The Necessities of Life

WATER Cells = 70% water Chemical reactions in metabolism require water Humans can only survive about 3 days without Water comes from fluids and food

AIR Air includes oxygen and carbon dioxide Oxygen is used in chemical process to release energy from food (cellular respiration) Green plants and algae need carbon dioxide to produce food (photosynthesis) Anaerobic organisms – will not grow in the presence of air (Clostridium botulinum – bacteria that make humans sick)

PLACE TO LIVE Need place that contains all of the things needed to survive Organisms often compete for space

FOOD Energy Replace cells Build body parts Organisms are grouped based on how they obtain food

PRODUCERS Plants and algae Energy from sun Water + carbon dioxide PHOTOSYNTHESIS Releases glucose (sugar) + oxygen gas

CONSUMERS Must consume other organisms for food

NUTRIENTS Made of molecules Molecules = 2 or more atoms Compounds = 2 or more different kinds of atoms Living things compounds include 6 elements: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur These elements form proteins, carbohydrates, lipids, ATP, and nucleic acids

PROTEINS Made up of smaller molecules called amino acids Protein in food is broken down to supply cells with amino acids Some proteins = a few amino acids Some proteins = 10,000 amino acids Red blood cells contain protein called hemoglobin Hemoglobin binds to oxygen to deliver and release oxygen throughout the body Some proteins protect cells Proteins called enzymes speed up chemical reactions in cells

CARBOHYDRATES Molecules made of sugars Cells use as source of energy an energy storage Simple carbohydrates – 1 or a few sugar molecules – table sugar and sugar in fruits Complex carbohydrates – organism has more sugar than it needs - made of 100’s of sugar molecules linked together Plants (potato) store extra sugar as starch

LIPIDS Cannot mix with water Some store energy Some form membranes of cell - Phospholipids – membranes help protect the cell and keep the internal conditions stable Fats and oils – store energy Fats – most solid – most stored in animals Oils – most liquid – most stored in plants

ATP Adenosine triphosphate Major energy-carrying molecules in the cell Energy in carbs and lipids must be transferred to ATP, which then provides fuel for cells

NUCLEIC ACIDS Blueprints of life Information for a cell to make proteins Large molecules made up of molecules called nucleotides Order of nucleotides stores information to make proteins

YOUR TASK Write a job description for one of the cell’s basic chemical building blocks. Describe the required job responsibilities. Include a description of the expected workload by explaining whether the building block will have to work constantly or sporadically. Indicate whether the building block will work independently or with other cell components.

YOUR TABLE Table 1 Proteins Table 2 Carbohydrates Table 3 Phospholipids Table 4 Fats and Oils Table 5 ATP Table 6 Nucleic acids