(AP Biology) Chapter 3: Carbon and the Molecular Diversity of Life

What type of bonds does carbon make with other elements?

What type of bonds does carbon make with other elements?

covalent

carbon chains form skeletons. What types of skeletons can be formed?

they may vary in length and can be straight, branched, or arranged in closed rings (some have double bonds)

define: hydrocarbon

an organic molecule consisting of only hydrogen and carbon; hydrophobic (ex. methane and ethane)

define: functional group

chemical groups that affect molecular function by being directly involved in chemical reactions

What chemical group does -OH belong to?

hydroxyl

What chemical group does C=O belong to?

carbonyl

What chemical group does COOH belong to?

carboxyl

What chemical group does -NH2 belong to?

amino

What chemical group does -SH belong to?

sulfhydryl

What chemical group does PO4 belong to?

phosphate

What chemical group does -CH3 belong to?

methyl

key component of ethanol (alcohol)

hydroxyl

key component of acetone and propanol

carbonyl

key component of carboxylic acid

carboxyl

key component of glycine

amino

key component of cysteine

sulfhydryl

key component of ATP

phosphate

Which chemical group can affect gene expression?

methyl

Which chemical groups are polar?

hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, and phosphate

Which chemical group is non polar?

methyl

Which chemical group is acidic?

carboxyl

Which chemical group is basic?

amino

Which chemical group forms disulfide bridges? (cross links that stabilize protein structure)

sulfhydryl

Which chemical group determines the two groups of sugar?

carbonyl

4 main classes of large molecules of all living things

lipids, proteins, carbohydrates, nucleic acids

define: polymer

long molecule consisting of many similar or identical building blocks linked by covalent bonds (proteins, carbohydrates, nucleic acids)

define: monomer

the repeating units that serve as the building blocks of the polymer. They are smaller molecules

What reaction connects monomers?

dehydration reaction: 2 molecules are covalently bonded together with the loss of a water molecule; -H comes from one monomer and -OH comes from the other

Polymers are converted to monomers in what type of reaction?

hydrolysis: the covalent bond is broken by the addition of a water molecule

What are the monomers of all carbohydrates?

monosaccharides--simple sugars

Most monosaccharides are some multiple of ____.

CH2O

define: aldehyde sugar (carbonyl)

have the C=O at the end of the carbon skeleton

define: ketone sugars (carbonyl)

have the C=O in the middle of the skeleton

All sugars have the same two functional groups…

carbonyl (C=O) and hydroxyl (-OH)

define: structural isomers

compounds that have the same molecular formulas but different structural formulas

What are the 3 hexosugars?

glucose, galactose, and fructose.

What two monosaccharides make up sucrose?

glucose and fructose

What two monosaccharides make up lactose?

glucose and galactose

What two monosaccharides make up maltose?

glucose and glucose

define: glycosidic linkage

a covalent bond formed between 2 monosaccharides by dehydration reaction

What are the two categories of polysaccharides?

storage and structural

What are the two storage polysaccharides?

starch- in plants

glycogen- in animals

What are the two structural polysaccharides?

cellulose- plant cell walls

chitin- exoskeletons of arthropods and the cell walls of fungi

Why can you not digest cellulose?

humans do not have the enzymes to break the beta 1,4 linkages between glucose monomers. Some protists and prokaryotes can digest cellulose, and they are present in the gut of herbivores

has 1-4 B glucose linkages

cellulose

is a storage polysaccharide produced by vertebrates; stored in your liver

glycogen

two monomers of this form maltose

glucose

glucose + ____ form sucrose

fructose

monosaccharide commonly called “fruit sugar”

fructose

“milk sugar”

lactose

structural polysaccharide that gives cockroaches their crunch

chitin

malt sugar; used to brew beer

maltose

structural polysaccharide that comprises plant cell walls

cellulose

What characteristics do all lipids share?

mix poorly with water bc they are hydrophobic

What are the building blocks of fats?

glycerol and fatty acids

What are ester linkages?

bond the forms between the glycerol and fatty acid when a H2O is removed

What element in a fatty acid chain makes it unsaturated?

double bonds because it causes “kinks” or bending of the chain

Why are unsaturated fats liquid at room temperature?

the kinks where the cis double bonds are located prevent the molecules from packing together closely enough to solidify at room temp

What is a trans fat?

an unsaturated fat that has been synthetically converted to a saturated fat by adding hydrogen

4 important functions of fats

1. energy storage

2. makes up cell membrane

3. insulate the body

4. protects the body

Why are the “tails” of lipids hydrophobic?

they are made of fatty acid chains

define: phospholipid

it consists of a hydrophilic head and hydrophobic tails

• has a glycerol attached to a phosphate group

What has a structure of three hexagons and a doghouse?

cholesterol, a steroid

• important in cell membranes and a precursor form which other steroids are made

What are two examples of steroids? (hint: sex)

estrogen and testosterone

enzymatic proteins

selective acceleration of chemical reactiosn

transport proteins

transport substances

hormonal proteins (hormones)

coordination of an organism’s actives

receptor protein

response of cell to chemical stimuli

structural protein

support

What are R groups?

side chains which are different for each amino acid

• there are 20 side chains

What determines the characteristics of the R groups?

functional groups present

define: peptide bond

covalent bond formed by a dehydration reaction between amino acids

define: dipeptide

2 amino acids joined by a peptide bond

define: polypeptide

many amino acids joined by a peptide bond

Primary Level of Protein Structure

peptide bonds; linear chain of amino acids

Secondary Level of Protein Structure

hydrogen bonds; regions stabilized by hydrogen bonds between atoms of the polypeptide backbone

Secondary Level of Protein Structure (alpha helix)

a coil held together by hydrogen bonding every 4th amino acid

Secondary Level of Protein Structure (beta pleated sheet)

2+ segments of the polypeptide chain lying side by side

Tertiary Level of Protein Structure

R groups; shape of a polypeptide resulting from interactions between R groups

Quaternary Level of Protein Structure

overall protein structure resulting from the aggregation of polypeptide subunits

sickle cell disease

glutamic acid, which is acidic and hydrophilic, is replaced with valine, which is hydrophobic. Therefore, the protein is folded differently which causes aggregation, deforming the blood cell

define: denaturation

when the environment that the protein is in is altering the shape (pH, increase in temp, salt content, etc.)

define: chaperonins

assist in the proper folding of proteins; they are large protein structures that can provide a particular environment (usually hydrophilic) to help a protein fold optimally

The flow of genetic information is from:

DNA→ RNA→ protein (central dogma)

4 nitrogen bases found in DNA

1. Adenine

2. Thymine

3. Guanine

4. Cytosine

4 nitrogen bases found in RNA

1. Adenine

2. Uracil

3. Guanine

4. Cytosine

How do ribose and deoxyribose sugars differ?

deoxyribose is missing an oxygen at the 2’ carbon (DNA)

ribose has the oxygen (RNA)

Why are DNA strands said to be antiparallel?

the sugar-phosphate backbones run in opposite 5’-3’ directions from each other

What two molecules make up the “uprights" in DNA?

sugars and phosphates

What molecules make up the “rungs”?

nitrogenous bases