Download Topic 2 Cells 2.1.1Outline the cell theory Cell theory: all living

Topic 2 Cells
2.1.1Outline the cell theory
Cell theory:
all living things are composed of cells
cells are the basic unit of structure and function in living
things all cells come from preexisting cells
2.1.2 Discuss the evidence for the cell theory
Theodor Schwann- 1838 " all plants made of cells"
Mathias Schleiden-1838 " all animals made of cells"
Rudolf Virchow- 1855 " all cells come from exisitng
cells"
Lynn Margolis -1970 " mitochondria and chloroplasts
were once free living"
Numerous supported hypothesis lead to a theory
Theorys can be modified with new evidence.
2.1.3 State that unicellular organisms carryout all
the functions of life.
Metabolism= catabolism + anabolism
Response to the environment
Homeostasis
Growth
Reproduction- heredity, DNA, evolution
Nutrition- carbon based life
2.1.4 Compare the relative sizes of molecules, cell
membrane thickness, viruses, bacteria, organelles,
and cells using the appropriate SI unit.
Molecules-1nm
Cell membrane thickness -10 nm
Viruses-100nm
Bacteria-1micron ( um)
Organelles- up to 10 microns
Cells- up to 100 microns
(See the size and perception powerpoint)
2.1.5 Calculate the linear magnification of drawings
and the actual size of specimens in images of known
magnification
Any drawings or reproductions of microscope
images should include the magnification. Multiply the
eyepiece ( usually 10x) times the occlular
magnification ( 4x, 10x, 40x) to get the magnification.
Field of view at 40 times is around 3.4 cm, at 100
times is 1.8 cm and at 400 times it is .034 cm.
2.1.6 Explain the importance of the surface area to
volume ratio as a factor limiting cell size.
Waste production, heat production, resource
consumption are factors of volume.
Exchange of waste, heat and resources are factors
of surface area.
As the diameter of a generally round cell increases,
the volume increases as a function of the radius3
while the surface increases as a function of the
radius 2
Cells then elongate, and convolute their surface to
increase surface relative to volume. Example, nerves
and red blood cells.
See the laser disk animations
2.1.7 State that multicellular
organisms show emergent
properties.
The whole is greater than the sum
of its parts.
Cells specialize, or differentiate. An
undifferentiated cell is called a stem
cell. Multicellular organisms can be
colonial like sponges, or like slimemolds, as well as multicellular like
most organisms we are aware of.
2.1.8 Explain that cells in
multicellular organisms differentiate
to carryout specialized functions by
expressing some of their genes but
not others.
Bacteria (prokaryotes) express all of
the genes inside them, which is why
they are useful for genetic
engineering. Multicellular eukaryotes
do not express all genes in all cells.
Control of gene expression is at the
cutting edge of science today.
2.1.9 State that stem cells retain the
capacity to divide and have the
ability to differentiate along different
pathways.
Until recently only fetal stem cells
were pluripotent ( could turn into any
kind of cell). We are unlocking the
pathways that allow other cells to
revert to stem cell status, then
develop into another kind of cell.
There are different kinds of stem
cells. Example, bone marrow cells
can turn into many different types of
blood cells… but nothing else.
2.1.10 Outline the therapeutic use of
stem cells
Most common is bone marrow
transplants
Growth of mylenation cells around
neurons was shown in 2005 in mice
( a potential multiple sclerosis cure)
Ethical issues abound concernng
harvesting of fetal stem cells, and theraputic
cloning.
2.2 Prokaryote
cells
2.2.1 Draw and label a diagram of the
ultrastructure of Echerichia Coli ( E. Coli)
as an example of a prokaryote
Nucleoid
Pili
2.2.2 Annotate the diagram from 2.2.1 with the
functions of each named structure.
Cell wall- provides structure and protection
Plasma membrane-forms selective barrier with the
outside world… all resources enter thru it, all wastes
leave from it.
Cytoplasm-the gel-like fluid of the cell, contains
nutrients and waste.. pretty much everything
Pili- hairlike structures that can form connections
with other bacteria ( conjugation) They also assist in
attaching the bacteria to surfaces and target cells.
Flagella- hairlike structures that provide movement
by spinning
Ribosomes- globular proteins and RNA where
proteins are made.
Nucleoid-the DNA of the bacteria. It is considered
“ naked” because the DNA is not wrapped around a
protein ( histones) as in Eukaryotes
plasmid- a separate, circular section of DNA that is
readily exchanged with other bacteria. This is what
genetic engineers use in their work.
2.2.3 Identify structures from 2.21 in electron
micrographs of E. Coli
2.2.4 State that prokaryotic cells divide by binary
fission
The bacteria copies its DNA and ribosomes, then
divides in half. Variation occurs with copy errors, and
with exhanges of plasmids from other bacteria.
2.3.1 Draw and label a diagram of the ultrastructure of a
liver cell as an example of an animal cell
Surface area to volume ratio limits their size
surface area increases by the square, volume increases by
the cube. All materials must pass through the surface to
reach the interior of the cell. Large cells cannot get enough
materials in or out.
2.3.2 annotate the diagram from 2.3.1
Parts of the Eukaryote cell:
Cell membrane- double phospholipid layer with proteins
(glycoproteins) sticking in it.It is selectively permeable.
Amphipathic molecule: both hydrophyllic and hydrophobic
regions 1.4.2
Fluid Mosaic model- proteins are not fixed on the
surface, but flow around the surface.1.4.1
Peripheral proteins- weakly attached on the inner or
outer surface of the membrane
Integral proteins- lie within the membrane, and are
important for cell transport
Functions of membrane proteins: hormone binding sites
( exterior chemicals can cause interior actions),
enzymes, electron carriers, channels for passive
transport and pumps for active transport. Identification
flags ( glycoproteins) 1.4.3
Interior membrane systems compartmentalize Eukaryotic
cell functions.
They include endoplasmic reticulum, nuclear membrane,
golgi apparatus, vacuoles, perioxiomes,lysosomes,
mitochondria, chloroplasts,plasmodesmata, central vacuole
( and tonoplast) Each membrane has unique proteins and
glycoproteins that determine specific functions.
Nucleus
Membrane bound organelle that contains most DNA.
The nuclear membrane has pores to allow large mRNA
molecules and RNA nucleotides to pass through.
Chromatin is complex of DNA and proteins that
provide organizational structure and editing/ reading
functions.
When condensed prior to replication, we call it
Chromosomes.
Nucleolus is the darker region of the nucleus where
mRNA is being actively transcribed off of the DNA ( note:
this does not have its own membrane around it)
Ribosomes ( also do not have membranes around them)
Protein and rRNA complexes that are sites of protein
synthesis. Ribosomes can be free in the cytoplasm or
associated with the endoplasmic reticulum ( rough)
Ribosomes are made up of two globular protein subunits...
the large and small subunit
( see fig 17.12 page 314 and fig 17.15 page 316)
Smooth endoplasmic reticulum is where lipids are made
for use within the cell. These include, phospholipids,
steroids, and oils
This is also where metabolism of carbohydrates occurs,
and the detoxification of drugs and poisons.. You detoxify by
adding hydroxyl groups ( OH-) which make the poison more
soluble in water and easier to remove. Continued use of
drugs and alcohol causes cells to enlarge the smooth
endoplasmic reticulum and so increases tolerance.
Rough endoplasmic reticulum
Ribosomes on the endoplasmic reticulum make it
appear bumpy or rough. This is where glycoproteins are
made and packaged for export from the cell.It may send
products to the Golgi Apparatus for further modifications
and sorting prior to excretion.
Golgi Apparatus
Another endomembrane that packages, sorts and
warehouses materials for the cell. Enzymes located on the
membrane can add carbohydrates to proteins and aid in
tertiary or quatenary folding of the protein.... remember :
shape is everything for proteins.
Lysosome
Membrane bound sac containing digestive enzymes. It
is very important to isolate these enzymes. The lysosome
can join with food vacuoles and digest them, or hydrolyse
( add water to) unneeded polymers within the cell for
recycling. A liver cell destroys and remakes half its
macromolecules each week.
Food vacuoles
Phagocytosis is the engulfing of particles to bring them
into the cell.
Contracile vacuoles
Very important in fresh water protists. They live in
hypotonic environment ( water moves into the cells)
Contractile vacuoles use ATP to pump excess water back
out against the osmotic gradient. When pumping stops, they
blow up.
Mitocondria and Chloroplasts
Not part of the endomembrane system. But are
semiautonomous organelles. Proteins in their membranes
are made both by free ribosomes in the cytoplasm, and by
ribosomes within the organelles. They have their own DNA
Cristae give mitochondria increased membrane surface
area. Thylakoids give chloroplasts increase membrane
area.
( Stacks of thylakoids are called grana, and the fluid outside
the thylakoids is called the stroma. The stroma contains
DNA and ribosomes
Peroxisome
A metabolic compartment that has enzymes that
transfer oxygen from various molecules ... producing
peroxide. ( H2O2 ) This can be used to break up fatty acids
for metabolism . Peroxides also chemically detoxify alcohol
and other poisons.
Cytoplasm
The fluid like material between the inner cell membrane
and the nucleus… a general term
Cytosol is the gelatin-like aqueous solution that has
dissolved salts, minerals and organic molecules
Cytoskeleton- a network of protein strands in the
Cytosol. It provides support and aides movement of
organelles within the cell. The proteins are organized into
microfilaments and microtubules
It is a dynamic system providing movement for
organelles and is constantly changing
Microfilaments - Move cilia and flagella, muscles
contract, various vacuoles are shipped around the cell.
ATP drives the movement “ walking along a filament” Actin is
the same as in muscles.Gives the cytoplasm the consistancy
of a gel. Cytoplasmic streaming is created by these motor
molecules.
Microtubules- are thickest form of cytoskeleton. They
are hollow tubes of a protein called tubulin. These are the
girders of cells, providing structural support. They also form
the spindles of mitosis and meiosis.
Intermediate filaments-bear tension in a cell. They
tend to be more permanent structures and can anchor
organelles in place.
Centrosome- area near the nucleus that microtubules
radiate out of, providing structural girders and the spindles
for mitosis and meiosis. Animals have a centriole within the
centrosome which is a microtubule structure which seems to
aid in the building of the spindle Plants do not have a
centriole.
Cilia and Flagella - hair like organelles that provide
mobility to the cell. Similar in structure ( 9+2). It is anchored
by a basal body which is structurally the same as a
centriole. ATP provides the energy for movement which is
chemically similar to the actin/ myosin motion.
2.3.3 Identify structures from 2.3.1 in electron
micrographs of liver cells.
2.3.4 Compare prokaryotic and eukaryotic cells
Prokaryotes- different Kingdom of life, simpler, with no
membrane bound organelles inside. Just a membrane full
of life chemicals. The first form of life on earth. Example:
Bacteria… Ruled the world for 1.8 billion years, starting 3.6
billion years ago
Eukaryotes-what most life on earth is. Have membrane
bound organelles inside like nucleus,
chloroplasts, mitochondria, etc. Appeared in fossil record
1.8 billion years ago
Prokaryotes have "naked" DNA while eukaryotic
DNA is associated with proteins ( histones)
DNA of prokaryotes is not enclosed in a nuclear
membrane, while eukaryotes DNA is.
Prokaryotes do not have any membrane bound
organelles such as mitochondria,while eukaryotes
do. Membrane bound organelles compartmentalize
metabolic functions.
Vacuoles, peroxisomes, lysosomes, nucleus,
mitochondria and chloroplasts are examples of
membrane bound organelles.
The size of the ribosome comlexes are smaller in
prokaryotes ( 70 svedlos) while eukaryote ribosomes
are a larger 80 svedlos
Eukaryotic DNA contains introns as well as
exons, while all of prokaryotic DNA is expressed as
proteins ( exons).
2.3.5 State three differences between plant and
animal cells
Plant cells have a large central vacuole, while
animal cells have few or no small vacuoles.
Plant cells have chloroplasts and
photosynthesize, while animal cells do not.
Plant cells have cell walls of cellulose outside
their plasma membranes, while animal cells do not.
Animal cells have centrioles that aide in the
assembly of the spindle fibers during mitosis and
meiosis, while plant cells do not have centrioles.
Plant cells are connected to the cytoplasm of
adjacent cells by plasmodesmata, while some
animal cells are connected to adjacent cells by gap
junctions.
2.3.6 Outline two roles of extracellular components
Plant cell wall contains cellulose fibers that
maintain cell shape, and aids in turgor pressure which
holds the plant upright.
Extra cellular matrix (ECM) secreted by animals
Lots of glycoproteins, including collagen. Act as
communication signals to outside the cell. Also aids
support, adhesion to other cells and movement
Intercellular junctions
Plasmodesmata- in plants are small passages that
connect cytoplasm of adjacent cells.
Tight junctions- in animals link adjacent cells together.
Prevents leakage of intercellular fluids. Epithelial cells.
Gap junctions- the animal equivalent of
plasmodesmata
Desmosomes- or anchoring junctions use keratin to
strengthen the linkage of sheets of cells.