Aerobic & Anaerobic Respiration, Photosynthesis

Unit 5: Cellular Energy and Plants

Adenosine triphosphate (ATP)

• Your body requires energy to power its cells.
• Food energy cannot be directly used.
• Usable energy is stored in food's chemical bonds.
• To access this energy, bonds must be broken and new ones formed.
• Once converted into a usable form, ATP transports it for cell functions.
• ATP is an energy-carrying molecule used by cells.
• ATP is the primary energy currency for cells.

Adenosine Triphosphate Structure

• A nitrogen base (adenine) is part of ATP's structure.
• A sugar ring (ribose) is part of ATP's structure.
• 3 phosphate groups are held together with high energy bonds.

ATP-ADP Cycle

• Much energy is stored in the bond between the last two phosphate groups.
• Energy is released when a phosphate group is removed and added to another molecule.
• ADP becomes ATP when a phosphate group is added.
• ADP is recycled during the ATP-ADP cycle.

ATP Summary

• When broken down, ATP releases energy for the cell to use, becoming ADP and a phosphate, as per the equation: ATP → ADP + P + energy.
• Because more energy is given off than required, this is overall an exothermic reaction.
• To create ATP, cells combine ADP and a phosphate using food energy, as per the equation: ADP + P + energy → ATP.
• Because energy is taken in, this is overall an endothermic reaction.
• ATP is formed in this way during cellular respiration.

Energy Sources

• Carbon-based molecules in food are the origin of energy.
• Carbohydrates are most often broken down by ATP, yielding ~36 ATP per glucose molecule and storing 4 cal/g of energy.
• Lipids (fats) are broken down after carbs, storing 9 cal/g of energy.
• Proteins are the least likely to be broken down for energy, storing 4 cal/g of energy.

Photosynthesis Overview

• Organisms need a constant energy supply to survive.
• The sun provides the ultimate source of energy for most life.
• Photosynthesis converts sunlight into a usable form of energy.
• Photosynthesis is the overall process by which sunlight (solar/light energy), water, and carbon dioxide are chemically converted into chemical energy stored in glucose (a sugar/carbohydrate.)
• The chemical equation is: 6CO2 + 6H2O → C6H12O6 + 6O2.

Photosynthesis Simplified

• Reactants are the ingredients in photosynthesis, including CO₂ (carbon dioxide) and H₂O (water).
• Products are the results of photosynthesis, including C6H12O6 (glucose) and O2 (oxygen).
• Solar energy is necessary for photosynthesis, but is not considered a reactant or product.

Chloroplast Structure

• Photosynthesis occurs in the chloroplast.
• The chloroplast includes the grana and stroma.
• Grana are pancake-like stacks of thylakoid membrane.
• Stroma is the fluid-like substance filling the space between the grana.

Stages of Photosynthesis

• The two reactions are:
• Light-dependent reactions require solar energy.
• Light-independent reactions do not require solar energy, and are sometimes called "dark" reactions.

Light-Dependent Reaction

• Capture energy from the sun and store energy in “energy-carrying molecules" (ATP and NADPH)
• Occurs in the grana (specifically the thylakoid membrane) where the chlorophyll is stored.
• Chlorophyll is the pigment that captures sunlight.

Light-Dependent Reaction Summary

• Energy from the sun is passed down the Electron Transport Chain and stored in ATP and NADPH bonds.
• Water molecules are split into hydrogen and oxygen.
• Oxygen is released as a waste product.
• ATP, NADPH, and Hydrogen (H+) leave the grana and enter the stroma for the next stage.

Light-Independent Reaction

• Use the energy from the "energy-carrying molecules" from the light-dependent reaction to make sugar (glucose).
• Occurs in the stroma.
• Calvin Cycle is the summary.
• Chemical reactions are powered by ATP and NADPH.
• Hydrogen from water combines with carbon dioxide to form sugar molecules (glucose = C6H12O6).
• Carbon dioxide and hydrogen from water are used to make glucose

The Purpose of Photosynthesis

• Photosynthesis converts water, sunlight, and carbon dioxide into chemical energy stored in glucose.
• Light-dependent and light-independent reactions are the two stages.
• Photosynthesis takes place in the chloroplast.

Chemosynthesis

• Chemosynthesis is a process used by organisms to create their own food using chemicals instead of sunlight.
• This is the energy-getting process producers use when they cannot perform photosynthesis

Cellular Respiration Overview

• Goals are to convert chemical energy in glucose/food, into chemical energy stored in ATP.
• The body uses carbohydrates first for energy, but any food can be broken down as an energy source.
• The chemical equation: C6H12O6 + 6O2 → 6H2O + 6CO2 + Energy (ATP).

Cellular Respiration Simplified

• The reactants are the ingredients, made up of C6H12O6 (glucose) and O2 (oxygen).
• The products are the results, made up of CO2 (carbon dioxide) and H2O (water).
• Energy is released in the form of ATP, but is not considered a product.

Mitochondria Structure

• Cellular respiration takes place in the mitochondria.
• Mitochondria has two main parts: the inner membrane and the matrix.
• The inner membrane is made of folded membranes.
• The matrix is a fluid-like substance that fills the space.

Glycolysis

• Glycolysis is the breakdown of glucose, and is the first stage in cellular respiration.
• The objective of glycolysis is to split the 6-carbon molecule of glucose in half to form two 3-carbon molecules called pyruvate.
• Glycolysis occurs in the cytoplasm.
• No oxygen is required.
• Glycolysis is anaerobic.
• Glycolysis produces 2 ATP and 2 NADH.

Decision Time

• After glycolysis, the cell has to make a decision.
• If oxygen is present, aerobic respiration happens.
• Aerobic respiration is a two-step process.
• If oxygen is not present, anaerobic respiration/fermentation happens.

Aerobic Respiration if O₂ is Available

• Citric Acid Cycle (aka Krebs Cycle)
  • Location is in the Mitochondrial Matrix.
  • Two pyruvate molecules from glycolysis are chemically converted in this cycle to make 2 ATP
  • Releases carbon dioxide as a waste product.
  • Some NADH and FADH2 is created.
• Electron Transport Chain
  • Location is the inner membrane of the mitochondria.
  • A series of reactions using the e- and hydrogens formed in the Krebs Cycle.
  • Makes 34 ATP and H₂O.
  • Most ATP comes from this stage.

Think About It...

• Photosynthesis equation: 6CO2 + 6H2O → C6H12O6 + 6O2
• Cellular respiration equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP)
• Photosynthesis is endothermic versus cellular respiration which is exothermic.
• Photosynthesis reactants: water and carbon dioxide.
• Cellular respiration reactants: glucose and oxygen.
• Photosynthesis products: glucose and oxygen.
• Cellular respiration products: water and carbon dioxide.
• Photosynthesis Step One: Electron Transport Chain which occurs in Grana and uses/splits water to make oxygen.
• Cellular respiration Step One: Krebs Cycle which occurs in the Mito. Matrix and uses glucose (as pyruvate after glycolysis) to make carbon dioxide.
• Photosynthesis Step Two: Calvin Cycle which occurs in Stroma using carbon dioxide to make glucose.
• Cellular respiration Step Two: Electron Transport Chain which occurs in Inner membranes of the mitochondria, to use oxygen to make water.

Anaerobic Respiration if O₂ is Unavailable

• Without oxygen, cells go through anaerobic respiration or fermentation.
• Lactic acid fermentation and alcohol fermentation are the two main types.

Lactic Acid Fermentation

• Lactic acid fermentation occurs in some bacteria and muscle cells of animals.
• Pyruvate from glycolysis is converted into lactic acid and 2 ATP.

Alcohol Fermentation

• Alcohol fermentation occurs in yeast when oxygen is not available.
• Pyruvate from glycolysis is transformed into alcohol, carbon dioxide, and 2 ATP.

Total ATP Produced

• Aerobic Respiration produces 36-38 ATP overall
  • It takes 2 ATP from Glycolysis
  • It takes 2 ATP from Krebs Cycle
  • It takes 34 ATP from Electron Transport Chain
• Anaerobic Respiration = 2-4 ATP

Commonalities Among Plants

• Plants are made of plant cells
  • Plant cells have cell walls, chloroplasts, central vacuoles and Organelles common to all eukaryotes such as a nucleus, ribosomes, mitochondria, etc.
• Plants are multicellular organisms
• Plants go through photosynthesis and use this processas the metabolic process to conver solar energy into chemical energy for plants to use

Diversity Among Plants

• Vascular and nonvascular plants are the two clades that plants are characterized into

Nonvascular vs Vascular Plants

• Nonvascular plants do not have vascular tissue.
  • These plants are smaller because these plants cannot transport water up the stem
  • Water is absorbed via osmosis instead
  • These plants lack true leaves, stems or roots
  • These plants have a thallus body and rhizoids (root-like structure)
• Vascular Plants Contain vascular tissue: xylem and phloem which allows these plants to transport water and sugars throughout
• Vascular Plants have specialized organs such as roots, stems and leaves

Types of Nonvascular Plants

• Mosses:
  • Are small and dense looking like green carpet
  • They can live in any biome
  • Are critical for the environment because they help prevent erosion
• Liverworts:
• Have liver-shaped lobes
• that can live in any biome, but prefer a tropical envuronment needing dim light and damp soil
• They do not have stomata for gas exchange
• Hornworts:
  • Have horn shaped structures that protrude
  • that can live in any biome, but prefer a tropical envuronment
  • Only have 1 chloroplast per plant cell

Vascular Plant Structure

• They have 2 organ systems: root system and shoot system
• Vascular Plants have 3 organs:
  • Roots Absorb water and nutrients and keep plant anchored
  • Stem : Transports fluids and stores nutrients and specialized cells create new growth and support leaves.
  • Leaves: collect sunlight in chloroplasts and have stomata for gas exchange during photosynthesis.
• All three structures (roots, stems, and leaves) have 3 tissues:
  • Dermal tissue
  • Ground tissue
  • Vascular tissue

Vascular Plant Tissues

• Dermal tissue Used for protection and to prevent water loss - Includes mostly epidermis. - It also Includes periderm.

• Vascular tissue: used for transport - Transports water from roots to shoot. - Phloem moves minerals from roots → shoot and Sugars and food made from leaves in shoots go → other parts of plant. The primary function of the Phloem is to transport sugars/food

• Ground tissue: used for metabolism storage and support. - There are 3 types: - Parenchyma or traditional plant cells - Collinchyma for support - Sclerenchyma or wooded and durable cells

Diversity among Plants

• Angiosperms, gymnosperms, and seedless plants make up the vascular clade

Types of Vascular Plants

• Angiosperms:

  • Are flowering plants that have seeds
  • Reproductive structures are flowers
    • Seeds are enclosed in an ovary (fruit)
      • Animals aid in seed dispersal

• Gymnosperms: - Have seeds but no flowers or fruit - Reproductive structures are cones - Wind aids in seed dispersal

• Seedless: - Have no seeds such as ferns and club mosses that reproduce most similarly to non vascular plants - They use spores, dispersed via water

Parts of a Flower(Angiosperms)

• Sepal: green tissue that covers the flower when it is a bud

• Petal: Colorful structure used to attract specific animal pollinators

• Pistil: female organs

  • The ovule is the female germ cell that becomes a seed after the egg is fertilized
    • The Ovaries protect the ovule, and becomes a ripened fruit.
  • Stigma is the opening at the top of the style, which is a "neck" that sperm can travel down

• Stamen: male organs

  • The anther makes the pollen and sits at the end of the filament.
  • Pollengrains- powdery substance, male gametophyte, give rise to sperm cells

Angiosperms

• Monicots and dicots make up the angiosperm clade

Types of Angiosperms

• Monocots which have:
  • 1 cotyledon (seed leaf) in the seed embryo
  • Parallel leaf veins
  • Flower petals in multiples of 3. -Net-like/fibrous root system
• Dicots that have:
  • 2 cotyledons in the seed embryo
  • Branching leaf veins
  • Flowers petals in multiples of 4 or 5
  • Taproot root system

Questions cover the processes of aerobic and anaerobic respiration, including the role of oxygen, ATP production, and key differences. Also compares photosynthesis and cellular respiration and key features common to both plant and animal cells.