Gas Exchange 1
What is the importance of the Great Oxidation Event in the evolution of life on Earth?
atmospheric oxygen reaches 0.2%, the Pasteur Point, life evolves aerobic respiration
What metal atom is used to bind oxygen in hemocyanin?
copper, Cu
Name 3 types of pathogens and if they are cellular or acellular.
cellular: parasitic worms, protozoa, fungi, prokaryotes
acellular: viruses, prions
What are the three ranges of action of hormones?
- short is autocrine, acts on same cell/cell type
- middle is paracrine, acts on neighboring cells
- long is endocrine, requires circulation
What endocrine gland receives hormones from the hypothalamus and releases tropic hormones in response?
Anterior Pituitary
How do diatomic oxygen and ROS cause oxidative damage?
They are extremely reactive and strong oxidizing agents, they react with molecules in cells and destroy them
How is CO2 transported in blood from metabolically active tissue to the lungs? How common is each method?
converted to carbonic acid then bicarbonate by carbonic anhydrase then pumped into blood by chloride-bicarbonate anion exchanger (70%), travels as dissolved CO2 in blood (7%), binds to amino termini of hemoglobin proteins (23%)
What are the three lines of defense against pathogens in jawed vertebrates? What about in agnathans?
jawed vertebrates have epithelial and mucosal barrier, innate immune system, and adaptive immune system. agnathans have epithelial and mucosal barrier, innate immune system, and an adaptive-like immune system (but evolved separately)
What are mechanisms for simple cell-cell communication?
- cytoplasmic exchanges of diffusible chemicals (gap junctions/plasmodesmata)
- receptor/ligand interactions on cell surface
What is the stimulus for activation of the HPA axis?
Stress or prolonged activity
Compare Anabaena and C. watsonii in terms of their mechanisms of protecting nitrogenase enzymes from contact with oxygen.
- anabaena separates in space by housing nitrogenase in specialized heterocyst cells which perform respiration but not photosynthesis to act as a respiratory shield
- C. watsonii separates in time by fixing nitrogen at night and doing photosynthesis during the day, and they same machinery is recycled to make both so they never occur at the same time
Name three differences between hemoglobin and myoglobin.
myoglobin has no cooperative binding, hyperbolic binding curve, found in muscle cells, only one protein subunit, higher O2 affinity so functions for oxygen storage
hemoglobin has cooperative binding, sigmoidal binding curve, found in red blood cells, has 4 protein subunits (tetramer), lower O2 binding affinity so functions for oxygen transport and delivery to cells
What are the three methods the body uses to recognize infection? Which immune systems do they activate?
- tissue damage, DAMPs are recognized and the innate immune system is activated
- microbial patterns are recognized as PAMPs, innate immune system activated
- non-self epitopes are recognized, adpative immune system activated
Compare lipophilic and hydrophilic hormones.
- lipophilic hormones travel in blood bound to transport proteins, diffuse across membranes of target cells and bind receptors in the cytoplasm or nucleus
- hydrophilic hormones travel freely in blood and bind to cell-surface receptors, activate intracellular cascades
Name 3 physiological effects of T3. (Bonus 100 if you can name what type of hormone T3 is)
Increase basal metabolic rate, increase protein synthesis, increase growth, increase body temperature, increase fat mobilization
T3 is an amine hormone!
Describe the importance of carbon concentrating mechanisms, and give 2 examples.
Carbon concentrating mechanisms are important to reduce photorespiration. Rubisco is a slow enzyme and has low affinity to bind CO2, so you need a high concentration to make the reaction run efficiently. Some examples are carboxysomes in cyanobacteria, pyrenoids in algae, or biological mechanisms by space and time in C4 and CAM plants
What allosteric regulators increase the amount of oxygen that is released to metabolically active cells?
pH (H+ ions), CO2, and 2,3-BPG
How does the adaptive immune system generate a large diversity of recognition receptors?
uses somatic DNA recombination to develop many B and T cells and antibodies with many shapes and binding specificity
Describe the pathway of a hormone which binds a GPCR and activates Ca++ as a second messenger.
GPCR activates a G protein, alpha subunit separates and activates phospholipase C, which cleaves PIP2 into IP3 and DAG, IP3 binds receptor on ER to open calcium channels, calcium flows into cell and activates various proteins to initiate cellular responses
Describe how insulin and glucagon regulate blood glucose levels through two negative feedback loops.
When blood glucose is high, insulin is secreted from beta cells of the pancreas. It signals cells to transport glucose into cells and for liver cells to store glucose as glycogen. This decreases blood glucose. When blood glucose is low, glucagon is secreted from alpha cells of the pancreas. It signals breakdown of glycogen in liver cells and release of glucose into blood. This increases blood glucose.
What makes nitrogenase such a remarkable enzyme? (why is it hard to break diatomic nitrogen? compare to human process)
It is able to break apart the very strong triple bind between the nitrogen atoms. The Haber-Bosch process is equivalent and this requires extremely high pressure and temperature to achieve the same reaction diazotrophs can do at room temp and atmospheric pressure with 16 ATP.
What adaptations in bird lungs make them more efficient at delivering oxygen to cells? Why are these adaptations important?
Unidirectional air flow through lungs prevents mixing of old and new air, cross-current exchange between blood capillaries and air capillaries to increase surface area for exchange
these are important bc birds fly at high altitudes where there is less oxygen in the atmosphere
How does the CRISPR Cas9 system function as an antiviral system in bacteria?
- bacteria captures pieces of the invading bacteriophage into CRISPR locus
- CRISPR locus transcribed into RNA, integrated into Cas 9 protein
- surveillance and DNA cleavage by RNA-mediated homology
How does auxin lead to phototropism in plants?
Auxin is distributed away from light, stimulates proton pumps in plasma membrane to pump protons from cytoplasm into cell wall, low pH activates expansin enzymes which loosen cellulose, cells swell and elongate so plant bends toward the light
Describe the pathway of the Growth Hormone axis, including all glands and hormones and their effects.
Hypothalamus secretes GHRH, anterior pituitary releases GH, GH travels to liver and other tissues and causes IGF-1 release, which acts on muscle and bone to increase growth (cartilage formation, skeletal growth, increased protein synthesis, cell growth and proliferation). GH also acts directly to increase fat breakdown and release, and on carbohydrate metabolism to increase blood glucose