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Fundamentals of Biology Chapter 4 Fundamentals of Biology

Types of Organisms All living organisms can be divided into two basic groups based on cellular composition: Prokaryotic 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

Levels of Organization in Living Organisms Atom – fundamental unit of all matter Molecule – two or more atoms chemically joined together

Levels of Organization in Living Organisms Organelle – specialized features of cells Cell – basic unit of life

Levels of Organization in Living Organisms Tissue – group of cells functioning as a unit Organ – many tissues arranged into a structure with a specific purpose in an organism

Levels of Organization in Living Organisms Organ system – group of organs that work together Whole organism (individual)

Levels of Organization in Living Organisms Population – group of organisms of the same species occurring in same habitat

Levels of Organization in Living Organisms 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 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 as examples

Temperature Control Ectotherms Generate body heat metabolically, but cannot maintain constant internal body temperature Examples: fish, reptiles

Temperature Control Endotherms Generate body heat metabolically and body temperature does not match the temperature of the surrounding environment Example:mammals

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

Modes of Reproduction 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

Modes of Reproduction 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

Modes of Reproduction 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

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 or above-average intelligence) can give one individual survival advantage over others in his/her 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.

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

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.