AP Bio Unit One Study Set (created by Wes Besikof)

Why is water polar?

Oxygen is very electronegative and Hydrogen is not, so the electron distribution is off centered

Define Cohesion

Attraction between molecules of the same substance

Define Adhesion

attraction between molecules of different substances

Why does water have a high specific heat?

it takes energy to break the hydrogen bonds

Why does ice float?

When water freezes, the hydrogen bonds form crystal lattices that are spacious. (The H-bonds in liquid water are constantly forming and breaking...) This makes ice less dense than water, so it floats

Does water dissolve polar or non polar substances? Why?

Polar (or fully ionic) substances because the negatively charged Oxygen is attracted to the other positively charged atoms, while the positively charged hydrogen is attracted to negatively charged atoms. This separates polar molecules (or ions) from one another.

What is formed when water dissociates?

H3O+ and OH-

In water, the amount of H3O+ and OH0- are...

equal. This is why water's pH is 7 (neutral)

More hydrogen ions means...

lower pH (acidic)

Less hydrogen ions means...

higher pH (basic)

Acids donate or accept protons?

donate protons [H+]

Bases donate or accept protons?

accept protons [H+]

Why is carbon so fundamental?

it's tetravalent, which means it makes 4 bonds to become stable. This leads to infinite variety

---OH

Hydroxyl Group

Hydroxyl group properties

polar (hydrophilic), can form hydrogen bonds

--C==O

carbonyl group

Carbonyl group properties

2 types of carbonyls

Ketone: a carbonyl group within the carbon skeleton

Aldehyde: a carbonyl group on the end of a carbon skeleton

--COOH

carboxyl group

Carboxyl (acid) group properties

acts as an acid (can donate H+) because the covalent bond between oxygen and hydrogen is so polar

--NH2

Amino Group

Amino properties

acts as a base, can pick up a proton (H+) from surrounding solution

--SH or --HS

Sulfhydryl Group

Sulfydral group properties

2 sulfhydral groups form a bridge (cross-linking) to stabilize a protein structure

--CH3

Methyl Group

Methyl group properties

non-polar (hydrophobic);

addition of a methyl group to DNA, or to molecules bound to DNA affects the expression of genes (it essentially "shuts off" the expression of DNA)

--PO4

Phosphate Group

Phosphate group properties

Ionic Group (In biology, it's often referred to as just polar); Found in nucleotides, the monomers of nucleic acids, and in phospholipids, the building blocks of cell membranes.

What is a macromolecule?

a large molecule made of a few, common atoms. They accomplish all life functions and can be very complex

Name the 4 main macromolecules

Carbohydrates, Lipids, Proteins, and Nucleic Acids

except for lipids, macromolecules exist in two forms. What are they?

monomers and polymers

What is dehydration synthesis?

the process of joining two or more monomers to form a polymer by removing water to form a bond (opposite of hydrolysis)

What is hydrolysis?

the process of breaking apart a polymer to form monomers by adding water (opposite of dehydration synthesis); "hydrolyzing" a molecule means adding water to break it up.

Define anabolic and catabolic

Anabolic: builds complexity (ex: dehydration synthesis)

Catabolic: reduces complexity (ex: hydrolysis)

Define exergonic and endergonic

Exergonic: releases energy (ex: hydrolysis)

Endergonic: requires energy (takes in energy) (ex: dehydration synthesis)

What atoms make up carbohydrates?

carbon, hydrogen, oxygen (1:2:1 ratio)

What do carbohydrates do?

they store short term energy and structure

What are the 3 "main" monosaccharides

glucose, fructose, galactose

How are disaccharides formed?

When two monosaccharides are linked together through dehydration synthesis

What are the three "main" disaccharides? What monomers make them up?

Glucose + Glucose = Maltose

Glucose + Fructose = Sucrose

Glucose + Galactose = Lactose

What are polysaccharides?

massive polymers of sugars

What are the 2 main functions of glucose polymers

energy storage and structural support

What are the polysaccharides used for storage in plants and animals?

plants: starch

animals: glycogen

What is the major component of plant-like cell walls?

cellulose

How do the structures of starch and cellulose differ?

Starch has alpha linkages between it's glucoses

Cellulose has beta linkages between it's glucoses

What are lipids?

fats, oils, and waxes

What atoms make up lipids?

carbon, hydrogen, oxygen (very little O compared to C)

What do lipids do?

they are used for long term energy storage and insulation

T or F: lipids are built of polymers

false: they're made of monomers

What are the three major groups of lipids?

triglycerides, phospholipids, steroids

What makes up a triglyceride?

1 glycerol and 3 fatty acids

How do unsaturated and saturated fats differ?

Saturated fats have no double bonds, they are unhealthier

Unsaturated fats have at least one double bond, and are healthier; the double bond causes a bend in the structure

What makes a phospholipid?

1 glycerol, 2 fatty acids and 1 phosphate

What are the properties of a phospholipid?

The molecule has a polar region (the head which inhabits the phosphate group), and a non polar region (the fatty acid legs). When combined with other phospholipids, they form a bilayer (hydrophobic tails away from water; hydrophilic heads near water) that is a major component of cell membranes

What are steroids?

lipids characterized by a carbon skeleton consisting of four FUSED rings. The presence of different functional groups leads to different functions. Ex: Cholesterol, testosterone, estrogen

What atoms make up proteins?

carbon, hydrogen, oxygen, nitrogen and a little sulfur

What are proteins made of?

polymers made by amino acids joined by peptide bonds (a bond formed by dehydration synthesis)

what 2 functional groups are found in amino acids? What are they bonded to?

carboxyl group and amino group. They bond to a central "alpha" carbon

Describe the primary structure of a protein

sequence of amino acids in a polypeptide chain

Describe the secondary structure of a protein

3D structures formed by hydrogen bonding between atoms in the carbon nitrogen backbone. (no R groups are involved). Either an "Alpha Helix" or "Beta Pleated Sheet" can be formed

Describe the tertiary structure of a protein

The specific 3D shape of a particular polypeptide chain ("conformation"). It's determined by the various interactions between the R-Groups

What kind of interactions occur to determine the tertiary structure?

Hydrogen bonds, hydrophobic interactions/van Der Waals interactions, disulfide bridge, ionic bonds

Describe the quaternary structure of a protein

Two or more polypeptide chains, each with its own tertiary structure, combine to form a functional protein

What do proteins do?

they're responsible for all life activities of the cell (Ex: enzymes and transport proteins)

Define denaturation

a change in the structure of a protein. Denatured proteins do not work well (if it all)

what causes a protein to denature?

change in temp, pH, salinity (amount of salt), polarity of solvent.

What atoms make up Nucleic Acids?

carbon, hydrogen, oxygen, nitrogen, phosphorus (no sulfur!)

What do nucleic acids do?

store and transmit genetic information

What are the two kinds of nucleic acids?

DNA and RNA

What are nucleotides?

monomers that make up nucleic acids

What do nucleotides consist of?

nitrogenous base ("ring" shape(s)), pentose sugar, phosphate group

Difference between DNA and RNA Pentose

DNA: deoxyribose

RNA: ribose

Difference between DNA and RNA Bases

DNA: Adenine, Thymine, Guanine, Cytosine

RNA: Adenine, Uracil, Guanine, Cytosine

Difference between DNA and RNA Strands

DNA: 2 strands

RNA: 1 strand

What functions do DNA serve?

it stores information about the primary structure of proteins (It tells the cell what order to put amino acids in to build each protein), and the sequence of RNA molecules

It's heritable (passed down through genes)

Describe the structure of DNA

There are 2 chains of covalently bonded nucleotides from sugar to phosphate ("phosphodiester bonds"). The chains are bonded to each other by weak hydrogen bonds between Nitrogenous bases.

- A bonds to T, and G bonds to C

what are purine and pyrimidine bases?

nitrogen bases that hold DNA strands together through hydrogen bonds.

Purines are Adenine and Guanine (A, G)(double rings)

Pyrimidines are Cytosine, Thymine, and Uracil (C, T, U) (single rings)

What functions do RNA serve?

they transmit and translate DNA information into proteins primary structures. They also have many enzymatic and regulatory functions

Describe the structure of RNA

less stable than DNA. 1 strand, but base pairing can still occur (Adenine bonds to Uracil)

What is the central dogma of molecular biology?

information stored in DNA moves to RNA before some of that information finally directs the construction of proteins:

DNA--> RNA --> Proteins