Unit 7

Cell Processes

Essential Question: How is matter transferred or energy transferred in living systems?

Energy

Without the ability to use and get energy cells would die

They use energy to make molecules/building blocks and enzymes and get rid of waste

They also carry out all the jobs in your body: circulation oxygen, breaking down food, contracting muscles, etc.

ATP

• Living things use chemical energy• ATP (Adenosine Triphosphate) – one of the

most important chemicals the cell uses to store and give off energy– It is made up of adenine, a sugar called ribose and

three phosphate groups– The phosphate groups are the key to how ATP

stores and releases energy

ADP

Adenosine diphosphate is similar to ATPADP only has two phosphate groups instead of

3This is how living things store energyWhen a cell has extra energy it stores it by

adding a phosphate group to ADP turning it into ATP

Releasing Energy

Cells can give off energy that is stored in ATP by breaking the chemical bond between the second and third phosphate groups

Using Chemical Energy

ATP is used to power active transportHelps to move protein in muscle helping them

to flexMakes proteins, carbohydrates, lipidsResponds to chemical signals If cells move they use this energy

Short-Term Storage

ATP is good for giving off a small amount of energy very quickly

It is not good at storing large amounts for a long time

For that we have the sugar glucose

ATP comes from food

• Once cells use up their ATP they must make more of it somehow

• Cells use the energy from the food we eat to make more ATP

• Different living things get their food from different sources

Heterotrophs

Living things that get food by eating other living things

Some eat plants and grassesSome eat other animalsSome break down the tissues of dead things

AutotrophsMake their own foodPlants, algae and some bacteria use light energy

from the sun to make their own foodThe energy in nearly all food molecule started

from the sunAll life on earth depends on autotrophs making

their own food using energy from the sunThis process is called photosynthesis

Light From The Sun

• The sun gives off energy called visible light• Visible light appears white but actually

contains every color

Plant Pigments

• Autotrophs – organisms that make their own food using the sun’s energy– They have specific pigments – Pigments – absorb certain wavelengths of light

and reflect others.• The color that is reflected is the color you see• Pigments determine what is absorbed and what is

reflected• Autotrophs need pigments to trap energy from the sun

to carry out photosynthesis

Chlorophyll

The most common and important photosynthetic pigment

It absorbs violet, blue and red light which provide energy for photosynthesis

It reflects green light which is why most plants look green

Found in the cholorplasts of plant cellsThis is where photosynthesis takes place

Other Plant Pigments