1. Chemical reactions inside cells
How do Cells Function?
Chemical reactions inside cells

2. For example: A cake can be broken down into its basic units.
What are cells made of?
The smallest unit of life is the cell.
All matter can be broken down into basic substances called elements.
Elements can be broken down to smaller units called atoms.
Therefore, the smallest unit of all matter, including life, are atoms.
For example: A cake can be broken down into its basic units.

3. All Matter is Made of Elements
There are about 100 different elements on Earth.

4. Elements are Built of Atoms
All elements can be broken down into their basic units, atoms.

5. What are cells made of? Oxygen 65.0% Carbon 18.5% Hydrogen 9.5%
Of all the elements, only 25 are necessary for life. And of those, only 6 make up 99% of the human body.
Oxygen %
Carbon %
Hydrogen %
Nitrogen %
Calcium %
Phosphorus %
Other %

6. What are cells made of?
This is another way of thinking about the organization of living things.

7. Atoms from different elements join together to form compounds
What are cells made of?
Atoms from different elements join together to form compounds
Compounds

8. What are cells made of? Atoms join together to form compounds
Water is a compound
A water molecule is made when 2 hydrogen atoms join 1 oxygen atom

9. What are cells made of?
The activities taking place inside cells involve the interaction of molecules and atoms
These interactions, called chemical reactions, will produce energy
Cells use chemical energy for life activities

10. Click a link, or here to move on
What are cells made of?
Cells are made of thousands of molecules
The four main types of large molecules that make up atoms are:
Carbohydrates
Lipids
Proteins
Nucleic acids
All these molecules share one characteristic
– carbon atoms.
Click a link, or here to move on

11. What are cells made of? Carbohydrates: Provide the cell with energy
Simple carbs are sugars made from Carbon, Oxygen, and Hydrogen
Simple sugars link into long chains to form complex carbs, such as: starch, cellulose, and glycogen
Starch and cellulose are made by plant cells
Animals get their energy by eating plants or other animals that eat plants
Click here to return

12. What are cells made of? Lipids: fatty acids glycerol
Are the fats, oils, and waxes found in living things
Simple lipids are made of atoms from Carbon, Oxygen, and Hydrogen
Can be used by cells for energy and for making structures
Common lipids consist of a molecule called glycerol bonded to long chains of carbon and hydrogen atoms
An extremely important property of lipids is that they cannot mix with water
fatty acids
glycerol
Click here to return

13. What are cells made of? Proteins:
Are made of smaller molecules called amino acids
Contain atoms from the elements Carbon, Oxygen, Hydrogen, Nitrogen and sometimes Sulfur
Cells use amino acids to build proteins needed for cell functions
Many types of protein:
Enzymes are proteins that control chemical reactions in cells
Some support growth and repair living matter
Some proteins in blood fight infections
Some proteins in blood deliver oxygen
Some transport materials in and out of the cell
Click here to return

14. What are cells made of? Nucleic Acids:
Are the molecules that hold the instructions for the maintenance, growth, and reproduction of a cell
There are 2 types:
DNA – provides the information used by the cell for making proteins
RNA – produce the proteins in the cytoplasm
Are made from Carbon, Oxygen, Hydrogen, Nitrogen, and Phosphorus
Have subunits called nucleotides
Click here to return

15. What are cells made of? Water:
All the chemical reactions inside the cell take place in water
Water inside the cell makes up 46% of your body’s mass
Water outside the cell (in body fluids) accounts for 23% of body mass
Water is polar, meaning it has a slight positive charge
Because water is polar, many substances dissolve in water
Most lipids do not dissolve in water

16. Question?
The cell membrane controls what enters a cell. It is made of a double layer of lipids.
What is one major property of lipids that you think helps the cell membrane do its job?
How do you think that property helps the cell membrane?

17. Answer
Lipids are large molecules which make up the fats, oils and waxes in living things. As such, a major property of lipids is that they cannot mix with water. Because the cell membrane is made of a double layer of lipids that have a water loving head and a water hating tail, lipids help separate the inside of the cell from the outside by keeping substances from entering freely. The polar quality of lipids and water makes this possible.

18. - the energy stored in the bonds between atoms of every molecule
How do cells use energy?
Cells need a constant supply of energy
Animal cells get energy from food
Plant cells get energy from sunlight
All cells use chemical energy
- the energy stored in the bonds between atoms of every molecule
Glucose is a major source of energy for all cells

19. - a light-absorbing pigment that traps the energy in sunlight
How do cells use energy?
Photosynthesis is the process plants use to change the energy in sunlight into the chemical energy in glucose
Photosynthesis takes place in plant cells that have chloroplasts
Chloroplasts contain chlorophyll
- a light-absorbing pigment that traps the energy in sunlight

20. How do cells use energy?
Chloroplast

21. Some Cells Capture Light Energy
Photosynthesis involves a series of steps:
The starting materials are carbon dioxide and water.
Plants get carbon dioxide from the air and water from the soil.
The process begins when those material enter the plants chloroplasts. Chlorophyll captures energy from sunlight, and uses it to change carbon dioxide and water into new products.
The products are oxygen and sugars such as glucose. The plant releases most of the oxygen to the air and keeps the glucose for energy.
Photosynthesis Diagram

22. Photosynthesis Carbon Dioxide (6CO2) Water (6H2O) Light Energy Glucose
(C6H12O6)
Oxygen
(6O2)

23. How do cells release energy?
Glucose and other sugars are cell food, the power source for cell activities in almost all living things
Chemical energy is stored in the bonds of sugars
When a sugar molecule is broken down, a usable form of energy is released
Cells release energy in two basic processes: cellular respiration and fermentation

24. How do cells release energy?
Cellular Respiration is the process cells use to release the energy stored in sugars such as glucose
Oxygen is used to release the energy
Cellular respiration takes place in the mitochondria
Both plant cells and animal cells release energy through cellular respiration
Some of the energy is transferred to other molecules, which carry the energy to where it’s needed in the cell
The rest of the energy is released as heat

25. How do cells release energy?
Mitochondria

26. How do cells release energy?
Cellular Respiration involves a series of steps:
The starting materials are sugars – such as glucose – and oxygen.
The process begins when glucose is broken down into smaller molecules that move into the mitochondria. At the same time oxygen enters the mitochondria. The smaller molecules are broken down further releasing hydrogen. Hydrogen combines with oxygen to form water.
The products are energy, carbon dioxide, and water.
Cellular Respiration Diagram

27. Cellular Respiration Glucose (C6H12O6) Oxygen (6O2) Carbon Dioxide
Water
(6H2O)
Chemical Energy

28. How do cells release energy?
Fermentation is the process by which cells release energy without oxygen
When glucose is broken down into smaller molecules a small amount of energy is released
Without oxygen cellular respiration cannot happen
Instead of entering the mitochondria, the small molecules that carry the energy stay in the cytoplasm
There are two main types of fermentation: alcoholic and lactic acid

29. How do cells release energy?
Fermentation is the process by which cells release energy without oxygen
In both kinds of fermentation sugars are broken down into smaller molecules
Without oxygen, the reactions produce either alcohol and carbon dioxide or lactic acid
Common foods we eat involve these processes.

30. Alcoholic Fermentation
Bread is made by mixing flour, milk, sugar and yeast. Yeast uses fermentation to convert the sugar into alcohol and carbon dioxide.

31. Lactic Acid Fermentation
yogurt
cheese
Some bacteria convert the sugar in milk into lactic acid. Lactic acid causes milk to partially solidify, producing the creamy texture of yogurt. If fermentation continues long enough milk solidifies into cheese.

32. Fermentation
Cellular Respiration