Download Notes: Cells

Microscopes
• simple light scope- used 1 lens and natural light
• compound light scope- series of lenses to
magnify objects in steps (this is what we use
in class)
Magnification- the ability to make objects appear larger
Resolution- the ability to distinguish between two
objects that are close together
Microscopes
electron scope- uses a beam of electrons instead of
natural light to magnify objects - 3 types
1. scanning electron scope (SEM)- used to scan the
surface of cells to determine their 3D shape
2. transmission electron scope (TEM)- used to study
the structures within a cell
3. scanning tunneling scope (STM)- uses electrons to
see the atoms attached to the surface of a molecule
Cells- the basic
unit of living
organisms
van Leeuwenhoek was the first to see
cells through a microscope.
Robert Hooke saw dead cork cells.
(1665)
Schleiden concluded that all plants are
composed of cells. (1838)
Schwann concluded that all animals are
composed of cells. (1839)
Virchow concluded that cells come from
other cells. (1855)
The Cell Theory
1. All organisms are composed of 1 or
more cells.(single celled or multicellular
organisms)
2. The cell is the basic unit of organization
of organisms.
3. All cells come from cells.
Cell Types
prokaryotes- cells that lack membrane bound organelles (internal
cell structures) (mainly a nucleus)
- usually unicellular Example: bacteria
Cell Types
eukaryotes- cells with membrane bound organelles
- mostly multicellular organisms
Example: plants & animals
EXCEPTION: yeast & algae are unicellular eukaryotes
- composed of a phospholipid bilayer
- 2 layers of lipids tail to tail
- lipids have a polar phosphate head (water loving)
attached to 2 non-polar fatty acid tails (water
hating)
The boundary between the cell and its environment
- maintains homeostasis
- regulates what goes in and out of the cell
*selectively permeable- it allows some
molecules to pass through while it keeps
other molecules out
proteins are embedded in the membrane
- recognition proteins identify the cell (AKA: cell
surface markers)
- transport proteins allow wastes and substances
to pass through the membrane (AKA: carrier
proteins)
- receptor proteins monitor the outside
environment and send information to the
nucleus
cholesterol is embedded in the membrane
- prevents fatty acid tails from sticking together
- provides strength and rigidity to the membrane
The Fluid Mosaic Model- the current model of the plasma
membrane.
Flexible and fluid like in movement & patterns of proteins look
like a mosaic
Nucleus- THE BOSS- contains the
directions to control cell activity
Nucleolus- organelle inside the
nucleus that makes ribosomes
Chromatin- loosely coiled strands of
DNA found within the nucleus
Nuclear Envelope- structure that
separates the nucleus from the
cytoplasm. It is a double membrane
made of two phospholipid bilayers
containing small nuclear pores for
substances to pass through.
Nuclear Matrix- protein skeleton helps
maintain shape
Cytosol- the clear, gelatinous fluid inside the cell
(cytoplasm)
Ribosomes- PROTEIN FACTORY- organelle in
charge of protein synthesis (not membrane
bound)
2 types: free floating, attached
Rough Endoplasmic Reticulum (ER)- ASSEMBLY
LINE- series of highly folded membranes that is
the site of cellular chemical reactions, ribosomes
attach to the outside to make the ER rough
Smooth ER- ASSEMBLY LINE- lacks
ribosomes, highly folded membranes
involved in the production and storage
of lipids
Golgi Apparatus- POST OFFICEflattened system of tubular membranes that
modifies proteins to be sent to various places
Vesicles- associated with the golgi apparatus,
membrane bound structures that carry proteins
Vacuoles- PANTRY- membrane bound space
used for storing materials (food, enzymes, etc.)
large in plant cells, small in animal cells
Lysosomes- HOMICIDE SAC- membrane bound
organelle that contains digestive enzymes, they
digest worn out organelles, viruses, bacteria, etc.
• Peroxisome
– Contains oxidative enzymes to perform
oxidation reactions
– Each cell has different types of peroxisomes
Mitochondria- POWER HOUSE- transforms
energy for the cell has an outer membrane and a
highly folded inner membrane (cristae
membrane); the mitochondria has its own DNA
*Cilia- short, numerous
hairlike projections that
help with movement
*Flagella- long whiplike
projections used for
locomotion Ex: sperm
Cytoskeleton- support structure within the
cytoplasm that helps keep cell shape and assist
organelles with movement
- Microtubules- thin, hollow cylinders of protein
- Microfilaments- thin, solid protein fibers
PLANT ORGANELLES
Plastids- organelles used for storage of pigments,
starches, lipids, etc.
- Chloroplast- organelle that captures light energy
and produces food for later use they contain
chlorophyll, a green pigment that traps light
energy
Cell Wall- rigid structure located outside the plasma
membrane that provides additional support and
protection, it will let anything pass through itpresent in plant cells, most bacteria, and fungi
ANIMAL CELL ORGANELLES – only found in
animal cells
Centrioles - Aid in mitosis, cellular
reproduction; found outside of the nucleus