Chemistry of Living Systems

Found outside the nucleus Chemistry of Atoms Atom: smallest unit of matter Three components of an atom are… Electrons -1 Protons +1 Neutrons 0 Found outside the nucleus Found in the nucleus Found in the nucleus

Count the electrons! # of electrons in the outer shell are clues! Greater than 4 in the outer shell will take from other atoms Less than 4 in the outer shell will give to other atoms Provides hints on how and what types of bonds form

Elements Essential to Life About 25 elements are essential to living organisms CHNOPS: Make up 97% of living matter

Natural Elements in the Human Body ATOMIC # % in HUMANS Oxygen (O) 8 65.0 Carbon (C) 6 18.5 Hydrogen (H) 1 9.5 Nitrogen (N) 7 3.3 Calcium (Ca) 20 1.5 Phosphorus (P) 15 1.0 Potassium (K) 19 0.4 Sulfur (S) 16 0.3 Sodium (Na) 11 0.2 Magnesium (Mg) 12 Chlorine (Cl) 17 0.1

Chemical Bonds Chemical Bonds are the attractive force that hold atoms together in a molecule Bonds form when electrons are shared OR transferred between atoms Covalent bonds – sharing electrons (“co-” means to share as in cooperate) Ionic Bonds – give and take electrons Hydrogen Bonds – weak attractions between molecules Stronger atoms try to “steal” the H’s electron, but it keeps a tiny hold on it.

Nonpolar Covalent Bonds Electrons are shared equally

Polar Covalent Bonds Share electrons as in other covalent bonds, but the nucleus of one atom attracts the electrons more strongly so it is not equal.

Ionic Bonding One atom gets extra electron(s) (becomes a negative ion) and one gives extra electron(s) (becomes a positive ion) the two ions attract each other.

CARBON Carbon is easy to synthesize (break down and be used). Why is carbon so important in biological molecules? Carbon is easy to synthesize (break down and be used). Molecules with carbon are called ORGANIC Molecules without carbon are called INORGANIC

What are the important molecules of life?

WATER

The Structure of Water “V” shaped molecule Unequal sharing of electrons causes oxygen to have a slightly negative charge called a polar molecule

Properties of Water Cohesion is the tendency of molecules of the same kind to stick to one another. Water has stronger cohesion than most liquids

Water molecules are also attracted to certain other molecules Attraction between unlike molecules is called adhesion

Cohesion pulls molecules at the surface tightly together, forming a film-like boundary This is surface tension

Carbohydrates (C,H, and O molecules in a ratio of 1:2:1) Carbohydrates are an important energy source for cells.

TYPES OF CARBOHYDRATES Monosaccharide – simple sugars made of one sugar molecule. (ex. Glucose)

TYPES OF CARBOHYDRATES Disaccharides – (ex. Sucrose) 2 monosaccharides linked together

TYPES OF CARBOHYDRATES Polysaccharides – ex. Starch, Cellulose) More than two sugars linked together.

Did you notice how the sugars all sound the same? They all end in “-ose” (-ose = sugar) Ex. Sucrose, Glucose, Fructose, Lactose

TYPES OF CARBOHYDRATES Simple Carbs ~ mono and disaccahrides Complex carbs ~ starches, polysaccharides

LIPIDS Made up of two parts: A head (it is hydrophillic) A tail made of a hydrocarbon chain (it is hydrophobic). This lets the lipids form bilayers creating waterproof barriers like in a cell’s membrane.

LIPIDS Fatty acids, waxes, fats, steroids and oils are formed by lipids (all are insoluble in water)

Proteins Molecules made up of one or more chains of amino acids. They are used for many functions…

Structure – they make collagen in skin and keratin in hair/nails/horn Proteins are used for… Structure – they make collagen in skin and keratin in hair/nails/horn

Proteins are used for… Movement ~ actin and myosin in muscle stimulate the muscle to move

Defense ~ antibodies in bloodstream Proteins are used for… Defense ~ antibodies in bloodstream

Storage ~ corn seeds are predominately made of protein Proteins are used for… Storage ~ corn seeds are predominately made of protein

Signals ~ growth hormones in your blood stream Proteins are used for… Signals ~ growth hormones in your blood stream

Proteins are used for… Nucleic Acids (used in DNA or RNA) – long chains of pieces called nucleotides. A nucleotide has 3 parts… 1. five carbon sugar (ribose or deoxyribose) 2. phosphate group 3. Nitrogen base (A,T,C or G)

Proteins are used for… Catalysis ~ enzymes which speed up processes in the body

So what is an Enzyme? An enzyme is used to speed things up or help break things down in your body.

Words You Should Know Enzyme (E): protein catalyst Catalysts: speed up reactions without being changed by the reaction Substrate (S): reactant(s) in the enzyme-catalyzed reaction Active site: area of enzyme where substrate(s) bind(s)

Enzymes Enzymes are proteins with a SPECIFIC SHAPE The active site is a part of the protein which recognizes and binds to the substrate Cofactors (e.g. Zn 2+, Cu 2+, B vitamins) some enzymes won’t hook-up to a substrates without these

Specificity ‘Lock and Key Model’ – says there is a perfect fit between active site and substrate Modified to ‘Induced Fit Model’ - active site can expand or contract to “fit” the substrate shape The induced fit model allows for small differences (possibility of letting several different kinds of substrates hook up)

How do enzymes speed up reactions? Enzymes lower the activation energy (EA=amount of energy that reactant molecules require to start a reaction)

Enzymes Are involved in every biochemical reaction and thereby control metabolism Are named according to the reaction that they facilitate Examples: Sucrase breaks down sucrose into glucose and fructose DNA Polymerase helps build DNA polymers

Did you notice that enzyme all sound the same? All enzymes end in “-ase” DNA Polymerase Sucrase

Factors affecting enzyme activity 1. TEMPERATURE 2. Concentration of Enzyme 3. Concentration of Substrate 4. pH 5. Inhibitors

Types of Inhibition Competitive inhibition - molecules bind to the active site and prevent the substrate from binding Non-competitive inhibition - molecules that bind to a site other than the active site but change the shape of the active site so that it cannot bind the substrate

Enzymes in Biotechnology How does pectinase work?

Pectin is the cement that holds plant cells together Pectin is the cement that holds plant cells together. Pectinase helps farmers break down the plant cells faster. For example it might help a farmer release the juice from apples faster to make lots of Apple Juice.

Other enzymes in biotechnology… Biological washing powder Meat tenderizer Production of glucose syrup