Prokaryotes vs. EukaryotesProkaryotes vs. Eukaryotes Prokaryotes:Prokaryotes: **NO NUCLEUS, but do have nucleiod NO NUCLEUS, but do have nucleiod

region with DNA present region with DNA present *Small and Simple – few organelles *Small and Simple – few organelles *Have cell membranes and cytoplasm *Have cell membranes and cytoplasm

Ex. BacteriaEx. Bacteria

Eukaryotes:Eukaryotes:*Contain nuclei *Contain nuclei *Contains organelles that perform *Contains organelles that perform

specialized functions specialized functions *Uni-or multicellular *Uni-or multicellular

Ex. Plant and animal Ex. Plant and animal cellscells

Figure 7.4 A prokaryotic cellFigure 7.4 A prokaryotic cell

Figure 7.7 Overview of an animal cellFigure 7.7 Overview of an animal cell

Figure 7.8 Overview of a plant cellFigure 7.8 Overview of a plant cell

Basic cell parts: cell membrane and Basic cell parts: cell membrane and cytoplasm cytoplasm

Cell membraneCell membrane – – *provides barrier between internal *provides barrier between internal

and external environment of and external environment of cellcell

*is *is semi-permeablesemi-permeable (some things (some things can go in, some cannot; can go in, some cannot; some things can exit, some some things can exit, some never can)never can)

*made up of phospholipid bilayer *made up of phospholipid bilayer with with proteins embedded that allow proteins embedded that allow for for needed passage of large needed passage of large

moleculesmolecules

Major job of cell membrane is to maintain Major job of cell membrane is to maintain the cell’s environment – establish the cell’s environment – establish homeostasis homeostasis

Surface Area to Volume RatioSurface Area to Volume Ratio

Surface area acts as limiting factor in size Surface area acts as limiting factor in size of cell because is a two dimentional unitof cell because is a two dimentional unit

Volume is three dimentional, so increases Volume is three dimentional, so increases more quickly than the surface area can more quickly than the surface area can accomodateaccomodate

Figure 7.5 Geometric relationships explain why most cells are microscopicFigure 7.5 Geometric relationships explain why most cells are microscopic

Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross sectionsection

Fluid Mosaic ModelFluid Mosaic Model

Cell membrane and embedded proteins Cell membrane and embedded proteins are not locked into position – they flow are not locked into position – they flow against one another as the cytoplasm and against one another as the cytoplasm and the external liquid environment dictatethe external liquid environment dictate

Figure 8.7 The structure of a transmembrane proteinFigure 8.7 The structure of a transmembrane protein

Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross sectionsection

CytoplasmCytoplasm

Entire region between the nucleus and the Entire region between the nucleus and the cell membranecell membrane

The semifluid substance that fills this area The semifluid substance that fills this area is called is called CYTOSOLCYTOSOL, and this is what the , and this is what the organelles are suspended inorganelles are suspended in

Cell WallCell Wall

Found in Found in plant cellsplant cells (another barrier in (another barrier in ADDITION to the cell membrane)ADDITION to the cell membrane)

Protects the cellProtects the cell Gives support to cellGives support to cell Made of polysaccharide called celluloseMade of polysaccharide called cellulose Is very porous and allows molecules to Is very porous and allows molecules to

pass through, but is pass through, but is NOT SELECTIVELY NOT SELECTIVELY PERMEABLEPERMEABLE