CELLS Basic unit of life (except virus) Prokaryotic, w/o nucleus, bacteria Eukaryotic, w/ nucleus Various cell types specialized for particular function. Differentiation. Over 200 human cell types

Cells 56% of body is fluid Similar to sea water Intracellular & extracellular Exchange regulated by cell membrane (plasma membrane) Passive transport (with gradient) Active transport (requires energy)

Cells Cell life supported by extracellular fluid containing: Ions: Calcium, Potassium, Sodium, … Nutrients: Glucose, Oxygen, Amino Acids, Vitamins, ... Regulatory chemicals: Steroids, Hormones, Paracrin/Autocrin factors, ...

Biochemistry Monomer Polymer Nucleic Acid Amino Acid Fatty Acid Sugar RNA, DNA Peptide, Protein Lipid Polysaccharide, Carbohydrate Genes Gene products Not coded by genes

Biochemistry Molecules or molecular regions (domains) are hydrophilic/hydrophobic Water is polar (+ and - charged sides) Charged and polar molecules are soluble in water Nonionic, nonpolar molecules are insoluble in water

Fig 1

Biochemistry C-C and C-H (hydrocarbons) bonds are nonpolar & hydrophobic In water, hydrophobic molecules and nonpolar regions of molecules aggregate to “hide” from water

Biochemistry Amino Acid H O H2N C C OH Carboxyl Amino R Side Chain (20)

Biochemistry Biochemistry H O H O H2N C C OH H2N C C OH R R +H2O H O H Amino end N-Terminus Carboxyl end C-Terminus R R

Biochemistry Enzymes - Catalyze reactions (not metabolized). All enzymes are proteins, but not all protein are enzymes. “Structural” proteins provide physical rather than chemical function.

Cells Cellular substructures called organelles made from membranes with similar structure floating in cytoplasm Membranes consist of bi-layer of phospholipid.

Membranes Phosphate rich protein head Charged - hydrophilic Lipid tail Hydrophobic

Membranes 2D Fluid, “oil slick” Semipermeable depending on size & charge Suspended proteins “float” in membranes. Hydrophobic regions w/in membrane, hydrophilic regions exposed Ion channels, pumps, transporters, exchangers, receptors

Organelles Endoplasmic Reticulum, smooth & rough SER - Site of lipid metabolism RER - Contiguous with outer nuclear membrane. Site of protein synthesis (translation), storage, post-translational modification, sorting, and transport. Many tubular and vesicular membranes.

Organelles Ribosomes - Contained in RER Responsible for translation of mRNA into protein. Made up of protein and specialized structural RNA called ribosomal RNA (rRNA)

Organelles Golgi Complex - Specialized portion of RER. Storage and sorting of protein vesicles prior to transport to membrane & secretion.

Organelles Mitochondria - “Engines” of the cell. Convert glucose to ATP. Number in the hundreds to thousands. Contain own DNA.

Organelles Lysosome - Lytic enzymes breakdown organic compounds and are sequestered lysosomes from rest of cell for protection. Proteins  Amino Acids Carbohydrates  Sugars

Cytoskeleton Give cell structure, motility, intracellular vesicular trafficking, and ability to replicate. Microfiliments 7-9nm Intermediate filiments 10nm Microtubules 24nm

Cytoskeleton Monomer Role Motor MF Actin Stiffen plasma membrane Myosin Provides motility by depolymerizing & A-M interaction IF Vimentin Strictly structural None Keratins One end attached membrane Others Integrates cells w/ other cells and into tissues MT Tubulin “Track” for vesicle transport Dynein Cilia and flagella motion Kinesin Alignment/separation of chromosomes

Organelles Nucleus - Repository of DNA. Site of RNA synthesis (translation). Double membrane, outer continuous with RER. Large channels for export of mRNA to cytoplasm. Nuclear matrix proteins give nucleus structure. Nucleolus - Large nuclear organelle where rRNA is synthesized and coupled with protein to form partial ribosomes.

Protein Synthesis RNA polymerase bind to gene promoter and converts DNA to complementary mRNA (transcription). Binding to promoter regulated by transcription factors. Non-coding mRNA is cleaved. Alternative splicing. Export of “mature” mRNA to ER Ribosome converts mRNA sequence to AA sequence by attaching tRNA+AA subunits in groups of three mRNA bases (codons).

Protein Synthesis Multiple ribosomes may be translating each mRNA over time or simultaneously This cannot occur for rRNA, so 80%-90% of DNA codes for rRNA. Post-translational modification - addition of lipids & carbohydrates, assembly of subunits. Intracellular and extracellular.

Ribosome (rRNA+Protein) ER Translation AA AA AA AA AA tRNA C U A G C T G U A G A C C G U C A U C U G G A U mRNA Ribosome (rRNA+Protein) ER Nucleus Transcription Export RNA Polymerase mRNA C G U C A U C U G G A G C A G T A G A C C T G G G G C DNA