UNIT 3

  1. Front: Glycolysis
    Back: The process by which glucose is broken down into pyruvate, yielding 2 ATP molecules and 2 NADH in the cytoplasm.

  2. Front: Acetyl-CoA Formation
    Back: A transition step converting pyruvate to acetyl-CoA in the mitochondria, producing NADH and releasing CO₂.

  3. Front: Krebs Cycle (Citric Acid Cycle)
    Back: A series of reactions in the mitochondrial matrix that produces ATP, NADH, FADH₂, and CO₂ by oxidizing acetyl-CoA.

  4. Front: Electron Transport Chain (ETC)
    Back: The final stage of cellular respiration where NADH and FADH₂ donate electrons to produce ATP through oxidative phosphorylation in the mitochondrial inner membrane.

  5. Front: Oxidative Phosphorylation
    Back: The production of ATP using the energy derived from redox reactions in the ETC, resulting in a proton gradient that drives ATP synthesis.

  6. Front: NADH
    Back: An electron carrier produced in glycolysis, acetyl-CoA formation, and the Krebs cycle, donating electrons to the ETC.

  7. Front: FADH₂
    Back: An electron carrier produced in the Krebs cycle, donating electrons to the ETC but yielding less ATP than NADH.

  8. Front: Proton Gradient
    Back: A concentration difference of protons across the mitochondrial inner membrane, driving ATP synthesis through chemiosmosis.

  9. Front: Chemiosmosis
    Back: The movement of protons across the mitochondrial membrane, driving the synthesis of ATP by ATP synthase in the ETC.

  10. Front: DNA (Deoxyribonucleic Acid)
    Back: The molecule carrying genetic information, composed of two complementary strands forming a double helix, made up of nucleotides (adenine, thymine, cytosine, guanine).

  11. Front: Nucleotide
    Back: The basic unit of DNA, consisting of a sugar (deoxyribose), a phosphate group, and a nitrogenous base (A, T, C, or G).

  12. Front: Double Helix
    Back: The twisted-ladder structure of DNA, with complementary base pairs (A-T, C-G) forming the "rungs" and the sugar-phosphate backbone forming the "sides."

  13. Front: Base Pairing Rules
    Back: Adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G) through hydrogen bonding, maintaining a uniform DNA structure.

  14. Front: Hydrogen Bonds in DNA
    Back: Weak bonds between complementary bases that hold the two DNA strands together; two bonds between A-T pairs and three between C-G pairs.

  15. Front: DNA Replication
    Back: The process of copying DNA, occurring in the S phase of the cell cycle, where each strand serves as a template for a new complementary strand.

  16. Front: Helicase
    Back: An enzyme that unwinds the DNA double helix at the replication fork, separating the two strands for replication.

  17. Front: DNA Polymerase
    Back: The enzyme responsible for adding nucleotides to a growing DNA strand in a 5' to 3' direction, following base pairing rules.

  18. Front: Leading Strand
    Back: The DNA strand that is synthesized continuously toward the replication fork by DNA polymerase during replication.

  19. Front: Lagging Strand
    Back: The DNA strand that is synthesized discontinuously in short fragments (Okazaki fragments) away from the replication fork, later joined by DNA ligase.

  20. Front: Okazaki Fragments
    Back: Short DNA fragments synthesized on the lagging strand during DNA replication, which are later joined by DNA ligase.

  21. Front: DNA Ligase
    Back: The enzyme that seals gaps between Okazaki fragments on the lagging strand, forming a continuous DNA strand.

  22. Front: Semi-Conservative Replication
    Back: The model of DNA replication in which each new DNA molecule consists of one original strand and one newly synthesized strand.

  23. Front: Cell Cycle
    Back: The series of stages a cell goes through to grow and divide, consisting of interphase (G1, S, G2) and mitotic phase (mitosis and cytokinesis).

  24. Front: Interphase
    Back: The phase where a cell spends most of its life, consisting of G1 (cell growth), S (DNA replication), and G2 (preparation for mitosis).

  25. Front: G1 Phase
    Back: The first growth phase in interphase, where the cell grows, produces organelles, and synthesizes proteins necessary for DNA replication.

  26. Front: S Phase
    Back: The synthesis phase in interphase, where DNA is replicated, resulting in two identical sets of chromosomes.

  27. Front: G2 Phase
    Back: The second growth phase in interphase, where the cell continues to grow, checks for DNA errors, and prepares for mitosis.

  28. Front: Mitosis
    Back: The division of a cell's nucleus into two identical nuclei, ensuring each daughter cell receives an identical set of chromosomes.

  29. Front: Cytokinesis
    Back: The division of the cytoplasm, resulting in two separate daughter cells with their own nuclei and organelles.

  30. Front: Checkpoints in Cell Cycle
    Back: Regulatory points (G1, G2, M checkpoints) where the cell assesses conditions to ensure accurate progression through the cycle.

  31. Front: G1 Checkpoint
    Back: Ensures the cell is ready for DNA replication, checking for adequate size, nutrient supply, and DNA integrity.

  32. Front: G2 Checkpoint
    Back: Checks for DNA damage after replication and ensures all DNA has been accurately replicated before mitosis.

  33. Front: M Checkpoint (Spindle Checkpoint)
    Back: Ensures chromosomes are correctly attached to the spindle apparatus, allowing for equal chromosome separation during mitosis.

  34. Front: Apoptosis
    Back: Programmed cell death, a mechanism to eliminate damaged or unneeded cells, often activated if cell cycle errors cannot be corrected.

  35. Front: Cancer and the Cell Cycle
    Back: Uncontrolled cell division due to loss of cell cycle regulation, often caused by mutations in genes controlling checkpoints.

  36. Front: Cyclins
    Back: Proteins that regulate the cell cycle by activating cyclin-dependent kinases (CDKs), essential for cell cycle progression.

  37. Front: Cyclin-Dependent Kinases (CDKs)
    Back: Enzymes that, when bound to cyclins, phosphorylate target proteins to push the cell through each phase of the cycle.

  38. Front: Tumor Suppressor Genes
    Back: Genes that produce proteins to prevent uncontrolled cell growth; mutations in these genes can lead to cancer.

  39. Front: Proto-Oncogenes
    Back: Genes that, when mutated, become oncogenes and can cause cells to divide uncontrollably, contributing to cancer development.

  40. Front: p53 Protein
    Back: A tumor suppressor protein that can halt the cell cycle at the G1 checkpoint if DNA damage is detected, allowing for repair or apoptosis.

  41. Front: Density-Dependent Inhibition
    Back: A property in which crowded cells stop dividing; often lost in cancerous cells.

  42. Front: Anchorage Dependence
    Back: The requirement that cells must be attached to a substratum to divide, a feature often absent in cancer cells.

  43. Front: Metastasis
    Back: The spread of cancer cells from their original site to other parts of the body, forming secondary tumors.

  44. Front: Acetyl-CoA Formation
    Back: The process following glycolysis where pyruvate is converted to acetyl-CoA, releasing CO₂ and forming NADH.

  45. Front: Chemiosmosis
    Back: The movement of ions across a membrane to generate ATP; in cellular respiration, protons move through ATP synthase to produce ATP.

  46. Front: Electron Transport Chain (ETC)
    Back: A series of proteins in the mitochondrial membrane that transfer electrons, releasing energy to pump protons and generate ATP.

  47. Front: ATP Synthase
    Back: An enzyme in the mitochondrial membrane that synthesizes ATP as protons flow back into the matrix, driven by the proton gradient.

  48. Front: NADH and FADH₂
    Back: Electron carriers that transfer electrons to the ETC, powering ATP production in oxidative phosphorylation.

  49. Front: Anaerobic Respiration
    Back: Cellular respiration occurring without oxygen, resulting in the production of lactic acid or ethanol and significantly less ATP.

  50. Front: Fermentation
    Back: A type of anaerobic respiration that generates ATP by converting glucose into lactic acid or ethanol when oxygen is unavailable.

  51. Front: Lactic Acid Fermentation
    Back: The process where glucose is converted to lactate in muscle cells during anaerobic conditions, regenerating NAD⁺ for glycolysis.

  52. Front: Alcohol Fermentation
    Back: A process in yeast and some bacteria where glucose is converted to ethanol and CO₂, regenerating NAD⁺ for glycolysis.

  53. Front: Semiconservative Replication
    Back: The process by which each new DNA molecule contains one original strand and one newly synthesized strand.

  54. Front: DNA Polymerase
    Back: An enzyme that synthesizes new DNA strands by adding nucleotides to the 3' end of an existing strand during replication.

  55. Front: Leading Strand
    Back: The continuously synthesized strand of DNA during replication, moving towards the replication fork.

  56. Front: Lagging Strand
    Back: The DNA strand synthesized discontinuously in short segments (Okazaki fragments), moving away from the replication fork.

  57. Front: Okazaki Fragments
    Back: Short DNA fragments formed on the lagging strand during DNA replication, later joined by DNA ligase.

  58. Front: DNA Ligase
    Back: An enzyme that joins Okazaki fragments on the lagging strand, creating a continuous DNA strand.

  59. Front: Helicase
    Back: An enzyme that unwinds the DNA double helix at the replication fork, allowing each strand to be copied.

  60. Front: Primase
    Back: An enzyme that synthesizes RNA primers, providing a starting point for DNA polymerase during replication.

  61. Front: Single-Strand Binding Proteins (SSBs)
    Back: Proteins that stabilize the unwound DNA strands, preventing them from re-forming a double helix during replication.

  62. Front: Topoisomerase
    Back: An enzyme that relieves the strain caused by the unwinding of DNA by cutting and rejoining the strands ahead of the replication fork.