Biology… …the study of LIFE!!!!
If something is living it has certain characteristics… …what are some of these characteristics?? Set up a page on which you will take notes These notes may help you as you work to understand our next unit Title “Notes on Photosynthesis” Date in left hand margin “1/18/19“ Chat with your neighbors and record as many characteristics as you can remember.
are made in an organized way, using the CELL as the building block of life • are able to reproduce, or play some role in doing so All living things … • are able to obtain and use energy in order to build and move parts • are able to sense and respond to signals in their environment • grow and develop • have cells that contain genetic material, which directs growth, development and response • are able to maintain an internal stable environment • are part of populations of similar organisms that over many generations evolve
Last semester we… …looked closely at the cell prokaryotic versus eukaryotic cells levels of organization in multicellular organisms specialized cells the cell membrane …considered cellular and organismal reproduction the mitotic and meiotic cell cycles
We are going to investigate the ability of life to capture and utilize energy Energy that is used to grow, develop, move and reproduce What is the first characteristic of life we are going to study this semester??
PHOTOSYNTHESIS!!! What was one of the first incredible inventions of life that allows life to capture and utilize energy? Life would not exist as we know it today without photosynthesis!!
Well, what do you know about PHOTOSYTHESIS? Chat with your neighbors and come up with three things that you know about PHOTOSYNTHESIS. Write the three things into your notes. But what the heck is PHOTOSYNTHESIS and why is it so important?
Intro to Cells • Intro to Biochemistry Frank Gregorio • Intro to Photosynthesis Frank Gregorio
The Amoeba Sisters!! Now, who better to teach us about PHOTOSYNTHESIS but …
Photosynthesis!! A complex, multistep process that… …uses sun energy …to combine carbons and oxygens (from CO2) and hydrogens (from H2O) …to make glucose (made of carbons, hydrogens and oxygens) …the food of the photosynthesizing organism Some oxygens are left over as O2
All plants perform photosynthesis The leaf structure allows for gas exchange CO2 in - O2out Through the stomata pores The leaf vein carries glucose to the rest of the plant
Set up your activity page with the following title… An Investigation of Photosynthesis Using Floating Leaf Discs Identifier info in upper right hand margin (name and period) Date (1/22/19) in left hand margin on first line where you will copy the following objective. Objective Students will understand the complex metabolic process of photosynthesis, including the involved reactants and products. Students will understand how the anatomy of the typical leaf allows for photosynthesis. Lab station: Partners: Fill in when these have been assigned
Your job Color the leaf anatomy page Stomata = Red Vein = Different Blue Air spaces = Blue The other colors you pick Photosynthetic cells = Green Write the chemical equation for photosynthesis on the page (use chemical symbols) Write the chemical equation in words Designate the “reactants” and “products” Show the path of gases (label them) into and out of the leaf Show where water comes from Show where glucose that is not used by the leaf cells goes
Your job… Listen and understand whet we are going to do in this lab!! You will have to answer questions gauging your understanding later. Turn to your “Notes on Photosynthesis” and date the left-hand margin where you will begin today’s entry. (1/23/19) In this lab we are going to measure how well photosynthesis works with or without carbon dioxide. We are going to measure photosynthesis by indirectly measuring how much O2 (molecular oxygen) is made. If we take the CO2 away, can the plant still perform photosynthesis and make oxygen?
Put leaves in water with dissolved CO2 and without dissolved CO2. How are we going to measure whether O2 is made or not (in other words, whether photosynthesis is working or not)? How are we going to provide or take away CO2? To understand this we have to understand the anatomy of the leaf. Observe the air spaces and the way in and out of the leaf through the stomata. Air typically fills the air spaces.
We are then going to put the leaves in water (either with CO2 or without CO2) and shine light on them. The leaves, without air, should sink. We are going to suck the air out of the air spaces and fill the spaces with water (either containing dissolved CO2 or not containing dissolved CO2). If photosynthesis is working, the leaf cells should be making O2, which will build up in the air spaces as a gas, displacing the water. As the air spaces fill up the leaf becomes more buoyant and will eventually float. The faster the leaves float the more photosynthesis is taking place!!
With a vacuum!! We will make a vacuum with a syringe!! How are we going to suck air out of the air spaces?
Procedure • Prepare two solutions – one with and one without dissolved CO2 • Punch out leaf discs with hole-punch • Place leaf discs in syringe and draw out air with partial vacuum • Place “deaired” discs in solutions (one with and one without dissolved CO2) • Shine light on discs and see which ones float quickest!! Today – establish understanding and prelab questions Thursday – lab prep Friday – run lab
On activity sheet date left-hand margin (1/23/19) where you will begin today’s entry and title section “Pre-Lab Prompts and Answers”. Get out activity sheet Assign and meet with groups to record work station and partners’ names Return to seats to answer prelab questions
1. Write the chemical equation for photosynthesis using chemical symbols. 2. Describe in general what we are testing in this lab. What is our independent variable? What role does the IV play in the chemical equation for photosynthesis. 3. What are we going to measure to indirectly determine the rate of photosynthesis? What is our dependent variable? What role does the DV in the chemical equation for photosynthesis? 4. How are we going to make one group with the IV? What would we call this group? 5. How are we going to make one group without the IV? What would we call this group? 6. Describe in your own words how we are going to prepare the leaf so that we can measure the DV. How are we going to measure the DV?
Instructions Use distilled water 1. Wash 2 large cups, 2 small cups, graduated cylinder and weigh boat Dry all except insides of cups and graduated cylinder (drip/shake dry) Remember the BPBs!!! 2. Tape all the way around each big cup; Label one “With CO2” and one “Without CO2” Also add period and table number 3. Weigh 3 grams (2% CO2)of carbon dioxide powder and deposit into “With CO2” cup Also add period and table number 4. Measure 148 milliliters of water and pour into “With CO2” cup 5. Measure 150 milliliters of water and pour into “Without CO2” cup 6. Place heat sink cups (empty) in large cups and place cups in designated storage boxes
Number of leaf chads that float over 10 minute time course in 1% CO2 and O% CO2 You add additional minutes to your table
PHOTOSYNTHESIS… …a metabolic pathway performed in cells of organisms called photoautotrophs. Organisms that can perform PHOTOSYNTHESIS are called photoautotrophs. So what is PHOTOSYNTHESIS exactly?? Date your notes in the left hand margin “1/24/19” Autotrophs are able to make their own food. Photoautotrophs use the energy from light to make their food.
All plants– eukaryotes that perform photosynthesis What types of critters are photoautotrophs? Some unicellular protists (eukaryotes) and some multicellular protists (seaweed like) perform photosynthesis Some prokaryotes (called cyanobacteria)perform photosynthesis
In eukaryotes photosynthesis occurs in an organelle called the chloroplast An important type of light/energy capturing molecule, found within the chloroplast, is called chlorophyll
Wait a minute – back up – what is a chemical reaction again? Let’s review chemical reactions. OK – so what is a “metabolic pathway”? A metabolic pathway is a long series of connected chemical reactions. In a chemical reaction the chemical bondsthat hold atoms together in compounds are broken and reformed, creating new compounds. Reactantsare converted intoProducts (the compounds that you begin with) (the compounds you end up with)
Carbon atom Compounds are combinations of atoms joined by chemical bonds. Atoms occur as different elements (elements are different kinds of atoms). Symbols for the different elements are found on the periodic table. H2O is water, which includes hydrogen (H) and oxygen (O) atoms. Compounds are symbolized by chemical formulas, such as H2O or CO2
A chemical formula (letters and small numbers together) indicates a compound (multiple atoms joined with chemical bonds) H2O = a water molecule Chemical reactions can be symbolized with chemical equations. How do you read a chemical equation? 2 molecules of hydrogen react with 1 molecule of oxygen to produce 2 molecules of water The coefficients refer to the number of compounds The subscripts refer to the number of a particular element in a compound When there is no coefficient or subscript it implies “one”
How many compounds in total? How many atoms in 2H2O? How many atoms in the reactants? How many compounds in the reactants? How many atoms in the reactants?
Practice Reading Chemical EquationsOn a separate page to turn in 1. What occurs in a chemical reaction? What is a chemical equation? 2. In a chemical equation, what in general are the products? Where do you typically find them in a chemical equation? 3. In a chemical equation, what in general are the reactants? Where do you typically find them in a chemical equation? 4. What does the arrow represent in a chemical equation? 5. What are the small numbers referred to as, and what do they represent? 6. What are the large numbers referred to as, and what do they represent? Go to next page…
Use the following chemical equation to answer #7 - 9 6CO2 + 6H2O --> C6H12O6+ 6O2 7. How many molecules are included in the products? Write out the products and circle the numbers of the chemical formulas that help you answer this question. What are these numbers called? 8. How many atoms in total are in the reactants? In regard to the reactants, write how many atoms there are of each type of element. What do you call the numbers that tell you about the number of atoms in a compound? 9. Write out the meaning of the equation but use only complete words, not numbers, elemental letters alone or symbols. 10. Using complete sentences explain how you determine how many atoms there are of each type of element in a chemical formula. Use these formulas as examples in your explanation. NH3 3CH4 Give detail!!
So what is A “METABOLIC Pathway” and what do MP have to do with PHOTOSYNTHESIS?? Date your notes in the left hand margin “1/29/19” A metabolic pathway (MP) is a long series of connected chemical reactions. MP usually build up or break down molecules in a number of steps (chemical reactions). In a MP the products of one reaction serve as the reactants of the next reaction. A + B AB + C ABC + D ABCD #1 #2 #3 #1 #2 #3 ABCD ABC AB A + B + D + C
In a long series of chemical reactions, PS combines six CO2(carbon dioxide) molecules with 12 hydrogens (H) to make one molecule of glucose (C6H12O6) The energy needed to build chemical bonds between these atoms is provided by light (a form of energy) Photosynthesis (PS) is a metabolic process
We can summarize the long series of chemical reactions by writing a chemical equation that shows us what goes in and what goes out Water is the source of hydrogens found in glucose, a kind of “sugar”or carbohydrate Molecular oxygen is made with the extra oxygen atoms
First part – “Light Reactions” Energy from light captured in the form of chemical energy (the energy that holds atoms together in compounds) H2O is broken apart to release hydrogens (H) Extra oxygens combined to make O2 Second part – “Calvin cycle” The energy captured in the LR is used to combine the carbons and oxygens from CO2 with the hydrogens from water (also from the LR) These carbons, oxygens and hydrogens are combined to make glucose (C6H12O6)
#1 Life is built with biomolecules Proteins, lipids, nucleic acids, carbohydrates All biomolecules are made from the glucose But why the big deal? What is so important about glucose? #2 Life needs energy to grow, move, maintain homeostasis, and so on That energy comes originally from sunlight, through glucose So basically photosynthesis is responsible for the building blocks and energy of life
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