Unit 3

• Binary fission is a type of asexual reproduction in which one parent cell divides into two
• Due to binary fission, bacteria can reproduce and mutate quickly.
• Resistant bacteria can pass down their resistant genes to offspring or undergo gene transfer.
• Gene transfer is the process by which bacteria exchange segments of DNA between each other.
• A population is a group of organisms of the same species living together in the same geographic area.
• Evolution is the change of allele frequencies in a population over time.
• Fitness is the relative ability of an organism to survive and reproduce in a particular environment.
• Natural selection is the greater survival and reproduction of individuals with certain traits in a particular environment that leads to changes in allele frequencies in a population over time.
• Adaptation is the process by which populations become better suited to their environment as a result of natural selection.
• Directional shift is when organisms with phenotypes on one end of the spectrum are favored by the environment.
• Stabilizing selection is when organisms near the middle of the phenotypic range are favored by the environment.
• Diversifying selection is when organisms with phenotypes at both extremes of the spectrum are favored by the environment
• Diversifying, stabilizing, and directional selections are all examples of what?

  natural selection
• What are strains that are especially resistant and lethal referred to as?

  superbugs
• In communities with rampant antibiotic use, resistant strains of bacteria may become more prevalent.
• MRSA stands for methicillin resistant Staphylococcus aureus, which are especially lethal. Many people are colonized, but not infected by it.
• Bacteria colonize when they exist on a person, but haven’t infected them.
• An infection is when bacteria comes in contact with a wound and bypasses the natural protection of skin.
• A strain is a genetic subtype of a microorganism which can differ in genetic makeup, the symptoms they produce, and their lethality/severity.
• What are the two classes of antibiotics?

  beta lactum, non beta lactum
• Beta-lactum antibiotics interfere with the bacteria’s ability to synthesize cell walls.
• Non beta-lactum antibiotics treat bacteria resistant to antibiotics
• What are the three phenotypes of bacteria in terms of survival?

  Antibiotic sensitive bacteria, moderately antibiotic-resistant bacteria, and highly antibiotic-resistant bacteria.
• Descent with modification is evolution via natural selection. It measures the changes within a population over time.
• Fossils form when organisms are trapped, buried, or frozen, and the normal decay of remains is prevented.
• Organisms may be buried in sediment layers or by freezing/drying out to form fossils.
• Direct dating of fossils is done through radiometric dating.
• An isotope is a form of an element with a differing number of neutrons and protons.
• In radioactive decay, unstable isotopes break down into other elements.
• Over time, the ratio of what to stable elements is used to directly determine the age of fossils?


  isotopes
• Relative dating of fossils uses sedimentary rocks that form layers as materials settle over time.
• Which type of species is especially rare to find fossilized?

  transitional
• Homology is the anatomical, developmental, or genetic similarity among organisms due to a common ancestry.
• Vestigial structures are those that serve no purpose, but are derived from an ancestor that originally had the function.
• List the two forms of evidence for evolution.

  vestigial structures, fossils
• Which type of homology observes the similar structures of animals originating from a common ancestor?

  anatomical
• Which type of homology observes the similar embryologic structures in different animals?

  developmental
• What type of homology states that all living things use the same genetic code, evidencing that all organisms share a common ancestor?

  genetic
• All humans are part of the same species, and are 99.9% identical.
• Melanin is the pigment produced by the skin, and melanocytes are cells that contain it.