How Organisms Obtain Energy

Section 8.1Pg 218-221

What is energy?

Energy is the ability to do work!

Thermodynamics

• Thermodynamics is the study of the flow and transformation of energy in the universe.

2 Laws!First law — energy can be converted from oneform to another, but it cannot be created nor

destroyed.Second law — energy cannot be converted

without the loss of usable energy.

How do you get your energy?

Autotrophs and Heterotrophs

• Organisms, such as plants, which make their own food, are called autotrophs.

• Organisms, such as animals, that must obtain energy from the foods they consume are heterotrophs.

Autotrophs and Heterotrophs

◦ Living things need energy to survive.◦ This energy comes from food. The energy in most food comes from the sun.

Metabolism

• All the chemical reactions in a cell is referred to as the cells metabolism.

• Brainpop

Metabolic pathways

• Catabolic-release energy by breaking down large molecules into small ones

• Anabolic- use energy to build large molecules from small molecules.

• Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell

• Is this Catabolic or Anabolic?

• Cellular respiration—organic molecules are broken down to release energy for use by the cell

• Is this Catabolic or Anabolic?

Compare the two FormulasPhotosynthesis

Cellular respiration

?Confused?

Don’t worry we will talk more about these two processes in 8.2 and 8.3.

• Energy comes in many forms including light, heat, and electricity.

• Energy can be stored in chemical compounds, too.

ATP = ENERGY!!!

ATP

• An important chemical compound that cells use to store and release energy is adenosine triphosphate, abbreviated ATP.

• ATP is used by all types of cells as their basic energy source.

• ATP consists of 3 parts:o adenineo ribose (a 5-carbon sugar)o 3 phosphate groups

ATP: The Unit of Cellular Energy

ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.

8.1 How Organisms Obtain EnergyCellular EnergyChapter

8

Storing Energy

• ADP or adenosine diphosphate has two phosphate groups instead of three.

• A cell can store small amounts of energy by adding a phosphate group to ADP

Releasing Energy

• Energy stored in ATP is released by breaking the chemical bond between the second and third phosphates.

The role of ATP

• The energy from ATP is needed for many cellular activities, including active transport across cell membranes, protein synthesis and muscle contraction.

• ATP’s characteristics make it exceptionally useful as the basic energy source of all cells.

• This is why ATP is known as the energy currency of the cell!!

ATP

Which law of thermodynamics explains why the ladybug receives the least

amount of usable energy?

Cellular Energy

8.1 Formative Questions

Chapter 8

True or False

All of the energy from the food you eat comes from the sun.

Cellular Energy

8.1 Formative Questions

Chapter 8

Why is cellular respiration a catabolic pathway?

Cellular Energy

8.1 Formative Questions

A. Energy is used to form glucose andoxygen.

B. Energy is converted from water tocarbon dioxide.

C. Energy that is lost is converted tothermal energy.

D. Energy is released by the breakdownof molecules.

Chapter 8

A. It captures light energy from the sun.B. It is produced in anabolic pathways.C. It stores and releases chemical energy.

Why is adenosine triphosphate (ATP) such an

important biological molecule?

Cellular Energy

8.1 Formative Questions

D. It converts mechanical energy to thermal energy.

Chapter 8