The Molecules of lifeThe Molecules of lifeChapter 5

5.1- Carbon is the main ingredient of organic molecules

Why are carbon atoms so common in living things? ◦4 electrons in its highest occupied level making

it very reactive. Organic molecules

Always contain carbonInorganic Molecules

Never contain carbon

Carbon Skeletons and Functional Groups Carbon Skeletons – “the backbones of organic

molecules.

Functional Groups – a group of atoms within a molecule that interacts in predictable ways with other molecules.

Monomers◦Smaller molecular

units, building blocks of polymers

Polymers◦Many monomers

linked together into long chains

Life’s Large (macromolecules)◦Carbohydrates◦Lipids◦Proteins◦Nucleic acids

Building and Breaking Polymers

◦Dehydration reaction Each time a monomer is

added to a chain, a water molecule is released

◦Hydrolysis reaction Cells break bonds between

monomers by adding water to them (the reverse of dehydration)

5.2 Carbohydrates provide fuel and building material◦Objectives

Describe the basic structure and function of sugars.

Name three polysaccharides and describe their functions

◦Key terms◦Carbohydrate◦Monosaccharide◦Disaccharide◦Polysaccharide◦Starch◦Glycogen◦Cellulose

What do athletes mean when they talk about “carbs”?

◦Carbs=Carbohydrates=sugar molecules Sports drinks- small molecules

Pasta- long molecules (Starch)

Sugars – The main fuel supply for cellular work. ◦Carbohydrate – An organic compound made up

of sugar molecules Carbon, Hydrogen, Oxygen Ratio – 1 C : 2 H : 1 O

◦Monosaccharide – Simple sugars containing just one sugar unit Examples – glucose, fructose and galactose.

Disaccharides – Using the dehydration reaction, cells construct a disaccharide (double sugar)◦Most common disaccharide-Sucrose

Glucose monomer and a fructose monomer

Polysaccharides – Long polymer made up of simple sugars monomers (Complex Carbohydrates)◦Common Polysaccharides-Starch, glycogen,

cellulose

5.3 – Lipids include fats and steroids

◦Objectives Identify a general characteristic of lipids Describe the structure and functions of fats Describe the structure and functions of steriods

◦Key terms Lipid Hydrophobic Saturated fat Unsaturated fat Steroid Cholesterol

“Do Now” – Salad Dressing containers usually have a label that says, “Shake well before using” Why?

The oil in most dressings doesn’t mix well with the vinegar (mostly water).

Characteristics of lipids◦Lipids are water-avoiding molecules

(Hydrophobic – water fearing)

Fats◦Consist of a three-carbon skeleton

(glycerol) attached to three fatty acids (long hydrocarbon chains).

Saturated fats◦Contains maximum number of

hydrogen atoms◦All single bonds

Unsaturated fats◦Contains less than the maximum

number of hydrogen atoms.◦One double bond

Steroids◦Lipid where the carbon skeleton

forms four fused “rings” Examples – Estrogen and

Testosterone Function – send chemical signals

throughout the body◦Cholesterol

A steroid that is found in the membrane surrounding your cells

High levels are linked with increase risk for cardiovascular disease (heart and blood vessel)

5.4 – Proteins perform most functions in cells.

Do now – Make a list of facts you already know about proteins.

Polymer Energy Builds muscles

Objectives ◦List functions of proteins◦Describe the structure of amino acids and

proteins◦Describe factors that influence protein shape

The Functions of Proteins◦A protein is a polymer made from only 20

monomers (amino acids)◦Responsible for day-to-day functions

Examples of typical protein functions◦Form hair and fur◦Make up muscles◦Defend the body from harmful microorganisms◦Send messages from one cell to another◦Control chemical reactions in cells

Amino Acids◦Monomer consists of a central carbon

atom bonded to 4 partners. Hydrogen group Carboxyl group Amino group Functional group (side group) or (R-

group)

Examples◦Leucine

◦Serine

Building a Protein◦Cells link monomers of proteins (amino acids)

together to create polypeptide Chains Building molecules needs a reaction. Which

reaction?◦Dehydration reaction

◦Alphabet = 26 letters◦Creates - ? Words◦Amino acids = 20 “letters”◦Creates - ? Polypeptide chains

Protein Shape◦Protein are not linear, but 3D

carefully twisted and folded into a particular shape.

◦Will not work properly unless it is in it’s unique shape.

◦Shape is influenced by its environment.

◦Changes in its environment can “unravel” the protein” (denaturation) Change in temperature pH

5.5 – Enzymes are proteins that speed up specific reactions in cells.

◦Objectives: Explain how enzymes affect activation energy. Describe how an enzyme’s shape is important to its function.

◦Key Terms Activation energy Catalyst Enzyme Substrate Active site

Enzymes and Activation NRG◦Where does the NRG from a lit

candle come from? From lighting a match. This is

start-up NRG or (activation energy)

Catalyst – compounds that speed up chemical reactions.◦By weakening bonds chemical

reactions occur faster and/or with less NRG

The main catalysts of chemical reactions in organisms are specialized proteins called enzymes.

Enzymes – Provide a way for reactions to occur at the cell’s normal temperature.◦As to not damage other

parts of the cell from excessive heat.

How do enzymes work?◦The enzyme fits with the

intended substrate at the active site, like a puzzle piece. *Only the right combination will work.