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Introduction to Cell Biology - Flashcards

What is Life?

  • Seven core characteristics (in the slide, listed with numbers but presented as a complete set):

    • Order

    • Reproduction

    • Growth and development

    • Energy processing

    • Regulation

    • Response to the environment

    • Evolutionary adaptation

  • Question framed: WHAT IS LIFE?

Themes of Biology

  • Organization

  • Information

  • Energy and Matter

  • Interactions

  • Evolution

Classification and Diversity

  • Domains:

    • Domain Bacteria (a)

    • Domain Archaea (b)

    • Domain Eukarya (c)

  • Typical cell size examples shown:

    • 2 \mu m

    • 100 \mu m

  • Kingdoms (within Eukarya shown):

    • Kingdom Animalia

    • Kingdom Plantae

    • Kingdom Fungi

    • Protists

  • Purpose: Classifying life

DNA is Universal

  • DNA is the chemical substance of genes; blueprint for heritable traits

  • Base letters (DNA alphabet): A, T, C, G

  • Example sequence snippet shown: A \; T \; C \; G \; C \; G \; A \; T \; A \; T \; G \; G \ldots C

  • Implication: Diversity of life arises from differences in DNA sequences

  • Note: Foundational topics will be covered in BIO 2001

DNA and Genes

  • Genes are the blueprints for proteins, the building blocks of life

  • Diversity of life arises from differences in DNA sequences

  • Core idea linking genotype (DNA) to phenotype (proteins and traits)

  • Summary line: You will cover all of these topics in BIO 2001

Evolution and Diversity

  • Evolution drives the diversity of life

  • Charles Darwin (1859): "descent with modification" (descend with modification)

  • Evolution = change over generations that is inherited by offspring of a population

  • Natural selection is one mechanism for evolution

    • Individuals that are most fit produce more offspring which share their traits

    • Those fit traits become more common over generations

  • Note: More detail to come in the next lecture

Process of Science

  • Key components of scientific method/activity:

    • EXPLORATION AND DISCOVERY

    • FORMING AND TESTING HYPOTHESES

    • SOCIETAL BENEFITS AND OUTCOMES

    • COMMUNITY ANALYSIS AND FEEDBACK

Mimicry Case Study: Coral Snake vs Scarlet King Snake

  • Eastern coral snake (venomous) vs Scarlet king snake (nonvenomous)

  • Traditional rhyme to distinguish species:

    • "Red on yellow, kill a fellow; Red on black, friend of Jack"

    • Alternative rhyme capturing variation: "Red into black, venom lack; red into yellow, kill a fellow."

  • Concept: Mimicry involves the mimic sharing a perceptual attribute with the model to avoid predation

  • Core mechanism: Selection is driven by the signal-receiver (predator)

Geographic Distribution and Mimicry Dynamics

  • Geographic distribution: eastern coral snake and scarlet king snake have partially overlapping ranges

  • Roles: venomous model vs nonvenomous mimic; predator–prey interactions influenced by geography

  • Visual of interaction: predator responds to color patterns that signal venom or nonvenom

Hypothesis in Mimicry Study

  • Hypothesis: The scarlet king snake will be preyed upon less often in regions that overlap with the eastern coral snake

  • Variables:

    • Venomous model (eastern coral snake) present vs absent

    • Mimic (scarlet king snake) vs nonmimic (plain brown)

    • Predator: real or simulated predation pressure

Experimental Design: Mimicry Study

  • Use artificial snakes (scarlet king snakes and plain brown snakes)

  • Place in areas that either contain or lack eastern coral snakes

  • Outcome measure: count the number of attacks on artificial snakes

  • Data presentation: graph the data as the percentage of total attacks on artificial snakes

Data Analysis: Mimicry Results (Presumed interpretation from slides)

  • Percent of total attacks on artificial snakes

  • In coral snake absent vs present conditions:

    • Artificial brown snakes: around 83\% and 84\% of total attacks

    • Artificial king snakes (mimics): around 17\% and 16\% of total attacks

  • Implication: Mimics experience fewer attacks than nonmimics, supporting mimicry theory under the tested conditions

Experimental Interpretation

  • Question: Can these results be extended to larger questions about mimicry and evolution?

  • Considerations:

    • Mechanisms explaining results (e.g., signal perception by predators, learning, and generalization)

    • How mimicry affects fitness and allele frequencies over generations

Was This Result Expected?

  • Revisit: The observed attack patterns (approximately 83–84% on nonmimics vs 16–17% on mimics) align with expectations of selective protection for mimics when a venomous model is present

  • The consistency of results across coral-snake present/absent conditions is discussed

Classroom Activity: YOUR Turn

  • Now it's YOUR turn!

  • Form groups of 3–4

  • Elect one person to take notes

Florida Camouflage Study: Background Information

  • Three population contexts:

    • Inland population

    • Beach population

    • Gulf of Mexico population

  • Geographic framing: Florida region with inland and coastal (beach) habitats

  • Visual map labels indicate areas: Inland population, Beach population, Gulf of Mexico

Research Question: Camouflage and Predation by Owls

  • Does camouflage protect the mouse from predation by the owl?

  • Three populations considered: Inland, Gulf of Mexico, Beach

Hypothesis (Florida study framing)

  • Not explicitly stated in the transcript, but context implies: camouflage (coloration matching habitat) reduces predation risk by owls in a given habitat

Experimental Design (Florida camouflage study)

  • Habitats considered: Inland, Gulf of Mexico, Beach

  • Model types:

    • Light models

    • Dark models

  • Treatment groups:

    • Camouflaged (control)

    • Non-camouflaged (experimental)

  • Overall design: test predation on different color morphs across habitats to assess camouflage effectiveness

Data Analysis: Predation on Models

  • Metric: Percentage of attacked models

  • Example data layout shown in the slide:

    • Habitat-specific comparisons (Beach vs Inland)

    • Models: light vs dark; camouflage status (camouflaged vs non-camouflaged)

  • Visual: graphs plotting percentage of attacks for each model type and habitat (0 to 100 scale)

Results Visualization (Beaches vs. Inland)

  • Beach habitat vs Inland habitat displays the rate of predation on light and dark models under camouflaged vs non-camouflaged conditions

  • Observed trend: camouflage generally reduces predation in the tested contexts, but specifics depend on habitat and model color

Conclusion?

  • Slide leaves the question open with a placeholder: "Conclusion?"

  • Encourages students to integrate data across habitats to draw a general conclusion about camouflage efficacy in owl predation

Evidence for Evolution Video and Homework (Course Wrap-Up)

  • Video link: https://www.youtube.com/watch?v=cC8k2Sb1oQ8

  • Homework for Friday, 8/22/2025 by classtime (2:00 pm EDT):

    • Watch the video (9:22) and take notes

    • List evidences for evolution for each of the 4 main groups (at least 2 examples per group)

    • Provide 3 facts about Charles Darwin

    • Upload to Blackboard as a Word or pdf file

    • Evidences for Evolution to cover:

    • Fossil evidence

    • Biogeographical evidence

    • Anatomical evidence

    • Biochemical evidence (includes DNA)

Evidences for Evolution (Overview)

  • Fossil evidence

  • Biogeographical evidence

  • Anatomical evidence

  • Biochemical evidence (including DNA)

  • Note: This list is framed for the homework task, and aligns with the four main groups of evolutionary evidence

Quick References and Concepts to Remember

  • DNA base pairs: A\text{-}T and C\text{-}G

  • Gene-protein relationship: Genes → proteins → traits

  • Evolutionary mechanism: Natural selection as a driver of adaptation

  • Mimicry definitions: Model, Mimic, Signal-receiver, Predator

  • Camouflage studies: Habitat-specific effectiveness of coloration in reducing predation

  • Process of science sections highlight how hypotheses are formed, tested, analyzed, and interpreted in a societal context

  • The content links foundational biology (DNA, evolution) to practical, real-world cases (mimicry, camouflage) and to the scientific method

1859 is a key year for Darwin’s theory: Darwin, C. (1859) On the Origin of Species by Means of Natural Selection

All numerical values included here are provided as figures from the transcript, for study context. If you need additional clarification on any specific figure or data point, I can extract and format it more precisely.