Untitled Flashcards Set

I'll create a detailed and extensive study guide covering all the topics, with explanations, examples, and relevant connections to biological concepts. This guide will provide definitions, explanations, and applications for each topic to help you prepare effectively for your midterm.

📖 Midterm Study Guide: Evolution and Cells

I. Evolution and Major Unifying Theories

1. Evolution and Cell Theory

Evolution: The process by which populations of organisms change over generations due to genetic variation, mutation, gene flow, and natural selection.

• Evolution explains the diversity of life and is supported by multiple lines of evidence (fossils, comparative anatomy, molecular biology, etc.).

Cell Theory: One of the fundamental principles of biology that states:

1. All living organisms are composed of one or more cells.

2. The cell is the basic unit of structure and function in all living things.

3. All cells arise from pre-existing cells (no spontaneous generation).

💡 Example: The discovery of microscopic cells by Robert Hooke and later studies by Schleiden, Schwann, and Virchow helped establish the modern cell theory.

2. Natural Selection

Definition: A process where organisms with favorable traits survive and reproduce, passing on these traits to offspring. Over time, this leads to adaptation and evolution.

Requirements for Natural Selection

1. Variation – Differences exist among individuals in a population (e.g., fur color in rabbits).

2. Differential survival and reproduction – Some traits provide an advantage, leading to higher survival and reproduction rates.

3. Heritability – The advantageous traits must be passed down to offspring.

🔍 Example: Peppered moths in England evolved from light-colored to dark-colored forms due to industrial pollution, as darker moths had a survival advantage against predators.

3. Evidence for Evolution

Antibiotic Resistance

• Bacteria that develop resistance to antibiotics survive and reproduce, leading to antibiotic-resistant strains.

• Example: MRSA (Methicillin-resistant Staphylococcus aureus), a superbug resistant to multiple antibiotics.

Homology

• Similar structures in different species due to common ancestry.

• Example: The pentadactyl limb in vertebrates (humans, whales, bats).

Genetic Code

• The genetic code is nearly universal, indicating a common ancestor.

Vestigial Genes

• Genes that have lost their function but are still present.

• Example: The GULO gene for vitamin C synthesis in humans is nonfunctional, whereas in most mammals, it produces vitamin C.

Convergent Evolution

• Independent evolution of similar traits in different lineages.

• Example: Wings in bats and birds; both evolved for flight but from different ancestors.

Biogeography

• Geographic distribution of species supports evolutionary relationships.

• Example: Marsupials are abundant in Australia but rare elsewhere.

Fossils & Stromatolites

• Fossil records show transitional forms.

• Stromatolites (layered rock formations) contain fossilized bacteria and provide the earliest evidence of life (~3.5 billion years ago).

II. Evolutionary History of Cells

1. Abiogenesis

• The idea that life arose from non-living matter.

• Example: The Miller-Urey experiment demonstrated that organic molecules could form under early Earth conditions.

2. Protocells & RNA World

• Protocells: Primitive cell-like structures that could self-replicate and maintain internal environments.

• RNA World Hypothesis: Suggests that RNA was the first genetic material capable of self-replication and catalysis.

3. Endosymbiogenesis (Eukaryotic Evolution)

• Theory: Mitochondria and chloroplasts originated from prokaryotic cells engulfed by a larger host cell.

• Evidence:

  • Both organelles have double membranes.

  • Both have their own circular DNA.

  • Both divide by binary fission like bacteria.

4. Multicellularity

• Evolved multiple times in different lineages (e.g., animals, plants, fungi).

• Allowed for specialized cells and increased complexity.

III. Biological Macromolecules

1. Elements Used by Living Organisms

• Major Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S).

• Trace Elements: Iron (Fe), Zinc (Zn), Iodine (I).

2. Polymers & Reactions

• Condensation Reaction: Links monomers together by removing water.

• Hydrolysis Reaction: Breaks polymers by adding water.

3. Carbohydrates

• Monosaccharides: Simple sugars (glucose, fructose).

• Disaccharides: Two sugars (sucrose, lactose).

• Polysaccharides: Long chains of sugars (starch, glycogen, cellulose).

4. Lipids

• Fatty Acids: Saturated (no double bonds) vs. Unsaturated (one or more double bonds).

• Neutral Fats (Triglycerides): Energy storage.

• Phospholipids: Major component of cell membranes.

• Steroids (Cholesterol): Hormones, membrane structure.

5. Proteins

• Amino Acids: 20 types; linked by peptide bonds.

• Four Structural Levels:

  1. Primary – Sequence of amino acids.

  2. Secondary – Alpha helices & beta sheets.

  3. Tertiary – 3D folding due to R-group interactions.

  4. Quaternary – Multiple polypeptides forming a functional protein.

IV. Prokaryotes (Bacteria & Archaea)

• Domains of Life:

  • Bacteria: Peptidoglycan cell walls.

  • Archaea: Unique membrane lipids, extreme environments.

1. Bacteria Properties

• Nucleoid: Region with DNA (no nucleus).

• Plasmid: Small circular DNA with extra genes.

• Cell Wall:

  • Gram-Positive: Thick peptidoglycan.

  • Gram-Negative: Thin peptidoglycan, outer membrane.

2. Reproduction

• Binary Fission: Asexual reproduction.

V. Eukaryotic Cell Structure

1. Organelles & Functions

• Nucleus: Stores DNA.

• Ribosomes: Protein synthesis.

• ER & Golgi: Protein/lipid processing.

• Mitochondria & Chloroplasts: Energy production.

VI. Metabolism & Thermodynamics

• Catabolic: Breaks down molecules (exergonic).

• Anabolic: Builds molecules (endergonic).

• ATP: Main energy carrier.

VII. Enzymes & Regulation

• Function: Lower activation energy, speed up reactions.

• Cofactors & Coenzymes: Assist enzyme activity.

• Inhibitors:

  • Competitive: Binds active site.

  • Non-Competitive: Alters enzyme shape.

  • Feedback Inhibition: End product inhibits an earlier step.