Macromolecules

Carbohydrates, Lipids, Proteins, and Nucleic Acids

Chapter 2, pg. 44-48SCOS Obj: 2.01

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What are they?

• The term “macromolecule” implies a large molecule (macro means large)

– A molecule is a stable group of at least 2 atoms held together

– Building blocks of cells (meaning they are inside cells)

• Also known as Organic Molecules• All are made up of the element Carbon• Found in all living things 2

Four Classes with Examples

• Carbohydrates-starches and sugars (a)

• Lipids-fats, waxes, steroids and cholesterol (d)

• Proteins-enzymes, hemoglobin and insulin (b)

• Nucleic Acids-DNA and RNA (c)

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Monomers/Polymers• They are synthesized

(created) by a process called polymerization where monomers (mono-one/single, meros-part) are assembled into large (macro) molecules (also known as polymers)

• Made by combining many single units into larger units

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Macromolecules and their monomers

• Carbohydrates-monosaccharide • Lipids-fatty acid and glycerol• Protein-amino acids

– Connected by peptide bonds that is why proteins are also known as polypeptides! (YES you need to write this down!!!!)

• Nucleic Acid-nucleotides

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Carbohydrates

• They are composed of the elements carbon, hydrogen and oxygen in the proportion of 1:2:1 (for every one carbon, there are two hydrogen and one oxygen)

• The general formula is CH2O• Carbs function is short-term energy storage (sugar),

intermediate-term energy storage (starch for plants and glycogen for animals-humans ARE animals) and structural components in cells (cellulose in the cell walls for plants/protists) and chitin in insects

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Sugars

• Carbohydrates are words that end in -ose• Sugars are the simplest carbohydrates

(monomers) they are the structural unit which makes up all other carbohydrates

• Monosaccharides are single sugars (important ones are glucose, fructose and ribose)– Glucose is the fuel in most living things

• Most basic of monosacharride – Fructose is sugar found in fruit– Ribose is a sugar that helps form proteins

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Disaccharides

• Disaccharides are formed when two (di=two) monosaccharides are chemically bonded together (sucrose and galactose are examples)– Sucrose is table sugar made from

glucose bonding with fructose– Lactose is milk sugar made

from glucose and galactose

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Polysaccharides• Polysaccharides are large molecules composed

of many individual monosaccharide units bonded together (starch, glycogen and cellulose are all made up of glucose bonding with itself)– Starch is made by plants as a storage form of sugar

made up of hundreds of glucose molecules– Cellulose is the structural component of plant cells

and are made up of thousands of glucose molecules (does NOT store glucose)

– Glycogen is the storage form of glucose in animals and accumulates in the liver and muscle tissues of animals

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Lipids

• Element are hydrogen, oxygen and carbon: contains a higher proportion of carbon and hydrogen compared to oxygen

• They DO NOT dissolve in water (insoluble)• Lipids store energy in the form of calories (not

as well as carbohydrates though)• Provide padding and insulation• Monomer: fatty acid tails and glycerol

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More About Lipids

• Lipids consists of three fatty acids joined by one glycerol molecule

• Main types are triglycerides (fats and oils), phospholipids (found in cell membranes), wax and steroids (these do NOT have a fatty acids, examples include cholesterol and steroid hormones

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More Examples• Waxes

– Used to coat and waterproof plants• Steroids

– Cholesterol is an important steroid found in all animal tissue (plants do not contain cholesterol), it adds strength to animals cells structures

• Phospholipids– Found in the membrane of a cell

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Triglycerides

Saturated

• All the bonds between carbon atoms are single bonds

• Mostly animal sources• Solid at room temperature• These can lead to health

problems such as heart disease

Unsaturated• Has at least one double

bond between carbon atoms which causes a bend in the chain

• Mostly plant sources• Liquid at room temperature

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Proteins

• Composed of the elements carbon, hydrogen, oxygen and nitrogen

• Not very good fuel for the body but are essential to life

• They are important in biological systems as control (enzymes and hormones) and structural elements (these function in the cell membrane and muscle tissue)

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More about Protein Examples-Enzymes

• Known as organic catalysts• Speed up the rate of reactions by lowering the

activation energy• Break things down• Two things that kill/denature/change the

shape: temperature and pH• Bind with a substrate at the active site on

enzyme• They end in -ase

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Hemoglobin

• Protein found in the red blood cells (RBCs)• In mammals, it makes up about 97% of the red

blood cell’s dry content • Transports oxygen from the lungs or gills to

the rest of the body where it releases the oxygen for cell use

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Insulin

• A hormone that is secreted by groups of cells within the pancreas called islet cells in response to detecting an increase in blood sugar

• When insulin binds to the cell, it activates other receptors designed to absorb glucose (sugar) from the bloodstream into the inside of the cell

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Amino Acids

• Amino acids are linked together by a bond called a peptide bond – Many amino acids bonded together are called

polypeptides• There are 20 essential amino acids• Average protein is 200 amino acids long• Only difference among amino acids is its “R”

group

The 20 amino acids represented in the genetic code are:

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Structure

• Proteins have four unique shapes that is determined by how the amino acids fold– The primary level is the basic level and is determined by the

sequence of amino acids (a straight line)– The secondary level is the bending of the bonds (like holding

a piece of yarn in both hands and twisting it back and forth)– Tertiary level occurs as the molecule folds back on itself

(such as a pretzel)– The quaternary level is when you combine two or more

proteins that are in the tertiary state (combining two or more pretzels together)

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Testing Foods

• Starch– Iodine is used– Positive result turns purple or

blue/black

• Lipid– Brown paper bag is used– Positive result, bag is see

through/translucent

• Monosaccharide– Benedicts solution is used– Positive results turns:

• Green-little sugar• Yellow-medium amount

Orange/red-high amount

• Protein– Biuret is used– Positive results turns

pinkish/purple

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Nucleic Acids

• They are the largest molecules made by organisms

• Composed of hydrogen, oxygen, nitrogen, carbon, and phosphorus

• They store and transmit hereditary, or genetic, information (DNA), used to make proteins (RNA) and for energy transfers (ATP)

• The monomer of nucleic acids are nucleotides

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Nucleotides• Nucleotides are made up of three things: 5-carbon

sugar, a phosphate group and a nitrogenous base– Sugars are either deoxyribose (DNA) or ribose (RNA)– Nitrogenous bases are A (adenine), C (cytosine), G

(guanine) and T (thymine) and U (uracil)• The phosphate group of one molecule is linked

together by covalent bonds to the sugar of the next

• Hydrogen bonds (they are very weak!) form between the specific bases of the nucleic acid chains

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Nucleotide Structure

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