BIOL 411 Lecture Notes Flashcards

  • Gamete formation in human cells: Meiosis is essential for sexual reproduction, producing haploid gametes (sperm and egg cells) with half the number of chromosomes as the parent cell.

  • Contrast steps of Meiosis I & II: Meiosis I involves the separation of homologous chromosomes, while Meiosis II separates sister chromatids, similar to mitosis.

  • Crossing over during Prophase I: Genetic recombination occurs, increasing genetic diversity.

  • Nondisjunction effects on fertilization: Can lead to genetic disorders such as Down syndrome.

  • Meiosis influences on genetic diversity and evolution: Introduces genetic variation through recombination and independent assortment.

Prophase I

  • Chromosomes condense, chiasmata form: Homologous chromosomes pair up and exchange genetic material.

  • Nuclear envelope disappears: Nucleolus also disappears.

  • Meiotic spindle forms: Facilitates chromosome movement.

Crossing Over

  • Recombinant chromosomes: new allele combinations: Increases genetic diversity.

  • Random fertilization: more variant combinations: Any sperm can fuse with any egg.

  • Genetic variation: raw material for natural selection: Enables adaptation and evolution.

Metaphase I

  • Homologous pairs align at metaphase plate: Orientation is random, leading to independent assortment.

  • Microtubules attach to kinetochores: Ensures proper segregation of chromosomes.

Anaphase I

  • Homologous chromosomes separate, move to poles: Sister chromatids remain attached.

  • Sister chromatids stay attached: Important for maintaining chromosome integrity until Meiosis II.

Telophase I and Cytokinesis

  • Haploid set of chromosomes at each pole: Each chromosome still consists of two sister chromatids.

  • Each chromosome: two sister chromatids: Ready for separation in Meiosis II.

  • Cytokinesis: two haploid daughter cells: Results in two cells with half the original chromosome number.

  • No chromosome duplication between meiosis I & II: Meiosis II immediately follows Meiosis I without intervening DNA replication.

Meiosis II

  • Five phases: Prophase II, Prometaphase II, Metaphase II, Anaphase II, Telophase II & Cytokinesis.

  • Similar to mitosis: Sister chromatids separate.

Prophase II

  • Spindle apparatus forms: Prepares chromosomes for separation.

  • Chromosomes move to metaphase plate: Facilitated by spindle fibers.

Metaphase II

  • Sister chromatids at metaphase plate: Aligned for separation.

  • Sister chromatids are not genetically identical due to crossing over in meiosis I: Adds to genetic variation.

  • Kinetochores attach to microtubules from opposite poles: Ensures each sister chromatid moves to opposite poles.

Anaphase II

  • Sister chromatids separate, move to opposite poles as individual chromosomes: Completes the process of chromosome segregation.

Telophase II and Cytokinesis

  • Nuclei form, chromosomes decondense: Prepares cells for the next stage.

  • Four haploid daughter cells result, genetically distinct: Each cell has a unique genetic makeup.

Mitosis vs. Meiosis

  • Mitosis: conserves chromosome number, identical cells: Used for growth and repair.

  • Meiosis: reduces chromosome number, genetically different cells: Used for sexual reproduction.

  • Meiosis: two divisions after replication: Results in four haploid cells.

Unique Meiosis Events

  • Occur in Meiosis I.

  • Crossover in prophase I: Homologous chromosomes exchange genetic information: Results in recombinant chromosomes.

  • Alignment of homologous pairs at metaphase plate: Leads to independent assortment.

  • Separation of homologs during anaphase I: Reduces chromosome number.

Exam 1 Topics

  • Organization of Life.

  • Elements and Atoms

  • Chemical Bonds: Covalent, Ionic, Hydrogen.

  • pH Scale.

Covalent Bonds

  • Single bond: one electron pair shared.

  • Double bond: two electron pairs shared.

  • Bonding capacity (valence): number of bonds an atom can form.

Ionic Bonds

  • Formed between oppositely charged ions.

Hydrogen Bonds

  • Polar water molecules: partial charges.

  • Hydrogen bond between water molecules.

pH Scale

  • Logarithmic scale for acidity/basicity.

  • Ranges 0-14.

Carbon & Macromolecules

  • Hydrocarbons: carbon and hydrogen only.

ATP

  • Energy source for cellular processes.

Polymers

  • Dehydration: monomers bond, water lost.

  • Hydrolysis: polymers break, water added.

Carbohydrates

  • Monosaccharides: simple sugars.

Fats

  • Saturated: solid at room temperature.

  • Unsaturated: liquid at room temperature.

Proteins

  • Functions: defense, storage, transport, communication, movement, structure.

Nucleic Acids

  • DNA: genes, nucleotides.

Cell Types

  • Eukaryotic vs. Prokaryotic

Prokaryotic Cells

  • No nucleus.

  • DNA in nucleoid.

  • No membrane-bound organelles.

Eukaryotic Cells

  • DNA in nucleus.

  • Membrane-bound organelles.

Organelles

  • Extensive internal membranes.

Endosymbiont Theory

  • Mitochondria and chloroplasts evolved from engulfed prokaryotes.

Membrane Transport
Membrane Proteins

  • Functions: transport, enzymatic activity, signal transduction, cell recognition, intercellular joining, attachment.

Passive Transport

  • Diffusion: movement down concentration gradient, no energy needed.

Active Transport

  • Requires energy (e.g., ATP).

Metabolic Pathways

  • Catabolic: release energy by breaking down molecules.

  • Anabolic: consume energy to build molecules.

Thermodynamics

  • 1st law: Energy conserved.

  • 2nd law: Entropy (disorder) increases.

Free Energy

  • Exergonic: release energy, spontaneous.

  • Endergonic: require energy.

Enzymes

  • Lower activation energy.

Enzyme Inhibition

  • Competitive: bind to active site.

  • Noncompetitive: bind elsewhere, change enzyme shape.

Cellular Respiration

  • Glycolysis, Citric Acid Cycle, Electron Transport Chain.

Glycolysis

  • Glucose to pyruvate.

Citric Acid Cycle

  • Completes glucose oxidation.

Chemiosmosis

  • Links electron transport chain to ATP synthesis.

ATP Yield

  • Up to 32 ATP per glucose.

Photosynthesis

  • Light Reaction, Calvin Cycle.

Light Reactions

  • Convert solar energy to chemical energy

  • H_2O is split to provide electrons and protons to reduce NADP^+ to NADPH.

  • O_2 is released as a waste product.

Calvin Cycle

  • Uses ATP and NADPH from light reactions to fix CO_2 into sugar.

DNA Replication

  • Occurs at origins of replication.

  • DNA strands separate, forming replication bubbles.

DNA Replication Complex

  • Proteins form a large complex (“DNA replication machine”).

Chromosome Structure

  • DNA packed with histones.

  • Nucleosomes, chromatin.

Transcription and Translation

  • Transcription: DNA to RNA.

  • Translation: RNA to protein.

mRNA
Triple Code

  • The flow of information from gene to protein is based on a triplet code: a series of nonoverlapping, three-nucleotide words.

  • The words of a gene are transcribed into complementary nonoverlapping three-nucleotide words of mRNA

  • These words are then translated into a chain of