The Working Cell: Energy From Food Chapter 7

Obtaining Food All organisms need food for energy. Autotroph- Makes its own food (photosynthesis); producers Plants, algae Heterotroph- Cannot make own food; consumers Animals Must eat producers or other consumers

How do heterotrophs get energy from food? Through Cellular Respiration Makes energy for the cell by breaking down glucose Uses oxygen to do this (why we need to breathe!) Energy is in the form of ATP

Food Stores Energy Energy =The ability to perform work. 2 forms: Kinetic Energy- energy of motion Thermal energy- random molecular motion (heat) Potential Energy- energy that is stored Chemical Energy- ready to do work; due to arrangement of atoms

Calories: Units of Energy Calorie- amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. Tiny number (too tiny to measure energy in food) Energy in food is expressed in kilocalories 1 kcal = 1000 cal

Measuring the Energy Content of a Peanut Burning peanut converts its stored chemical energy into thermal energy, releasing heat Measure increase in water temp– calculate # of calories in a peanut 1 peanut has 5000 calories (5 kcal) ____ °C x ____ mL = ____ cal/ 1000 = ___ kcal

Do Cells “Burn” our food? Use enzymes to break down organic molecules through cellular respiration, thus releasing energy.

Online Activities www.phsuccessnet.com Complete online activities 7.1, 7.2, and ch. 7 prelab questions

Lab: Food as Fuel Calorimeter: Measures calorie content in food We will be burning food to measure their calorie content. Remember: 1000 cal = 1 kcal Remember: Calorie- amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. Animation

Lab: Food as Fuel The longer something burns, the more energy (kcal) it has. Proteins/ carbs 4 kcal/g Fats 9 kcal/g

ATP Adenosine Tri-Phosphate Stores energy Provides energy for chemical reactions.

The ATP Cycle ATP is continuously converted to ADP as your cells do work. ATP is “recyclable” Energy that makes this happen is from food

Mighty Mitochondria Mitochondria makes energy! Site of cellular respiration in a cell Cristae (folds) & matrix (thick fluid)

Cellular Respiration Converts energy in food to energy in ATP glucose+ oxygen  carbon dioxide + water + energy C6H12O6 + 6O2  6CO2 + 6H2O + 38ATP

Try This… The atoms in cellular respiration are merely rearranged by breaking the bonds. Using the molecular model kits, model the process of cellular respiration. C6H12O6 + 6O2  6CO2 + 6H2O + 38ATP

Review 6 H2O C6H12O6 + 6O2  6CO2 + 6H2O + 36ATP Subscript: # of atoms Coefficient: # of molecules C6H12O6 + 6O2  6CO2 + 6H2O + 36ATP

Lab Review Lab- we burned food to release energy (different from our bodies… we use enzymes to do this) The more fat, the longer it burned (what is this telling us?) What is a calorie? A kilocalorie?

CR Review Cellular Respiration is making energy (in the form of ATP) from glucose. CR takes place in the mitochondria of cells (“mighty mitochondria”) Activity with ball-and-stick models shows that atoms are neither created nor destroyed in CR, just rearranged to release energy.

glucose+ oxygen  carbon dioxide + water + energy C6H12O6 + 6O2  6CO2 + 6H2O + 38ATP

Three Stages of CR 1) Glycolysis (in CYTOPLASM of cell) 2) Krebs Cycle (in MITOCHONDRIA CRISTAE) 3) Electron Transport Chain (in MITOCHONDRIA MATRIX)

Glycolysis Glucose Pyruvic Acid + 2 ATP 2 ATP used to make this happen Oxygen is NOT needed (anaerobic)

Krebs Cycle Cristae of mitochondria Pyruvic Acid carbonic acid + CO2 + 2 ATP Needs Oxygen!

Electron Transport Chain Matrix of mitochondria Most of the energy is made here! Carbonic acid + O2 H2O + 34 ATP Needs Oxygen!

Is it possible to make ATP without oxygen??

Fermentation in Human Muscle Cells Long Distance Running– muscles regenerate ATP through CR Sprint– lungs/blood can’t supply oxygen fast enough to make enough ATP! How does this happen?? FERMENTATION- makes ATP without using oxygen

Lactic Acid Fermentation Occurs in muscle cells But only small amts of ATP made Glycolysis still occurs Glucose Pyruvic Acid + 2 ATP Pyruvic acid CO2 + Lactic acid Lactic Acid is what makes your muscles sore after a lot of hard exercise!

Training Improves ATP production Weight lifting & sprinting = increase glycogen & lactic acid tolerance Long-distance running= increase mitochondria & oxygen delivery to cells

Alcoholic Fermentation No oxygen present in yeast cell environment Ethyl alcohol produced instead of lactic acid Pyruvic acid CO2 + ethyl alcohol

Cellular Respiration Lab Cell Respiration- converting the chemical energy of organic molecules into a form immediately usable by organisms What is this chemical energy called? What is the usable form called?

Cellular Respiration Lab All organisms, including plants and animals break down glucose for energy using oxygen. Peas undergo CR during germination.

Germination of Peas What does germination mean?

Cellular Respiration Lab Today, you will be using the CO2 gas sensor to measure the rate of CR in germinating and ungerminating peas.

Lab Procedure Do you expect the carbon dioxide levels to increase or decrease? Will the rates be the same in the germinating and ungerminating peas?

1 ATP Organisms that make their own food are called ______________.

1 ATP Organisms that cannot make their own food and must obtain energy from the foods they eat are called _______________.

2 ATPs Cell respiration uses oxygen to convert the chemical energy stored in organic molecules into _________.

3 ATPs Energy is released from ATP when a ____________ is released.

4 ATPs What is the chemical equation for cellular respiration? Hint: Glucose + oxygen = carbon dioxide + water + energy

2 ATPs How many total ATPs are made as a result of cellular respiration?

3 ATPs What is the net gain of ATPs as a result of glycolysis?

3 ATPs List the steps of cellular respiration in order.

3 ATP The Krebs cycle starts with _____________ and yields carbon dioxide.

2 ATP What process is used to make bread rise?

1 ATP Is cellular respiration aerobic or anaerobic?

1 ATP Is fermentation aerobic or anaerobic?

2 ATP Where does lactic acid fermentation take place?

2 ATPs Where in the cell does glycolysis take place?

2 ATPs Where in the cell does the Krebs cycle take place?

2 ATPs Where in the cell does the electron transport chain take place?

3 ATPs Without oxygen, a cell can make only _______ ATPs from each glucose molecule.

3 ATPs Glysolysis converts glucose into 2 molecules of _____________.

4 ATPs What is the difference between kinetic and potential energy?

4 ATPs What is the definition of a calorie?

1 ATP # 4 is the __________ of the mitochondria.

3 ATPs The device used to measure the amount of calories in a piece of popcorn is called a __________.

2 ATPs There are __________ calories in a kilocalorie.

2 ATPs What is the function of ATP?

4 ATPs What does ATP stand for?

3 ATPs Most energy made from cellular respiration comes from this stage.

2 ATPs What makes your muscles sore after hard exercise?