cellular organization. cell theory all living things are composed of cells cells are the functional...
Post on 18-Dec-2015
215 Views
Preview:
TRANSCRIPT
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 50-106 trillion cells
• 200 different cell types
• Range from 2 micrometers to 1 meter in length
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
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
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
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
RNARIBONUCLEIC 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
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
TRANSCRIPTIONRNA SYNTHESIS
• mRNA is synthesized using a DNA molecule as a template
• mRNA carries MESSAGE out of the nucleus to the ribsome in the cytoplasm
TRANSLATIONPROTEIN 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
– 50-100 nucleotides lost each division.
top related