Photosynthesis & Cellular respiration
Remember…Characteristics of Living Things made up of units called cells reproduce based on a universal genetic code (DNA) grow and develop obtain and use materials and energy (metabolism) respond to their environment (adapt) maintain a stable internal environment (homeostasis) taken as a group, organisms evolve
Energy and Life
Energy Energy: the ability to do work Living things must be able to obtain and use energy in order to exist. ATP (adenosine triphosphate) – chemical compound that living things use to store energy
ATP is made of adenine, ribose (sugar), and 3 phosphate groups. Energy is stored in bonds between the phosphate groups. When a cell needs energy, one of the phosphates is removed (leaving ADP or adenosine di-phosphate). Energy that had been stored in the bond can now be used by the cell. Chemical Energy & ATP
ATP can be compared to a rechargeable battery. Charged battery ADP Partially charged battery (needs charging)
ATP and Glucose (C6H12O6) Most cells have only a small amount of ATP Lasts for a few seconds of activity Efficient at transferring energy but not for storing energy over a long term A single sugar molecule stores more than 90 times the energy of 1 molecule of ATP! Cells can regenerate ATP from ADP as needed by using the energy in carbohydrates like glucose
So…where do living things get energy? To live, all organisms need food and must release energy from that food. FOOD
So…how do living things get food? Autotrophs Organisms that make their own food through photosynthesis (AKA: producer) Examples: plants, some protists, certain bacteria Chemosynthesis: process by which ATP is synthesized by chemicals as an energy source instead of light Heterotrophs Organisms that consume or eat food (AKA: consumer) Examples: animals, fungi, some bacteria, some protists
Photosynthesis: An Overview
Photosynthesis… Plants, algae, and some bacteria Reactants Products Sunlight H20 (water) CO2 (carbon dioxide) C6H12O6 (glucose) O2 (oxygen) Light energy is converted into chemical energy!
Photosynthesis Equation Photosynthesis: a process that uses the energy of sunlight to convert water and carbon dioxide into glucose and oxygen 6CO2 + 6H2O sunlight C6H12O6 + 6O2 (carbon dioxide) (water) (glucose) (oxygen)
The Reactions of Photosynthesis
Inside a Chloroplast Photosynthesis takes place within chloroplasts. Thylakoid membranes (labeled B) – saclike membranes in the chloroplasts that contain chlorophyll to capture energy from the sun Light dependant reactions take place within the thylakoids. Stroma (labeled A) – fluid outside the thylakoid membranes Light independent reactions (Calvin Cycle) takes place within the stroma.
Reactions of Photosynthesis: Light Dependent reactions Requires water and light which is captured by the chlorophyll Converts ADP and NADP+ into ATP and NADPH which are energy carriers needed to provide energy for the Calvin Cycle Releases oxygen as waste Reactions of Photosynthesis: Light Dependent reactions
light 6CO2 + 6H2O C6H12O6 + 6O2 carbon dioxide water 6 carbon sugar: glucose oxygen gas
The second stage of photosynthesis uses energy from the first stage to make sugars
Converts carbon dioxide into glucose Reactions of Photosynthesis: Calvin cycle or light-independent reactions Requires energy from ATP and NADPH produced during the light dependent reaction Converts carbon dioxide into glucose Regenerates ADP and NADP+ which go back to the light-dependent reactions for re-charging
Overview of the light-independent reactions 6CO2 + 6H2O C6H12O6 + 6O2 carbon dioxide water glucose oxygen gas
Factors Affecting Photosynthesis photosynthesis occurs best between 0C and 35C; above or below this temp the enzymes that control photosynthesis are affected so photosynthesis slows down Temperature photosynthesis requires water so low water availability would slow down the rate of photosynthesis Water more light would speed up the rate of photosynthesis; eventually the rate reaches a maximum rate that it cannot exceed Light
Functions of photosynthesis Does more than make sugars! Provides materials for plant growth and development Removes CO2 from the atmosphere
How We Came to Understand Photosynthesis
The Question: How does a tree increase its mass. From the soil The Question: How does a tree increase its mass? From the soil? From the water? From the air?
Van Helmont’s Experiment (1643) Concluded that it was water!!
Priestley’s Experiment (1771) Candle burned in the presence of oxygen A candle could be relit near a plant and it would burn longer because the plant released oxygen
Ingenhousz’s Experiment (1779) Showed Priestley’s experiment only worked when the plant was exposed to light Light is necessary for plants to produce oxygen
Photosynthesis completed!
But wait… How do leaves change color?
Absorption of Light Energy Light energy is a form of radiation Energy in the form of waves that travel through space Different types of radiation (i.e. light, heat) have different wavelengths
Pigment Chlorophyll Carotenoid A light-absorbing substance that gives another substance or mixture its color Absorbs certain wavelengths and reflect others Chlorophyll Green Pigment Absorbs violets, blues and reds and reflects greens and yellows Therefore plants exhibit green and yellow colors Carotenoid A pigment that absorbs mostly blue and green light Therefore it produces yellow and orange fall leaf colors Color of many fruits, vegetables and flowers
Leaf Color Comes From Pigments Chlorophyll (green) Carotenoid (yellow, orange, and brown) Anthocyanins (red) Chlorophyll covers the carotenoid -- that's why summer leaves are green, not yellow or orange Trees respond to the decreasing amount of sunlight in the fall by producing less and less chlorophyll
Leaf Color Comes From Pigments Eventually, a tree stops producing chlorophyll When that happens, the carotenoid already in the leaves can finally show through The leaves become a bright rainbow of glowing yellows, sparkling oranges and warm browns
PART II
Is like a mirror of photosynthesis Cellular respiration Is like a mirror of photosynthesis
Cellular respiration makes atp by breaking down sugars Reactants Products H20 (water) CO2 (carbon dioxide) Energy (ATP) C6H12O6 (glucose) O2 (oxygen)
Chemical Energy and Food Food provides cells with energy and serves as raw materials for building new molecules. How do organisms get the energy from their food? Cells release energy from glucose and other food compounds by the processes of cellular respiration, fermentation, or both.
Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O + energy enzymes Glucose oxygen gas carbon dioxide water ATP
Overview of Energy Releasing Processes Cellular Respiration a process that produces energy (ATP) by breaking down food molecules in the presence of oxygen Fermentation a process that produces energy (ATP) by breaking down food molecules in the absence of oxygen
The first process cells use to break down food and release energy. Occurs in the cytoplasm and breaks glucose in half into 2 pyruvic acid molecules creating 2 ATPs. Glycolysis
Cellular Respiration When oxygen is present, products of glycolysis enter Krebs Cycle and electron transport chain (in mitochondria). 36 ATPs produced during cellular respiration. Carbon dioxide and water are waste.
Fermentation When oxygen is NOT present, products of glycolysis go through fermentation instead. Fermentation regenerates starting materials of glycolysis so glycolysis can continue making ATP (only 2 ATPs). Alcoholic fermentation Lactic acid fermentation
Alcoholic vs. Lactic Acid Fermentation Alcoholic Fermentation performed by yeast and other microorganisms used in bread and alcohol industries because alcohol and carbon dioxide are waste products Lactic Acid Fermentation occurs in muscle cells during strenuous exercise when cells aren’t getting enough oxygen lactic acid produced as a waste product causes muscles to burn during a strenuous workout
Comparing Photosynthesis & Cellular Respiration Function to store energy by making food to release energy by breaking down food Location Chloroplasts Mitochondria Reactants Carbon Dioxide + Water + Sunlight Glucose + Oxygen Products Carbon Dioxide + Water + Energy Equation 6H2O + 6CO2 C6H12O6 + 6O2 C6H12O6 + 6O2 6H2O + 6CO2 Organisms autotrophs autotrophs and heterotrophs
The Cycle of Matter and Energy sunlight Photosynthesis and Cellular Respiration work together to cycle matter and energy CO2 + H2O O2 + C6H12O6 ATP
Remember…Characteristics of Living Things made up of units called cells reproduce based on a universal genetic code (DNA) grow and develop obtain and use materials and energy (metabolism) respond to their environment (adapt) maintain a stable internal environment (homeostasis) taken as a group, organisms evolve