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
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