Photosynthesis, Cell Resp & Muscles

• ATP (Adenosine Triphosphate):


  Universal energy source for living things; needs to be constantly replenished.

  Nucleotide made up of:

  • 5C sugar (ribose)
  • Nitrogenous base (adenine)
  • 3 phosphate groups w/energy bonds

  Ribose & adenine = adenosine.
• Endergonic Rxn:


  A rxn that requires the input of energy.

  • ADP + P + energy → ATP
• Photophosphorylation vs Dephosphorylation

  Photophosphorylation: Adding a phosphate molecule to make ATP

  • ADP + P + energy → ATP

  Dephosphorylation: Removing a phosphate molecule from ATP, releasing energy.

  • ATP → ADP + P + energy
• ETS: Energy Transport System


  Found in the cell membrane, it is a series of progressively stronger e- acceptors. Everytime an e- is transported, energy is released/absorbed & ATP is made.
• Redox Rxns


  Oxidation (OIL): 'Oxidation Is Loss' of e-, results in a more + charge.

  Reduction (RIG): 'Reduction Is Gain' of e-, results in a more - charge.
• Photosynthesis


  Endothermic rxn (reactants=more stored energy) in autotrophs that converts sunlight into chemical potential energy (glucose).

  • CO₂ + H₂O + light → C₆H₁₂O₆ + O₂ + H₂O
  • Palisade mesophyll > chloroplast > thylakoid membrane & stroma
• Structures: Chloroplast, Carotenoids, Stroma, Thylakoid Discs, Grana, Lamellae

  Chloroplast: Organelle w/ photosensitive pigment: chlorophyll, which absorbs red/blue light (short & long wavelengths) but reflects green light (medium wavelengths).

  Carotenoids: Accessory pigment that absorbs blue/violet light; reflects yellow (adaptation 4 temperate areas in fall).

  Stroma: Inside space of a chloroplast; site of dark rxn.

  Thylakoid Discs: Photosynthetic membrane; site of light rxn.

  Grana: Stacks of thylakoid discs (light absorbs through multilayers).

  Lamellae: Unstacked thylakoids b/w grana.
• Photosynthesis: Light RXN


  1. Light captured by chlorophyll
  2. Photolysis: Water split by light (2H2O + light = 4H+ + 4e- + O2)
  3. ETC: E- are moving through ETC, releasing energy used to make ATP

  • Cyclic Photophosphorylation: E- move from P2 to P1, then to NADP+ factor.
  • Chemiosmosis (facilitated diffusion): Protons (H+) move across thylakoid membrane, creating a concentration gradient (ATP synthase). Then ATP is released and the H+ ions join NADP+ to create NADPH.

        4. The rxn products ATP & NADPH move to the stroma for dark rxn.
• Photosynthesis: Dark RXN


  (Doesn't need sunlight)

  1. RuBP (ribulose bisphosphate), a 5C sugar acts as a CO2 acceptor
  2. The new 6C sugar is split into two 3C PGA molecules.
  3. using H from NADPH and ATP, PGA becomes PGAL
  4. PGAL can convert to glucose, or recycled if there's not enough PGAL, ATP, or NADPH to produce glucose. It can also be used to make starch, sucrose, glycerol or cellulose & can be converted to amino or fatty acids.

  3 turns = PGA molecule is produced

  6 turns = Glucose molecule is produced

  Produces ADP & NADP+
• Why is photosynthesis an intermediate reaction?

  No energy is being produced. However, it's making products (C6H12O6) that can eventually be used in energy producing rxns (cell resp) by breaking down the bonds & releasing potential energy as ATP & heat.
• CO2 fixation


  The C from CO2 becomes the C in C6H12O6 (glucose)
• Cyanobacteria


  First, most efficient (90%) photosynthesizing organism and also the first to create oxygen.
• What is the advantage to a plant of having more than one pigment?

  The plant can absorb a wider range of wavelengths during photosynthesis, increasing efficiency.
• Photosystem


  Proteins that contain chlorophyll (light absorbtion) and act as a transporter of e- (light transporter)
• Cellular Respiration


  Process within the mitochondria used to convert sunlight and glucose to cellular energy (ATP)

  C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP

  • Cristae is the site of ETC and ATP synthase
  • Matrix is the site of pyruvate oxidation & Kreb's Cycle
• Anaerobic Cellular Respiration 


  Anoxic fermentation.

  • Survival mode CR (cell death after 7-10m)
  • Glucose = 2ATP & either ethanol/lactic acid

  Process:

  1. Glycolysis (cytoplasm):
  2. Glucose -> 2 3C pyruvate & net 2 ATP
  3. Fermentation (cytoplasm)
  4. NADH from glycolysis transfers H atoms to acetaldehyde (make ethanol) or pyruvate (make lactic acid). NAD+ stored for future oxic respiration.
  5. Yeast product (makes ethanol and CO2): wine, beer, bread, cheese, etc.
  6. Lactic acid: Muscle problems bc of oxygen debt.
• Aerobic Cellular Respiration


  Normal, oxic cellular respiration

  • Net 36 ATP (Total 38 but 2 are needed to run glycolysis), CO2 (byproduct of Krebs) & H2O (result of O2 final acceptor)
• Aerobic Cellular Respiration Process:

  1. Glycolysis (cytoplasm):
  2. Glucose -> 2 3C pyruvate & net 2 ATP
  3. Pyruvate oxidation (matrix):
  4. Pyruvate decarboxylated & oxidized = acetyl, co-A added = acetyl Co-A, CO2 released & NAD+ reduced to NADH.
  5. Kreb's Cycle (matrix):
  6. Energy transfer from organic molecules (reduction of H+ carriers) to ATP, NADPH & FADH2; CO2 released (acetyl oxidation)
  7. ETC & Chemiosmosis (cristae):
  8. NADH, FADH2 carry H+ (pump into intermembrane space)and e-
  9. H+ thru concentration gradient = ATP; O2 is final e- acceptor (w/o O2, no energy is made).
• Mitochondria


  Organelle found in every cell, since they all need energy.
• Cardiac Muscles


  Involuntary contraction & relaxation (myogenic) bc it's controlled by the ANS (always pumping blood; doesn't need electric impulse from CNS).

  Striated cells: Why it beats non-stop

  Cells will contract rhythmically and steady w/o input. If 2 muscle cells are in contact, whichever contracts first will stimulate the other to contract (synchronized).
• Smooth Muscles


  Found in hollow organs with lining (stomach, uterus, blood vessel walls, esophagus)

  Contraction/relaxation is involuntary bc of functions like digestion or pushing a baby out.

  Not striated but are narrow spindle-shaped cells with central nucleus.
• Skeletal Muscles


  Found attached to bones by tendons & are responsible for movement, protection and body temperature control (80% of all energy used to contract muscles is lost as heat).

  Cells are striated & skeletal muscle contraction/relaxation is voluntary.
• Effects of Exercise (THERMA)


  • Tetanus: Constant muscle contraction caused by bites or metal entering the bloodstream
  • Hypertrophy: Exercise induced increase in muscle mass
  • Endurance: Make slow twitch fibres; increase blood flow
  • Resistance strength: Thicken fast twitch; increase muscle size
  • Muscle spasms: Involuntary muscle contractions often due to a pinched nerve
  • Atrophy: Reduce muscle size, tone & power due to decreased use. Can lead to permanent loss of muscle function.

  Hypertrophy & Atrophy don't change the number of muscle fibres, can change size.
• Rigour Mortis


  Body cells die = No ATP production = No breaking actin-myosin cross bridge. 
• Slow twitch vs Fast twitch muscles

  Slow twitch: Smaller, resist fatigue (more blood vessels & mitochondria)

   

  Fast twitch: Larger, more power (rich in glycogen, use anaerobic energy)
• Muscle Twitch


  Muscle contractions that last a fraction of a second.

  • Latent stage: Time between stimulus and initiation of contraction
  • Contraction stage: Time for muscle fibres to shorten (needs Ca2+)
  • Relaxation stage: Time for muscle to return to regular length (needs ATP)

   
• Muscle Complications


  Soreness: Limited ATP storage requiring constant replenishment via aerobic respiration.

  Fatigue: ATP demand can't be met, leading to lactic acid build up & muscle tightness.

  Creatine phosphate helps replenish ATP (converts ADP to ATP)
• ATP synthase


  Protein channel that H+ ions move through to make ATP (chemiosmosis).
• NADP+


  Cofactor serving as an e- acceptor & transporter. When reduced (picking up e- and H+), it becomes NADPH.
• How does muscle contraction occur (sliding filament theory)?

  Nanny's truck carries tropical bridges ahead fully.


  
  

  1. NT released to muscle sarcoplasm, signalling contraction.
  2. Muscle's ER release Ca2+ ions near actin, into sarcoplasm.
  3. Ca²⁺ binds to troponin, causing tropomyosin to rotate & reveal actin binding sites.
  4. Actin & myosin form crossbridge.
  5. Myosin ATP head heaves and pulls muscle fibre.
  6. ATP repeatedly breaks & attaches crossbridge until full contraction.

  Side Note: Ca²⁺ helps break down ATP, providing energy for contraction and allowing actin to detach from myosin.
• Tropomyosin & Troponin


  Tropomyosin: Protein string blocking myosin binding sites

  Troponin: Protein dot blocking myosin binding sites 

   

  Ca2+ moves them off so bonding can happen
• Label the following mitochondria diagram:

  A) Outer Membrane

  B) Inner Membrane

  C) Matrix

  D) Cytoplasm

  E) Cristae

  
• Label the following chloroplast diagram:

  A) Outer Membrane

  B) Thylakoid Inner Membrane

  C) Stroma

  D) Grana (stack)

  E) Thylakoid Discs

  
• Myofilaments


  Skeletal Muscle > Sarcolemma (membrane enclosing fibres) > Fibres (bundle of cells) > Myofilament bundles > Sarcomere (Individual Myofilament section) > Actin and myosin which overlap to create a striated look

  • Actin: thin, long, light bands of myofilament.
  • Myosin: thick, short, dark bands of myofilament.

  
• Skeletal Muscle Sarcomere Structure (HIAZ)


  H-zone: Space b/w 2 actin; myosin found here.

  I-band: Space b/w 2 myosin; actin found here.

  A-band: Length of myosin; both actin & myosin found here.

  Z-line: Length of 1 sarcomere; anchors actin to each other & to bone.

  
• Describe Muscle Contractions & Graphs

  Muscles shorten to contract (bends the arm upwards) and lengthen to relax. Central nervous system sends nerve impulse signals to muscles to either contract (excitatory) or relax (inhibitory), never both at once.

  A) Normal Contraction

  B) No Contraction (No Ca2+ present)

  C) No Contraction (No ATP present)

  
• Why are leafy plants more efficient photosynthesizers than needle plants?

  More leaves = more palisades (always directed towards the sun) = more chloroplasts. Plants w/o leaves will die bc they are needed for photosynthesis.
• Label the muscles:

  A) Skeletal

  B) Smooth

  C) Cardiac

  
• What does no Ca2+ or no ATP do to muscle contractions?

  Ca2+: Troponin & tropomyosin stay blocking myosin binding sites; crossbridge is not formed.

  ATP: Myosin heads will stay attached to actin: stiffness/rigor mortis.

  • No Ca2+, too much ATP: Crossbridge remains detached bc of no CA2+: No contraction; If Ca2+ was present, ATP would keep detaching & reattaching.
• Describe anaerobic cell resp in ginger ale:

  Purpose is survival mode. Tightly stoppering ginger ale, forces yeast into anaerobic cell resp (alcohol fermentation), producing CO2 & ethanol. The CO2 dissolves, making fizz.