Biology I: Chapters 9-14

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Biology I: Chapters 9-14
2014-11-15 12:47:00
biology nsu bio

Biology I Chapters 9-?
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  1. Fermentation
    A process that results in the partial degradation of sugars or other organic fuel without the use of oxygen.
  2. Aerobic Respiration
    Oxygen is consumed as a reactant along with the organic fuel.

    Done by most eukaryotic and prokaryotic organisms.

    Some prokaryotes use substances other than oxygen as reactants in a similar process called anaerobic respiration.
  3. Cellular Respiration
    Technically includes aerobic and anaerobic processes but refers mostly to aerobic respiration.

    C6H12O6+ 6O2 -> 6CO2 + 6H2O + Energy (ATP+Heat)

    Process is exergonic (negative ^G change, spontaneous)

    Includes: oxidation and reduction
  4. Redox Reactions
    ~Also called: Oxidation-Reduction Reactions

    ~Transfer of one or more electrons from one reactant to another.

    • ~The loss of electrons from one substance is called OXIDATION.
    • ~The addition of electrons to another substance is called REDUCTION

    • ~Reducing Agent: Electron donor
    • ~Oxidixing Agent: Electron acceptor

    ~Oxidation and Reduction ALWAYS go hand in hand

    ~Not all redox reactions involve the complete transfer of electrons from one substance to another

    ~Oxygen is one of the most potent oxidizing agents because it's so electronegative

    ~Energy MUST be added to pull an electron away from an atom
  5. Reducing Agent
    Oxidizing Agent
    • Electron Donor
    • &
    • Electron Acceptor
  6. NAD+
    • An electron carrier, functioning as an oxidizing agent during respiration
    • A coenzyme
    • Can cycle easily between oxidized (NAD+) and reduced (NADH) states
  7. Electron Transport Chain
    • In cristae of mitrochondrion
    • Consists of a number of molecules (mostly proteins) built into the inner membrane of the mitochondria of eukaryotic cells
    • Respiration uses an ETC to break the fall of electrons to oxygen into several energy-releasing steps
    • Thousands in each mitochondrion
    • Does not generate ATP
  8. Glycolysis
    • Occurs in the cytosol
    • Begins the degradation process by breaking glucose into two molecules of pyruvate
    • Carbon (6-carbon sugar) is split into two 3-carbon sugars, then oxidized, then rearranged to form two molecules of pyruvate
    • Two phases: energy investment phase (ATP spent) and energy payoff phase (ATP gained)
  9. Citric Acid Cycle
    • Functions as a metabolic furnace that oxidizes organic fuel derived from pyruvate
    • Catabolic - Oxidizing acetyl CoA and using energy to synthesize ATP
  10. Oxidative Phosphorylation
    • Mode of ATP synthesis powered by the redox reactions of the electron transport chain
    • Adds an inorganic phosphate to ADP
  11. Substrate-Level Phosphorylation
    Mode of ATP synthesis that occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP,
  12. Acetyl CoA
    • Acetyl Coenzyme A
    • Pyruvate converted to Acetyl CoA in step linking glycolysis and the citric acid cycle
  13. How many ATP molecules produced per glucose molecule? How many during glycolysis? How many during the citric acid cycle?
    • 4 ATP Molecules
    • 2 during glycolysis
    • 2 during citric acid cycle
  14. How many CO2 needed to produce 1 G3P?
    3 CO2 (Each completing cycle alone; 3 Calvin Cycles)
  15. How many times must the Calvin Cycle take place for one G3P?
    Three times (3 CO2)
  16. Cytochromes
    • Proteins
    • Most of the remaining electron carriers between ubiquinone and ozygen in ETC
  17. ATP Synthase
    • Protein complex
    • The enzyme that makes ATP from ADP and inorganic phosphate
    • Works like an ion pump running in reverse
    • Populates inner membrane of the mitochondrion or prokaryotic plasma membrane
    • Uses the energy of an existing ion gradient to power ATO synthesis
  18. Chemiosmosis
    • Process in which energy stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work
    • Example: the synthesis of ATP
    • The flow of H+ across a membrane
  19. Proton-Motive Force
    The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping H+ across a biological membrane during chemiosmosis
  20. Energy flow during respiration
    Glucose -> NADH -> ETC -> Proton-Motive Force -> ATP

    *ETC: Electron Transport Chain
  21. Fermentation & Types
    • A way of harvesting chemical energy w/o using either oxygen or any ETC (w/o cellular respiration)
    • Alcohol and Lactic Acid
  22. Alcohol Fermentation
    • Pyruvate converted to Ethanol in two steps
    • Step 1: Release CO2 from pyruvate, which is converted to the 2-carbon compound acetaldehyde
    • Step 2: Acetaldehyde is reduced by NADH to ethanol (regenerates supply of NAD+ needed for glycolysis)
    • Many bacteria carry out AF under anaerobic (w/o air) conditions
  23. Lactic Acid Fermentation
    • Pyruvate reduced directly by NADH to form lactate w/ no release of CO2
    • Certain fungi/bacteria used by dairy industry to make cheese and yogurt
    • Used by human muscle cells to make ATP when oxygen is scarce (during strenuous exercise)
  24. Anaerobic
    Without air
  25. Aerobic
    Cellular Respiration
  26. Differences between Fermentation and Cellular Respiration
    • -Both use glycolysis to oxidize glucose and other organic fuels to pyruvate
    • -Cellular respiration produces much more ATP
    • -Fermentation Final Electron Acceptor: Pyruvate
    • -Cellular Respiration Final Electron Acceptor: O2
  27. Biosynthesis
    • The body uses small molecules to build other substances
    • Small molecules may come directly from food, from glycolysis, or from the citrci acid cycle
  28. Photosynthesis
    • The conversion from solar to chemical energy
    • Most plants, algae, some prokaryotes, and some unicellular eukaryotes
  29. Autotrophs
    • Autotrophs: Sustain themselves w/o eating anything derived from other organisms (plants)
    • Heterotrophs: Obtain their organic material from other organisms; Consumers (humans)
  30. Photoautotrophs
    • Plants
    • Organisms that use light as a source of energy to synthesize organic substances
  31. Chloroplasts
    • All green parts of a plant have chloroplasts
    • Found mainly in the mesophyll (tissue in the interior of the leaf)
    • Has an envelope of two membranes surrounding a dense fluid called the stroma
  32. What is the major site of photosynthesis?
    Leaves (in most plants)
  33. Mesophyll
    • The tissue in the interior of the lead
    • Has about 30-40 chloroplasts, 2-4um by 4-7um
  34. Stomata
    • Microscopic pores
    • Oxygen exits the leaf through the stomata
  35. Stroma
    • A envelope of two membranes surrounding a dense fluid
    • Contains membrane system made up of sacs, called thylakoids, which segregates the stroma from the thylakoid space inside the sacs
  36. Thylakoids
    • Sacs that segregate the stroma from the thylakoid space inside these sacs
    • In some places, they are stacked in columns called grana (singular granum)
    • Chlorophyll found here
  37. Grana (singular name?)
    • Columns of thylakoids
    • Singular: granum
  38. Chlorophyll
    • The green pigment that gives leaves their color
    • Found in the thylakoid
  39. Chemical Equation for Photosynthesis
    • 6CO2 + 6H2O + Light Energy -> C6H12O6 + 6O2
    • 6CO2 + 12H2O + Light Energy -> C6H12O6 + 6O2+6H2O
  40. What are the two stages of photosynthesis?
    • 1- Light Reactions (photo)
    • 2- The Calvin Cycle (synthesis)
  41. Light Reactions
    • The steps of photosynthesis that convert solar energy to chemical energy
    • Water is split (providing electrons & protons)
    • O2 released
    • No sugar produced
  42. Photophosphorylation
    Process in which ATP is generated by using chemiosmosis to power the addition of a phosphate group to ADP
  43. The Calvin Cycle
    • Anabolic - Building carbs from smaller molecules and consuming energy
    • Incorporates CO2 from the air into organic molecules already present in the chloroplast (called Carbon Fixation)
    • The fixed carbon is then reduced to carbohydrates by the addition of electrons
    • 3 Phases: Carbon Fixation, Reduction, Regeneration of the CO2 Acceptor
  44. Carbon Fixation
    The initial incorporation of carbon into organic compounds
  45. Wavelength
    • The distance between the crests of electromagnetic waves
    • Range from less than a nanometer to more than a kilometer
  46. Electromagnetic Spectrum
    • The entire range of radiation
    • Less than a nanometer-More than a kilometer
    • Segment most important to life: 380nm-750nm
  47. What segment of the electromagnetic spectrum is most important to life?
    • 380nm-750nm
    • Called visible light
  48. Visible Light
    • 380nm-750nm
    • Segment of the electromagnetic spectrum most important to life
    • Can be detected as various colors by the human eye
  49. Photons
    • Discrete particles
    • Not tangible objects, but act like objects in that each of them has a fixed quantity of energy
  50. What is the relationship between the amount of energy and wavelength of the light?
    • The amount of energy is inversely related to wavelength of light
    • The shorter the wavelength of light, the greater the energy of each photon of that light
  51. What radiation drives photosynthesis?
    Visible Light
  52. Absorption Spectrum
    A graph plotting a pigment's light absorption versus wavelength
  53. Chlorophyll a
    The key light-capturing pigment that participates directly in the light reactions
  54. Chlorophyll b
    The accessory pigment
  55. Carotenoids
    • Separate group of accessory pigments
    • Hydrocarbons that are various shades of yellow and orange because they absorb violet and blue-green light
    • May broaden the spectrum of colors that can drive photosynthesis
    • Some function as photoprotectors - Absorb and disspate excessive light energy that would otherwise damage chlorophyll or interact with oxygen, forming reactive oxidative molecules that are dangerous to the cell
  56. Action Spectrum
    • Profiles the relative effectiveness of different wavelengths of radiation in driving the process
    • Prepared by illuminating chloroplasts with light of different colors, then plotting wavelength against some measure of photosynthetic rate
  57. What happens when chlorophyll and other pigments absorb light?
    The colors corresponding to the absorbed wavelengths disappear from the spectrum of the transmitted and reflected light (but energy cannot disappear)
  58. A green plant reflect what color?
  59. Photosystem
    • Composed of a reaction-center complex surrounded by several light-harvesting complexes
    • Photosystem I and Photosystem II
    • Each photosystem functions in the chloroplast as a unit
    • Converts light energy to chemical energy, which will ultimately be used for the synthesis of sugar
  60. Reaction-Center Complex
    • An organized association of proteins holding a special pair of chlorophyll a molecules
    • Contains a molecules capable of accepting electrons and becoming reduced (primary electron acceptor)
  61. Light-Harvesting Complex
    • Consists of various pigment molecules (may include chlorophyll a, b, and multiple carotenoids) bound to proteins
    • Enables a photosystem to harvest light ove a larger surface area and a larger portion of the spectrum than any single pigment alone
  62. Primary Electron Acceptor
    A molecule capable of accepting electrons and becoming reduced
  63. What is the first step of light reactions?
    The solar-powered transfer of an electron from the reaction-center chlorophyll a pair to the primary electron acceptor
  64. What is a redox reaction?
    As soon as the chlorophyll electron is excited to a higher energy level, the primary electron acceptor captures it
  65. Photosystem II (PSII)
    • Functions 1st in light reactions
    • P680
  66. Photosystem I (PSI)
    • Functions 2nd in light reactions
    • P700
  67. Linear Electron Flow
    • A flow of electrons through the photosystems and other molecular components built into the thylakoid membrane
    • Occurs during the light reactions of photosynthesis
    • Generates ATP and NADPH
  68. Cyclic Electron Flow
    • Uses photosystem I only
    • No production of NADPH or oxygen
    • Generate ATP
    • Occurs in photosynthetic bacteria with one photosystem (PSII or PSI)
    • Can occur in photosynthetic organisms with both photosystems
  69. Chemiosmosis in Mitochondrion
    Chemiosmosis in Chloroplasts
    • in Mitochondrion: Chemical Energy (from food) transfer to ATP
    • in Chloroplasts: Light energy transforms to Chemical Energy of ATP
  70. The Calvin Cycle
  71. G3P
    • Glyceraldehydr 3-Phosphate
    • The carbohydrate produced directly from the Calvin Cycle
    • 3-Carbon Sugar
    • For the net synthesis of one molecule of G3P, the cycle must take place 3 times (3 CO2)
  72. How many molecules of ATP and NADPH are consumed by the Calvin Cycle for one G3P?
    • 9 ATP
    • 6 NADPH
  73. How many molecules of ATP and NADPH are consumed by the Calvin Cycle for one molecule of glucose?
    • 18 ATP
    • 12 NADPH
  74. How many Calvin Cycles needed for one molecule of glucose?
    6 (6CO2)
  75. C3 Plants
    • Plants that use the Calvin Cycle for the initial steps that incorporate CO2 into organic material, producing 3-Phosphoglycerate
    • Examples: Rice, Wheat, Soybeans
  76. C4 Plants
    • Plants in which the Calvin Cycle is preceded by reactions that incorporate CO2 into a 4-carbon product
    • Examples: Sugarcane, Corn
  77. CAM Plants
    • Plants that use crassulacean acid metabolism*
    • Examples: Pineapple

    *An adaptation for photosynthesis in arid conditions
  78. Crassulacean Acid Metabolism
    An adaptation for photosynthesis in arid conditions
  79. Bundle-Sheath Cells
    Arranged into tightly packed sheaths around the veins of the leaf
  80. Photorespiration
    • A process that occurs in the light and consumes O2 while producing CO2
    • Uses ATP
    • Produces no sugar
    • Decreases photosynthesis output
  81. Cell Division
    Reproduction of cells
  82. Cell Cycle
    • The life of the cell from the time it is first formed during division of a parent cell until its own division into two daughter cells
    • Crucial Function: Passing identical genetic material to cellular offspring
  83. Genome
    • A cell's genetic info
    • Prokaryotic genomes - single DNA molecule
    • Eukaryotic genomes - a number of DNA molecules
  84. Chromosomes
    • Structures containing DNA molecules
    • # in Human Somatic Cells: 46 (2 sets of 23)
    • # in Human Gametes: 23 (one set)
  85. Genes
    • The units of info that specify an organism's inherited traits
    • Program the specific traits that emerge as we develop from fertilized eggs into adults
    • Written in the language of DNA
  86. Chromatin
    • The entire complex of DNA and proteins that is the building material of chromosomes
    • Varies in its degree of condensation during cell division
  87. Somatic Cells
    All body cells except the reproductive cells
  88. How many chromosomes in human cells nuclei?
    • 46 chromosomes
    • Two sets of 23 (one set inherited from each parent)
  89. Gametes
    • Reproductive Cells
    • Sperm and Eggs
    • One set of chromosomes (half as many somatic)
    • In humans: one set of 23 chromosomes
    • The vehicles that transmit genes from one generation to the next
  90. Sister Chromatids
    • Joined copies of the original chromosome
    • Initially attached all along their lengths by protein complexes called cohesins
  91. Cohesins
    Protein complexes that initially attach sister chromatids along their lengths
  92. Chromatid Cohesin
    The attachment of sister chromatids to each other
  93. Mitosis
    • The division of the genetic material in the nucleus
    • Usually followed by cytokinesis (the division of the cytoplasm)
  94. Phases of the Cell Cycle
    • Mitotic (M) Phase
    • Interphase (Sub-phases: G1 Phase, S Phase, G2 Phase)
    • Prophase
    • Prometaphase
    • Metaphase
    • Anaphase
    • Telophase
    • Cytokinesis
  95. Interphase
    • Accounts for 90% of the cell cycle
    • Includes sub-phases: G1 Phase, S Phase, and G2 Phase
    • A cell grows by producing proteins and cytoplasmic organelles such as mitochondria and endoplasmic reticulum
  96. S Phase
    • Sub-phase of interphase
    • Duplication of the chromosomes occurs entirely
  97. Mitotic Spindle
    • Consists of fibers made of microtubules and associated proteins
    • Begins to form in the cytoplasm during prophase
    • Includes: The centrosomes, The spindle microtubules, and the asters
  98. G2 Phase
    • A nuclear envelope (double membrane) encloses the nucleus
    • Two centrosomes have formed by duplication of a single centrosome
    • Each centrosome contains two centrioles
  99. Prophase (mitosis)
    • The chromatin fibers become more tightly coiled
    • The nucleoli disappear
    • Each duplicated chromosome appears as two identical sister chromatids joined at their centromeres
    • The mitotic spindle begins to form
    • The centrosomes move away from each other
  100. Prometaphase (mitosis)
    • The nuclear envelope fragments
    • The microtubules extending from each centrosome can now invade the nuclear area
    • The chromosomes have become even more condensed
    • Each of the two chromatids of each chromosome now has a kinetochore (specialized protein structure at center of centromere)
    • Some of the microtubules attach to kinetochores, becoming "kinetochore microtubules," which kerl the chromosomes back and forth
  101. Metaphase (mitosis)
    • The centrosomes are now at opposite poles of the cell
    • The chromsomes have all arrived at the metaphase plate (a plane equidistant between spindle's two poles)
    • For each chromosome, the kinetochores of the sister chromatids are attached to kinetochore microbtubules coming from opposite poles
  102. Anaphase (mitosis)
    • Shortest stage of mitosis
    • Begins when the cohesin proteins are cleaved, allowing the two sister chromatids of each pair to part suddenly (each chromatid becomes a full-ledged chromosomes)
    • The two liberated sister chromosomes begin moving toward opposite ends of the cell
    • The cell elongates as the nonkinetochore microtubules lengthen
    • By the end of this stage, the two ends of the cell have equivalent (and complete) collections of chromosomes
  103. Telophase (mitosis)
    • Two daughter nuclei form in the cell
    • Nuclear envelopes arise from the fragments of the parent cell's nuclear envelope
    • Nucleoli reappear
    • The chromosomes become less condensed
    • Any remaining spindle microtubules are depolymerized
    • Mitosis is complete
  104. Cytokinesis (mitosis)
    The division of the cytoplasm is usually well under way by the late telophase, so the two daughter cells appear shortly after the end of mitosis
  105. Centrosomes
    • A subcellular region containing material that functions throughout the cell cycle to organize the cell's microtubules
    • A pair of centrioles at center
  106. Aster
    • A radial array of short microtubules
    • Extends from each centrosome
  107. Kinetochore
    A structure made of proteins that have assembled on specific sections of DNA at each centromere
  108. Metaphase Plate
    • A plane midway between the spindle's two poles
    • Imaginary plate
  109. Cleavage Furrow
    • A shallow groove in the cell surface near the old metaphase plate
    • The 1st sign of cleavage
    • Deepens until the parent cell is pinched in two, producing two separate cells
    • Animal cells, not plant cells
  110. Cleavage
    • Process by which cytokinesis occurs
    • 1st Sign: Cleavage Furrow
  111. Cell plate
    • Produced in plant cells when vesicles from the Golgi move along microtubules to the middle of the cell, where they coalesce (come together)
    • Enlarges until its surrounding membrane fuses with the plasma membrane along the perimeter of the cell
  112. Binary Fission
    • "Division in Half"
    • Refers to the process and asexual reproduction of single-celled eukaryotes (bacteria)
  113. Cell Cycle Control System
    • A cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle
    • Proceeds on its own, according to a built in "clock"
    • Regulated at certain checkpoints by internal and external adjustment
  114. Checkpoint
    • A control point in the cell cycle where stop and go-ahead signals can regulate the cycle
    • Three important checkpoints found in G1, G2, and M Phases
  115. Cyclin
    • Protein
    • Cyclically fluctuating concentration in the cell
  116. Cyclin-dependent Kinases (Cdks)
    • Enzymes that activate or inactivate other proteins by phosphorylating them
    • Activity rises and falls with changes in the concentration of its cyclin partner
  117. Which checkpoint is most important? Why?
    • G1 Checkpoint
    • If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the G1, S, G2, and M phases and divide
    • If a cell does not receive a go-ahead signal at the G1 checkpoint, it may exit the cycle, switching into a nondividing state called the G0 phase
  118. G0 Phase
    • Nondividing state
    • The result of not receiving a go-ahead signal at G1 checkpoint
    • Most cells of human body at this phase
  119. Growth Factor
    • A protein released by certain cells that stimulates other cells to divide
    • Different cell types respond specifically to different growth factors or combinations of growth factors
  120. Density-Dependent Inhibition
    A phenomenon in which crowded cells stop dividing
  121. Anchorage Dependence
    • To divide, cells must be attached to a substratum
    • Signaled to the cell cycle control system via pathways involving plasma membrane proteins and elements of the cytoskeleton linked to them
  122. Benign Tumor
    • Most do not cause serious problems
    • Most can be removed by surgery
    • A mass of abnormal cells within otherwise healthy tissue that remains at the original site (too few genetic and cellular changes to survive at another site)
  123. Malignant Tumor
    • A mass of abnormal cells within otherwise healthy tissue whose genetic and cellular changes enable them to spread to new tissues and impair the functions of one or more organs
    • "Cancer"
  124. Metastasis
    Spread of cancer cells to locations distant from their original site
  125. Heredity
    • Transmission of traits from one generation to the next
    • Also called inheritance
  126. Variation
    Differences between members of the same species
  127. Genetics
    Scientific study of heredity and hereditary variation
  128. Locus
    • A gene's specific location along the length of a chromosome
    • Plural: loci
  129. Asexual Reproduction
    • A single individual is the sole parent and passes copies of all its genes to its offspring without the fusion of gametes
    • Example: Single-celled eukaryotic organisms,
    • Some multicellular organisms
  130. Sexual Reproduction
    • Two parents give rise to offspring that have unique combinations of genes inherited from the two parents
    • Offspring vary genetically¬† from their siblings and parents
    • Variations not replicas
  131. Life Cycle
    • The generation-to-generation sequence of stages in the reproductive history of an organism
    • Conception to own reproduction
  132. How many chromosomes in each somatic cell?
    46 Chromosomes
  133. How many chromosomes of each type?
    • Each chromosome has two pairs
    • 23 x 2 = 46
  134. Karyotype
    • Ordered display of chromosomes
    • Starts with longest
  135. Homologous Chromosomes
    • Also called homologs
    • A pair of chromosomes of the same length, centromere position, and staining pattern
    • Possesses genes controlling the same inherited characteristics
    • Exception: X and Y Chromosomes
  136. Human females have XX or XY chromosomes?
  137. Human males have XX or XY chromosomes?
  138. XY or XX Chromosomes
    • Sex chromosome
    • Males: XY
    • Females: XX
  139. Homologs
    • Also called homologous chromosomes
    • A pair of chromosomes of the same length, centromere position, and staining pattern
    • Possesses genes controlling the same inherited characteristics
    • Exception: X and Y Chromosomes
  140. Autosomes
    Chromosomes that are not sex chromosomes
  141. Diploid Cell
    • Any somatic cell with two chromosome sets
    • Has a diploid number of chromosomes, abbreviated 2n
    • Humans: Diploid # = 46 (2n=46)
  142. Haploid Cell
    • Any gamete with one chromosome set
    • Has a haploid number of chromosomes, abbreviated n
    • Humans: Haploid # = 23 (n=23)
  143. Fertilization
    • The union of gametes
    • Result: Zygote, fertilized egg
  144. Zygote
    • Fertilized egg
    • Diploid because it contains two haploid sets (paternal and maternal copy of chromosomes)
  145. What are the only cells not produced by mitosis?
  146. Where are gametes developed?
    • In germ cells, in the gonads
    • Ovaries and Testes
  147. Meiosis
    • Type of cell division involved in gamete formation
    • Occurs in germ cells (in the gonads)
    • Reduces the number of sets of chromosomes from two to one in the gametes, counterbalancing the doubling that occurs at fertilization
    • Meiosis I and Meiosis II
  148. Alternation of Generations
    • Plants and some species of algae
    • Includes both diploid and haploid stages that are multicellular
    • Sporophyte: Muticellular Diploid Stage
    • Gametophyte: Muticellular Haploid Stage
    • The sporophyte generation produces a gametophyte as its offspring, and the gametophyte produces the next sporophyte
  149. How many stage of Meiosis are there?
    • Two
    • Meiosis I and Meiosis II
  150. What results from Meiosis I and Meiosis II?
    4 daughter cells, each with only half as many chromosomes as the parent cells
  151. Stages of Meiosis
    • Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis
    • Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis
  152. Prophase I (meiosis)
    • Centrosome movement, spindle formation, and nuclear envelope breakdowns
    • Chromosomes condense progressively
    • Each chromosome pairs with its homolog, aligned gene by gene, and crossing over occurs
    • Each homologous pair has one or more X-shaped regions called chiasmata, where crossovers have occured
    • Microtubules from one pole or the other will attach to the two kinetochores (one at the centromere of each homolog)
    • The homologous pairs will then move toward the metaphase state
  153. Metaphase I (meiosis)
    • Pairs of homologous chromosomes are now arranged at the metaphase plate, each pair facing its own pole
    • Both chromatids of one homolog are attached to kinetochore microtubules from one pole
  154. Anaphase I (meiosis)
    • Breakdown of proteins that are responsible for sister chromatid cohesion along chromatid arms allows homologs to separate
    • Homologs move toward opposite poles
    • Sister chromatid cohesion persists at the centromere, causing chromatids to move as a unit toward the same pole
  155. Telophase I and Cytokinesis (meiosis)
    • Each half of the cell has a complete haploid set of duplicated chromosomes
    • Cytokinesis usually occurs simultaneously with telophase I, forming two haploid daughter cells
    • In animal cells, a cleavage furrow forms
    • In some species, chromosomes condense and nuclear envelopes form
    • No chromosome duplication occurs between Meiosis I and Meiosis II
  156. Prophase II (meiosis)
    • Spindle apparatus forms
    • Chromosomes move toward metaphase II plate
  157. Metaphase II (meiosis)
    • The chromosomes are positioned at the metaphase plate
    • Because of crossing over in meiosis I, the two sister chromatids of each chromsome are not genetically identical
    • The kinetochores of sister chromatids are attached to microtubules extending from opposit poles
  158. Anaphase II (meiosis)
    • Breakdown of proteins holding the sister chromatids together at the centromere allows the chromatids to separate
    • The chromatids move toward oppiste poles as individual chromosomes
  159. Telophase II and Cytokinesis (meiosis)
    • Nuclei form, the chromosomes begin decondensing, and cytokinesis occurs
    • The meiotic division of one parent cell produces four daughter cells (each w/ haploid set of chromosomes)
    • The four daughter cells are genetically distinct from each other and the parent cell
  160. Synaptonemal Complex
    • Zipper-like structure
    • The formation of which holds one homolog tightly to the other
  161. Synapsis
    During - The DNA breaks are closed up so that each broken end is joined to the corresponding segment of the nonsister chromatid
  162. What are the two sources of variation among offspring?
    • Independent Assortment of Chromosomes
    • Crossing Over
  163. Character
    • A heritable feature that varies among individuals
    • Example: Flower color
  164. Trait
    • Each variant for a character
    • Example: Purple or white color for flowers
  165. True-Breeding
    Organisms produce offspring of the same variety over many generations of self-pollination
  166. Hybridization
    • The crossing of two true-breeding varieties
    • P Generation: true-breeding parents
    • F1 Generation: hybrid offspring of P Generation
    • F2 Generation: offspring from F1 Generation
  167. P Generation
    Two true-breeding parents
  168. F1 Generation
    Hybrid offspring of P Generation
  169. F2 Generation
    Offspring of F1 Generation
  170. Alleles
    Alternative versions of a gene
  171. What are the four related concepts that make up Mendel's Model?
    • Alternative versions of genes account for variations in inherited characters.
    • For each character, an organism inherits two copies (two alleles) of a gene, one from each parent.
    • If the two alleles at a locus differ, than one (the dominant allele) determines the organisms appearance; the other (the recessive allele) has no noticeable effect on the organisms appearance
    • The two alleles for a heritable character segregate during gamete formation and end up in different gametes (The Law of Segregation)
  172. The Law of Segregation
    • States that the two alleles for a heritable character segregate during gamete formation and end up in different gametes
    • An egg or a sperm gets only one of the two alleles that are present in the somatic cells of the organism making the gamete
  173. Punnett Square
    A diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup
  174. Homozygous
    Name for an organism that has a pair of identical alleles for a character
  175. Heterozygous
    • Name for an organism that has two different alleles for a gene
    • Not true-breeding
  176. Homozygous Recessive
    Name for an organism that has a pair of identical recessive alleles for a character
  177. Phenotype
    • An organism's appearance or observable traits
    • Example: PP and Pp (purple vs white colored petals) have the same phenotype, which is the purple petals
  178. Genotype
    • An organism's genetic makeup
    • Example: PP and Pp (purple vs white colored petals) have different genotypes, PP vs Pp
  179. Testcross
    • Breeding an organism of unknown genotype with a recessive homozygote
    • Can reveal the genotype of the unknown organism
  180. Monohybrids and Monohybrid Cross
    • Monohybrid: An organism is heterozygous for one particular character
    • Monohybrid Cross: A cross between two heterozygous organisms with a single differing character
  181. Dihybrids and Dihybrid Cross
    • Dihybrid: An organism heterozygous for two characters
    • Dihybrid Cross: A cross between two heterozygous organisms with two differing characters
  182. Law of Independent Assortment
    • Two or more genes assort independently - each pair of alleles segregates independently of each other pair of alleles - during gamete formation
    • Only applies to genes located on different chromosomes or to genes that are very far apart on the same chromosome
  183. What is the probability scale of Mendelian Genetics?
  184. Multiplication Rule
    To determine the probability that two or more independent events will occur together in some specific combination: Multiply the probability of one event by the probability of the other event
  185. Addition Rule
    The probability that any one of two or more mutually exclusive events will occur is calculated by adding their individual probablities
  186. Incomplete Dominance
    • Neither allele is completely dominant
    • Example: Red and White flower mate - Produce Pink offspring
  187. Complete Dominance
    • The phenotype of the heterozygote and the dominant homozygote are indistinguishable
    • Example: Red and White flower mate - Produce dominant colored offspring
  188. Codominance
    • Two alleles each affect the phenotype in separate, distinguishable ways
    • Example: Red and White flower mate - Produce Red and White speckled offspring
  189. Tay-Sachs Disease
    • An inherited disorder in humans
    • Brain cells cannot metabolize certain lipids because a crucial enzyme does not work properly
    • Symptoms: Seizures, blindness, degeneration of motor/mental performances, and death
  190. Pleiotropy
    • Multiple phenotypic characters
    • Most genes have this property
  191. Epistasis
    Phenotypic expression of a gene at one locus alters that of a gene at a second locus
  192. Quantitative Characters
    Example: human skin color
  193. Polygenic Inheritance
    • An additive affect of two or more genes on a single phenotypic character
    • Example: Height. Over 180 genes affect height
  194. Multifactorial
    Characters that have many factors, both genetic and environmental, influence phenotype
  195. Pedigree
    A family tree describing the traits of parents and children across generations
  196. Carriers
    Heterozygotes that may transmit the recessive allele for a genetic disorder to their offspring
  197. Cystic Fibrosis
    • Most common lethal genetic disease in the US
    • 1/2500 people
    • Can cause death by 5 years old
    • Abnormally high concentration of extracellular chloride, which causes mucus coating certain cells to become thicker and stickier
  198. Sickle-Cell Disease
    • Most common inherited disorder among people of African descent
    • 1/400 African-Americans
    • Red blood cells sickle-shaped
  199. Amniocentesis and Chorionic Villus Sampling
    Techniques that can determine whether the developing fetus has Tay-Sachs disease