Energy and Cellular Respiration

Chapter 7

Cellular Respiration vs. Photosynthesis• Formulas

Cellular Respiration vs. Photosynthesis

• Organelles• Mitochondria

• Eukaryotic cells• Structure is key

− Two membranes− Space between membranes− Matrix makes up inner

membrane– Lots of enzymes found

here for chemical reactions

− Complex folding=many sites for reactions to take place– Maximizes ATP production

• Chloroplast• More about this one later…

Energy• Heat (thermal)• Light (solar)• Electrical• What carries energy?

• Electrons (little energy packets)• Negatively charged particle• Involved in making bonds between atoms• Electromagnetic spectrum

How is Energy Transferred?• Think food chain!• First Law of

Thermodynamics aka the Law of Conservation of Energy• E cannot be created or

destroyed, only transferred (converted)

Kinetic vs. Potential• Energy of

motion• Anything

moving or in motion

• Ex.• Climbing stairs• Leg muscles

working

• Stored energy due to an objects position or arrangement

• As you climb up, you are getting higher, more gravitational pull, increase potential E

Two Types of Kinetic Energy• Directed kinetic

energy• Ex. Your body as it

moves down slide

• Random kinetic energy of molecular motion• Thermal energy• Ex. When your body

collides with water. Air and water molecules are forced to move and collide at random, transferring energy

• Thermal Energy• Created from Random molecular motion• “Heat” is thermal energy that is

transferred from warmer object to cooler object

So exactly what happens as you go down the slide?

• As you climb up the slideKinetic E

• When you reach top of slidepotential E

• As you slide downdirected kinetic E

• When you hit water and stopRandom kinetic E of molecular motion

• You cannot retrieve thermal energy, so you must get new source of energy to climb back up the slide

• What do you do?

Eat food!• Food is composed

of organic compounds• Carbohydrates• Fats • Proteins• All rich in E

• These organic compounds contain a form of potential energy we call

• CHEMICAL ENERGY

Organic compounds• Potential to do work is in

the arrangement of atoms in the molecules

• Amount of potential energy depends on the structure of the molecules

• When you break a bond, you release E

• Energy now available for muscles to do work

• Structures of…• Proteins• Carbohydrates• Fats

Cells and Cars use Combustion• Cells

• Glucose• Oxygen• Energy to do work

• Transport, mechanical, chemical

• Releases carbon dioxide and water

• Cars• Hydrocarbons (in

gasoline)• Oxygen• Energy to do

mechanical work• Releases carbon

dioxide and water

calorie • Amount of energy required to raise the

temperature of 1 g of water 1*C• Very tiny• Not practical to measure energy in food• Express in kilocalories (kcal), or

Calories, what is on the nutrition label• KHDmdcm

Burning food…• Changes chemical energy to

thermal energy (releases heat)• Measure increase of water

temperature and definition of calorie to find out how much chemical energy is in food

Practice problem• If a peanut is burned and the

temperature of 1 kilogram of water is raised by 8*C, how many calories are in the peanut?

• How many Calories (kcal)?• How many calories?

Find the amount of calories in each food and which provides the most energy1 2 3