Transcript Cell Biology Lecture

Cell Biology
Cells
• Definition: The
smallest most basic
unit of all living things
that is still considered
alive.
• Examples of cells:
bacteria, muscle cells,
nerve cells, fatty
tissue is made of fat
cells, skin, bone
marrow, pancreas
cells…..
Gametes (Sex Cells)
• Egg
• Sperm
Classification of Cells
• Prokaryotic
• Do not have membrane
bound organelles
(structure within a cell
that are surrounded by a
membrane).
• Most notably, no nucleus.
• Make up single celled
organisms called Bacteria
• In fact, the only
prokaryotic cells present
today are Bacteria cells
Examples of Prokaryotic Cells
Rod Shaped
Bacteria
Billion year old bacteria
Classification of Cells
• Eukaryotic:
• Do have membrane
bound organelles within
the cell.
• So, do contain a nucleus.
• Make up both single
celled and multicellular
organisms.
• Examples of eukaryotic
organisms include:
animals, plants, amoeba,
paramecium….
Eukaryotic Cell detail: note the
many membrane bound organelles
Examples of Single Celled
Eukaryotic Cells
Paramecium
Diatom
Algae
Viruses
• Not necessarily living: not
a cell because it lacks the
ability to replicate on it’s
own.
• Made up of a protein coat
(shell) surrounding a
nucleic acid molecule
(either DNA or RNA).
• Function: inject DNA/RNA
into cell and turn cell into
a virus factory that makes
many copies of the virus.
More Viral Structures
•
Microscope picture of WSSV virus: kills
shrimp. (source: Wageningen University,
Laboratory of Virology)
Bacteriophage
Virus that
causes pink
eye
•Ebola Virus
Compare/Contrast Prokaryotic,
Eukaryotic Cells and Viruses
• Q: Which have an outer
membrane?
• A: Prokaryotic/Eukaryotic
cells
• Q: Which have a protein
coat?
• A: Viruses
• Q: Which have DNA?
• A: All
• Q: Which rely on other
cells for replication?
• A: Viruses
• Q: Which have
membrane bound
organelles?
• A: Eukaryotic cells
• Q: Which can live on their
own?
• A: Prokaryotic/Eukaryotic
cells
• Q: Which can cause
disease?
• A: All
Cell Membrane
• Structure of all cells that regulates what
enters and leaves the cell.
• Selectively permeable:
• Some chemicals can pass through
membrane while others cannot
Structure of Cell Membrane
•
•
•
1. Phospholipid bilayer: fluid layer
2. Proteins imbedded in the lipid bilayer act as pumps/channels, receptors, and
identification markers
3. Cholesterol attaches to phospholipid tails, inhibiting movement. Result is cell
membrane is less fluid.
Function of Cell Membrane
• It is a barrier between the
interior of the cell and its
exterior environment.
• Both the internal and
external environment of
cells are liquidy: water
solvent with various
solutes such as proteins,
gases, ions, sugars,
amino acids, nucleotides.
Movement of Substances across
the Cell Membrane
• Passive Transport:
• Does not require
cellular energy
• Types of Passive
Transport include
diffusion and osmosis
• Active Transport
• Do require cellular
energy
• Types of active
transport include
movement through a
protein pump,
endocytosis, and
exocytosis
Passive Transport: Diffusion
• Definition of Diffusion:
• When molecules move
from an area of greater
molecule concentration
(conc.) to an area of
lesser molecule
concentration.
• Example:
• Perfume diffuses through
the air.
• The perfume molecules
move from an area of
greater perfume molecule
conc. to an area of lesser
perfume conc.
• Another (more gross)
example:
• Someone farts…..
Passive Transport: Diffusion
Examples
• 1:
• 2:
Passive Transport: Diffusion
Examples
• 3:
• Gas exchange in
our lungs is an
example of
diffusion in our
bodies.
• Water absorption
in our skin when
we swim or take a
bath is also an
example of
Diffusion in our
bodies (as water
diffuses into our
skin, the skin
puffs up;
however, because
it is attached to
the inner layer of
skin it wrinkles)
Passive Transport:
Osmosis
• Definition of
Osmosis:
• When water
molecules
diffuse across a
selectively
permeable
membrane.
• Examples:
• When there is a higher
water concentration
outside a cell than
inside a cell, the water
molecules will diffuse
across the cell
membrane into the cell
• When water passes
through a plastic bag
with holes that are only
big enough for the
water to pass through
but nothing else.
Passive Transport: Osmosis
Example
Passive Transport: Osmosis
Example with RBC
Active Transport: Endocytosis
• Using cellular energy to actively take
something into a cell.
Active Transport: Exocyctosis
• Using cellular energy to actively expel
something from a cell.
•
•
•
•
•
Secretion of Proteins
1. Proteins are
made at the
Ribosomes.
2. From there they
travel through the
cell in the
Endoplasmic
Reticulum.
3. A vesicle pinches
off from the
Endoplasmic
Reticulum and
travels to the Golgi
Apparatus and
fuses to it.
4. The proteins are
modified in the
Golgi Apparatus
5. Then a vesicle
pinches off from the
endoplasmic
reticulum, travels to
the cell membrane
and fuses to it.
Ribosomes
2.
1.
3.
4.
5.
Examples of Protein secretions
• Saliva
• Venom in snakes and scorpions
• Digestive enzymes in our stomach and
pancreas
• Neurotransmitters that carry messages
between our nerve cells
• Poisons in spiders and stinging jellyfish
• Enzymes in tears
Energy in cells: involves two organelles
• Photosynthesis: Chloroplasts
in plant cells
• Organisms that make their own
food through photosynthesis
are called autotrophs.
• Cell respiration: Mitochondria
in plant and animal cells
• Organisms that need to
consume other living things for
food are called heterotrophs.
1. Sunlight
captured by chloroplasts
2. Chloroplasts
make glucose
(cellular food)
3. Organisms
eat plants, or other animals
that eat plants, and take in glucose
4. Glucose
diffuses into a cell through a
membrane protein
5. Glucose broken down in mitochondria
to release cellular energy (ATP)
Photosynthesis
• Equation:
• 6 CO2 + 6 H2O
•
C6H12O6 + 6O2
Sunlight Energy
• The light energy from the sun gets trapped into a
molecule of glucose.
• Where do the reactants come from?
• Where do the products end up?
Cell Respiration
• C6H12O6 + 6O2
6 CO2 + 6 H2O
•
ATP
• When glucose is broken down in the
mitochondria, the energy that was trapped in the
glucose molecule is released as cellular energy.
• The cell uses cellular energy for growing, moving,
reproducing, making proteins, building
biomolecules, digesting biomolecules.