8.1 Energy and Life

Biology

I. Autotrophs and Heterotrophs

• Energy is the ability to do work– Need to use and obtain

energy or living things will die

• Energy comes from food or sun

• Autotrophs– Use light energy to make

their own food

– Plants, some bacteria

• Heterotrophs– Organisms that cannot

make their own food

– Eat food to get energy

– Example: us, leopards, etc

– Can also be decomposers

• Ex: mushrooms, fungi

II. Chemical energy and ATP

• Energy has many forms like heat, light, electricity– Also in the form of chemical

compounds• To release energy from

chemical compounds, bonds are broken that hold the elements together

• ATP (adenosine triphosphate)– Cellular energy– Made of adenine (sugar),

ribose (sugar), and 3 phosphates

Storing energy

• ADP (adenosine diphosphate) only 2 phosphates attached– When a cell has energy, it can store it by adding

a 3rd phosphate to make ATP

Releasing Energy

• To release energy in ATP, the last bond that holds the 3rd phosphate is broken– Energy is released

III. Using biochemical energy

• Uses of ATP– Active transport

– Making proteins and nucleic acids

– Produce light (firefly)

• Cell only keeps a small amount of ATP on hand– Its more efficient

– Make more energy by using the food we take in

• Cellular energy is created in the mitochondria

Photosynthesis Equation

• Carbon dioxide + water + light

glucose (C6H12O6) + oxygen

Light and Pigments

• Plants use sun’s energy to go thru photosynthesis

• Pigments in plants help to absorb light– Pigment-light

absorbing molecule

• Main pigment– chlorophyll

Lights and Pigments• The color you see is

reflected• Chlorophyll reflects

green light and absorbs reds and blues very well

• Other pigments are present– Xanthophylls (reflect

yellow) and carotene (orange)