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General Biology Final Exam Key Concepts

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  • Four levels of protein structure

    Primary: amino acid sequence; Secondary: alpha helices and beta sheets via hydrogen bonds; Tertiary: 3D folding via noncovalent interactions; Quaternary: multiple polypeptide subunits assembled.

  • Noncovalent interactions in protein structure

    Include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals forces that stabilize protein folding and function.

  • Factors modifying protein/enzyme structure and function

    Changes in pH, temperature, ionic strength, and presence of inhibitors can alter enzyme shape and activity.

  • Competitive enzyme inhibitors

    Bind to the enzyme's active site, competing with substrate; can be reversible or irreversible; reduce enzyme activity by blocking substrate binding.

  • Measuring enzyme inhibition

    Compare reaction rates with and without inhibitor; use assays to determine changes in Vmax and Km.

  • Allosteric regulation of enzymes

    Binding of molecules at sites other than the active site modulates enzyme activity; negative feedback inhibits, phosphorylation often activates enzymes.

  • Overall equation of photosynthesis

    \(6CO_2 + 6H_2O + light \rightarrow C_6H_{12}O_6 + 6O_2\); CO2 is reduced to glucose, water is oxidized to oxygen.

  • Overall equation of cellular respiration

    \(C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP\); glucose is oxidized, oxygen is reduced.

  • Light reactions in photosynthesis

    Light energy excites electrons in PSII, generating ATP via electron transport and proton gradient; PSI uses electrons to reduce NADP+ to NADPH.

  • Role of ATP and NADPH in photosynthesis

    ATP provides energy and NADPH provides reducing power for the Calvin cycle to fix carbon into sugars.

  • Calvin cycle key steps

    CO2 fixation by RuBisCO, reduction of 3-PGA to G3P using ATP and NADPH, and regeneration of RuBP to continue the cycle.

  • Oxidative phosphorylation overview

    NADH donates electrons to the electron transport chain in mitochondria, creating a proton gradient that drives ATP synthesis.

  • Electron transport chain location and function

    Located in the inner mitochondrial membrane; transfers electrons through complexes, pumping protons to create a gradient for ATP synthase.

  • Transcription control regions in eukaryotes

    Upstream sequences include promoters and enhancers; downstream sequences are transcribed into pre-mRNA.

  • mRNA processing steps

    5' capping, 3' polyadenylation, and splicing remove introns; these modifications stabilize mRNA and enable translation.

  • Initiation of transcription

    Activators bind enhancers, RNA polymerase binds promoter; transcription copies the template (antisense) DNA strand into RNA.

  • Initiation of translation

    mRNA binds small ribosomal subunit; initiator tRNA pairs with start codon; large subunit joins to form functional ribosome.

  • Elongation during translation

    tRNAs bring amino acids to ribosome; peptide bonds form; ribosome moves along mRNA to synthesize polypeptide chain.

  • Types of signaling molecules and receptors

    Extracellular signals: polar (bind membrane receptors) and non-polar (bind intracellular receptors); receptor types include GPCR, RTK, ion channels, and intracellular receptors.

  • GPCR-cAMP pathway overview

    Ligand binds GPCR, activates G protein, stimulates adenylate cyclase to produce cAMP, which activates protein kinase A leading to glycogen breakdown.

  • RTK pathway and cell division

    Ligand (e.g., PDGF) binds RTK, receptor dimerizes and autophosphorylates, triggering a cascade that activates gene transcription for cell division.

  • Cancer and RTK pathway mutations

    Cancer results from uncontrolled cell division; mutations in RTK or downstream proteins (e.g., Ras) can cause pathway overactivation.