Download CELLS : the Structural and Functional Units of All Life Forms

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 of
 Cell 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 bilayer
 Amphopathic
 Selectively permeable

More PROKARYOTIC information










Pro (before) and karyon (kernal or center)
Small, 0.1 mm (micrometers) to 10 mm
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 cells
Larger
 Found in plants, animals, fungi and protista
 Contain 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 organelles
 Cytosol refers to just the solution
 ALL cells have ribosomes (slight dif.)
 ALL cells have DNA (euk. contained)
 Organelles like ribosomes are solid
 Many eukaryotic organelles are
membranes bound. (packages)

List of organelles –

Cell membrane


Nucleus



Nuclear membrane, chromosomes, chromatin, centrioles,
nucleolus, spindle fibers
Ribosomes ( attached and free )
Membrane bound organelles “surrounded by membrane”


Cilia, flagella, plasmodesmata
Mitochondrion, chloroplast, plastid, vacuole, Golgi apparatus,
smooth endoplasmic reticulum (sER) and rough endoplasmic
reticulum (ER), lysosomes,
Other

Microtubules, microfilaments (actin), etc.