CELLULAR ORGANIZATION

CELL THEORY All Living Things Are Composed of Cells Cells Are the Functional Unit of the Body Complementarity: Subcellular structures control biochemical activities Continuity of Life: Cells come from other cells

CELL DIVERSITY Human Body contains trillion cells 200 different cell types Range from 2 micrometers to 1 meter in length

TYPICAL COMPOSITE CELL Cell membrane Nucleus Cytoplasm Organelles

CELL MEMBRANE Gives form to the cell, forms outermost limits of the cell Controls what enters and leaves the cell Selectively permeable FLUID MOSAIC MODEL –Phospholipid bilayer –Proteins

LIPID BILAYER 2 Layers of phospholipids –Heads Polar (charged) Hydrophilic –Tails Nonpolar (uncharged) Hydrophobic Glycolipids - have attached sugar groups

PROTEINS - responsible for specialized functions Integral - embedded –Channels / Pores –Transporters / Carriers –Receptors Peripheral - attached –Enzymes –Glycocalyx - “sugar coating” –Cell ID markers

NUCLEUS Cell control center- directs activities Bounded by a double membrane, the nuclear envelope Contains genetic information (DNA) in the form of genes Nucleolus - site of ribosome assembly Multinucleate - many nuclei Anucleate - no nucleus

CYTOPLASM Cell forming material –cytosol - viscous transparent fluid –cytoplasmic organelles - “little organs” –inclusions - chemical substances that may be stored in the cytoplasm

ORGANELLES Endoplasmic reticulum –rough ER - transport & membrane synthesis –smooth ER - lipid synthesis & drug detoxification Ribosome - synthesize proteins Golgi apparatus - series of flattened membrane sacs that process, sort and modify proteins and lipids for export or cell use

ORGANELLES Mitochondria - ATP formation Lysosome - contains hydrolytic enzymes to break down molecules, digest bacteria Microtubules / Microfilaments - form part of the cytoskeleton that serve as support structures and assist with cell movement –Cilia -numerous, short, transport substnces across the membrane –Flagella - often single, propels the cell

ORGANELLES Peroxisomes - contain enzymes that oxidize toxic substances (neutralize free radicals) Centrosomes/centrioles - function in cell division Storage organelles - Vacuoles, Vesicles, may contain: –fats, oils, melanin

CELL PHYSIOLOGY Membrane Transport

PASSIVE PROCESSES Do not require energy –simple diffusion –facilitated diffusion –osmosis isotonic hypotonic hypertonic – bulk flow/filtration

ACTIVE PROCESSES REQUIRE ENERGY / ATP Goes against the concentration gradient –active transport using carrier proteins –vesicular transport endocytosis - phagocytosis pinocytosis exocytosis - cell export

Source of Cell Energy ATP Catabolism Adenosine triphosphate (ATP) ATP - 5 carbon sugar (ribose) nitrogen containing base (adenine) 3 phosphate groups ATP---P ~ P ~ P ATP---ADP + P + Energy

CELL DIVISION Process by which a cell reproduces itself Nuclear division - mitosis, meiosis –Mitosis - somatic cell division in which the cell retains the same number of chromosomes –Meiosis - reductional division in which the chromosome number is reduced Cytoplasmic division - cytokinesis

CELL CYCLE Growth Phase 1 - synthesis of lipids, proteins and carbohydrates S Phase - DNA synthesis Growth Phase 2 - formation of spindle fibers for cell division, centrioles divide Mitosis / Meiosis INTERPHASE

STAGES OF MITOSIS PROPHASE METAPHASE ANAPHASE TELOPHASE

PROPHASE Chromatin condenses into chromosomes Spindle Fibers appear Nuclear membrane disappears Nucleolus disappears Centrioles move to opposite poles Chromosomes begins to migrate toward equator

METAPHASE / ANAPHASE Chromosomes line up along equator centromere of each pair attached to a spindle fiber Centromeres split; sister chromatids separate Chromatids migrate to opposite poles

TELOPHASE & CYTOKINESIS Opposite of Prophase Chromosomes elongate forming indistinct chromatin Nuclear membrane reappears Nuclear reorganization occurs Two new daughter cells formed

NUCLEIC ACID STRUCTURE DNA - forms genetic code RNA - functions in the process of protein synthesis

DNA - DEOXYRIBONUCLEIC ACID Double stranded helix; nucleus Contains: 5 carbon sugar, phosphate group, nitrogenous base Nitrogenous bases –adenine-thymine –cytosine- guanine Base pairing occurs

DNA RELICATION DNA makes an exact duplicate of itself DNA strands separate into separate strands and each one is used as a template for a new strand of nucleotides Two double- helix molecules are formed, each contains an original strand and a newly synthesized strand

RNA RIBONUCLEIC ACID Single stranded Uracil substitutes for thymine consists of 5 carbon sugar ribose, phosphate group, nitrogenous base Bases: adenine, guanine, cytosine, uracil RNA types: mRNA, tRNA, rRNA

GENETIC CODE What are genes?

GENE Is a segment of a DNA molecule that may consist of 1,000 pairs of nucleotides that code for a specific protein ONE GENE=ONE POLYPEPTIDE=ONE PROTEIN

AMINO ACIDS Each amino acid is coded for by a triplet of bases Codon - triplet of bases that codes for a single amino acid

TRANSCRIPTION RNA SYNTHESIS mRNA is synthesized using a DNA molecule as a template mRNA carries MESSAGE out of the nucleus to the ribsome in the cytoplasm

TRANSLATION PROTEIN SYNTHESIS Genetic code is translated forming a specific sequence of amino acids mRNA attaches to ribosomes in cytoplasm tRNA molecules bring specific A.A. to the ribosome for placement in the dictated sequence Ribosome bonds amino acids together to form proteins / polypeptides Protein is released

Cell Aging Wear & Tear Theory - cell damage by chemicals and free radicals have cumulative effect Immune Theory - weakening of immune response or auto-immune disorders Genetic Theory - “Telomere Clock” –Telomere = string of nucleotides on the end of chromosomes; (TTAGGG) repeated >1000X – nucleotides lost each division.