Marine Ecosystems and Biochemical Functions

Wandering Albatross

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Procellariiformes
• Family: Diomedeidae
• Genus: Diomedea
• Species: D. exulans

Fundamentals of Biology

• FNR 201: Marine Biology

Sunlight in Ecosystems

• Sunlight is the initial energy source in most ecosystems.

Photosynthesis

• Sunlight fuels photosynthesis in organisms.
• Chlorophyll captures solar energy.
• Carbon dioxide (CO2) and water (H2O) are transformed into glucose (C6H12O6), an organic compound.
• Oxygen (O2) is released into the environment.
• Chemical energy (ATP) is stored.
• Seaweed is an example of an organism involved in this process.

Macromolecules

• Macromolecules are large molecules with many atoms.
• Four major classes:
  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic Acids

Carbohydrates

• Translation: "Carbon water"
• Composed of C, H, and O in a 1:2:1 ratio.
• Referred to as sugars.
• Monosaccharides: Simple sugars (e.g., glucose) are a basic fuel source for cells.
• Disaccharides: Two monosaccharides linked together. (e.g., sucrose = glucose + fructose) used in transport in marine plants.
• Polysaccharides: Chains of monosaccharides (3+). Polymers, molecules with repeating units. (e.g., glycogen).
• Glycogen: Multi-branched polysaccharide of glucose, used for energy storage in animals, fungi, and bacteria.
• Other polysaccharides include starches, cellulose, and chitin.
  • Starches: Easily separated glucose chains, stored energy in plants, algae, and microorganisms.
  • Cellulose: Glucose chains resistant to separation, part of cell walls.
  • Chitin: Modified glucose chain, resistant to separation, part of invertebrate exoskeletons.

Lipids

• Includes fats, oils, and waxes.
• Composed primarily of carbon and hydrogen (C & H).
• Triglycerides: Simple fats, store energy, provide insulation, and buoyancy.
• Steroids: Chemical messengers in animals.
• Waxes: Protective coatings on plant surfaces, but also present in some animals.
• Excess glucose is converted to fats when glycogen stores are full.

Proteins

• Polymers of amino acids.
• 20 different amino acids exist in living organisms.
• Polypeptides: Chains of amino acids coiled and folded into complex, three-dimensional protein molecules.
• Functional roles:
  • Structural components of animal muscles and connective tissues.
  • Enzymes: Catalysts for chemical reactions in organisms.
  • Chemical transport or storage (e.g., hemoglobin).

Nucleic Acids

• Nucleic acids are polymers of nucleotides.
• Nucleotides = monosaccharide + nitrogen base + phosphate group.
• Two types:
  • DNA
  • RNA

DNA

• Deoxyribonucleic acid; a double-stranded helix.
• Contains:
  • Deoxyribose (sugar)
  • A phosphate group
  • Nitrogen base (adenine, guanine, cytosine, or thymine)
• Genes: Instructions for protein synthesis.

RNA

• Ribonucleic acid, usually single-stranded.
• Contains:
  • Ribose (sugar)
  • A phosphate group
  • Nitrogen base (adenine, guanine, cytosine, or uracil)
• Evolves specific roles in cells. Roles include:
  • Protein synthesis
  • Messengers (mRNA)
  • Translators (rRNA)

Protein Synthesis

• Central dogma: DNA → RNA → Protein, a process that occurs in cells.
• Transcription and RNA splicing occur in the nucleus.
• mRNA is exported to the cytoplasm.
• Translation occurs in the cytoplasm.

Levels of Organization

• Cell: The smallest living unit. Contains DNA, a cell membrane, etc.
• Tissue: Groups of cells working together on a specific task.
• Organ: Two or more tissues interacting to perform a task.
• Organ System: A group of organs working together to carry out a specific task.
• Multicellular organism: Individual made of multiple tissues, organs, and organ systems.

Cells

• Basic units of living organisms.
• Prokaryotic cells
  • Lack a nucleus and membrane-bound organelles.
  • Bacteria and Archaea.
  • Contain a circular ring of DNA.
  • Unicellular.
• Eukaryotic cells
  • Have a nucleus and membrane-bound organelles.
  • Eukaryotes may be unicellular (e.g., yeasts) or multicellular (e.g., humans).

Organelles in Eukaryotic Organisms

• Nucleus: Contains chromosomes (with DNA).
• Mitochondria: Site of cellular respiration.
• Golgi complex: Manufactures, packages, and transports cellular products (e.g., proteins).
• Ribosomes: Site of protein synthesis.
• Chloroplasts: Site of photosynthesis.
• Vacuoles: Storage of water and nutrients.

Osmosis

• Diffusion of water across a selectively permeable membrane, from high water concentration to low.
• The movement of water.
• Water flow can affect cells depending on concentration of water.
• Important for homeostasis.

Osmoregulation - Freshwater Species

• Blood plasma salt concentration higher than the surrounding freshwater.
• No drinking.
• Large urine volume.
• Salts lost via diffusion.
• Salts obtained through active transport, and by feeding.

Osmoregulation - Marine Species

• Blood plasma salt concentration lower than the surrounding seawater.
• Drink large volumes of seawater
• Conserve water by producing small volume of urine.
• Salts actively transported out of gills.

Salt Excretion

• Salt glands in certain animals for excess salt excretion.

Endothermy

• Classification of animals by their response to changes in external temperature.
• Homeotherms maintain stable internal temperatures.
• Endotherms generate metabolic heat to maintain internal temperature.
• Ectotherms' temperature varies with external temperature

Biological Classification

• Dear King Philip Came Over For Good Soup (taxonomic hierarchy) to classify organisms into domains, kingdoms, phyla, classes, orders, families, genera, species.
• Example organisms/species classified using the mentioned hierarchy is listed.

Domains

• Prokaryotes: Bacteria and Archaea
• Eukaryotes: Animals, Fungi, Plants and Protists.

Ecology

• Ecology: The scientific study of interactions between organisms and their abiotic environment.
• Oikos (house) + Logos (study), or the study of our house.

Populations

• Population: A group of individuals of the same species that live in the same place and interact.

Interactions Among Organisms

• Competition
  • Intraspecific: Among members of the same species.
    • Factors affected are birth rate, mortality rate, and growth rate.
    • Responses to intraspecific competition include: social hierarchies and territory.
  • Interspecific: Between members of different species.
    • Factors affected are growth rate, reproduction and survival
• Predation: A biological interaction where the predator feeds on its prey (predator, prey).
• Symbiosis: a close relationship between two species.
  • Mutualism: Both species benefit.
  • Commensalism: One species benefits, and the other species is neither harmed nor helped.
  • Parasitism: One species (parasite) benefits, and the other species (host) is harmed.