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Chapter 4 Physiology of Cells. Movement through cell membranes. Substances move through cell membranes in two ways: Passive Transport: does not require any energy activity from the cell membrane Active Transport: requires expenditure of metabolic energy by the cell. PASSIVE TRANSPORT.
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Movement through cell membranes • Substances move through cell membranes in two ways: • Passive Transport: does not require any energy activity from the cell membrane • Active Transport: requires expenditure of metabolic energy by the cell
PASSIVE TRANSPORT • Diffusion: • The spreading of molecules from an area of high concentration to an area of low concentration • Simple Diffusion: molecules travel across the phospholipidbilayer • Makes the membrane permeable.
Osmosis: • Diffusion of water through a selectively permeable membrane • Osmotic Pressure • Develops from the water pressure during Osmosis • Potential Osmotic Pressure-the maximum osmotic pressure that could develop when separated from pure water by a selectively permeable membrane • Isotonic • Two fluids have the same osmotic pressure • Hypertonic • Water flows out of the cell and the cell shrivels as a result • Solute concentration greater outside of the cell • Hypotonic • Water flows into the cell and the cell swells up as a result • Solute concentration greater inside the cell
Dialysis • Selectively permeable membrane separates larger solute particles into smaller solute particles • Facilitated Diffusion • Transports substances down a concentration gradient • The collision energy of the solute provides required energy
Active Transport movement of solute particles from an area of low concentration to high concentration and up a concentration gradient by the use of a carrier molecule • Endocytosis- bringing extracellular material into the cell • Phagocytosis- large particles engulfed by the plasma membrane and fuse with lysosomes, where the particles are digested • Pinocytosis- fluid and the substances dissolved in it enter the cell • Exocytosis- large molecules (proteins) are pulled by the cytoskeleton and leave the cell through the plasma membrane
This is one of multiple images that display receptor-mediated endocytosis.
Cell Metabolism the chemical reactions that occur within the cell • ENZYMES – a protein that changes the rate of a chemical reaction • Structure • Proteins • Lock-and-Key Model: active site where the enzyme molecule fits into the substrate molecule • Chemical catalysts • Speed up reaction by reducing the amount of energy needed to start reaction • Regulate cell metabolism • Continually destroyed and replaced • Catalyze a chemical reaction in both ways
CATABOLISM – operates on the pathway of cellular respiration (breakdown of glucose to carbon dioxide and water) • Glycolysis • Net yield of 2 ATP • Anaerobic (does not require oxygen) • Occurs outside mitochondria • Glucose is broken down into pyruvic acid molecules and that energy is transferred into ATP and NADH • Citric Acid Cycle • Also known as Krebs Cycle • Net yield of 2 ATP • Pyruvic acid is converted into acetyl and enters the cycle after losing CO2 and transferring some energy into NADH, ATP, and FADH2 • Occurs inside the inner chambers of the mitochondria • Electron Transport System (ETS) • Net yield of 32 ATP • Energized electrons are embedded in the cristae of the mitochondria
ANABOLISM – protein synthesis • Deoxyribonucleic acid (DNA) • Shape of a double helix • Polymer (large molecule made up of many smaller molecules) made up of nucleotides • Genes contains the codes for synthesizing one polypeptide • Transcription • mRNA forms along a segment of DNA to copy a portion of the DNA code and undergoes editing • Translation • mRNA links with a ribosome • tRNA transfers amino acids to the ribosome • Joined by peptide bonds which then eventually produces an entire polypeptide chain
Cell Growth/Reproduction • Cell Life Cycle. • Kind of important… just a tiny bit. • Humans are simple people. • So 2 phases.
Cell Growth • Cell is already made. Start here. • Produce Cytoplasm and Plasma Membrane • Protein Synthesis (anabolic process) • Amino Acids to Polypeptide to larger more comple • = structural proteins and Enzymes
DNA Replication • RNA synthesized by enzyme • Larger cell triggers mechanisms • Synthesizes entire set of DNA • Steps of synthesis? • Before Reproduction: Chromatids attached by Centromere
Cell Reproduction. • No, cells do not have sex to reproduce. • 1 parent cell = 2 daughter cells. • Cytokinesis • Mitosis
Mitosis • Interphase • Prophase • Metaphase • Anaphase • Telophase • Meiosis • Haploid and Diploid
Chapter 7Skeletal System (Click on it)