CELLS : the Structural and Functional Units of All Life Forms

Microscopes are used to view objects too small to be seen clearly with the human eye CLM- compound light microscopes use many lenses and a

beam of light to magnify objects up to 3000X. Require a translucent specimen. See in micrometers

SEM – scanning electron microscopes, use beam of electrons, object must be stained with heavy metal, see the outside surface in 3D, 100,000X, nanometers

TEM - transmission electron microscope, electron beam, heavy metal stain, through thin slices, powerful

Scanning Tunneling Electron Microscope – can be used to guide electrons into specimen, “virtual tour” , can see macromolecules ( not atoms )

Cytology

Cytology is the study of cells‘cyto’ means cell, ‘ology’ is the study ofCell fractionation – uses centrifuge to

take cells apart and separate their organelles based on density

Centrifuge – 80,000 rpm, spins cells in liquid to break them apart.

Cell Types

Prokaryotic cells Small Found only in bacteria (Archea and Eubacter kingdoms) Cell membrane, cytoplasm, DNA without a nuclear membrane

and special ribosomes No internal membranes or membrane bound organelles

Eukaryotic cells Larger Found in plants, animals, fungi and protista Contain cell membrane, cytoplasm, DNA inside of a nucleus Many organelles bounded by membranes.

Surface area to volume ratio

Surface area is represented by cell membrane (product in and out) – this unit is ‘squared’

A sphere is the shape with the largest surface area to volume ratio

Volume is represented by cytoplasm (site of all reactions) – this unit is ‘cubed’

Need to match supply with demand and import with export, energy amts and pollution also need to be considered

IT is more EFFICIENT to have many, small cells than fewer large cells.

Cell Membrane

Fluid mosaic model phospholipid bilayerAmphopathicSelectively permeable

More PROKARYOTIC information

Pro (before) and karyon (kernal or center) Small, 0.1 m (micrometers) to 10 m Found only in bacteria (Eubacteria and Archeabcter) Cell membrane, cytoplasm, DNA without a nuclear

membrane and special ribosomes No internal membranes or membrane bound

organelles DNA is in the form of one circular chromosome Few hundred genes Region is called nucleiod Ribosomes are 70 s MAY contain capsules, pili, flagella and plasmids

More EUKARYOTE information

Eukaryotic cellsLargerFound in plants, animals, fungi and protistaContain cell membranes, cytoplasm, DNA

inside of a nucleus Many organelles bounded by membranes.Organelles vary greatly from kingdom to

kingdom.

Eukaryotic nucleus

Nuclei is plural of nucleus; “center” Function of nucleus is to control everyday activity of

the cell and to control cell reproduction (of information) Nuclear membrane is similar to plasma membrane Membrane is porous to certain nutrients Contains DNA in the form of many chromosomes Chromosomes can’t leave, membrane must dissolve

during cell division. Cells can be multinucleate or coenocytic

Eukaryotic Organelles

Cytoplasm is fluid and organellesCytosol refers to just the solutionALL cells have ribosomes (slight dif.)ALL cells have DNA (euk. contained)Organelles like ribosomes are solidMany eukaryotic organelles are

membranes bound. (packages)

List of organelles –

Cell membrane Cilia, flagella, plasmodesmata

Nucleus Nuclear membrane, chromosomes, chromatin, centrioles,

nucleolus, spindle fibers Ribosomes ( attached and free ) Membrane bound organelles “surrounded by membrane”

Mitochondrion, chloroplast, plastid, vacuole, Golgi apparatus, smooth endoplasmic reticulum (sER) and rough endoplasmic reticulum (ER), lysosomes,

Other Microtubules, microfilaments (actin), etc.