Reactants of Photosynthesis Carbon Dioxide - Comes from all the animals including us (it's what we exhale). Water - Interacts with the other ingredients to mix and make glucose.
Sunlight – trapped in the chloroplasts by chlorophyll. Uses the energy to break apart the parts of a cell they need to work with. Without sunlight, the plants would not give off oxygen.
Products of Photosynthesis Glucose - The food that plants made from photosynthesis. It is used as their food source to make energy. Oxygen - What we use to make our own energy - which in turn helps plants to also make their energy in a cycle.
Chlorophyll – A green pigment in chloroplasts that absorbs light energy to start photosynthesis.
Disc-like sacs called “thylakoids” contain the chlorophyll that absorbs light energy to start photosynthesis.
Photosynthesis can be broken down into 2 stages: 1. Light-Dependent Reactions –within the thylakoid membranes 2. Calvin Cycle (“Light-Independent Reactions) – Takes place in the space outside the thylakoid membranes called the “stroma.”
Light-Dependent Reactions Use energy from sunlight plus water to produce ATP, NADPH, and Oxygen. Takes place in the thylakoid membranes of chloroplasts. ATP and NADPH are energy carriers.
ATP & NADPH Are not stable enough to store energy for more than just a few minutes. So…
Calvin Cycle Plants use the ATP and NADPH from the light-dependent reactions to produce high-energy sugars. These reactions do not require light. 6 carbon dioxide molecules from the atmosphere are needed to produce a single 6-carbon sugar.
The Calvin Cycle takes place in the stroma of the chloroplast (outside the thylakoid membrane).
Why do plants do this??? Plants use the sugars for energy to build more complex carbohydrates such as starches and cellulose. It needs these for growth and development!
Summary of Photosynthesis Fill out your handout!
Cellular Respiration Energy in food is stored as carbohydrates, proteins & fats. Before you can use that energy, it must be released and transferred to ATP.
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Oxygen + Glucose CO 2 + H 2 O + Energy
3 Steps of Cellular Respiration If cellular respiration took place in just one step, all energy would be released at once and our cells need to control this.
1.Glycolysis – The process in which one molecule of glucose is broken in half, producing 2 molecules of pyruvic acid (a 3 carbon compound) Glucose C 6 Pyruvate C 3 2 ATP NADH
Glycolysis… Takes place in the cytoplasm Net gain of 2 ATP Takes place without oxygen (anaerobic) NADH is formed (electron carrier)
Two Things Can Happen: 1. Anaerobic Respiration - If no oxygen is present, pyruvate goes through a process called “fermentation.” 2. Aerobic Respiration – If oxygen is present, pyruvate enters the mitochondria and enters the “Kreb’s Cycle.”
Fermentation – Recycles the NAD+ that is needed to make ATP in the absence of oxygen. ~ Takes place in the cytoplasm Pyruvate Alcohol Lactic Acid (plants) (animals) 2 ATP CO 2
Lactic acid is produced in your muscles during rapid exercise when the body cannot supply enough oxygen to the tissues. The buildup of lactic acid causes a painfull burning sensation.
2. Krebs Cycle – A stage of aerobic (requires oxygen) respiration in which pyruvate is converted into CO 2, water and ATP. ~ Takes place in the mitochondria
The Kreb’s Cycle is a continuous cycle of electrons transferred to energy carriers. Citric acid is broken down, CO2 is released (you exhale it out), and ATP is released to be used in cellular activities. What happens to all of the high energy electrons???
3. Electron Transport Chain – Takes place along the inner membrane of the mitochondria. A protein in the membrane called ATP synthase. These enzymes convert ADP to ATP. 34 ATP are produced (Lots of energy!)
The Totals In the absence of oxygen, glycolysis produces just 2 ATP molecules per glucose.
In the presence of oxygen, everything changes. The Kreb’s Cycle & electron transport chain allow the cell to produce 34 more ATP molecules. 36 total ATP!
18 times as much can be generated from glucose in the presence of oxygen. The final waste products are water and carbon dioxide.
38% of the energy in glucose is used to make ATP. 62% is released as heat. (This is why you become warm when you exercise).