Reminder

Midterm on Wed.
No class on Monday
Office hours after class in 5117
VLSB
All lectures are now posted on
Rachels Paperless Handouts
page on the Bio 11 website
Cell Composition
Early Cell Discoveries
Early 1600s GalileoGalilei used two lenses and a tube
to examine insect eyes.
Mid 1600s - Robert Hookeobserved and described cells
in bark.
Late 1600s - Antonyvan Leeuwenhoek observed sperm,
microorganisms.
1820s - Robert Brown observed and namednucleus in
plant cells.
Cell Theory
1. All organisms are made of cells.
2. The cell is the smallest unit of life.
3. All cells are derived from pre-existing cells.
Types of Cells
There are two kinds of cells:
1. Prokaryotic(bacteria)
2. Eukaryotic(everything else)
Eukaryotic cells have organelles.
General Cell Structures
Plasma Membrane
Region where DNA is stored (Nucleus eukaryotes)
Cytoplasm
Plasma Membrane
lipid bilayer
cytoplasm
fluid
Plasma Membrane lipid bilayer
one layer
of lipids
one layer
of lipids
Plasma Membrane
phospholipid
Hydrophillic
Phosphate head
polar
Hydrophobic
Fatty acid
tail
nonpolar
Fluid Mosaic Model of Cell Membranes
1. Cell membrane has a fluid quality.
2. Fluid bathes outer and inner surfaces.
3. Cytoplasm fills inside of cell (jelly-like, 80% water)
4. Membrane has mixed composition of lipids, sterols,
and proteins
5. Constituents can drift within the cell membrane.
Plasma Membrane
Fluid mosaic model
EXTRACELLULAR ENVIRONMENT
(cytoskeletal protei ns
beneath the plasma
membrane)
ADHESION
PROTEIN
ol i gosacchari de
groups
phospholi pi d
chol esterol
LIPID BILAYER
RECOGNITION
PROTEIN
RECEPTOR
PROTEIN
CYTOPLASM
PLASMA MEMBRANE
(area of
enl argement)
TRANSPORT PROTEINS
open
channel
protei n
gated
channel
protei n
(open)
acti ve
transport
protei n
gated
channel
protei n
(cl osed)
Cell Membrane Proteins
1. Transport proteins.
2. Receptor proteins.
3. Recognition proteins.
4. Adhesion proteins.
These membrane proteins control the flow of substances
and signals into and out of the cell, thereby maintaining
The cytoplasmic composition and volume.
Plasma membrane
Fluid Mosaic Model Animation Nucleus
Function:
Isolate DNA molecules from the metabolic
machinery of cytoplasm.
Maintain controlled environment for DNA
functions and replication.
Nucleus
Components:
Nuclear envelope
Nucleoplasm
Nucleolus
Chromosomes
Chromatin
Nuclear Envelope
pores
Nuclear envelope
2 lipid
bilayers
Nucleolus
Dense mass of material in
nucleus
May be one or more
Cluster of DNA and
proteins
Materials from which
ribosomal subunits are built
Chromatin v. Chromosome
Chromatin is the cells collection of DNA and
associated proteins.
Chromosome is a single DNA molecule and its
associated proteins.
Endomembranesystem
Function:
Assembyof polypeptides onribosomes.
Modification of polypeptides into functions proteins.
Transportation of proteins out of the cell.
Alsoinvlovedin assembly and transportation of lipids.
Endomembrane
system
assorted
vesicles
Golgi
body
smooth ER
rough ER
The chai ns (green) are
assembled on ri bosomes
in the cytoplasm.
Ribosomes
Rough Endoplasmic
reticulum(ER)
Smooth ER
Golgi bodies
Vescicles
Nucleus
Endomembrane
system
Golgi
body
smooth ER
Rough
Endoplasmic
Reticulum
(RER)
The chai ns (green) are
assembled on ri bosomes
in the cytoplasm.
Nucleus
1. DNA coding for proteins
make mRNA strands,
which are transported out
of the nucleus and onto
ribosomesof the RER.
2. Ribosomeson the RER
translate the mRNA code
into strings of amino
acids to forma
polypeptide.
Endomembrane
system
Golgi
body
smooth ER
The chai ns (green) are
assembled on ri bosomes
in the cytoplasm.
Nucleus
Rough
Endoplasmic
Reticulum
(RER)
3. Polypeptide chains are
modified into functional
proteins in the RER.
4. Some proteins are
packaged intovescicles,
which transport the
proteins to theGolgi body
for more processing and
preparation for their
journey out of the cell.
3. Polypeptide chains are
modified into functional
proteins in the RER.
Endomembrane
system
Golgi
body
smooth ER
Rough
Endoplasmic
Reticulum
(RER)
The chai ns (green) are
assembled on ri bosomes
in the cytoplasm.
Nucleus
5. TheGolgi body releases
the prepared proteins and
lipids invescicles, which
fuse with the cell plasma
membrane and releases
the proteins out of the
cell.
assorted
vesicles
Cytoskeleton
Interconnected system of protein filaments.
Present in all eukaryotic cells.
Basis for cell shape, internal organization
and structural support.
Allows organelle movement within cells, cell
division and sometimes cell motility.
Cytoskeleton
Microtubules organize cell
interior and move structures
around
Microfilaments reinforce
cell shape or cause it to
change.
Intermediate filaments
strengthen and maintain cell
structures.
3 General types:
Microtubule
Microfilament
Intermediate filament
Eukaryotic cells
Have a nucleus and other organelles.
Mitochondria
Chloroplast
Endoplasmic reticulum
Golgi body
Eukaryotic organisms
Plants
Animals
Protistans
Fungi
Animal Cell Features
Plasma membrane
Nucleus
Ribosomes
Endoplasmic
reticulum
Golgi body
Vesicles
Mitochondria
Cytoskeleton
Plant Cell Features
Cell wall
Central vacuole
Chloroplast
Plasma membrane
Nucleus
Ribosomes
Endoplasmic
reticulum
Golgi body
Vesicles
Mitochondria
Cytoskeleton
Mitochondria animals & plants
1. Energy (ATP) producing powerhouses.
2. All eukaryotes have at least one
mitochondrion. Some have many!
3. Mitochondria have own DNA,
resemble bacteria. May have
evolved from ancient bacteria
that were engulfed, not digested.
4. Mitochondrial DNA is only
inherited from the mother and can
be used to trace maternal lineages.
Useful in forensics.
outer
compartment
inner
compartment
outer membrane
inner membrane
repeated foldi ngs of
inner membrane (cristae)
Chloroplast - plants
outermost
membrane
layers (two)
part of
the inner
membrane
system
(thylakoid
membrane)
granum stroma
Convert sunlight
energy to ATP
through
photosynthesis.
Like mitochondria,
chloroplasts have
their own DNA,
RNA andribosomes
Prokaryotic Cell Characteristics
1. No nucleus.
2. Most have cell wall.
3. Plasma membrane.
4. Small amount of cytoplasm.
5. Many small, free ribosomes where proteins are assembled.
6. Nucleoidis a region with a circular strand of DNA and is
contiguous with the cytoplasm.
7. Flagella often present.
8. Pili (protein projections) help bacteria attach to surfaces
Prokaryotic Structure
DNA
pilus
flagellum
cytoplasm
with ribosomes
capsule
cell
wall
plasma
membrane
Blue-Dog says
Good luck on the midterm!