulum --> Golgi apparatus -->
lysosomes --> plasma membrane
Membrane
flow
What is this structure?
Smooth ER. What’s
its function?
Name this structure
Smooth ER. What’s
its function?
Rough ER. What’s
its function?
Transport vesicle
from ER
New vesicle
forming
Transport vesicle
from golgi
Function of Golgi:
• Modifies stores and routes products of
ER
• Alters membrane phospholipids
• Targets products for parts of the cell
Lysosomes
• Membrane-bound sac of hydrolytic
enzymes
• Animal cells only
• pH=5 (best for enzymes) –
compartmentalization
• Fuse w/food vacuoles
• Autophagy: recycle cellular material
• Programmed cell death
Vacuoles
• Larger than vesicles
• food vacuoles =
Vacuoles
• Larger than vesicles
• food vacuoles = formed by phagocytosis
• contractile vacuole =
Vacuoles
• Larger than vesicles
• food vacuoles =
formed by
phagocytosis
• contractile vacuole =
found in fresh water
protozoans, keep
water balance
• central vacuole =
Vacuoles
• Larger than vesicles
• food vacuoles = formed by phagocytosis
• contractile vacuole = found in fresh
water protozoans, keep water balance
• central vacuole = found in most plant cells
stores organic compounds, has enzymes
to break macromolecules, has poisonous
and unpalatable compounds,etc...
Mitochondria and Chloroplasts
• Not part of endomembrane system
• their membrane proteins are made by free
ribosomes and their own ribosomes
• Both have small amount of DNA
• Grow and reproduce on their own within the
cell
• Have a double membrane structure
• Involved in Energy transformation
• ENDOSYMBIONT THEORY
Chloroplasts
• Found in photosynthetic plant cells and
autotrophic protists
• Thylakoids inside embedded with
chlorophyll
Cytoskeleton
• Provides structural support
• Functions in motility and motion
Microtubules
• Tube shaped, made of tubulin
• Cellular support
• provides tracks for movement within the
cell: e.g. transport vesicles
• Composes cilia and flagella, locomotive
appendages of certain cells.
• separation of chromosomes during cell
division (spindle fiber)
• composes centrioles in animal cells
Let’s Review:
Name the cell structure and its
function.
Be able to tell if this structure is
found in prokaryote, eukaryote,
plant and/or animal cells
Take a
closer
look!
Smooth ER fxn
• Synthesis of lipids (phospholipids,
steroids, oils)
• Detox of drugs (adds OH groups to
increase solubility)
Functions of Rough ER
• Secrete modified proteins (ex.
glycoproteins)