Chemical Compounds in Cells and The Cell in its Environment
Dec 31, 2015
Elements and Compounds What is an element?
An element is any substance that cannot be broken down into simpler substances
The smallest unit of an element is an atom.
All living things include carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur.
What is a compound? A compound is made up of two or more
elements. Carbon dioxide is a compound. What
elements make up carbon dioxide? Carbon and oxygen
Organic and Inorganic Compounds
o Organic compounds contain carbon, inorganic compounds do not.
o Carbohydrates, lipids, proteins and nucleic acids all contain carbon. oThese are common compounds in
the food we eat.
Organic Compounds• Carbohydrates-
energy rich– Sugars are
produced during the food making process in plants
– Fruits and some vegetables have high sugar content
• Lipids- energy rich– Fats, oils and
waxes are lipids– Cell membranes
are made of lipids
More Organic Compounds• What do bird’s
feather, a spider’s web and your finger nail have in common?– They are all made
of protein.– Proteins are made
up of amino acids – There are 20
common ones that combine to form thousands of different proteins.
• Much of the structure and many of the organelles of cells are made up of proteins.
Water• Most chemical reactions within
cells could not take place without water.–Water helps cells keep their size
and shape.–Water helps keep the temperature
of the cell from changing rapidly.
The Cell in Its Environment• The cell membrane separates the
cell from the outside environment.• The cell membrane is selectively
permeable.– This means some substances can
pass through while others cannot.
Diffusion• Diffusion is the main method by
which molecules move across the cell membrane.– In diffusion, molecules ALWAYS
move from an area of higher concentration to an area of lower concentration.
Osmosis
• Osmosis is the diffusion of water through a semipermeable membrane.
• Cells depend on osmosis because, they cannot function properly without water.
• Why can’t people drink large amounts of salt water?
Active Transport• Passive transport if the movement
of dissolved material through the cell membrane without using cellular energy (high to low).
• Active transport requires cellular energy (low to high). This can be done in 2 ways.– Transport proteins “pick-up” method– Engulfing