Download CELL STRUCTURE AND FUNCTION OVERVIEW Cells: the building

CELL STRUCTURE AND FUNCTION
OVERVIEW
Cells: the building blocks of organisms, smallest unit of living matter (viruses, prions?)
any and all organisms are composed of cell(s).
Cytology: study of cells
Monomers: building blocks of polymers
Atoms: building blocks of molecules / compounds
Remember sequence in structural complexity:
Atom, Molecule, Cell, Tissue, Organ, O System, O’ism, Popl’n, Com’ty, Ecosystem,
Biosphere
Prokaryotes and Eukaryotes
Pro – no membrane bound nucleus or organelles, do have cell wall
Eu – membrane bound nucleus and organelles
(membranes are made of what?)
Nucleus contains DNA as chromatin, condensed into chromosomes
Chromosome number varies by organism
Membrane bound organelles: often protein producers
Energy:
Chloroplasts use sun’s E to produce CHO
Mitochondria break down CHO to ATP
A cytoskeleton may give a cell shape (does an amoeba have one?)
CELL THEORY (Schleiden and Schwann 1830’s)
All organisms composed of cells(s)
The basic units of structure and function of organism
Cells are self-reproducing and cells only come from existing cells
(where’d the first one come from? Was there a “first” one?)
Why are cells small? A chicken egg is one cell; why is it NOT small?
SA:V ratio is larger in smaller shapes
Allows greater per unit opportunity of uptake and elimination
A chicken egg is not metabolizing (using E to grow) and doesn’t need to gain or lose
cmpds. But it will begin dividing if incubated. Certain specialized cells maximize SA:V,
minimizing SA:V also can be found in nature (remember fox ears?)
PROKARYOTES (Greek: before kernel): no membrane bound nucleus, single celled.
Domains Archae, and Bacteria.
Bacteria: single-celled, but sometimes colonial.
Bacilli: rod-shaped
Cocci: round
Spirilla: rigid spirals, Spirochetes: bendy spirals
Cell envelope consisting of Cell Wall and Cell Membrane, and Glycocalyx
Membrane: phospholipid bylayer, SELECTIVE MEMBRANE
Can pinch off mesosomes to provide transport vesicles, increase SA:V
Wall: holds shape with structural polysaccharide (CHO) Peptidoglycan (like cellulose in
plants)
Glycocalyx: capsule-like and rigid or slimy and sticky (snot is made of the same stuff)
Interior of a Bacterium (single bacteria)
Cytoplasm is an aqueous (water-based) matrix containing the stuff, mesosomes
DNA: in a Single Chromosome in the Nucleoid
Plasmid: free-floating, extrachromosomal DNA for various purposes
Ribosome: SITE OF PROTEIN SYNTHESIS, where it all begins, DNA -> protein
Archae: have more shapes than Bacteria
No peptidoglycan (structural polysaccharide, CHO)
Membrane lipids bind to HC, not fatty acids
Tolerance to extreme environs indicates early inception on earth
But more genetically similar to eukaryotes than bacteria
EUKARYOTES: Protists, Fungi, Plants, Animals (DOMAIN EUKARYA, third of three
domains)
Have a Membrane-bound Nucleus containing DNA
And other compartmentalized Organelles
So, they are larger cells than Prokaryotes and Archae
So, smaller SA:V ratio
Made up for by compartmentalized (membrane-bound) organelles
Both Eukaryotes and Prokaryotes have Plasma (Cell) Membrane
Plants, like Bacteria, have Cell Walls, but composed of a different material
Cellulose vs. Peptidoglycan
Maintains cell shape without interfering with molecular transport
Cytoskeleton: protein lattice providing pathway for movement of material within cell
Organelles: compartmentalized structures performing specific cellular functions
Nucleus: the brain, contains Chromatin which condenses to form Chromosomes at Cell
Division
All cells of an individual contain the Same # of Chromosomes
Genes are carried on DNA, RNA: units of heredity on Chromosomes
Different kinds of RNA code for different results
Ribosomes: Not Membrane Bound (occur in Prokaryotes, too)
DNA coded protein synthesis occurs here
DNA -> m(messenger) RNA -> r(ribosomal) RNA -> protein synthesis
Ribosomes can be free in cytoplasm or attached to Endoplasmic Reticulum
Endomembrane System
ER, Golgi, and Nuclear Membrane (envelope)
Specific protein synthesis happens in proper location
ER: Rough (with ribosomes) and smooth (w/o); both sites of protein synthesis
(DNA coded) and provide membrane bound transport to other organelles.
Golgi Apparatus (or Body): named for discoverer, receives info, via vesicles,
from ER
Second step between DNA/RNA coded protein synthesis and function
Also produces transport vesicles (membrane bound bubbles)
Lysosomes: contain toxic (low pH) substances and produced by Golgi Apparatus.
Digest unwanted or unneeded materials. Break these materials down into component parts, often
monomers – building blocks.
Exocytosis: Elimination of unwanted materials by transport from Endomembranes to
Cell Membrane.
Perioxisomes: membrane-bound lytic vesicles NOT produced by Endomembrane
Vacuoles: also membrane-bound for storage generally, or elimination (contractile
vacuole) pumps out excess water, accumulated by diffusion, in Protists.
Central Vacuole: in Plants. Occupies much space. Maintains turgor (water pressure) in
Plants. Also stores wastes in Plants, which do NOT have lysosomes, but do have digestive
enzymes which produce building blocks from larger molecules.
ENERGY
Mitochondria (animal and plant) and Chloroplasts (plant and some Protists) have little
communication w/ remainder of cell and contain genetic material.
Originally symbiotic, incorporated Prokaryotes?
Chloroplasts: Use sun’s energy (generally, ultimate source of all energy on earth) to
produce CHO and derivatives
Mitochondria: break down these CHO into ATP for E production.
Photosynthesis: sun (E) + CO2 +H20 -> CHO + O2
Respiration: CHO + O2 -> CO2 +H2O + E
E, here, refers to ATP, a nucleic acid
CYTOSKELETON
Structural Protein based network maintaining cell structure and providing transport
protein filament interacting with motor molecule (myosin) providing stretching, moving,
contracting, aid in cell division
microtubules form 9+0 formation
cilia and flagella: for motility, 9+2 formation