Transcript Water

Fundamentals
of
Biology
Shark embryo, Squalus acanthias
What does it mean to be alive??
• You may find that your definition, or view, of
life differs radically from your neighbor’s.
• You wouldn’t be alone there. Most
scientists can’t agree on it either!
• Today’s material will cover the basics of
biology.
What Scientists Do Agree Upon
• Life uses energy for metabolism
• Life maintenances itself (homeostasis).
• Life grows
• Life reproduces
• Life reacts to changing conditions
• Life finds a way!!
What does it take?
• If you are trying to determine what it takes
to be alive what would you do?
• Water would be a good starting point.
• Most organisms are composed largely of
water.
Where to go next?
• Organic molecules also play a major role
in life processes.
• Organic molecules are those which
contain a source of carbon (except CO2
which is still considered inorganic),
hydromen, and oxygen.
• Most of these simple
organic molecules
are organized into more
complex molecules
such as proteins,
carbohydrates,
and lipids (fat).
• This is done in order to
manipulate energy stored
within the molecules.
Just imagine how much energy is stored in this whale
blubber (fat).
• Conversely, equal
amounts of energy may
be stored within the cellulose
walls of this giant kelp in the form
of carbohydrates (sugar).
• Carbohydrates are common in
the marine environment for energy
and for structure.
• They are also found inside and
outside of animals (chitin in shells).
•Other organic compounds of
great importance are proteins.
•Proteins consists of
amino acids which
contain nitrogen.
• Proteins are used as
building blocks for
tissues such as
muscles and nerves.
•They are also used for
hormones…
…and even antifreeze!
Other necessities…
• In addition to proteins,
carbs., and lipids,
organisms rely on DNA,
RNA, and ATP to transfer
genes, build proteins, and
store energy,
respectively.
• ATP is extremely
important because it
serves as “energy
currency” for most cells.
Most energy used by organisms originates from photosynthesis.
• Photosynesis makes it
and respiration takes it!!
• Each process is
essentially the reverse of
the other.
Photosynthesis and respiration
combine to facilitate
primary production.
Primary producers are
photosynthetic organisms for
the most part.
Each relys on Nitrates (NO3-1),
phosphates (PO4-2), and
occasionally silica (SiO2).
Cells, or the basic unit
of life, contain a nucleus,
and various cellular
organelles which carry
out cell specific functions.
In addition to the
organelles listed certain
bacteria also contain
motility structures called
flagella or cilia.
Sometimes, all you need in life is one cell, especially
if you’ve got 10,000 buddies just like yourself!!
(The first labor unions???)
Challenges to life!
Introduction
• Maintaining steady-state equilibrium in the
internal environment of aquatic and marine
organisms is challenging.
• Much is done involuntarily (hormones, enzymes,
osmoregulation, etc.) so little physical action is
required, however…
• “Pick-up-and-move” still an option!
(Poor environment.)
Definitions
• Homeostasis = maintaining steady state
equilibrium in the internal environment of an
organisms
• Solute homeostasis = maintaining equilibrium
with respect to solute (ionic and neutral solutes)
concentrations (i.e. salts)
• Water homeostasis = maintaining equilibrium
with respect to the amount of water retained in
the body fluids and tissues
Osmoregulation in different
environments
• Challenge to homeostasis depends on
– Solute concentration of body fluids and
tissues…
– …concentration of environmental solutes
• marine: ~34 ppt salinity = 1000 mosm/l
• freshwater: < 3 ppt salinity = 1 - 10 mosm/l
Osmoregulation in different
environments
• Each species has a range of environmental
osmotic conditions in which it can function:
– stenohaline - tolerate a narrow range of
salinities in external environment
– euryhaline - tolerate a wide range of salinities
in external environment
• short term changes: estuarine - 10 - 32 ppt,
intertidal - 25 - 40
• long term changes: diadromous fishes
(salmon)
Four osmoregulatory strategies in fishes
1. Isosmotic (nearly isoionic, osmoconformers)
2. Isosmotic with regulation of specific ions
3. Hyperosmotic (fresh H20 fish)
4. Hyposmotic (salt H2O fish)
Osmoregulation Strategies
Osmoconforming (no strategy) Hagfish internal
salt concentration = seawater. However, since
they live IN the ocean....no regulation required!
Osmoregulation Strategies
Elasmobranchs (sharks, skates, rays, chimeras)
–
Maintain internal salt concentration ~ 1/3 seawater,
make up the rest of internal salts by retaining high
concentrations of urea & trimethylamine oxide
(TMAO).
–
Bottom line…total internal osmotic concentration
equal to seawater!
–
How is urea retained?
•
Gill membrane has low permeability to urea so it is
retained within the fish. Because internal inorganic
and organic salt concentrations mimic that of their
environment, passive water influx or efflux is
minimized.
Osmotic regulation by marine teleosts...
–
–
–
–
ionic conc. approx 1/3 of seawater
drink copiously to gain water
Chloride cells eliminate Na+ and Clkidneys eliminate Mg++ and SO4=
advantages and disadvantages?
Saltwater teleosts:
active tran.
passive diff.
H2O
drink
Na+, Cl-
Na+,
Cl-
Mg++, SO4=
Na+, Cl-
Mg++, SO4=
chloride cells
kidneys
Osmotic regulation by FW teleosts
–
–
–
–
–
Ionic conc. Approx 1/3 of seawater
Don’t drink
Chloride cells fewer, work in reverse
Kidneys eliminate excess water; ion loss
Ammonia & bicarbonate ion exchange mechanisms
advantages and disadvantages?
Freshwater teleosts:
active
passive
don’t
drink
H2O
Na+, Cl-
Na+, Cl-
Ion exchange
pumps; beta chloride cells
water
kidneys
Thermoregulation in Fishes
Temperature is always an issue.
It affects metabolism, digestion, and reproductive behavior
Fish are conformers (well, sort of...)
• Body temperature is that of the environment
(poikilothermic ectothermy)
• Each species has particular range of
temperatures that they can tolerate and that
are optimal
• Big difference!
Behavioral Thermoregulation in Fishes
• Although fish are ectotherms, they can
alter their body temperature by moving to
habitats with optimal temperature
• Some fish can maintain body temperature
greater than ambient - tunas, billfishes,
relatives (nearly endothermic)
Hot Fishes
• Billfishes have warm brains – excess heat
production from muscles around eye
Size matters...when you’re small!!!
Animals with high surface-to-volume ratios don’t hold heat.
• “Floyd, I am soooooooo tired, how long can this
go on?
-Heavy Metal (80’s)
• “Life moves pretty fast, if you blink you just might
miss it.”
-Ferris Buhler’s Day Off (90’s)
Budding in coral allows multiple replications of the same entity.
Since coral uses itself as a template, this is a form of asexual
reproduction.
Rhizomes (runners) sent from sea grass is another
example of asexual reproduction.
Sexual reproduction: Union of two gametes.
Reproductive strategies may
involve mass production
of young…like this jawfish.
Advantage???
or single offspring with a high degree of parental care.
Next time…real animals and real names.