Photosynthesis and Cell Respiration A beginner’s guide…

Why are we learning this? Standard we have to master: SB3a: Explain the cycling of energy through the processes of photosynthesis and respiration.

Hmmm… What is an autotroph? What is a heterotroph? Any organism that can produce its own sugar inside its cells. Example: Plants, some protists and some bacteria What is a heterotroph? Any organism that needs to eat to get its sugar Examples: animals, fungi, some protists

ATP What is ATP? What does ATP stand for? What is it made of? It is the energy molecule for cells. What does ATP stand for? Adenosine Tri-Phosphate What is it made of? Adenine Ribose 3 phosphates

Wait just a dern minute!!! Adenine + ribose + phosphate? That sounds familiar…. Hmmm….. OH! It’s a nucleotide! Wait….so ATP is a nucleic acid? No…it’s a nucleotide (monomer), but it is not chained together to be a nucleic acid (polymer).

Is ATP a Nucleic Acid? Why? No. It is just one nucleotide. To be a nucleic acid, there has to be more than one nucleotide in a chain.

ATP Cycle Copy onto your notes:

Hmmmm???...Questions to consider… Why are plants green? Because of the chlorophyll in the chloroplasts. What does chlorophyll do? It absorbs light. Which wavelength (color) of light is not absorbed by chlorophyll? Green That’s why plants appear green….They REFLECT green light and you SEE the green light that is reflected.

Chloroplasts 3 main parts: Thylakoid: Granum: Stroma A disk-shaped structure in the chloroplast where specific reactions take place. Looks like a quarter or a dime Granum: A stack of thylakoids Plural = grana Looks like a stack of quarters or dimes Stroma The cytoplasm inside the chloroplast

Photosynthesis Is the process by which plants make sugars needed for energy production. Requirements (aka: Reactants): Carbon Dioxide (CO2) Water (H20) Light

Hmmm… Where do plants get sunlight from? The sun. Where do plants get Carbon Dioxide from? The atmosphere. Where do plants get water from? The ground

Photosynthesis Equation: 6 CO2 + 6 H2O + light  C6H12O6 + 6 O2 What is C6H12O6 ? What are the “reactants”? What are the “products”? A sugar called Glucose CO2, H20, & LIGHT C6H12O6 & O2

2 parts (reactions) of photosynthesis: 1.) Light Dependent Reactions Need light to occur. Occurs in the thylakoids. Produces oxygen (waste), ATP and NADPH NADPH is an electron carrier ATP is a storage molecule for energy Oxygen is…well, oxygen

2.) Light Independent Reactions AKA:; the Calvin Cycle Occur in the Stroma. Can occur with or without light. Produces glucose (C6H12O6)

Factors effecting photosynthesis These things can either speed up or slow down the rate of photosynthesis: 1.) Amount of light 2.) Amount of water 3.) Temperature

Question #1 Where in the plant does Photosynthesis take place? A.) in the nucleus B.) in the cytoplasm C.) in the chloroplast D.) in the ribosome

Question #2 Which of the following is NOT a reactant for photosynthesis? A.) water B.) sugar C.) carbon dioxide D.) light

#3 Which of the following is the correct equation for photosynthesis? A.) 6 CO2 + light  C6H12O6 + 6 H20 + 6 O2 B.) 6 CO2 + 6 H20 + light  C6H12O6 + 6 O2 C.) C6H12O6 + 6 O2  6 CO2 + 6 H20 + light D.) C6H12O6 + 6 H20 + 6 O2  6 CO2 + light

#4 Which of the following occurs in the light reactions? A.) CO2 is produced. B.) Oxygen is produced C.) sugar is produced D.) Light is produced.

#5 The Light Independent reactions: A.) can only occur in the dark. B.) can occur whether there is light or not. C.) produce oxygen D.) Produce ATP

Opener… should take fewer than 15 minutes. Turn to page 116 in your textbook and complete the Data Analysis activity at the bottom of the page. For question 1: Explain what is going on in the graph. Be detailed. For question 2…explain WHY the CO2 levels in the atmosphere are changing throughout the 24 hour day.

Draw graph from p. 116 here.

Fun for all eukaryotic organisms…. Cell Respiration Fun for all eukaryotic organisms….

Background Cell respiration (C.R.) occurs in the cytoplasm and the mitochondria. It occurs in ALL eukaryotic cells. The purpose: use glucose to make 36 ATP molecules.

Equation C6H1206 + 6 O2  6 CO2 + 6 H20 + 36ATP Hmmmm…does this look familiar? What are the reactants? Glucose and oxygen What are the products? Carbon dioxide, water, and ATP

There are 3 major parts to cell respiration: 1.) Glycolysis 2.) The Krebs cycle 3.) The electron transport chain

Let’s talk about glycolysis: Where does it occur? In the cytoplasm of the cell Does it need oxygen? No! This part of C.R. is “anaerobic” An- = without -aerobic = oxygen What happens? Glucose is broken in half to create 2 “pyruvic acid” molecules. 4 ATP are produced, but 2 are used in the process of glycolysis, leaving a net gain of 2 ATP.

Let’s talk about the next step…the Krebs Cycle AKA: the citric acid cycle Where does it occur? In the mitochondria Does it require oxygen? YES!!! What happens? The pyruvic acids (produced in glycolysis) are changed into citric acid. Result: 2 ATP are produced.

Come on ride that chain….ride it! Whoot Whooo!!! The Electron Transport Chain! Where does it occur? In the mitochondria Does it need oxygen? YES!!! What happens? In glycolysis and the Krebs cycle, high energy electrons were produced. These electrons are used to make 32 ATP

Summary Step Where does it occur Does it use Oxygen? How many ATP produced (net) Glycolysis Krebs Cycle Electron Transport Chain cytoplasm No 2 Mitochondria Yes 2 Mitochondria Yes 32

What happens if there is a lack of oxygen? Then “Lactic Acid Fermentation” occurs. After glycolysis, IF there is a lack of O2 (perhaps due to increased exercise), the pyruvic acid cannot/will not enter the Krebs Cycle. Instead, the 2 pyruvic acids are changed into lactic acid, which when used by your cells gives 2 ATP. Problem: lactic acid is poison for the cells, which you feel as “burning” when you exercise. You cannot continue for long with this burning, so typically, you slow down and breathe more to get oxygen.

Another fermentation…not in your cells. Alcohol Fermentation: Occurs in yeast when making bread and beer. Yeast produces alcohol as a waste product when there is low oxygen levels. Yes, THAT kind of alcohol. THIS DOES NOT HAPPEN IN YOUR CELLS!

Let’s review: Comparison Photosynthesis Cell Respiration Function: Location: Equation: Reactants: Products: What type of organisms do this? Glucose production Energy (ATP) Production Cytoplasm and Mitochondria Chloroplasts You write it down.  Once again…you do it. CO2; H20; light Glucose & O2 CO2; H20; 36 ATP Glucose & O2 All Eukaryotes! (so…NO BACTERIA!) Autotrophs, such as plants.