September 12, 2012
How we look at cells
Anthony Van Leeuwenhoek – Early Microscope (1673)
Robert Hooke (1635-1703) – First to coin the term CELL – looking at cork
Electron Microscope: Compound – Looking at living things looking through,
Transmission Electron Microscope – Looking at non-living organisms/cells insid
Scanning Electron Microscope - Viewing surface of things
Cell Fractionation: Dissembling cells to look at components using a centrifuge to
look at the organelles. (Higher speed = smaller organelles)
The Cell: Simplest form of matter, lowest hierarchal level, basic unit of life,
performs functions that keep us alive.
Virus: Occur in every organism, highly specific to host, can only reproduce in a cell
(Not a cell)
Bacteria – NO NUCLEUS
Genetic info is in the Nucleoid
Visible Components: Pasma
ribosomes, nucleoid, cytoplasm.
May Have: Cell wall, pili, flagella
Many Shapes and sizes, largest is
4 Kingdoms: Prostista
Fungi, animalia, plants
True Nucleus: MEMBRANE BOUND
Visible Components: Cytoplasm,
Ribosomes, endomembrane system,
Skeleton, MAYBE: Matrix, flagella, cell
The Nucleus: Contains most of the genes, has a double membrane (Phospholipid
Bi-layer), 5 microns in diameter. Is fretted with pores to allow who goes in and
out, pores called nuclear lamina, intermediate filaments that maintain the shape.
- DNA in the form of chromatin appears as a diffuse mass
- When the cell divides the chromatin fibers condense into chromosomes
- The nucleolus is inside the nucleus carries out protein synthesis
Some celles have more than 1 nuclei, results from failure to form a plasma membrane
Cytoplasm: Between cell membrane and nuclear envelope. Variable viscosity,
contains 80% water, also has nucleic acids proteins, lipids etc.
Ribosomes: Responsible for protein synthesis, has 2 subunits that link together.
Can be free ribosomes in the cytoplasm, or bound ribosomes to the endoplasmic
reticulum. Can do both roles.
Endoplasmic Reticulum: Rough – Studded with ribosomes, responsible for the
synthesis of proteins. Membranes are made here. Smooth – Not studded with
ribosomes, responsible for the synthesis of lipids. Loaded with enzymes, makes
phospholipids, lipids, steroids. Smooth ER can also catalyze important reactions
with glucose. Smooth ER contains enzymes that detoxify drugs and poisons
Endomembrane System: Many of the internal membranes are connected
directly or by vesicles transporting goods
Golgi Apparatus: Vesicles from the ER are transported here. Processing plant:
manufacturing, warehousing, sorting and shipping. Extensive cells specialized for
secretion. Made of flat pancake like membranes (Sacs) called cisternae. There are
2 sides, cis and trans, material goes in cis and comes out trans. Material exits in
vesicles that are posted with where to go.
- Products from the ER can be modified, it can manufacture its own
Lysosomes: Contains hydrolytic enzymes that digests macromolecules.
Membrane bound, made in the golgi apparatus. Look like vesicles. Optimal pH is
5, rather than the cytosol 7.2. Proteins in the lysosomal membrane pump
hydrogen ions from the cytosol to the lumen of the lysosomes (pH control).
- Massive leakage can result in the cell dying (Autodigestion)
- Lysosomes fuse with food vacuoles via phagocytosis(Cell eating)
- Lysosomes can fuse with another organelle or part of the cytosol,
Vacuoles: Storage vesicles. Food Vacuoles: Fuse with lysosomes, Contractile
Vacuoles: pump excess water out of the cell Central Vacuoles: found in many
- Plant central Vacuole: found in plants bigger than the nucleus in plants.
The membrane (tonoplast) selects what goes in and out of the central using
transport proteins. The vacuole is responsible for maintaining turgor
pressure and keeping the plant rigid as it fills and holds water. Low
- Also used for storage, pigments in vacuoles produce the many colors
among different flowers
- Sometimes contains enzymes making them much like a lysosome
Mitochondria: Double membrane bound powerhouse. Converts energy from one
for to another. Location of cellular respiration (generating aTP from catabolically
breaking down sugars/fats.
- Contain their own DNA, and divide using it. They
sense their environment (muscle cells)
- Cristae inside increase surface area for ETC
- Depending on energy needs, their may be a need
for mitochondria with more cristae or larger in size
- All mitochondria in humans are inherited by
mitochondria (Egg cell has room, sperm does not)
Robert hooke (1635-1703) first to coin the term cell looking at cork. Electron microscope: compound looking at living things looking through, Transmission electron microscope looking at non-living organisms/cells insid. Scanning electron microscope - viewing surface of things. Cell fractionation: dissembling cells to look at components using a centrifuge to look at the organelles. (higher speed = smaller organelles) The cell: simplest form of matter, lowest hierarchal level, basic unit of life, performs functions that keep us alive. Virus: occur in every organism, highly specific to host, can only reproduce in a cell (not a cell) The nucleus: contains most of the genes, has a double membrane (phospholipid. Is fretted with pores to allow who goes in and out, pores called nuclear lamina, intermediate filaments that maintain the shape. Dna in the form of chromatin appears as a diffuse mass. When the cell divides the chromatin fibers condense into chromosomes. The nucleolus is inside the nucleus carries out protein synthesis.