Fundamentals of Biology

Challenges of life in the sea

• How to maintain suitable conditions inside organisms’ bodies?

• How to “stay” within one’s habitat?

• How to regulate temperature?

Salinity

• Diffusion presents a major problem to organisms because ions will diffuse in and out of their bodies until an equilibrium has been established.

• How does an organism maintain the right concentration of ions?

• The Cell membrane is a barrier that blocks the passage of common ions in seawater and other organic molecules.

– It is “selectively permeable” meaning only some materials, like water, O2 and CO2 can pass through, while things like ATP and proteins do not.

– Osmosis is the diffusion of water across a selectively permeable membrane.

– Active Transport is the process that opposes osmosis. Here proteins in the cell membrane pump materials in the opposite direction.

Hypertonic- more solute on outside of cell

Hypotonic- more solute on inside of cell

Isotonic- equal amounts of solute inside and outside cell

Organisms and balance• Osmoconformers change their internal

concentrations as the salinity of water changes - they must remain in a “friendly” environment – MOST freshwater fish and MOST open ocean organisms

• Osmoregulators control their internal concentrations.

- they keep the internal concentration of ions the same as what is in the water, not necessarily, the “types” of ions. – MOST marine organisms and freshwater which can handle salty concentrations…

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Regulation of salt and water balance

• Marine fishes: Water flows by osmosis from dilute body fluids to seawater. Fish drinks seawater to avoid dehydration, excreting little urine. Some salts pass through gut without being absorbed. Those absorbed are excreted in urine or through gills.

• Freshwater Fish: Tend to gain water by osmosis because the water has lower salinity. To avoid swelling, they don’t drink and they produce large amounts of urine. Salts are absorbed by gills to replace those lost in the water.

Sea Turtles have glands near their eyes that excrete excess ions, creating salty tears.

Temperature

• Metabolic reactions are faster at higher temperatures.

• Reactions double with a 10 degree rise in temperature.

• Temperature largely determines where sea creatures can live.

Organisms

• Ectotherms (coldblooded)– heat generated by metabolism is quickly lost to the environment. They are poikilotherms

• Endotherms (warmblooded) – they maintain their own temperature by controling their metabolism. Generally insulated with feathers, blubber

Marine organisms are restricted to specific regionsthat correspond to average water temperatures.

Surface to Volume Ratio

• S/V is very important! 1. Determines heat loss

2. Determines speed of exchange of gases, nutrients and waste products with environment

3. Small organisms have a larger S/V ratio than larger ones. They can rely on exchange while larger ones must develop organ systems.

Reproduction

• Individual cells reproduce by dividing and form daughter cells

1. In prokaryotes, process is cell fission

2. In eukaryotes, process is mitosis

Asexual Reproductionin plants called vegatative reproduction

1. Asexual reproduction produces exact copies of parent cell or clones.

e.g. anemones

2. In budding, parent develops small growths that break away and become individuals.

3. Plants send out runners that take root and break off.

Two identical cells created by division of one cell.Dinoflagellate :Dinophysis tripos

Sexual Reproduction

- Union of two gametes (cells), each usually from a different parent.

- Ovaries – female gonads, produce eggs (largest cells of an organism).

- Testes – male gonads, produce sperm

- Zygote – fertilized egg

- Larval stages – immature stages of an organism

Reproductive Strategies

• Broadcast spawning – millions of eggs and sperm are released into the water where fertilization occurs and they never see their offspring.

• Some species have different larval stages, others develop directly from egg to adult.

• Some reproduce asexually, some sexually, some do both.

Natural Selection and Adaptation

• The best adapted individuals are the most successful and produce more offspring. Evolution is the genetic change in the population that results because favorable charactistics are passed on to young.

• Theory of evolution was proposed by Darwin and Wallace

BroadcastSpawning

of the GiantClam

Yellow jawfish carries eggsin his mouth

until they hatch.

Building Blocks of Life

• Organic chemicals – carbon plus hydrogen, oxygen, (nitrogen)

- release energy when broken down

- organisms control this release of energy

Types of Organic Compounds

Carbohydrates- Composed of C, H and O- Simplest: glucose and simple sugars- Complex: combination of sugars in chains

Starches- Longer chains of sugars and other

components

Carbohydrate function

Important role in metabolism

Starches store energy

Provide support and protection (cellulose)

Animals use chitin, a modified carbohydrate as a skeletal material.

Proteins

• Most varied and complex organic compounds

• Composed of chains of amino acids

Protein function

• Enzymes are proteins that speed up specific reactons

• Muscles are made largely of protein

• Hair, skin and skeletons of marine animals are made of proteins

• Hormones are proteins

• Proteins act as poisons, send chemical signals, produce light

Blubber on whales are made mostly of lipids.

Lipids

• Fats, oils, waxes

• Used for energy storage

• Repel water

• Useful in buoyancy

• Hormones may be lipids or proteins

Nucleic Acids

• Chains of simple sugars joined to molecules containing P and N (nucleotides) e.g. DNA

• Sequence of nucleotides forms a code containing genetic information

• Store and transmit genetic information

• Complete genetic information of an organism - genome

Other nucleic acids

• RNA contains three chains that are similar to DNA and one that is different

• Translates genetic info in DNA into protein molecules

Photosynthesis of Kelp in sub-polar and temperate waters

Photosynthesis

• Sun’s energy is captured to make glucose

• H2O + CO2 glucose + O2

• Photosynthetic pigments (chlorophyll) absorb solar energy which converts carbon from inorganic CO2 to organic C in the process of nitrogen fixation to make glucose.

Classification of organisms

• Autotrophs - some are capable of photosynthesis e.g. Algae, plants, bacteria

• Heterotrophs – obtain energy by eating organic matter

Respirationused by auto and heterotrophs

• Cellular respiration is the reverse process of photosynthesis

• Sugars are broken down using oxygen and carbon dioxide and water are given off.

• glucose + O2 H2O + CO2

• Energy released is stored in ATP

Nutrients

• Includes minerals, vitamins and other substances

• N in the form of NO3-1 is the most

important form of N in the ocean• P in the form of PO4

-3 is needed for nucleic acids

• Silica, SiO2, , is used in making shells of diatoms, radiolarians and silicoflagellate

• Iron is also critically important

Cell organization

Cell membrane or plasma membrane isolates the gelatinous cell contents, the cytoplasm, from the world, allowing some substances to pass in or out.1. Interior membranes act as sites for photosynthesis and respiration2. Organelles are compartments that contain specialized structures3. Cytoskeleton is a framework that supports the cell, helps it move, change shape and divide

Prokaryotes

• The most ancient of cell types, the simplest and smallest cells

• Have no organelles• Are microscopic• Cell wall lies outside cell membrane• Ribosomes (made of protein and RNA) are

attached to plasma membrane• Flagella are whip like extensions that

propel cells

Eukaryotes

• More organized and complex• Nucleus contains chromosomes with DNA

holding genetic info and directing cell activities• ER (endoplasmic reticulum) and Golgi apparatus

make, package and transport organic moleclues.• Mitochondria are site of respiration• Plants have chloroplasts and cell walls• Eukaryotes have cilia (short flagella)

Animal Cell

Plant Cell

Sponges are only multicellular animalsThat are at the cellular level of organization

Levels of Organization• Unicellular – one celled (all prokaryotes and some

eukaryotes)

• Multicellular – most eukaryotes

• Cellular level of organization – each cell is independent and can perform all functions needed to sustain organism.

• Tissues – specialized groups of cells to perform certain functions

• Organs – organization of tissues to carry out certain functions. ( muscle tissue)

Levels of Organization

• Organ systems – – Digestive, circulatory, nervous and

reproductive systems contain organs that act together in a system.

• Organisms – – Individual members of a particular population

Populations, etc

• Populations are groups of organisms of the same species

• Communities are populations of different species that occur in the same place

• Ecosystems are made up of communities with the biotic and abiotic components of a specific area.

Blue mussels growing on a rocky shore in New Zealand are part of a population.

Taxonomy

• What is a species?– Organism that can reproduce with other

members and produce viable offspring

• Binomial nomenclature– Two name system to describe the scientific

name of organisms– Latin– Italicized, first name capitalized, second not

Taxonomy

• Why?– Confusion with common names– Ex: puma, mountain lion, panther, cougar– All Puma concolor

Taxonomy

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

Taxonomy

• 5 Kingdoms– Animalia– Plantae– Protista– Fungi– Monera