UNIT 5 PHOTOSYNTHESI S Standard H B 3
UNIT 5 PHOTOSYNTHESI S Standard H. B. 3
Warm-Up #1 – Biochemistry Review 1. Which of the following molecules found in the food we eat is most commonly broken down to make ATP energy? a. b. c. d. lipids carbohydrates proteins nucleic acids 2. What are the elements are found in a carbohydrate molecule? 3. Plants store excess/extra glucose as ___________ for short-term energy.
ATP Objectives: Compare and contrast ATP and ADP molecules. Explain the ATP-ADP cycle.
Cellular Energy • Cells require a constant supply of energy. Energy within a cell exists in the form of chemical energy, which is the energy stored in the bonds of molecules.
ATP • A source of this chemical energy is a compound called adenosine triphosphate (ATP). • ATP is the molecule that transfers energy from the breakdown of food molecules to cell processes. • ATP is the most important biological molecule that supplies energy to the cell (builds organic molecules, like DNA and proteins, and transports organic molecules across the cell membrane via protein pumps, endocytosis, and exocytosis).
3 Parts of ATP • 3 Parts of an ATP molecule: 1. Adenine (nitrogen base) 2. Ribose (sugar) 3. 3 phosphate groups • What does the prefix tri- in triphosphate mean? 3 • Adenosine is a word made up of a combination of letters from 2 different words/molecular names. What are the two words/molecular names? Adenine and Ribose
Gaining Energy from ATP • Carefully remove one phosphate from the end of your ATP model. • How many phosphate groups are still attached to the original molecule? 2 • This new compound with one fewer phosphate group than before is called adenosine diphosphate (ADP). What does the prefix di- mean? 2
• Explain how an ATP molecule is changed to an ADP molecule. the bond between the 2 nd and 3 rd phosphate group is broken and a phosphate group is removed • What is released when ATP is changed to ADP? (hint – think about breaking bonds) ENERGY • Which molecule has more energy to do work, ATP or ADP? WHY? ATP because it has more bonds and bonds store energy
ADP • When ATP loses a phosphate it is changed into a compound called adenosine diphosphate (ADP). • The breaking off of a phosphate group releases energy for biological work in a cell.
ATP-ADP Cycle • To continually supply the cell with energy ADP must be changed back into ATP, but this reaction requires the input of energy from food. • During cellular respiration (an energy-releasing process), energy from the breakdown of glucose is used to supply energy to rehook a phosphate group to ADP to form ATP again.
PHOTOSYNTHESI S OVERVIEW Objectives: Explain the importance of photosynthesis to organisms on Earth. Recall the equation for photosynthesis. Describe the importance of glucose to plants.
Organisms & Energy • All organisms need energy to survive • 2 types of organisms based off how they get energy: 1. Autotrophs – make their own food; producers • Ex-plants, algae, and some bacteria 2. Heterotrophs – eat other organisms to get food; consumers • Ex-humans, fungi, animals • Dependent upon the producers for food and oxygen • ALL energy ultimately comes from the sun
Photosynthesis Basics • Process where autotrophs make their own food by trapping and converting light energy into chemical energy (carbohydrates) • Occurs in the chloroplasts • 2 main stages: 1. Light-dependent reactions 2. Light-independent reactions • Overall equation:
Check for Understanding 1. What is the main source of energy on Earth? 2. What are the two stages of photosynthesis? 3. Where does photosynthesis occur? 4. What are the overall reactants of photosynthesis? 5. What are the overall products of photosynthesis?
Importance of Glucose/Simple Sugars 1. Can be used by the cell for energy to make ATP during cellular respiration 2. Can be converted into starch or cellulose to store energy for short periods of time
Importance of Glucose/Simple Sugars • Can be converted into lipids to store energy for long periods of time • CHO in 1: 2: 1 ratio in carbohydrates • CHO – very little O in lipids
Importance of Glucose/Simple Sugars • Can act as carbon skeletons to interact with other elements/minerals to make proteins • Carbohydrates = CHO • Proteins = CHON
Importance of Glucose/Simple Sugars • Can act as carbon skeletons to interact with other elements/minerals to make nucleic acids (DNA/RNA) • Carbohydrates = CHO • Nucleic acids = CHONP
Check for Understanding 1. What does a plant do with excess glucose produced during photosynthesis? 2. What organic molecule acts as a carbon skeleton to form other organic molecules like proteins and nucleic acids? 3. What must a plant absorb from the soil in order to transform glucose into a protein? 4. Where does a plant get nitrogen and phosphorus to make nucleic acids?
Warm-Up #2 – Fate of Glucose • Study the flow-chart below and answer the following questions. • What happens to excess glucose formed in plants? • What are the 3 main fates of glucose?
BASIC PLANT STRUCTURE AND LAB Objectives: Discuss the structure of a stoma. Discuss the structure of a chloroplast. Perform a lab to observe pigments and stomata in a leaf.
Stomata • Plants take in carbon dioxide (CO 2) through tiny openings in leaves called stomata (singular: stoma). • Stomata open and close to: • Take in CO 2 • The carbon in carbon dioxide is used to make sugar. • Release O 2 • The oxygen that is released is the very oxygen that we ourselves need to breathe!
Chloroplasts • Chloroplasts mainly found in the leaves of plants (million per square millimeter)
Chloroplast Structure: • Structure of the chloroplast: • Inner membrane is folded to form thylakoids, which are stacked to form a granum (pl. -grana) • Fluid around grana is called the stroma
Pigments • Thylakoid membranes contain pigments • Main plant pigment = chlorophyll • There are two types of chlorophyll – chlorophyll a & chlorophyll b • mostly absorb red and blue wavelengths of light • reflect green wavelengths of light (why plants look green) • Accessory pigments = carotenoids • Lycopene – reflects red • Xanthophyll – reflects yellow • Carotene – reflects orange
Photosynthesis Lab • Part 2 – Holly Leaf Stomata • Underside of leaf • Allow for gas exchange (CO 2 in and O 2 out)
Warm-Up #3 – Chloroplast Structure • Label the structure below.
LIGHT DEPENDENT REACTIONS Objectives: Recall the equation for photosynthesis. Recall the inputs and outputs of the light-dependent reactions. Discuss the importance of the light-dependent reactions.
Light-Dependent Reactions • The first stage of photosynthesis • Requires sunlight • Where does it happen? • thylakoid membranes • What goes in? • sunlight (light/solar energy), water, NADP+, ADP • What comes out? • oxygen, NADPH (energy carrier molecule), and ATP • Purpose • Make energy (ATP and NADPH) for light independent reactions
Light-Dependent Reaction Steps 1. Light/Solar energy splits water to release: • O 2 leaves chloroplast and cell as a waste • Electrons from broken bonds go into thylakoid membranes 2. Light/solar energy is also absorbed by the pigments in the thylakoids and transfer energy to electrons 3. Then electrons transfer energy to ADP and NADP+ to make ATP and NADPH
Check for Understanding 1. Where do the light-dependent reactions occur? 2. What is produced in the light reactions? 3. What is NADPH? 4. What is released into the atmosphere as waste during the light reactions? 5. What is the purpose of the light reactions if they don’t make sugars?
LIGHT INDEPENDENT REACTIONS Objectives: Recall the equation for photosynthesis. Recall the inputs and outputs of the light-independent reactions. Discuss the importance of the light-independent reactions.
Light-Independent Reactions • The second stage of photosynthesis • DOES NOT require sunlight (AKA dark reactions or Calvin Cycle) • NADPH and ATP made in the light reactions supply energy • Where does it happen? • stroma of the chloroplast • What goes in? • NADPH, ATP, and CO 2 • What comes out? • glucose, ADP, and NADP+ • Purpose • Make sugars (glucose)
Light-Independent Reaction Steps 1. CO 2 enters the leaves via stomata and diffuse into the chloroplast’s stroma 2. ATP and NADPH from the light reactions transfer energy to CO 2 and fix it into a simple sugar (glucose) 3. NADP+ and ADP are sent back to light dependent reactions to be recharged
Check for Understanding 1. What are other names for the light-independent reactions? 2. Where do the light-independent reactions occur? 3. What is produced in the dark reactions? 4. What happens to ATP and NADPH once they transfer energy to CO 2 to make sugars? 5. What is the purpose of the Calvin cycle?
The Whole Picture
Check for Understanding • Label the diagram of photosynthesis: 11. 7. 6. 3. 13. 2. 14. 4. 5. 9. 10. 1. 8. 12.
Warm-Up #5 – Light and Dark Reactions in Photosynthesis • What is recycled between the light reactions and the Calvin cycle? • What are the inputs in the Calvin cycle? • Where are sugars produced in photosynthesis? • Where does the Calvin cycle take place in the chloroplast?
Warm-Up #6 – Photosynthesis Rate • Look at the graph to the right. As carbon dioxide levels increase, plants will produce more ________. • What is happening at “C” in the graph to the right?
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