BMSC 220 2 Structure and diversity of cells

• Theodor Schwann, Jakob Schleiden
• 1.  All organisms are composed of one or more cells
• 2.The cell is the structural and functional unit of life

• Rudolph Virchow
• 3.  Cells can arise only by division from a preexisting cell

• Nucleic Acids    
• Proteins    
• Lipids    
• Carbohydrates

• •Organic molecules (carbon-based)
• •Molecules for catalysis of chemical reactions and self-replication
• •A barrier between the internal cell environment and the external environment

•Spontaneous synthesis of organic molecules probably provided the basic materials from which the first living organisms arose.

RNA probably first genetic material is only molecule able to both catalyze chemical reactions (ribozyme), and self replicate (through nucleotide base pairing)

•Phospholipids are the basic components of all present-day biological membranes, including the plasma membranes of both prokaryotic and eukaryotic cells.

• •Archaebacteria
• •Eubacteria
• •Cyanobacteria

were prevalent in primitive Earth and often live in extreme environments

a large group of organisms (including common forms of bacteria) that live in a wide range of environments, including soil, water, and other organisms (e.g., human pathogens).

the largest and most complex prokaryote, synthesizes its energy from photosynthesis.

• a single circular molecule
• Where the DNA of Bacteria is found

in all eukaryotic cells, are the sites of oxidative metabolism

found only in cells of plants and green algae, are the sites of photosynthesis

provide specialized metabolic compartment for digestion of macromolecule

perform various oxidative reactions

• variety of functions in plant cells
• -digestion of macromolecules and storage of waste products and nutrients.

• -an extensive network of intracellular membranes
• - functions in the processing and transport of proteins, and in the synthesis of lipids.

• -sorts and transports proteins destined for secretion and serves as a site of lipid synthesis  -(in plant cells)
• - synthesis of some of the polysaccharides that compose the cell wall

• -provides the structural framework of the cell -responsible for the movements of entire cells, and intracellular transport / positioning of organelles and other structures
• -Composed of actin filaments, intermediate filaments, microtubules

the simplest eukaryotes; more complex than bacteria, smaller and simpler than cells ofanimals or plants.

• -commonly studied yeast 
• - unicellular, but communicate between cells

• 1) ground tissue
• 2) dermal tissue
• 3) vascular tissue.

200

• Epithelial
• Connective
• Blood
• Nervous
• Muscle

• form sheets that cover the surface of the body and line the internal organs. 
• -specialized for protection, secretion, absorption

• bone, cartilage, and adipose tissue
• Fibroblasts .

are a cell type that fill the spaces between organs and tissues in the body.

• -contains red blood cells (erythrocytes) and white blood cells
• -red blood cells don’t have nucleus

-composed of supporting cells and nerve cells, or neurons, which are highly specialized to transmit signals throughout the body.

• -responsible for the production of force and movement
• Skeletal, smooth muscle Cardiac muscle

• -relative simplicity and ease of propagation.
• •Divide every 20 min. under optimal conditions to produce clonal colonies.
• •Small genome  4.6 million bp,  4300 genes.
• •Ability to carry out biosynthetic reactions in simple defined media -  useful in elucidating biochemical/genetic pathways.
• •Useful for DNA/gene cloning and   manipulation

• -more manageable experimentally than the genomes of complex eukaryotes such as humans
• •Readily grown in the lab - divides every 2 hrs
• •studied by many of the same molecular/genetic approaches as for E. coli
• .•Yeast mutants -  used to study fundamental processes in eukaryotes, - DNA replication, transcription, RNA processing, protein sorting, regulation of cell division.

• -is a relatively simple multicellular organism (959 somatic cells)
• •entire cell lineage known
• •easily grown and subjected to genetic manipulations in the laboratory

• -easily maintained and bred in the laboratory
• -Studies of development, pattern formation

• -early vertebrate development eggs develop outside mother
• -all stages of development from egg to tadpole can be  studied in the laboratory.

easy to maintain, reproduce rapidly, amenable to genetic manipulation, and have transparent embryos.

• -easy to keep in lab, complete genome sequence
• - Often used as transgenic animals to study known human genetic disease

• •Robert Hooke invented the first simple light microscope in 1665.
• •In the 1670s, Antony van Leeuwenhoek microscope magnified objects up to 300 times-sperm, blood, bacteria.

• •The light microscope remains a basic tool of cell biology
• -can to magnify objects up to 1000X.

Objective lens: adjustable lense just above specimen

condenser lense: focus' light source

-ability to distinguish objects

• •optical systems that convert variations in density or thickness
• -contrast that can be seen in the final image without staining.
• •Allows visualization of live cells

• -widely used and very sensitive method to study intracellular distribution of molecules.
• -Fluorescent markers, dyes and proteins (eg. green fluorescent protein(GFP))  used to visualize proteins/structures in living cells

• -allowed visualization (without staining/killing) of specific molecules and structures in living cells
• -first isolated in jelly fish

• Albert Claude, Keith Porter, and George Palade -1940 and 50s.
• Achieve much greater resolution - wavelength of electrons shorter than visible light

• •electron beam reflects off sample surface- coated with metal
• -provides 3-dimensional surface image

passes a beam of electrons through a specimen to form an image on a fluorescent screen.

separates and isolates organelles (size and density) for use in biochemical studies.

-can rotate samples at very high speeds (over 100,000 rpm) to produce forces up to 500,000 times greater than gravity.

-The force of an ultracentrifuge causes cell components to move toward the bottom of the centrifuge tube and form a pellet at a rate that depends on their size and density

are the first cell cultures established from a tissue (limited number of divisions before death).

- embryonic stem cells or cells derived from tumors that may proliferate indefinitely in culture.

serum, salts, glucose, amino acids and vitamins.