AP Biology Unit 1 Chemistry of Life

What are the four classes of macromolecules?

- Carbohydrates

- Nucleic acids

- Lipids

- Proteins

Carbon can...

Form up to 4 single bonds, form rings or chains, and form strong covalent bonds

Organic molecules

Contain carbon (typically covalently bonded to hydrogen)

Functional groups

Clusters of atoms with characteristic structures and functions

Polar molecules are...

Hydrophilic (adhere to water)

Nonpolar molecules are...

Hydrophobic (repel with water)

Monomer

1 subunit of an organic molecule (general term)

Polymer

Many subunits of an organic molecule (general term)

Dehydration synthesis / Condensation reaction

Forming polymers by removing water

Hydrolysis

Breaking down polymers by adding water

Carbohydrates are composed of...

Carbon, hydrogen, and oxygen (CHO)

Basic/general formula for carbohydrates

CH2O

Where is energy stored in sugars?

C-C bonds

What is the suffix most sugars end in?

-ose

Monosaccharide

Simple 1 monomer sugars, either used as first energy source or to form polymers

Disaccharidase

Simple 2 monomer sugars

How are sugars classified?

By the number of carbons

Glycosidic linkage

Bond between two sugars

What is the main function of carbohydrates?

Energy (body's primary source of energy), as well as energy storage

What are the three hexose monosaccharides?

Glucose, fructose, and galactose

What is the formula for hexose monosaccharides?

C6H12O6

Glucose

Most common monosaccharide and monomer

Fructose

In corn syrup and fruits, makes things sweet

Galactose

Basic milk sugar

How are disaccharides formed?

Dehydration synthesis

Glucose + Fructose = ?

Sucrose (C12H22O11) + Water (H2O)

Glucose + Glucose = ?

Maltose (C12H22O11) + Water (H2O)

Glucose + Galactose = ?

Lactose (C12H22O11) + Water (H2O)

How is the energy release of simple sugars/monosaccharides and disaccharides?

Quick but little amount of energy

How do you test for sugars?

Add substance into test tube, add Benedict's solution, heat in boiling water bath for 3-4 mins; color change represents sugar (blue control, more green = less sugar, more red = more sugar)

Polysaccharide

Polymer of sugars

Building polysaccharides...

Stores energy (forms bonds)

Breaking down polysaccharides...

Releases energy (breaks bonds)

If sugars aren't used, they're stored as...

Polysaccharides

Glycogen

Stored energy in animals

Starch

Stored energy in plants

Cellulose is found in...

Plants' cell wall

Chitin is found in...

Arthropods' exoskeleton and the cell wall of fungi

How do you test for starches?

Drop of iodine on unknown substance; color change represents starch (darker black/purple = more starches)

What part of the structure of cellulose and starch makes them different? (Why is one digestible while the other isn't?)

Cellulose is made of beta-glucose monosaccharides and starch is made of alpha-glucose monosaccharides (these are different isomers of glucose, meaning they are built of the same atoms, but form different structures.) Cellulose is indigestible to humans because we lack the enzyme, cellulase, to break the beta-glycosidic bonds.

What is the most abundant organic compound on Earth?

Cellulose

How can herbivores digest cellulose?

Herbivores have evolved a mechanism to digest cellulose. For example, they tend to have longer digestive tracts and multiple stomach chambers to break down fibrous material. Herbivores also have bacteria that live in their digestive system, which helps them digest cellulose-rich food.

How is the energy release of complex sugars/polysaccharides?

Medium speed and more energy than simple sugars

Polymerization

The process of making polymers through dehydration synthesis

Examples of monosaccharides

Glucose, fructose, galactose, ribose, deoxyribose

Examples of disaccharides

Sucrose, maltose, lactose

Examples of polysaccharides

Cellulose, chitin, glycogen, starch

What are the two main groups of nucleic acids?

DNA and RNA

Nucleic acids are composed of...

Carbon, hydrogen, oxygen, nitrogen, phosphorus (CHONP)

DNA

Deoxyribonucleic acid

RNA

Ribonucleic acid

ATP

Adenosine triphosphate

What is the sugar in DNA?

Deoxyribose

What is the sugar in RNA?

Ribose

What is the sugar in ATP?

Ribose

What is the name of the monomer of DNA, RNA, and ATP?

Nucleotide

What are the three parts of a nucleotide?

Sugar (ribose/deoxyribose), nitrogen base, and phosphate group

What are the nitrogen bases in DNA?

Adenine, guanine, cytosine, and thymine

What are the nitrogen bases in RNA?

Adenine, guanine, cytosine, and uracil

What is the nitrogen base in ATP?

Adenine

Purine

2 rings: adenine and guanine

Pyrimidine

1 ring: cytosine, thymine, and uracil

Which nitrogen bases bond with each other?

Adenine and thymine, guanine and cytosine (because purine always bonds to a pyrimidine)

Qualities of RNA

- Single-stranded

- Ribose sugar

- A, U, G, and U nitrogen bases

- Located in nucleus and cytoplasm

- Helps genetic info turn into proteins

Qualities of DNA

- Double-stranded (helix)

- Deoxyribose sugar

- A, T, G, and C nitrogen bases

- Located only in nucleus

- Holds genetic info

Lipids are composed of...

Carbon, hydrogen, and oxygen + sometimes phosphate (CHO + P)

All lipids are...

Hydrophobic

Do lipids form polymers?

No

What are the main "family groups" of lipids?

- Fats

- Phospholipids

- Steroids

- Waxes

What are fats made of?

Glycerol + fatty acid chains (hydrocarbon chains)

Glycerol

3C alcohol (C3H8O3)

Fatty acid

Long hydrocarbon "tail" with carboxyl group head

How many fatty acid chains are in a triglyceride?

3

What is the backbone of fatty acids made of?

Carbon

Properties of hydrocarbon chains

- Non-polar (no charge)

- Hydrophobic

What is the function of fats?

Energy storage (if you don't use sugars for energy, they are stored as fats), as well as to cushion and insulate body

How is the energy storage of fats?

- Concentrated (mostly in many H-C bonds)

- Twice as much energy as carbs

- Lots of energy, slow to break down

What is the order in which the body derives energy?

1. Simple sugars (eg. glucose)

2. Stored sugars (glycogen)

3. Stored fats

4. Proteins (last resort)

Saturated fats

- All C bonded to H

- Only single bonds

- Long, straight chains

- Solid at room temp

Unsaturated fats

- C=C double bonds in fatty acids, 1 or more

- Kinked chains

- Liquid at room temp

Why are saturated fats solid at room temperature?

The straight fatty acid chains stack on top of each other easily

Why are unsaturated fats liquid at room temperature?

The kinked fatty acid chains prevent packing together easily.

Examples of saturated fats

Most animal fats (eg. butter, tallow, lard)

Examples of unsaturated fats

Fish oils, vegetable oils

Why are the fatty acid chains in unsaturated fats kinked?

The double bonding of the carbon causes bending in the molecule, leading to the kinks.

Monounsaturated fats

One double bond in fatty acid chain, non-essential (body can produce),

Polyunsaturated fats

Many double bonds in fatty acid chain, essential (body cannot produce)

Why are saturated fats considered less healthy than unsaturated fats?

Saturated fats have more hydrogen atoms than unsaturated fats (causes it to be more solid, thus having more artery-clogging potential)

What are phospholipids made of?

Glycerol + 2 fatty acid chains + phosphate group (PO4) instead of 3rd fatty acid chain

Why are phospholipids polar?

The phosphate group head has a charge, while the fatty acid tail does not have a charge, making the molecule (as a whole) polar

What is the function of phospholipids?

Form phospholipid bilayer (main component of cell membrane)

How are different steroids made?

By attaching different functional groups to rings

What is special about the structure of steroids?

There are 4 fused hydrocarbon rings (numbered consecutively from A to D)

Examples of steroids

Cholesterol, sex hormones (estrogen, testosterone)

What is the precursor of all steroids?

Cholesterol

HDL cholesterol

High-density lipoprotein, considered "good" cholesterol because it removes excess cholesterol to liver

LDL cholesterol

Low-density lipoprotein, considered "bad" cholesterol because it transports cholesterol from liver throughout body

What does cholesterol do for cells?

Component of cell membrane, providing structural support

Why is cholesterol considered bad?

High levels of cholesterol in blood may contribute to cardiovascular disease (builds up plaque in artery walls)

How are trans fats made?

Through a process called hydrogenation, where hydrogen atoms are added to the double bonds of fatty acid chains