Chapter 5-Photosynthesis and Respiration Section 1-Energy and living things Photosynthesis-Is the process by which light energy is converted to chemical energy. Autotrophs-Organisms that use energy from sunlight or from chemical bonds in inorganic substances to make organic compounds. – Most are plants!! Some live at the bottom of the sea floor and get their energy from chemical from vents.

Heterotrophs-Organisms that must get energy from food instead of directly from the sunlight or inorganic substances. Cellular respiration- – Metabolic process similar to burning fuel. Releases much of the energy in food to make ATP. ATP provides cells with the energy they need to carry out the activities of life.

Adenosine Triphosphate Things you need to know about ATP – When cells break down food, some energy in the molecules is released as heat. – Portable form of energy. – Delivers energy wherever energy is needed in a cell. – Most chemical reactions required less energy than is released from ATP – Enough energy is released from ATP to drive most of a cell’s activities.

ATP is a nucleotide with two extra energy-storing phosphate groups. Phosphate groups store energy like a compressed spring, when bond is broken, energy is released. H₂O + ATP  ADP + P + energy End ofsection 1

Photosynthesis The three stages of photosynthesis 1.Energy is captured from the sun. 2.Light energy is converted to chemical energy, which is temporarily stored in ATP and the energy carrier molecule NADPH. 3.The chemical energy stored in ATP and NADPH powers the formulation of organic compounds, using carbon dioxide, CO₂. 4.6CO₂ + 6H₂O  C₆H₁₂O₆ +6O₂

Stage 1-Energy from the sun Pigments-Structures contain light-absorbing substances. Chlorophyll-The primary pigment involved in photosynthesis. Carotenoids-Pigments that produce the yellow and orange colors of leaves, and the color of fruit. Thylakoids-Cluster of pigments embedded in the membranes, they are disk-shaped. LET’S LOOK AT FIGURE 7, PAGE 99

Stage 2-Conversion of Light Energy Electron Transport Chains-The series of molecules through which excited electrons are passed along a thylakoid membrane.

NADPH-Electron carrier that provides the high energy electrons needed to make carbon-hydrogen bonds in the third stage of photosynthesis.

SUMMARIZATION OF PHOTOSYNTHESIS – Pigment molecules in the chloroplasts absorb light energy. – Electrons in the pigments are excited by light and move through electron transport chains in thylakoid membranes. – Electrons are replaced by electrons from water molecules, which are split by an enzyme. – Oxygen atoms form water molecules combine to form oxygen gas. – Hydrogen ions accumulate inside thylakoids, setting up a concentration gradient that provides the energy to make ATP.

Stage three-Storage of Energy Carbon-dioxide fixation-The transfer of carbon dioxide to organic compounds. Calvin Cycle-A series of enzyme-assisted chemical reactions that produces a three-carbon sugar. There are FOUR steps. – Step 1-Each molecule of carbon-dioxide, CO₂, is added to a five-carbon compound by an enzyme. – Step 2-The six-carbon compound splits into two-three carbon compounds. Phosphate groups from ATP and electrons from NADPH are added to the three-carbon compounds, forming three-carbon sugars.

– Step 3-The three-carbon sugars is used to make organic compounds, which are starches and sucrose, to be used later for energy. – Step 4-Other three-carbon sugars are used to regenerate the initial five-carbon compounds, therefore completing the cycle.

Calvin Cycle

Section 3-Cellular Respiration Your cells transfer the energy in organic compounds, especially glucose, to ATP through a process called cellular respiration. Aerobic respiration-Metabolic processes that required oxygen. Anaerobic respiration-Metabolic processes that do not required oxygen.

Stages of Cellular Respiration Stage 1-Glucose is converted to pyruvate, producing a small amount of ATP and NADH Stage 2-When oxygen is present, pyruvate and NADH are used to make a large amount of ATP. Aerobic respiration occurs in the mitochondria. Anaerobic respiration pyruvate is converted to either lactate or ethanol, and carbon dioxide. AEROBIC RESPIRATION PRODUCES MOST OF THE ATP MADE BY CELLS.

Stage one-Breakdown of Glucose Glycolysis-Is an enzyme-assisted anaerobic process that breaks down one six-carbon molecule of glucose to three-carbon pyruvate ions. NADH-Electron carrier – Step 1-Phosphate groups from two ATP molecules are transferred to a glucose molecule. – Step 2-The six carbon compound is broken down to two three carbon compounds each with a phosphate group – Step 3-Two NADH molecules are produced, one more phosphate group is transferred to each three carbon compound. – Step 4-In a series of four reactions, each three carbon compound is converted to a three carbon pyruvate, producing four ATP molecules in the process.

Stage Two-Production of ATP When oxygen is present, pyruvate produced during glycolysis enters a mitochondria and is converted to a two carbon compound. Krebs citric acid cycle- – Step 1-Acetyl-CoA combines with a four carbon compound, forming a six carbon compound and releasing coenzyme A. – Step 2-Carbon dioxide is released from the six carbon compound. Electrons are transferred to NAD⁺, making a molecule of NADH. – Step 3-Carbon dioxide is released from the five carbon compound resulting in a four carbon compound. A molecule of ATP is made, and a molecule of NADH is produced. – Step 4-The four carbon compound is converted to a new four carbon compound. Electrons are transferred to an electron acceptor called FAD, making FADH₂ (which is another electron carrier). – Step 5-The new four carbon compound is then converted to the four carbon compound that began this cycle.

Electron Transport chain ATP and water are formed inside the inner membranes of the mitochondria. Fermentation in the absence of oxygen Fermentation-The recycling of NAD⁺using an organic hydrogen acceptor. – Two types of fermentation, lactic acid fermentation and alcohol fermentation.