Organization: The 6 Essential Elements Section 4

I. Why do living things need the six essential elements (CHNOPS)? Organization of an Organism – Living things are composed of two main types of chemical compounds: Inorganic: compounds that do not contain carbon, oxygen, and hydrogen C

I. Why do living things need the six essential elements (CHNOPS)? Water – (hydrogen and oxygen) the most important inorganic compound to living organisms 60-90% of all living organisms are made of water. Ex. the most abundant compound that makes up a cell is water Most chemical reactions occur in water because it provides an optimum environment Ex. transport of molecules in the cell

I. Why do living things need the six essential elements (CHNOPS)? Salts – often donate trace elements and influence the environment of the cell Ex. NaCl dissolves in solution to form Na+ and Cl-

I. Why do living things need the six essential elements (CHNOPS)? Organic: compounds that DO contain carbon, oxygen, and hydrogen Carbohydrates (carbon, hydrogen, oxygen) Ex. Provide energy source for respiration (glucose) Lipids (carbon, hydrogen, oxygen) Ex. Insulate and protect organs in the body (fats) Nucleic Acids (carbon, hydrogen, oxygen, nitrogen and phosphorus) Ex. Allow traits to be passed from parent to child (DNA) Proteins (carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus) Ex. Provide specifically shaped molecules that can carry other molecules (hemoglobin carries oxygen)

I. Why do living things need the six essential elements (CHNOPS)? To Maintain Homeostasis The elements make up essential organic and inorganic compounds. Each type of molecule performs specific jobs in organisms (see examples above). Hydrogen is donated or accepted by weak acid-base pairs to regulate the pH of a system (i.e. cell, blood). These weak acid-base pairs are called buffers.

Ahhhhh – just the right pH! Buffers Regulate pH Not enough hydrogen? Here’s another H atom! Too much hydrogen? I’ll hold a hydrogen atom! Ahhhhh – just the right pH! Buffers can donate hydrogen Buffers can accept hydrogen.

Review Questions What are the six essential elements? CHNOPS What is the most important inorganic compound to life? Water What are the four major organic compounds important to life? Proteins, Carbohydrates, Lipids, Nucleic Acids How do the six essential elements help organisms maintain homeostasis (two ways)? H and O can form water, which provides the optimum environment for chemical reactions C, H, and O can form carbohydrates which help maintain energy C, H, and O can form lipids which help keep some animals warm C, H, O, N, P, and S can form proteins which help regulate reactions H can be donated or accepted by buffers to help regulate pH

How does synthesis provide important organic macromolecules using six essential elements? Carbohydrates Carbon, hydrogen, and oxygen make up subunits called monosaccharide. Many monosaccharides bond together forming larger carbohydrates. In plants many monosaccharides called glucose (C6H12O6) bond together to form starch. In animals excess glucose bond together to form a compound (similar to starch) called glycogen.

Functions of carbohydrates Energy is released when carbohydrates are digested. This is because glucose is used for cellular respiration. Monosaccharides (simple sugars) provide short term energy. Starch and glycogen are considered longer term energy sources because they can be broken down over a period of minutes, hours or days to provide glucose for energy.

Some carbohydrates are very stable and can be used for structure and support in the cell and body (cellulose in the cell wall of plant cells). Carbohydrate chains on the surface of cell membranes are used as identifiers (like name tags).

How does synthesis provide important organic macromolecules using six essential elements? Lipids There are several types of lipids, but all contain subunits of glycerol and fatty acids made of carbon, hydrogen, and oxygen. These combine to make a very large molecule (macromolecule), but not a chain. Fats can be saturated (usually solid at room temperature) or unsaturated (usually liquid). Phospholipids also contain a phosphate group and make up most of the cell membrane.

Functions of lipids Because of the numerous bonds and the way the body stores lipids, they can be used as very long-term (weeks, months) energy sources. Ex. Bears accumulate a layer of fat before winter (when food will be less available) Fats stored in the body act as insulation and protection for internal organs. Some hormones are composed of lipids (steroids).

Review Questions What three elements make up both carbohydrates and lipids? Carbon, hydrogen, and oxygen What function do both carbohydrates and lipids provide? Energy use in the body What is the subunit of both starch and glycogen? Glucose What are the two subunits found in all lipids? Glycerol and fatty acids

II. How does synthesis provide important organic macromolecules using six essential elements? Nucleic Acids Carbon, hydrogen, oxygen, nitrogen, and phosphorus make up subunits called nucleotides. Many nucleotides bond together to make up a long chain – a nucleic acid. DNA is a double chain of nucleotides found in all living cells. RNA is a single chain of nucleotides that provides the structures needed for the cell to make proteins.

RNA is used in the production of proteins. Functions of nucleic acids DNA makes up the genes. Genes are used to pass traits from parent to offspring. Genes determine traits. DNA controls cellular activities by controlling the production of proteins in response to hormones and other cellular signals. RNA is used in the production of proteins.

How does synthesis provide important organic macromolecules using six essential elements? Proteins All six essential elements may be used in the production of small subunits called amino acids. Amino acids bond to form a long chain called a protein. These chains of amino acids fold into a particular shape when forming. The shape of a protein will determine its function. If a protein denatures (loses its shape) it can no longer function. Hemoglobin is a protein shaped to hold oxygen for transport through the bloodstream. A group of proteins called enzymes are shaped to fit and react with specific molecules.

Functions of proteins Some proteins absorb light to maintain homeostasis. These are called pigments. They create color by reflecting certain wavelengths of light. Ex. Chlorophyll absorbs light to gather energy for photosynthesis. Some proteins are constructed by cells to bind with and inactivate foreign particles in the body. These are called antibodies. Proteins may form structural parts in an organism – such as keratin in hair and nails.

Some proteins are used for transport through the cell membrane or in the bloodstream (ex. hemoglobin) Some proteins are used for communication between cells. These may be hormones (insulin) or neurotransmitters. Enzymes (a special class of protein) act to speed up chemical reactions.

Review Questions What is the subunit of a nucleic acid? Nucleotide What is the function of DNA? Hereditary material and Protein synthesis What is the subunit of proteins? Amino acids How do amino acids form specific shapes when they bond to make a chain? They fold to make a three-dimensional shape What protein carries oxygen? Hemoglobin Name three functions of proteins. Pigments Antibodies Structures Transport Communication Enzymes

III. Why are enzymes necessary for life? Enzymes help maintain homeostasis All organisms have metabolism. Metabolism includes all of the chemical reactions that occur in that organism. Metabolism includes digestion and production. Metabolism (chemical reactions) requires certain conditions to occur. Enzymes regulate metabolism, allowing life to continue. Metabolism (each reaction) has a small range of temperature and pH at which it can proceed. Each reaction also needs some energy to begin. This is called activation energy. Enzymes allow reactions to occur at lower activation energy (body temperature). This means enzymes act as biological catalysts (speeds reactions).

Graph of a reaction with and without an enzyme

B. The structure of an enzyme determines its function Enzymes are usually proteins. Proteins have a definite 3-D structure because the amino acid chains fold. On the enzyme, there is a place where the target molecule can attach. This place is called the active site. The target molecule/chemical is the substrate. If the enzyme’s active site changes shape too much, the substrate will not fit. An enzyme may change shape if it is denatured by a change in temperature, pH, or salinity. This means the enzyme will not be able to speed up the reaction.

Enzymes mediate (help) chemical reactions using a specific chemical pathway (series of steps). The enzyme collides with the substrate. The enzyme and substrate fit together at the active site like a lock and key. The enzyme changes the substrate in some way It may help break the substrate apart. It may hold two (or more) substrates together closely so the two parts interact. The enzyme and the substrate separate. The substrate (now changed) is called the product.

Enzyme-Mediated Pathway

C. Enzymes have distinguishing characteristics Enzymes are biological catalysts. This means they speed up chemical reactions in living things. Enzymes are specific. This means enzymes will catalyze only one specific reaction because only certain substrates fit due to the shape of the active site. Enzymes are reusable. Notice in the diagram above that the enzyme did not change shape or split. This means it can now fit with another substrate or set of substrates and repeat its role in speeding up the reaction. Reversible Enzyme Reactions Animation

Review Questions What do enzymes lower, allowing reactions to occur at body temperature? Activation Energy What organic compound are most enzymes? Proteins What is the name of the target chemical on which the enzyme works? Substrate Is the active site located on the enzyme or the substrate? Enzyme Name two characteristics of enzymes. Enzymes are catalysts; they speed up reactions Enzymes are specific Enzymes are reusable; they are not used up in the reaction

IV. How do we use technology to identify chemical compounds? Indicators – a chemical or tool that indicates a substance is present by changing color. These may be necessary for analyzing blood, hair, or urine in a drug test. Below are a few examples: pH can be determined using pH paper (different colors indicate different pH levels) or bromothymol blue/BTB (turns yellow in the presence of an acid). The presence of starch (a carbohydrate) is indicated when iodine changes from a rusty brown to a blue or black. The presence of blood is indicated when luminal is added and glows under a black light.

IV. How do we use technology to identify chemical compounds? Chromatography – the separation of chemicals in solutions based on differing chemical properties so that each part can be identified. Ex. Gas chromatography may be used to identify unknown chemicals found at a crime scene or samples from other planets

Review Questions What is an indicator? A chemical or tool that changes color in the presence of a particular substance. How does iodine indicate the presence of starch? It turns a blue-black color What allows the separation of chemicals in chromatography? The different chemical properties (such as solubility)