Energy in cells (Respiration and Photosynthesis)

Photosynthesis Chemical process that captures light energy and stores it as potential chemical energy, only in autotrophs Occurs in the … 2 Stages –Light phase –Dark phase

Structure of a chloroplast Granum – thylakoids membranes 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 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 CO 2 + H 2 O C 6 H 12 O 6 + O 2

Carriers molecules in P/S ATP – the energy carrier –ADP (empty) –Transports energy from light phase to dark phase NADP – the hydrogen carrier –NADPH 2 (full) –Transports hydrogen from light phase to dark phase

Stages in Photosynthesis StageRaw material Source raw material By productLocation 1. Light or light dependent phase 2. Dark or light independent phase

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

Factors affecting photosynthesis reaction rate: Photosynthesis is controlled by enzymes so anything that affects enzymes also affects photosynthesis, including; Temperature (most plants have an optimum range) Light intensity (can differ for different plants, canopy verses forest floor plants), no photosynthesis in the dark! CO 2 concentration (substrate) Low water availability causes the stomata to close and CO 2 diffusion to stop.

Biozone Level 7 Biology text Read pages 130 – 132 Do Exercises 1-4 page 130 Do Exercises 1 – 2 page 131 Do Exercises 4 – 6 page 132 And you should have already done Exercises 1 – 4 page 123

Cellular 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 auto 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 Cellular respiration with oxygen Also guided by enzymes Glucose (food) and oxygen convert to lots of energy (ATP) with waste products of CO 2 and H 2 O C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP glucose oxygen carbon dioxide water energy

4 Stages of aerobic respiration –Glycolysis, –Link reaction (formation of Acetyl Coenzyme A), –Krebs cycle, –Electron transport chain The stages are linked by carrier molecules…

4 stages of aerobic respiration StageNameLocation in cell Energy (ATP) produced Link to equation 1 Glycolysis 2 none 3 Matrix of mitochondria 4 H 2 combines with O 2 to form water

Carriers (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 –NADH 2 (full) –Transports hydrogen from Krebs cycle to Electron transport chain

Anaerobic respiration Respiration without oxygen Stops after glycolysis (stage 1) Much less energy (ATP) produced Different waste or byproducts produced Plants Glucose  carbon dioxide + ethanol + 2ATP Animals Glucose  lactic acid + 2ATP

Factors affecting respiration All respiration reactions are controlled by enzymes. The same things that effect enzymes can affect the respiration plus: Too much toxic product. Too much carbon dioxide (any 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. List the other factors that affect respiration reactions from your enzyme notes….

Biozone Level 7 Biology text Read pages 126 – 129 Do Exercises 1 – 3 page 128 Do Exercises 1-3 page 129

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 P P P P

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

Energy in cells summary P/S Respiration Light Energy CO 2 and H 2 O Glucose O2O2 O2O2 All Autotroph and Heterotroph cells ATP Heat Energy H2OH2O CO 2 Photosynthetic Autotroph cells ADP kJ

Biozone Level 7 Biology text Read pages 124 – 125 Do Exercises 1 – 2 page 124 Do Exercises page 125