GenBio Exam

• Photosynthesis

  An anabolic (building up), endergonic (absorbs energy), carbon dioxide (CO2) requiring process that uses light energy (photons-particles of light) and water (H2O) to produce organic macromolecules (glucose)

  
• Photosynthesis


  6CO2 + 6H2O → C6H12O6 + 6O2

  
• Chloroplast


  • An organelle where photosynthesis takes place

  
• Parts of a leaf?

  1. Stoma - opening through a leaf; exchanging gases with the environment
  2. Mesophyll cell - leaf cell where photosynthesis occurs
  3. Chloroplast - organelle where photosynthesis takes place (plant cells)
  4. Granum - stacks of thylakoids; in the chloroplast
  5. Thylakoid - pancake-shaped compartments; in the chloroplast; site of light reactions
  6. Thylakoid membrane - lipid bilayer; photosystems are embedded
  7. Photosystems - cluster of pigments and proteins; participates in light reactions
  8. Thylakoid space - enclosed by thylakoid membrane
  9. Stroma - fluid inside chloroplast; site of carbon reactions
• Redox reaction


  Reduction - gaining of electrons/hydrogen ions, Oxidation - losing electrons/hydrogen ions

  
• Stages of photosynthesis

  • Light Reaction or Light—Dependent Reaction
  • Dark Reaction or Light-independent Reaction or Calvin Cycle

  
• Light Reaction


  The process in which the solar energy is absorbed by the chlorophyll and converted to chemical energy, light energy is used to split the water molecules into hydrogen and oxygen, photochemical light reactions; occurs in the thylakoid membranes

  
• Photosystem


  • Light capturing unit of the thylakoid, contains proteins, chlorophyll and other pigments

  
• Electron Transport Chain (ETC)


  • Sequence of electron carrier molecules that transfer electrons, the energy released is used to make ATP
• Photolysis


  The O2 liberated by photosynthesis is made from the oxygen in water (also produces H+ and e-)

  
• Chemiosmosis


  As electrons move through the ETC, H+ ions are pumped from the stroma to the thylakoid space, H+ ions go through a protein channel (to go back to the stroma) which is connected to ATP synthase forming ATP
• Dark Reaction


  Does not directly require light, the process in which ATP and NADPH from the light reaction are used to produce glucose, occurs in the stroma
• Calvin Cycle


  The Calvin Cycle can only accommodate 3 carbon dioxide molecules at a time, To make one molecule of glucose, the Calvin Cycle must turn twice to produce two molecules of glyceraldehyde-3-phosphate (one per each turn) which will be combined to make glucose, It consists of three steps: carbon dioxide fixation, reduction of CO2 and regeneration of RuBP, The energy carrying molecules (ATP and NADPH) generated from the light dependent reactions will be utilized in the Calvin Cycle
• Cell division


  The cell's way of reproducing itself
• Chromosomes


  Structures in the nucleus that contain the DNA strands (which carry the genes)

  
• Parts of a chromosome

  • Chromatid - strand of duplicated chromosomes
  • Centromere - holds 2 chromatids together
  • Kinetochore - where the microtubules of the spindle apparatus will attach
  • Telomere - highly repetitive DNA at the end of the chromosomes; related to the aging process
  • Locus - specific location of a gene in the chromosome
  • Chromatin - smaller subunits or structures of the chromatids; collective DNA strands

  
• Chromosome number


  The number of chromosomes at the time of the formation of the zygote/fertilized egg

  
• Examples of chromosome numbers: human = 46, 23 pairs

  
• Homologous chromosomes


  Chromosomes that are structurally alike (same size and length) and contain the same genes at the same loci but possibly different genetic information

  
• 2 types of cells based on chromosome number

  • Somatic cells (diploid number)
  • Reproductive cells/gametes (haploid number)

  
• Cell cycle


  The cycle of growing and dividing that cells go through
• Stages of the cell cycle

  • Interphase
  • Mitosis
  • Cytokinesis

  
• Interphase


  The cell grows, develops into a mature, functioning cell, duplicates its DNA and prepares for division

  
• Stages of interphase


  • Gap 1 (G1) - cell grows; prepares to replicate DNA
  • Synthesis (S) - cell copies DNA
  • Gap 2 (G2) - cell prepares for division of nucleus; proteins that makes microtubules are synthesized
• Mitosis


  A process of cell division that results in the production of 2 daughter cells from a single parent cell

  
• Stages of mitosis


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase

  
• Prophase


  • The nucleolus has disappeared, and duplicated chromosomes are visible. Centrosomes (microtubule organizing center) begin moving apart and the mitotic spindle is forming.

  
• Metaphase


  • The chromosomes align at the center of the cell. The center of the cell is called the equator or the metaphase plate.

  
• Anaphase


  • The centromeres split as the sister chromatids separate and move towards opposite poles.

  
• Telophase


  • Nuclear envelope and nucleolus form at each pole. Chromosomes decondense. Spindle disappears.
• Cytokinesis


  The division of the cytoplasm that accompanies mitosis in most cells

  
• How cytokinesis differs in plants and animals

  In animals, a contractile ring of actin and myosin proteins pinches the membranes together to form a cleavage furrow. In plants, a cell wall must be formed between the two daughter cells using vesicles containing cellulose.

  
• Importance of mitosis

  • Maintenance of chromosome number from parent to daughter cell, for growth and repair of damaged cells/tissues, used for asexual reproduction

  
• Meiosis


  The production of sex cells, starting with specialized diploid cells called germ cells. Results in haploid cells to maintain a stable number of chromosomes from generation to generation.

  
• Stages of meiosis I

  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I

  
• Prophase I in meiosis

  • The duplicated chromosomes pair with their homologues in a process called synapsis. Crossing-over or recombination of genes between homologous chromosomes can occur.

  
• Stages of meiosis II

  • Prophase II
  • Metaphase II
  • Anaphase II
  • Telophase II

  
• Prophase II in meiosis

  • DNA does not replicate, as it did not pass to the interphase. It will start with the 23 chromosomes from telophase I, marking the transformation from diploid to haploid.

  
• Cellular respiration


  Metabolic pathway that breaks down high energy molecules (glucose) to generate ATP to be used by the cell in its activities

  
• Cellular respiration is exergonic and catabolic as high-energy glucose is broken down into CO2 and H2O