The Ocean Tuesday April 29 2014 6 15 PM 3 4 of the planet is covered with water The average depth of the ocean is 3800 meters For every 10 meters depth increase pressure increases 1 atm Deep sea defined as the ocean below either 200 or 1000 meters Characterized by low temperature approximately 2 4 C high hydrostatic pressure up to 1 500 atm in the Mindanao Trench no sunlight Sunlight necessary for photosynthesis does not penetrate to these depths and thus there is low food availability and this affects the adaptations of organisms at these depths Deep sea species have characteristic depth distribution patterns which may be affected by pressure Pressure acts on volume changes of the entire solute solvent system Increased pressure inhibits a process that proceeds with a positive volume change accelerates a process that proceeds with a negative volume change Only if there is no net volume change is a process unaffected by pressure increases Biochemical processes can be affected Examples of what can be affected rates of catalysis binding of substrates assembly of subunits The volume changes associated with these processes may result from the interaction of enzymes and substrates with water The water may be more organized by interactions with charged substrates or amino acids Membrane fluidity is also affected High pressure acts like low temperature causing membranes to freeze Free vehicles not attached to vessel e g monster cameras Deep Submergence Vehicles e g Johnson Sea Link Alvin HOV Alvin Human Occupied Vehicle Owned by the U S Navy and operated by Woods Hole Oceanographic Institution 1966 recovered a hydrogen bomb lost in the Mediterranean Sea Explored the hydrothermal vents surveyed the Titanic The Story of Alvin s Lunch in the fall 1969 Alvin sank in 1540 m water temperature 3 C and was recovered 11 months later On board were lunches for pilot and 2 scientists Bullion soup bologna sandwich with mayonnaise apples Samples were eaten and they were okay Some put back in refrigerator at 3 C Decayed in 3 weeks Learning Objectives final Page 1 Rattails Decayed in 3 weeks Sparked interest in metabolic rates in the deep sea which continues to today Bioluminescence Biologically produced light used for among a number of roles species recognition camouflage and in some cases hunting Bioluminescence and color play role in being invisible Different wavelengths of light penetrate to different depths Typical wavelengths of bioluminescence are in the blue range These fish belong to the family Macrouridae and are the predominant deep sea teleost boney fish family These fish also have the common name of grenadiers If one is interested in examining how organisms adapt to the high pressures of the deep sea this family of fishes provides a useful model Different rattail species occupy different depths and thus experience different pressure regimes One can compare species that differ primarily in the variable of interest hydrostatic pressure without possible confounding variables such as phylogenetic distance or different lifestyles or body temperatures Learning Objectives final Page 2 Cell Signaling Tuesday April 29 2014 6 29 PM What are first messengers An extracellular chemical messenger ex Hormones What are two examples of second messengers Cyclic adenosine monophosphate cAMP Synthesized from ATP Calcium What is signal amplification and how does it benefit the cell Amplify faint signal A few 1st messenger molecules Many 2nd messenger molecules Elicit a coordinated response Amplification Each step in the cascade recruits more molecules What is the role of phosphorylation cascades in signal amplification Each step in the cascade creates more 2nd messenger molecules amplifying the signal Where are the receptors involved in cell signaling located Plasma membrane Signal amplification in the breakdown of glycogen Epinephrine adrenaline activates a GPCR in liver cells e g Fig 11 10 11 16 45 7 and 45 9 Learning Objectives final Page 3 Learning Objectives final Page 4 Calcium activates a phosphorylation cascade in skeletal muscle after the Protein Kinase A step in Fig 11 16 activating the enzyme phosphorylase kinase The relationship of adenylyl cyclase and cAMP Adenylyl cyclase produces cAMP How is adenylyl cyclase activity regulated Learning Objectives final Page 5 How is adenylyl cyclase activity regulated Regulated by the alpha subunit of the G protein Named after the alpha subunit Gs stimulatory G protein Stimulates adenylyl cyclase Gi inhibitory G protein Decreases adenylyl cyclase What reactions do protein kinases and phosphatases catalyze The transfer of phophate between their substrates In other words the steps of the signaling cascade What is the role of cAMP dependent Protein Kinase Protein Kinase A in cell signaling Enzyme which phosphorylates target proteins Covalent transfer of phosphate group from ATP to specific amino acids of target protein Post translation modification What are the subunits of Protein Kinase A and what do they do Protein kinase A R2C2 Inactive kinase 4 subunits a tetramer 2 regulatory subunits 2 catalytic subunits In the cytoplasm cAMP binds to the R subunit R2C2 dissociates into an R dimer and 2 C monomers What is the subunit composition of the active enzyme C monomers catalyze phosphorylation reactions Of the inactive enzyme In the cytoplasm cAMP binds to the R subunit What is G protein cycle Be sure you know all of the steps in the cycle and can reproduce it from memory Learning Objectives final Page 6 What are examples of the types of G proteins Gs stimulatory G protein Stimulates adenylyl cyclase Gi inhibitory G protein Decreases adenylyl cyclase Golf olfactory G protein Gt transducin the G protein involved in vision What are the subunits of G proteins Consists of 3 subunits alpha beta gamma Inhibitory and stimulatory signals and receptors What would happen if the G protein cycle is disrupted by mutations Figures 11 5 Learning Objectives final Page 7 11 6 11 7 Learning Objectives final Page 8 11 9 Learning Objectives final Page 9 11 10 11 11 Learning Objectives final Page 10 11 12 11 15 Learning Objectives final Page 11 11 16 Learning Objectives final Page 12 Hormones Tuesday April 29 2014 8 42 PM What is homeostasis Steady state physiological condition constancy of the interior environment of an organism What are examples of homeostasis e g constant pH body temp ion concentrations What is meant by antagonistic Two hormones work against each other to maintain
View Full Document
Unlocking...