oceanography: marine biology notes - sewell's science...

Oceanography: Marine Biology Notes

A Brief Introduction to

BIOLOGY

The Essential Building Blocks of Life

• Just like water is a molecule, there are other molecules important to life.

• Four organic (contain carbon, hydrogen and oxygen) molecules make up living organisms:

– Carbohydrates

– Proteins

– Lipids

– Nucleic acids


• Carbohydrates:

– Made of carbon, hydrogen and oxygen at a 1:2:1 ratio (example: glucose is C6h12O6).

– Most carbohydrates are used for energy for organisms.

– Some are used to store energy to be used later (like starch found in plants and some algae.

– Some are used in structure such as chitin found in the shells of some animals (like crabs, lobsters and shrimp) or cellulose found in plants.


• Proteins: – Composed of smaller units known as amino acids

– Enzymes are specialized proteins necessary for chemical reactions in an organism

– Some proteins are hormones that act as chemical messengers within an organism

– Others can be used in structure, immunity, internal transport among other duties

Enzymes_and_Coenzymes.asf


• Lipids: – Lipids are mainly hydrophobic (do

not mix with water – remember the saying that oil and water don’t mix).

– Due to this principle, many marine organisms use a coating of lipid to cover fur or feathers which provides an insulating layer.

– Some also have a layer of lipid (fat) underneath the skin for insulation.

– Many lipids are used for energy storage within an organism.

– They can also be used for internal structure or as hormones.


• Nucleic Acids:

– Made of smaller units called nucleotides.

– DNA and RNA are nucleic acids.

– DNA is the molecule of heredity; it provides the instructions for making every part of an organism.

– RNA helps with this duty in multiple ways.

Energy and Life • Many organisms use sunlight to

drive the process of photosynthesis.

• In photosynthesis, plants, algae and other autotrophs use pigments to capture the energy in sunlight.

• This energy is used to build carbohydrates.

• The source of carbon for building carbohydrates is carbon dioxide; oxygen is released as a by-product

Cellular_Energy__Photosynthesis.asf

Energy and Life

• Whether an organism makes their own carbohydrates (autotrophs) or gets carbohydrates by eating other organisms (heterotrophs), they still must break down the carbohydrates within their cells for energy.

• This process is known as cellular respiration.

• Respiration consumes oxygen and produces carbon dioxide and water as by-products.

Energy and Life

• Some of the carbohydrates made by photosynthetic organisms are converted into other types of molecules such as:

– Proteins

– Lipids

–Nucleic acids

Energy and Life

• When these autotrophs make more energy than they can use, the excess is called primary production

• Organisms responsible for this primary production are called primary producers

• Marine organisms are a major source of worldwide primary production

Energy and Life

• Marine organisms require nutrients to convert carbohydrates to other types of molecules

• These nutrients can include minerals, vitamins and even raw elements

• Ex: silica is required to make the shell of some organisms

Types of Organisms

• All living organisms can be divided into two basic groups based on cellular composition:

1. Prokaryotic

2. Eukaryotic

Types of Organisms

• Prokaryotic Organisms:

– Lack a nucleus

– Posses ribosomes

– Contain a circular ring of DNA

– Some may also have plasmids, extra pieces of DNA

– Cell wall is normally present

– May have a flagellum

– Unicellular

Types of Organisms

• Eukaryotic Organisms

– Possess DNA enclosed inside a nucleus

– Posses many specialized organelles (look at organelles in Fig. 4.8)

– Eukaryotic organisms can be unicellular or multicellular

Example Organelles in Eukaryotic Organisms

• Mitochondria- site of cellular respiration

• Golgi complex and endoplasmic reticulum- manufacture, package and transport cellular products such as proteins (Vesicles – transport things from one place to another.)

• Ribosomes- manufacture proteins

• Chloroplasts- site of photosynthesis

• Vacuole- storage of water and nutrients

• Centrioles- assist in movement of chromosomes during cellular reproduction

Levels of Organization in Living Organisms

• Atom – fundamental unit of all matter

• Molecule – two or more atoms chemically joined together


• Organelle – specialized features of cells

• Cell – basic unit of life


• Tissue – group of cells functioning as a unit

• Organ – many tissues arranged into a structure with a specific purpose in an organism


• Organ system – group of organs that work together

• Whole organism (individual)


• Population – group of organisms of the same species occurring in same habitat


• Community – all species that exist in a particular habitat (ex: all the organisms on a coral reef)

• Ecosystem – combination of the community and the physical environment

Diffusion and Osmosis

• Solutes (substances dissolved in water) will move from areas where they are more concentrated to an area where they are less concentrated

• This movement is called diffusion

• Movement of water from an area where it is more concentrated to an area where it is less concentrated through a semipermeable membrane is called osmosis.

Diffusion and Osmosis

• Since marine organisms live in a very solute-rich environment, they have a tendency to gain solutes and lose water

• This can result in the death of cells if the water loss/solute gain is significant

• These organisms must find ways to deal with this diffusion and osmosis

Regulation of Solute/Water Balance

• Osmoconformers-

– Do not attempt to control solute/water balance

– Their internal concentration varies as the salinity in the water around them changes

– Most can only tolerate a very narrow range of salinity

Regulation of Solute/Water Balance

• Osmoregulators

– These organisms control their internal concentrations

– Can generally tolerate a wider range of salinities than osmoconformers

– This can be done in a variety of ways such as secreting very little urine or using specialized glands to secrete salts.

OSMOREGULATORS

Assignment • Go to www.cellsalive.com/

– In the left-hand column labeled “Interactive,” click “Puzzles”

– On the “Cells Alive! Puzzle Page,” complete both “Animal Cell” and “Plant Cell” Jigsaw puzzles.

http://www.cellsalive.com/

Temperature Control

• Ectotherms

– Generate body heat metabolically, but cannot maintain constant internal body temperature

– Examples: snakes, lizards, frogs, insects

• Poikilotherms

– Body temperature mimics the surrounding environment. They do not use their metabolisms to heat or cool themselves.

– Many ectotherms are poikilotherms.

– Examples: fish, reptiles

Temperature Control • Endotherms

– Generate body heat metabolically and body temperature does not match the temperature of the surrounding environment

– All birds and mammals

• Homeotherms

– These organisms retain metabolic heat and can control metabolism to maintain a constant internal temperature

– Homeotherms are endotherms

Modes of Reproduction

• Asexual reproduction

– Does not involve mating of two individuals

– Young are produce by a single parent organism

– The young produced are genetically identical to the parent


• Examples of Asexual Reproduction

– Fission – the splitting of one organism into two smaller organisms of equal size

– Budding – the organism develops buds (small clones) that eventually break off and become another organism

– Vegetative reproduction – a plant reproduces new individuals by sending an underground stem (rhizome) sideways from which new plants will sprout


• Sexual reproduction

– Normally involves two individuals

– Parent individuals produce gametes (eggs or sperm) that unite to produce a new, genetically unique individual

– Ovaries are the organs that produce eggs

– Testes are the organs that produce sperm

Modes of Reproduction • Many marine organisms release their eggs and

sperm directly into the water, this is known as broadcast spawning.

• For broadcast spawning to be effective, millions of gametes must be released into the water at roughly the same time to ensure fertilization will occur

• Many broadcast spawning species time the release of their eggs to tides, moon phase, water temperature, etc. to ensure success


• Other marine organisms rely on internal fertilization, where a copulatory organ is used to insert sperm directly into the female’s reproductive tract

• This method requires contact between parent individuals, but less gametes are required for success

Modes of Reproduction • Hermaphrodites – individuals that have male

and female reproductive tissues either simultaneously or at different phases during the life. Examples: – Protandry- an individual spends the first portion

of the life as a functional male then becomes a female later in life after some cue initiates the change

– Protogyny- an individual spends the first portion of the life as a functional female then becomes a male later in life after some cue initiates the change

Evolution and Natural Selection

• Evolution is defined as a change in the genetic make-up of a population over time

• In the wild, any genetically derived traits (such as faster swimming, variations in coloration or above-average intelligence) can give one individual survival advantage over others in their population.

Evolution and Natural Selection • These advantages can be translated into

reproductive advantage as well.

• If one organism is better survivor, more of their gametes will make it into the next generation in a population.

• Those individuals that are less advantaged may not survive to reproduce or will reproduce less.

• This is known as natural selection.

Evolution and Natural Selection

• Natural selection therefore strengthens the gene pool of a species by eliminating less advantageous traits through lack (or reduction) of reproductive events in these individuals.

• It is crucial to understand that the pressures that influence natural selection are primarily environmental. NS does not have an intended goal – other than survival.

Taxonomy

• Taxonomy is the science of classifying and naming organisms.

• This classification is done by a variety of methods including DNA and protein analysis, comparing embryos, looking at the fossil record and comparing internal and external body structures.

Taxonomy

• Taxonomy uses several levels of classification shown below from the largest (most species inclusive) to the smallest (only one species):

• Domain Kingdom Phylum Class Order Family Genus Species

Taxonomy

• There can be millions of different organisms in a domain or kingdom, while a species by definition is just one type of organism.

• So, what defines a species? Common characteristics and the ability to breed successfully with other members of their species (biological species concept)

• For example, there are 7 species of flounder (fish) that exist in the southeast U.S. No matter how much they look alike, they cannot breed with each other and produce viable (functionally reproductive) offspring (reproductive isolation).

Phylogenetics

• Phylogenetics is defined as the study of evolutionary relationships (relatedness) in organisms.

• Biologists may use many factors to determine the relatedness of organisms such as structure, reproductive patterns, embryological or larval development, fossils, behavior or DNA/RNA.

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