BIO 102

The Process of Science Wrap-up/What is Life?/Introduction to Natural Selection & Adaptation

Announcements

  • PSA: Staying on Top of Your Assignments

    • Use the "To-Do" list on the Canvas landing page to keep track of assignments typically due within a week.

    • Find active assignments under the "Assignments" navigation link on the left side of your Canvas page and in the course calendar.

    • Make it a habit to log into Canvas daily for all your courses to stay updated on tasks and announcements.

  • Labs Reminder:

    • If you haven’t attended your in-person lab meeting this week, make sure to do so!

Gradebook Notes

  • The Canvas gradebook updates frequently and may not reflect your final grade accurately.

  • Some assignments will have grade drops applied later; missed days or assignments might seem more impactful than they are right now.

  • Thanks for staying engaged and on top of your work! Asking questions is encouraged.

Review Question

  • Hypothesis/Theory of Gravity Exercise:

    • Jane drops a marshmallow out a window and hits Thor in the face. Has she proven the hypothesis/theory of gravity yet again?

    • A. True

    • B. False

Daily Engagement Check

  • What is MRSA?

    • A. any infectious agent that is drug-resistant

    • B. any strain of staph bacteria that is resistant to particular antibiotics

    • C. any strain of bacteria that might cause severe illness in humans

    • D. any strain of staph bacteria that lives on the skin of humans

Last Class Review: Population Size in Colonies with and without White-Nose Syndrome (WNS)

  • Displayed a graph indicating winter counts of bats in Colony A (WNS present after 2006) and Colony B (uninfected).

  • Graph Data:

    • Year Range: 1985 to 2010

    • Count range: 0 to 700 bats

Using Science to Address Environmental Problems

  • Drafting and implementing policies is complex.

    • Precautionary Principle: acting conservatively when data are uncertain or when severe consequences are possible.

Policy and White-Nose Syndrome (WNS)

  • The decline of bats poses an environmental issue due to their ecological roles (pollination and pest control).

  • U.S. Fish and Wildlife Service (USFWS) National Plan to Combat WNS:

    • Protection lists (adding/removing bat species from the Threatened or Endangered Species List)

    • Outreach programs to educate the public on best practices for containment

    • Cave closure policies to prevent fungal spore spread

    • Disease surveillance to monitor bat health and policy adjustments

Validity in Science

  • Peer Review: Defined as the evaluation of an article by experts before publication to ensure the integrity and accuracy of the research presented. It serves to weed out sloppy or inferior research.

Historical Perspective in Science

  • Anton van Leeuwenhoek:

    • Built powerful, small microscopes that allowed him to observe human blood cells and other microorganisms.

  • October 20, 1676 Correspondence:

    • His observations of "myriad little animals" in rainwater were humorously dismissed by the Royal Society, delaying publication of his findings.

Evaluating Scientific Information

  • The ability to discern trustworthy scientific information isn’t solely on journalists and scientists; it is also a responsibility for consumers and citizens.

Types of Sources

  • Primary Source: Original data or firsthand information (e.g., scientific journals like Science).

  • Secondary Source: Presents and interprets information from primary sources (e.g., newspapers such as The New York Times).

  • Tertiary Source: Uses information from at least one secondary source (e.g., textbooks, websites).

Nutrition Overview: The New Pyramid

  • Food Groups and Servings:

    • Meat, Poultry, Fish, Dry Beans, Eggs & Nuts: 2-3 servings

    • Fruit Group: 2-4 servings

    • Vegetable Group: 3-5 servings

    • Milk, Yogurt & Cheese Group: 2-3 servings

    • Bread, Cereal, Rice & Pasta Group: 6-11 servings

Certainty in Science

  • Feedback Mechanism: Certainty in science ranges from evidence to hypotheses to scientific theories. The common public misconception is that a scientific theory is a mere guess, whereas, in science, a theory is a well-supported explanation encapsulated by extensive evidence.

Scientific Theory Definition

  • A scientific theory explains a general class of phenomena or observations supported by a wide body of evidence, contrasting the everyday use of “theory” which can imply speculation.

Properties of Life

  • All living organisms share five properties that define them as "alive":

    1. Grow:

    • Unicellular organisms increase cell size before reproduction.

    • Multicellular organisms increase by adding more cells.

    1. Reproduce:

    • Process of producing new organisms, where offspring are similar but not identical to parents.

    1. Maintain Homeostasis:

    • Stability in internal environment despite external changes.

    1. Sense and Respond to Stimuli:

    • Organisms react to environmental stimuli (e.g., moving towards food).

    1. Obtain and Use Energy:

    • Organisms require energy, sourced through food or photosynthesis.

    • Metabolism is the sum of all chemical reactions in an organism.

Properties of Life Listing

  • Key properties:

    • Order

    • Growth and Development

    • Reproduction

    • Homeostasis

    • Sense & Response to Stimuli

    • Obtain and Use Energy

    • Adaptation (evolution)

Order in Biological Systems

  • Example: A pig represents a highly organized structure consisting of cells, tissues, organs, and organ systems.

  • Each level of biological organization includes:

    • Organelles: E.g., nucleus in cells.

    • Cells and Tissues: Examples include human blood cells and skin tissues.

    • Organs and Organ Systems: Organs work together in systems, such as the digestive system.

    • Ecosystems: Comprise living organisms and their environments.

    • Biosphere: Encompasses all ecosystems on Earth.

Cells

  • All cells possess certain structures:

    • Common Traits: All cells have cell membranes, cytoplasm, ribosomes, and DNA.

    • Prokaryotic vs. Eukaryotic Structure Differences:

    • Eukaryotic cells possess membrane-bound organelles, whereas prokaryotic cells do not.

Growth and Development

  • Growth is defined as the process of increasing in size.

  • For single-celled organisms, growth occurs via increases in cell size; for multicellular organisms, it occurs via cell division leading to an organism's size increase.

Homeostasis

  • Homeostasis involves maintaining a stable internal environment.

  • Example: Oxygen levels in blood can become imbalanced due to red blood cell (RBC) count reductions which can lead to hypoxia. Kidneys release erythropoietin, stimulating RBC production to restore balance.

Response to Stimuli

  • Example of a plant responding to stimuli: Mimosa pudica exhibits rapid movement in response to touch.

Energy Processing

  • All living organisms can obtain and use energy.

  • Energy is harnessed from food or sunlight, leading to metabolism, which is the total of all chemical reactions sustaining life.

Adaptation and Evolution

  • Over time, species adapt through evolutionary processes.

The “Central Dogma” of Molecular Biology

  • Central Dogma Overview:

    • Refers to the flow of genetic information in cells from DNA to RNA to protein, highlighting the role of genetic material in evolution.

Alleles

  • Defined as alternative versions of the same gene, which influence protein functions due to differences in nucleotide sequences.

Evolution of Populations

  • A population evolves when favorable traits increase due to natural selection.

    • Phenotype: Observable characteristics determined by genotype and environmental interactions.

    • Genotype: Collection of alleles or genes inherited from parents.

Drug-Resistant Bacteria: MRSA

  • MRSA Overview:

    • Methicillin-Resistant Staphylococcus aureus is a harmful bacterium that can cause serious health issues and is resistant to standard antibiotic treatments.

    • Infection statistics: Approximately 33% of the U.S. population carries S. aureus; about 2% carry disease-causing MRSA.

    • Transmission occurs via direct or indirect contact, with athletes particularly at risk due to higher contact rates.

Antibiotic Functionality

  • Antibiotics disrupt essential bacterial cell structures, such as their ability to synthesize cell walls.

The Concept of Fitness in Evolution

  • Fitness Definition: The ability of an organism to survive and reproduce within its environment.

    • Higher fitness leads to increased allele transmission to successive generations.

    • Relative fitness refers to the comparative reproductive success between different phenotypes within a population, especially under selective pressures such as antibiotics.

Impact of Evolution on Drug Resistance

  • Resistance has developed in various organisms due to their genetic adaptability to survive chemical treatments. This includes bacteria, insects, and plant resistance to pesticides and drugs.

Today’s Objectives

  • Understand how scientific findings are validated against personal anecdotal evidence.

  • Identify and describe key properties of living organisms.

  • Explain the basic functions of DNA in relation to genotype and phenotype.

  • Outline evolutionary processes in populations.

  • Understand the concept of fitness regarding evolution.

Assigned Reading for Next Class

  • Review Chapter 13 and delve into milestones regarding evolution.

    • Explain the significance of genetic heterogeneity and allele introductions in unicellular populations.

    • Distinguish between artificial and natural selection processes.

    • Explain the types of natural selection: directional, stabilizing, diversifying, and frequency-dependent selection.

    • Discuss how sexual selection impacts patterns of natural selection.

    • Understand the genetic connections to evolutionary concepts.