History of the cell
All living organisms are made up of cells.
Cells are:
• The basic unit of structure and function of
a living organism.
• Organsims can be either:
– unicellullar
– multicellular
History of the cell.
• 1665 Anton van Leevwenhoek:
– constructed first simple microscope.
– viewed pond water and saw tiny moving
structures
– called them “wee little beasties” or “animalcules
• .
• 1670 Robert Hooke
– Inventor of first compound light
microscope.
– Viewed cork
– Viewed tiny, hollow units and called them
“cells”.
Approximately 200 years later…
• 1833 Robert Brown
– First to see a nucleus within a cell.
– They now knew that:
• cells were not hollow like the cork.
• that there were structures within the “cells”
• 1835 Two German scientist, Theodor
Schwann (Zoologist) and Matthias
Schleiden (Botanist) collectively came to
the conclusion that all plants and all
animals are made up of cells.
• 1855 Rudolf Virchow recorded that “all
cells come from other like and pre-existing
cells.
• 1869 Fredrick Miescher:
• discovered DNA’s presence (not its
structure)
• did not know its importance until much
later.
• He called it nuclein.
• 1879 Walter Flemming: Identified
chromosomes in the nucleus. Once again
did not know the true importance of them.
The Cell Theory
• 1. Every living organism is made up of
one or more cells.
• 2. Cells are the basic unit of structure and
function of all living organisms.
• 3. All cells arise from like, pre-existing
cells.
Two types of cells exist:
Prokaryotic and
Eukaryotic Cells
Prokaryotic Cells
• Word means “before nucleus”
• Includes all bacteria
1.Believed to be the first cells on Earth in the
primordial soup
2. Lack a nucleus and all membrane bound
organelles.
3. Genetic material just floats around the center
of the cell.
Eukaryotic Cells
• Word means “contains a true nucleus”
• Includes all animals, plants, fungi, and
protist.
• Evolved from prokaryotic cells.
1. Theory is one prokaryotic cell engulfed
another and now there was a cell within
another cell.
2. Eukaryotic cells contain a nucleus and
membrane bound organelles.
3. Organelles are “tiny organs” within a cell,
each having their own function.
Two types of eukaryotic cells:
Plant-like
Animal-like
Traits common to both
prokaryotic and eukaryotic
cells
-Plasma / cell membranes
-Cytoplasm
-Cell wall
-Ribosomes
-Genetic material
Cell Membrane
Plasma or Cell Membrane:
Function:
1. Outer boundary of the cell
-separates one cell from another
2. Allows for interaction between like cells within
a tissue.
3. Acts as a “gatekeeper”
-regulates what is allowed to enter
or leave the cell.
Oxygen
Food Molecules
Water
Carbon dioxide
Cellular Waste
Excess water
4. Aids in protection and support.
-keeps out bacteria
-provides some shape
Fluid Mosaic Model
hyperlink
-model of the structure of a cell membrane
-discovered in 1972
The cell membrane:
-Composed of a phospholipid bilayer/double
layer of phospholipids with proteins and some
carbohydrates scattered throughout it.
Components of the Cell
Membrane
Carbohydrate chains
Used for cell recognition
Phospholipid bilayer
Type of lipid
Contain pores/openings
Proteins:
- receptor proteins
- transporting proteins
- adhesion proteins
Phospholipid
-type of lipid
-most abundant component in the membrane
Hydrophilic Head
-water loving
-polar
Hydrophobic Tail
-water fearing
-nonpolar
Extracellular Fluid: Cells watery environment
Intracellular Fluid: Cells liquid center/cytoplasm
Several types of proteins embedded in the
bilayer:
1. Receptor proteins: act as a docking
area for items to attach to like hormones.
2. Transporting proteins: Hyperlink
-transports items across the bilayer
3. Adhesion Proteins:
-project outward from
bilayer and help cells
within a tissue to stick
together.
Cytoplasm:
1. -liquid part of the cell
2. -found in all areas between the
nucleus and the cell membrane
3.-made mostly of
water with salts,
amino acids,
nucleotides, etc…
dissolved in it.
Function:
-to suspend and
allow structures
to move about.
Cell Wall:
1.-surrounds cell membrane
-found in plants, fungi, some
bacteria and some protist.
2.-located outside the cell membrane
3.-provides shape and support
4. -has openings so items can pass
through.
5. -made up of cellulose and pectin in
plants and chitin in fungi.
Turgor Pressure:
1. -Pressure created by water
-cell loses water
-turgor pressure decreases
-cell wall bows inward
-cell shrinks in size
2. Cell takes in water
- turgor pressure increases
- cell wall bulges out
- cell swells
Complete part A and B of
Cell Lab
Genetic Material:
1.-made up of DNA
2.-has instructions for making all cellular proteins.
Prokaryotic Cells:
-Have no nucleus
-DNA is free floating
-DNA is in 1 circular
loop
Eukaryotic Cells:
-DNA contained in a nucleus
-many linear pieces of DNA known as
chromosomes.
Ribosomes:
The cells “workbench”
Job: Makes proteins,
in their linear form, by
assembling amino acids
in the correct order
based on DNA’s code.
Ribosomes are made up of RNA and proteins.
Found attached to the endoplasmic reticulum
or
Free floating in the cytoplasm
Structures of Eukaryotic Cells
-Nucleus and Nucleolus
-Mitochondria
-Chloroplast
-Rough Endoplasmic Reticulum
-Smooth Endoplasmic Reticulum
-Golgi bodies
-Lysosomes
-Vacuoles
-Plastids
-Peroxisomes
-Cytoskeleton
Nucleus:
1.-Brain of cell
2.-Cells control center
3.-Contains DNA
4.-Made up of another lipid bilayer
5.-contains pores for items to move in and out.
Nuclear Envelope:
-outside of nucleus, studded with pores
Nucleolus:
-circular structure within nucleus
-makes ribosomes
Nucleoplasm:
-cytoplasm inside
the nucleus
Chromatin:
1.-loosely coiled DNA found within the nucleus
2.-can tightly coil into a bow tie shaped “chromosome”
Chromosomes are
made up of genes.
Genes:
-segments of DNA
which code for
specific proteins
Quicktime movie: 4 min
Mitochondria:
1. -cell’s powerhouse
2. -the place were the cell converts food into energy.
3. -found in all eukaryotic cells~plant-like and animal like.
4. -site of cellular respiration
sugar + oxygen  ATP energy + carbon dioxide + water
Form of energy
used by a cell
to do “work”.
-12 to 1000 mitochondria per cell
-plant cells have less than animal cells.
Why?
-less active
-require less energy
-Which cells in our body would have the most
mitochondria?
-muscle cells ~ very active
Mitochondria are made up of 2 membranes:
-outer membrane
-inner membranes known as cristae.
Cristae increase the surface area so more
energy can be produced without taking up
too much room.
Analogy:
Population 5,000 in
1/4 square mile.
Population 5,000 in
10 square mile.
verses
Quicktime movie (6 min)
Chloroplast:
-Found only in plant-like cells
-site of photosynthesis
Sun + CO2 + H2OC6H12O6 + O2
CHLOROPLAST:
-Trap energy of the sun and convert
it into sugars which can be stored by the
plant or broken down in the mitochondria
into ATP energy.
Plant store
sugar in their
fruits, stems,
and roots.
Thylakoids: platelike structures which collect the sun’s
energy.
Grana or Granum: Stacks of thylakoids (10 to 100/chloroplast)
Stroma: Liquid part of the chloroplast
Lumen: Inside thylakoids ~ contains chlorophyll
ROY G BIV
GREEN
ROY G BIV
Absorbs:
-all spectrums
of light but green
is reflected.
Complete part C, D and E of
Cell lab
Ribosomes Review:
The cells “workbench”
Job: Makes proteins, in their linear form,
by assembling amino acids in the correct
order based on DNA’s code.
Ribosomes are made up of RNA and proteins.
Attached ribosomes:
-attached to the endoplasmic reticulum
or
Free floating ribosomes:
- Floating around in the cytoplasm throughout the cell
Endoplasmic Reticulum (ER):
-Known as the “cells subway system
-Transports proteins around the cell
The E.R is a made up of a series of
interconnected, hollow channels.
Two types of E.R:
1. Smooth E.R.
-has no ribosomes
attached.
-responsible for making
phospholipids for new
membranes
2. Rough E.R.
-has ribosomes attached
-aids in protein synthesis
1.Proteins, made by the ribosomes, travel
through the hollow channels of the rough ER
into the smooth ER.
2.The end of the smooth ER pinches off
around the protein forming a “transporting
vesicle”
3. Transporting vesicle transports the newly
formed protein to the golgi body.
Golgi Complex, Apparatus or Bodies
-a stack of flattened
membranes clustered in
one area.
-Made up of a collection
of transporting vesicles.
Known as the Fed-Ex man
Job: Collects, stores, modifies
and packages materials
it receives from the
transporting vesicles/ER
and then deliver them to where
they need to go.
-Where a protein gets it 3D shape
Example: Insulin production in a pancreas cell
Lysosomes:
Nickname: Clean Up Crew or Suicide Sack
Job: Organelles which contain digestive enzymes
made by the ribosomes and processed in the
golgi.
Three Jobs:
1. Fuse to an old or damaged cell
organelle, injects its enzymes into it and digest
the old organelle .
2. Lysosomes fuse to food and digest the food for the
cell.
3. Lysosomes in an older or damaged
Cell breaks open and releases enzymes into the
Cytoplasm ~ digesting the cell from the inside out.
Example:
RBC’s
WBC’s
Sperm
lifespan
120 days
8 days
5 days
Lysosomes are rarely found in plant cells.
-when plant cells die, parts of the cell
remains.
Formation of a lysosome:
1. Ribosomes made dig. enzyme
2. Travel through ER
3. Smooth ER pinches off and dig. enzyme is
contained in a transporting vesicle.
4. Transporting vesicle fuses with golgi
5. Golgi modifies enzyme giving it a 3D shape
6. Section of golgi moves away with enzyme
inside it ~ now a lysosome.
Lysosomes
Vacuoles:
Stores excess
water, food or
waste.
Storage area for cell
Plant-like cells have 1 or 2 large central
vacuole which stores excess water or
sugars
Animals-like cells have many small
vacuoles which store excess water and
waste.
Plastids: specialized vacuoles in plants
Chloroplast:
Stores chlorophyll
Leucoplast:
Stores starch
Chromoplast:
Stores color pigments
Cytoskeleton: cell’s framework
Cyto
= cell
skeleton
= support
A woven web-like system embedded into a plant and
animal cell’s cell membrane and cytoplasm,
provides some support to the cell.
Different animal cells have specific shapes:
Cytoskeleton is made up of both:
1. Microfilaments:
-long, solid tubes of proteins
-allow for movement within cell
tissue like muscles.
2. Microtubules:
-long, hollow tubes of protein
Flagella: Long whip like tail Cilia: short hairlike
Centrioles: used by animal cells for cell division
Villi: fingerlike projections or extensions of the cell
membrane. Increases the surface area of the cell’s
membrane.
Plant and Animal Cell
Comparison
Plant cells have:
Animal cells have:
cell wall and membrane
cell membrane
chloroplast
no chloroplast
1 or 2 large vacuole
many small vacuoles
No centrioles
1 pair of centrioles
Has plastids
No plastids
Rectangular in shape
Roundish in shape
Small # of mitochondria
Large # of mitochondria
Quicktime movie (6 min)