DOC PREVIEW
Mizzou BIO_SC 1010 - Exam 3 Study Guide

This preview shows page 1-2-3-4-5-6 out of 17 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 17 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Bio Sc 1010 1st EditionExam # 3 Study Guide Lectures: 14 - 18Staphylococcus Aureus• S. aureus is a bacterium that can be passed from person to person• Staph bacteria are harmless to most people who carry them• Between 30% and 40% of the population carries staph on their skin or in their noses• About 1% of the population carries drug-resistant strains of staph • Healthy people: staph infection causes only minor skin eruptions-boils or pustules that can resemble spider bits• People with weakened immune systems are at especially high risk of developing diseases-pneumonia-infections of the bloodstream-infections of surgical wounds caused by staph• In recent years there have been several cases of healthy people becoming severely ill from MRSA infection -infected by a strain of drug-resistant staph Stopping Superbugs• Because the over-use of antibiotics• Bacterial populations evolve antibiotic resistance • The best way to control resistance is to change practices that enable resistant strains to thrive Antibiotics• Are chemicals that either bacteria kill or slow their growth by interfering with the function of essential bacterial cell structures Acquiring Resistance• Random mutations create new alleles and generate genetic diversity• Bacteria can acquire mutations when their DNA replicated during reproduction• Bacteria reproduce asexually• Binary fission- a type of asexual reproduction in which one parental cell divides into two• Asexual reproduction does not require a partner• Each time DNA is replicated, there is a chance that genetic mutations will occur -new alleles carried into each daughter cell• Bacteria reproduce much more rapidly than other organisms-accumulate mutations at a relatively high rate • A bacterium can also acquire new alleles through gene swapping-swap pieced of DNA with other bacteriaHow Populations Evolve• A population is a group of organisms of the same species living together in the same geographic area • An entire population of organisms with a new trait can arise only when the environment favors that trait -carrying the specific trait is advantageous • Evolution- change in allele frequency in a population through time• Change through time• Population’s environment favors some traits over others• Frequencies of the alleles that code for those traits in the population change over time• Fitness- an organism’s ability to survive and reproduce in a particular environment• The greater an organism’s fitness, the more likely that alleles carried by that organism will be passed on to future generations• When natural selection favors some traits over others, the population shows adaption• Differential survival and reproduction of individuals within a population in response to environmental pressure is known as natural selection• Natural selection occurs in populations, not individuals • Individual organisms do not experience a change in allele frequencies over time• Organisms can be fit in one environment and not in anotherNatural Selection Occurs in Patterns • Scientists have defined three patterns of selection• Directional selection occurs when organisms with phenotypes at one end of a spectrum are favored by the environment• Stabilizing selection occurs when organisms with phenotypes near the middle of the phenotypic range of variation are favored by the environment• Diversifying selection occurs when organisms with phenotypes at both extremes of the phenotypic range of variation are favored by the environmentCharles Darwin• In 1859, published On the Origin of Species by Means of Natural Selection• In the Origin of Species Darwin introduced the concepts of evolution and natural selectionMost Scientists had a different view of life• Earth held unrelated and unchanging species.• The discovery of fossils (1700s) suggested-the Earth was very old-species could change over time.-extinctions can occurBy the 1800s New Views about Species and the History of Earth had emerged • Lamarck was one of the first to suggest that species change over time (evolution)• Lyell suggested that an old Earth had gradually changed through slow, accumulating processesDarwin’s Influences and Experiences led him to his Theory of Evolution• As a youth, Darwin spent time observing nature• His travels allowed him to compare species from different regionsDarwin began an in-depth study of Change over Time (Evolution)• Darwin spent decades reading, analyzing his specimens, and discussing ideas with colleagues• Darwin was the first to propose a mechanism to explain how species could evolve: natural selectionIn the Origin of Species Darwin made two important points 1. Modern species have descended from common ancestors (evolution)2. Natural selection is the mechanism of evolution-Darwin arrived at the idea of evolution by natural selection through several important observations and conclusionsPopulations produce more individuals than can survive• Observation: overproduction-more individuals are born than can be supported by the environment • Observation: limited resources-the amount of resources (such as food, water, shelter, sunlight) stays relatively constant Competition was a factor for all living things• Conclusion: competition-not all individuals survive and reproduce• Observation: variation-no two individuals are alike Darwin concluded that favorable variations will be naturally selected• Conclusion: natural selection-those individuals with variations that make them best suited to their environment will, on average, be more likely to survive and reproduce. Darwin concluded that natural selection can lead to evolution• Observation: heritability-the traits of an organism are likely to be passed to the next generation• Conclusion: evolution-because traits are passed from one generation to the next, and because certain members are more likely to survive and reproduce, a population will change over time, becoming better suited to its environment.Important points about evolution• Individuals don’t evolve-natural selection acts on individuals, but only populations evolve• Natural selection works with heritable traits-only genetically coded traits are subject to natural selection• Evolution does not have a goal-evolution occurs in response to local environmental conditions, not future ones.Populations and Genetic Diversity• From a genetic perspective, each population of an


View Full Document
Download Exam 3 Study Guide
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Exam 3 Study Guide and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Exam 3 Study Guide 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?