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5.1 All organisms are composed of cells. 3 main features: plasma membrane nucleus or nucleoid cytoplasm. amoeba. neuron. sperm & egg. skeletal muscle. A plasma membrane surrounds all cells. bilayer fluid mosaic Singer, Nicolson 1972. Genetic Information. DNA. - PowerPoint PPT Presentation
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5.1 All organisms are composed of cells
neuron
skeletal muscle
amoeba
sperm & egg
3 main features: plasma membrane nucleus or nucleoid cytoplasm
A plasma membrane surrounds
all cells
bilayer fluid mosaic
Singer, Nicolson 1972
Genetic Information
prokaryotes
DNA
eukaryotes
nucleoid
plasmids
DNA as chromosomes during cell division
1 Circular chromosomal DNA
2 Extra-chromosomal plasmid DNA
Cell Discovery/Theory
cells are the unit of structure and function
cells fromcells
cell walls of cork ‘little
animicules’
Why are cells small?
As an object increases in size…
Volume increases as the cube (x3) of its diameter
while
surface area increases as the square (y2)
The membrane (surface) must allow for sufficient & rapid exchange to support the cell contents
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Prokaryotic vs Eukaryotic
small & simpleribosomes, nucleoidpeptidoglycan wall3.5bya
large & complex organelles, chromosomescytoskeleton1.5bya
Features in common
Unique to eukaryotes, organelles allow for division of labor
Prokaryotes: so what?
Decomposition nutrition
disease sewage treatment digestion
soil contamination clean upnutrient recycling symbiosis normal flora
Energy transformers history of life genetic engineering human health
An amphipathic molecule
Charged phosphate creates a polar ‘head’
H-C tails are non-polar, hydrophobic
The Plasma Membrane is built primarily of Phospholipids
Phospholipid molecules self-organize, tails avoiding water of both the cytoplasm and the environment
creates a bilayer
tails a barrier to charged ions and polar molecules
channels, carriers, aquaporins
membrane stability
relay information in/out of cell
facilitate rxns
Membrane proteins
move molecules across
bind cells tightly together
keeps molecules from ‘escaping’ from tissues
TIGHT JUNCTIONS
Steroids – cholesterol in animal cells – modify the fluidity of the membrane so it stays intact at both warm and cold temperatures.
Membrane as Mosaic
Glycoprotiens and glycolipids function in cell to cell attachment, recognition, and cell signaling