(Photosynthesis and Respiration) Energy in cells (Photosynthesis and Respiration)

Photosynthesis Chemical process that captures light energy and stores it as Chemical Potential Energy, only occurs in autotrophs Is a series of reactions controlled by enzymes Occurs in the … 2 Stages Light phase 1 Dark phase 2

Structure of a chloroplast Granum – stacked thylakoids containing chlorophyll. Stroma – clear liquid interior How can you tell which phase occurs where? How has surface area been maximised? What is the green colour from?

Photosynthesis reaction summary: The purpose is to capture light energy from the sun and store it as chemical energy in glucose molecules for use inside the plants. It also: Removes carbon dioxide from the air Needs water, gained by osmosis from the soil into the root hair cells and up the xylem vessels Makes oxygen gas for use in respiration in all living organisms Photosynthesis reaction summary: Carbon dioxide + water glucose + oxygen + water CO2 + H2O C6H12O6 + O2 + H20

Stages in Photosynthesis Raw materials Source of raw materials Products (waste) Location within Chloroplast Phase 1. Light or Light Dependent (LD) Phase 2. Dark or Light Independent (LI)

Stages in Photosynthesis Raw materials Source of raw materials Products (waste) Location within Chloroplast Phase 1. Light or Light Dependent (LD) Light Water ADP NAPH Sun Air Dark Reaction ATP NADPH2 (Oxygen) Thylakoids of Grana Phase 2. Dark or Light Independent (LI) Carbon Dioxide Light Reaction Glucose Stroma

Carrier molecules in Photosynthesis ATP – the energy carrier ADP (empty) Transports energy from light phase to dark phase NADP – the hydrogen carrier NADPH2 (full) Transports hydrogen from light phase to dark phase

How plants maximise the rate of photosynthesis See handout and discuss this concept in relation to the leaf model and the chloroplast diagram

Factors affecting photosynthesis reaction rate: Photosynthesis is controlled by enzymes so anything that affects enzymes also affects photosynthesis, including; Light intensity (can differ for different plants, canopy verses forest floor plants), no photosynthesis in the dark! Temperature (most plants have an optimum range) CO2 concentration (substrate concentration) Low water availability causes the stomata to close and CO2 diffusion to stop so photosynthesis stops as well.

Respiration All living cells must carry out cellular respiration and the purpose is too release the energy stored in food (glucose) and make it available to power all other metabolic reactions (in both autotrophs and heterotrophs) Occurs in the (name organelle here?) There are two types (aerobic and anaerobic)

Structure of a mitochondria Cristae are the folded inner membranes. Why are they folded? The matrix is the liquid inside . What stages take place here? Mitochrondria are found in all living cells but in general animals cells have more than plants and any cells that need more energy have more e.g. muscle and liver cells have high energy demands so have more….

Aerobic Respiration (with O2) Cellular respiration with oxygen Also a series of reactions controlled by enzymes Glucose (food) and oxygen convert to lots of energy (ATP) with waste products of CO2 and H2O C6H12O6 + 6O2  6CO2 + 6H2O + ATP glucose oxygen carbon dioxide water energy

4 stages of aerobic respiration Name Location in cell Energy (ATP) produced Link to equation 1 2 3 4

4 Stages of aerobic respiration (with oxygen) Glycolysis, Link reaction , Krebs cycle, Electron transport chain These stages are linked by carrier molecules in a similar way to photosynthesis reactions…

4 stages of aerobic respiration Name Location in mitochondria or cell Energy (ATP) produced Link to equation 1 Glycolysis (breakdown of glucose) Cytoplasm 2 ATP Forms Pyruvate No O2 needed 2 Link reaction Matrix none Forms Acetyl Co enzyme A and CO2 3 Krebs Cycle or Citric Acid Cycle Produces H2 4 Electron Transfer Chain Cristae 32 ATP O2 needed, combines with H2 to produce H2O

Carrier molecules in respiration (molecules that link stages of aerobic respiration) Co-enzyme A – an acetyl carrier Acetyl co-enzyme A (full) Transports acetyl group from glycolysis to Krebs cycle NAD – the hydrogen carrier NADH2 (full) Transports hydrogen from Krebs cycle to Electron transport chain

Anaerobic respiration (no O2) Respiration without oxygen Another series of reactions controlled by enzymes Stops after glycolysis (stage 1) Much less energy (ATP) produced Different waste or by-products produced Plants Glucose  carbon dioxide + ethanol + 2ATP Animals Glucose  lactic acid + 2ATP

Factors affecting respiration All respiration reactions are controlled by enzymes …so again all things that effect enzymes affect both types of respiration, plus: Too much toxic product. Too much carbon dioxide (aerobic respiration) and too much ethanol or lactic acid (anaerobic respiration) is toxic. Toxic products must be removed during respiration for it to continue efficiently.

See Factors Affecting Enzymes… Temperature, pH, Surface Area, Substrate (reactant) concentration, Enzyme concentration, Co-Factors (enzyme helpers), Inhibitors (heavy metals, poisons).

ATP Adenosine triphosphate (ATP) is the universal energy carrier in all cells Cellular respiration is the process of recharging ADP (Adenosine diphosphate) to ATP P P

Role of ATP (Energy carrier molecule) Energy released from breaking off one phosphate (-P) from ATP. Where? ATP ADP Respiration recharges ADP to ATP using energy and adding one phosphate (+P). Where? +P

Energy in cells summary Photosynthetic Autotroph cells All Autotroph and Heterotroph cells Light Energy O2 CO2 and H2O P/S Glucose ADP Respiration kJ O2 ATP H2O Heat Energy CO2