The Need for Energy

University:
Texas A&M University
Course:
BIOL 111 | Introductory Biology I
Academic year:

2019
Views:

149

Pages:

12
Author:

Athena Harrison

1 The Need for Energy All organisms require energy for • Active transport • Cell division • Movement • Production of proteins Energy is stored in the ATP molecule • ATP: adenosine triphosphate • Made up of adenosine + 3 phosphate groups Adenosine Phosphate ATP Adenosine ADP Phosphate Phosphate High-energy bond: Stores much energy *This energy is released when the bond is broken* Phosphate Phosphate Energy 2 • ADP: Adenosine diphosphate • Cells recycle the ADP to make new ATP to store more energy for future use • Many proteins have spots where ATP attaches to provide energy for the protein to do its job, then the ADP is released for recycling Photosynthesis • Process that uses the sun’s energy to make glucose • Carried out by green plants and some bacteria • Purpose is to trap sun’s energy and store it in glucose (food for the plant) • Photosynthesis occurs in the chloroplast • Structure of the chloroplast: Stroma: Space inside the chloroplast Thylakoid: Green disk in the chloroplast Granum stack: Stack of green thylakoids 3 • Thylakoids are green because they contain chlorophyll • Chlorophyll: green pigment in plants that absorbs light energy • Pigment: light-absorbing compound Chemical equation for photosynthesis • 6CO2 + 6H2O + light energy → C6H12O6 + 6O2 • carbon dioxide + water + sunlight → glucose + oxygen Steps of photosynthesis 1. Light reaction (Light-dependent reaction) ➢ First step of photosynthesis that traps sunlight and makes electrons and ATP to run the dark reaction 2. Dark reaction (Light-independent reaction) 3. Second step of photosynthesis that uses ATP and electrons from the light reaction and carbon dioxide from the air to make glucose Photosynthesis Step 1: Light Reaction – occurs in the thylakoids inside the chloroplast - e 1b 1a Electron transport chain 1c Chlorophyll in the thylakoids e- - ee 1d Water 1a. Light energy is absorbed by the chlorophyll e1b. Electrons jump out of the chlorophyll atoms NADPH ATP Oxygen 1c. Electrons move down the electron transport chain (series of proteins that pass the electrons along). Electrons are caught by the NADPH compound. ATP is made. 1d. Photolysis: Water is broken down into oxygen (given off by plant) and electrons (replace lost electrons in chlorophyll). These electrons recharge the system so the light reaction can happen again. 6 Photosynthesis Step 2: Dark Reaction (Calvin Cycle) – Occurs in the stroma NADPH - ee e- - e ATP 2a. Electrons and ATP from light reaction get dumped into the Calvin Cycle to run it e- Carbon dioxide from the air Calvin Cycle PGAL 2 PGAL = 1 glucose 2b. Calvin Cycle: Series of steps that build up compounds using carbon dioxide from the air 2c. PGAL compound sometimes leaves the cycle. 2 PGAL compounds added together make 1 glucose. 7 Cellular Respiration • The process by which mitochondria break down glucose to make ATP • Two types o Aerobic respiration: requires oxygen and carried out by plants, animals, and some bacteria o Anaerobic respiration: requires no oxygen and carried out by yeast, some bacteria, and sometimes animals Chemical equation for aerobic respiration • C6H12O6 + 6O2 → 6CO2 + 6H2O + chemical energy • glucose + oxygen → carbon dioxide + water + ATP Some of aerobic respiration occurs in the mitochondria (plural of mitochondrion) • Makes energy for the cell through aerobic respiration • Structure of a mitochondrion Inner membrane Outer membrane Cristae: Fold in the inner membrane 8 Steps of aerobic respiration 1. Glycolysis: First step breaks down glucose into pyruvate (Intermediate step: Change pyruvate to acetyl CoA) 2. Citric Acid Cycle: Second step uses the acetyl CoA to make electrons for the last step 3. Electron transport chain: Third step uses the electrons to make a lot of ATP Step 1: Glycolysis – Occurs in the cytoplasm ATP Enzymes Glucose Pyruvate Pyruvate ATP Glucose breaks down into 2 pyruvate (2 ATP are also made) 9 Intermediate step: Pyruvate becomes acetyl CoA (Occurs in the cytoplasm) Pyruvate Acetyl CoA Step 2: Citric Acid Cycle (Krebs Cycle) – Occurs in the mitochondria ATP Acetyl CoA Citric Acid Cycle ATP Citric acid e- e- - ee NADH Step 3: Electron Transport Chain – Occurs in the mitochondria NADH - ee e- Made in Step 2 10 ee- Electrons move down the electron transport chain (series of proteins that pass the electrons along). Electrons are caught by oxygen to make water. 32 ATP are made. Electron transport chain e- 34 ATP Oxygen we breathe Water We use for energy 11 ATP Totals for aerobic respiration: Glycolysis – 2 ATP Citric Acid Cycle – 2 ATP Electron Transport Chain – 32 ATP 1 Glucose = 36 ATP in all for aerobic respiration Photosynthesis and respiration are the opposite of each other Photosynthesis Plants * use sunlight to make glucose * take in carbon dioxide * give off oxygen *carbon dioxide + water + sunlight → glucose + oxygen Respiration Animals and plants * eat plants to get glucose * take in oxygen * give off carbon dioxide *glucose + oxygen → carbon dioxide + water + ATP 12 Anaerobic respiration (requires no oxygen) • Also called fermentation • 2 types: alcoholic fermentation and lactic acid fermentation o Both begin with glycolysis o No citric acid cycle or electron transport chain Glycolysis Glucose → pyruvate + 2 ATP Alcoholic fermentation Pyruvate → ethyl alcohol + carbon dioxide • • Carried out by yeast and some bacteria Used in brewing beer, making wine, and baking bread and cakes Only 2 ATP are made in anaerobic respiration so it is not as good as aerobic respiration (36 ATP) Lactic acid fermentation Pyruvate → lactic acid • • Carried out by your muscles when you’re exercising hard (need ATP) and can’t get oxygen into you fast enough (can’t do aerobic respiration) Causes muscle cramps and soreness

Related Documents

Recommended Documents

Description

Related Documents

Free up your schedule!

Take 5 seconds to unlock