BIOL 1201 Lecture : BIOLOGY LECTURE Final
BIOLOGY LECTURE (FINAL EXAM) 5/8/2012 7:57:00 PM
Thursday march 29, 2012
Environment of the deep sea
• Cold, constant temperatures (0-4 degrees C)
• No sunlight
o No primary production from photosynthesis at depth
Hydrostatic pressure
• Increased 1 atm (=101.325 kPa) for every 10m increase in depth
• At the deepest 1150 atm
What is the average depth of the ocean? 3800 meters
Species depth distribution patterns
• Populations
o Narrow depth range
o Broad depth range
• Individuals
o Diurnal vertical migration
Bioluminescence
• Biologically produced light- bacterial symbionts
• Uses ATP to biochemically produce light
• Luciferin and luciferase
• Typically in the blue wavelengths
• Camouflage
o Down welling light
• Identify mates
• Distracts predators
Angular fish males are parasites. True
Predatory fish with a “sniper scope”
• Illuminate prey
• See red light to illuminate red organisms
• Predators can see in the red wavelength
Tuesday April 3, 2012
On Moodle: cell signaling folder
Communication and coordination
• Cell signaling
Cell communication
• Coordinate metabolic processes
• Receive “messengers” from both local and distant sources
o The messenger is a chemical signal
• Respond to the signal through a change in the metabolic processes
of the cell
o Changes can be relatively rapid, or very slow
o Ex: synthesis
An extracellular chemical signal
• It transduced into an intracellular response
• Communication occurs across the plasma membrane
• Extracellular signal is amplified within the cell via a signaling
cascade
Local signaling
• Paracrine
o Diffusion of “first messengers” over short distance between
cells
• Synaptic
o Chemical signals from a nerve axon diffuse across a synapse
to another nerve cell or a muscle cell
Long-distance signaling
• Hormonal signaling
o Endocrine (ductless) glands produce chemicals (hormones)
o Hormones move through the circulatory system to their
targets
Communication by direct contact between cells
• Gap junctions in animal cells
• Plasmodesmata between plant cells
• Cell recognition through surface receptors
Cell signaling
• An extracellular chemical messenger
• The extracellular first messenger is transduced (transformed) into
an intracellular chemical messenger
o Second messenger
• Elicits a metabolic change within the cell
• May involve a receptor in the plasma membrane
o An integral membrane protein
• May involve an intracellular receptor
o Ex: steroid hormone receptors
G protein- coupled signaling
• Important class of signaling
• More than 1000 different receptors in mammals
• Coupling= receptors interact with G proteins
How many different types of G protein coupled reactions are there in a
mammal? 1,000
Guanine-nucleotide- binding proteins (G proteins)
• Link an extracellular signal and an intracellular response
Before they were finally called G proteins another name win contention was:
N proteins (nucleotide binding protein)
Three components of G proteins (in signaling system)
• Receptor in the plasma membrane
• G protein on the intracellular face of the plasma membrane
• “effector” element such as an enzyme or ion channel
Membrane receptor
• Over 1000 G proteins coupled receptors (GPCRs)
• Integral membrane protein with 7 alpha helical regions spanning
the membrane (heptahelical)
• Amino terminus extracellular
• Carboxy terminus intracellular
• Activated by binding of a first messenger signal molecule
o Hormone
o Neurotransmitter
• Interacts with a G protein
Heterotrimeric G protein
• 3 subunits labeled alpha, beta, and gamma
• interacts with receptor occupied by a signaling molecule
• when activated interacts with an effector element
• associated with the intracellular face of the plasma membrane
