Molec Cell Ch 2- Molecules:

Covalent bond

Formed by unequal sharing of electrons.

Ionic bonds

Formed by the gain and loss of electrons. (Transfer)

Hydrogen bonds

noncovalent attraction between a hydrogen and an electronegative atom. Important for many biological molecules.

4 weak interactions that help bring molecules together in cells:

van der waals attraction, electrostatic attractions, hydrogen bonds, and hydrophobic (nonpolar) interactions.

There are four major families of small organic (carbon compound) molecules:

1.sugars -> energy sources/subunits

2.fatty acids -> components of cell membranes

3.amino acids -> subunit of proteins

4.nucleotides -> nucleic acids/subunit of RNA/DNA

What are the large organic molecules created from the small organic building blocks of the cell?

sugars -> polysaccharides and oligosaccharides

fatty acids -> fats and membrane lipids

amino acids -> proteins

nucleotides -> nucleic acids

Monosaccharides

Formula of (CH2O)n where n can be 3 (trioses), 4, 5 (pentoses), or 6 (hexoses). Contain either an aldehyde (aldose) or ketone (ketoses) group.

Monosaccharides

trioses -> pentoses -> hexoses:

Aldoses: glyceraledhyde -> ribose ->glucose

Ketoses : dihydroxyacetone -> ribulose -> fructose

Disaccharides

The condensation of two monosaccharides produces one disaccharide. -[The carbon that carries the aldehyde/ketone can react with the hydroxyl group on a second sugar molecule to form a disaccharide] -glycosidic bond

Most common:

maltose (glucose + glucose)

lactose (galactose + glucose)

sucrose (glucose + fructose)

Are glucose, galactose and fructose isomers?

Yes - All have the same formula: C6H12O6

T or F? Condensation (dehydration) reactions are energetically unfavorable. Hydrolysis reactions are energetically favorable.

True

T or F? Biological polymers are broken down through hydrolysis reactions.

True

Fatty acids are essential building blocks for the phospholipids that form the lipid bilayer of cell membranes.

Fatty acids

All fatty acids have a hydrophilic carboxyl group at one end and a long hydrophobic hydrocarbon tail at the other. The length and extent of saturation vary. Fatty acids with no double bonds in their tail are saturated.

Triacylglycerols: [three fatty acids]

Fatty acids are stored in cells as an energy reserve (fats and oils) through an ester linkage to glycerol to form triacylglycerols.

Degrees of saturation of fatty acids

-This determines the physical properties of the fat molecules. Saturated are solid at room temperature and unsaturated are liquid at room temperature.

Phospholipids (amphipathic) in biological membranes typically contain one saturated and one unsaturated fatty acid. [two fatty acids]

True.

-saturated fatty acids make the membrane less fluid and tend to aggregate.

-cis unsaturated fatty acids reduce membrane rigidity because they do not form solid aggregates.

Phospholipid Molecule

hydrophilic head (polar group/phosphate/glycerol) and two hydrophobic fatty acid tails

Steroids are another class of lipids and all share a common multiple-ring structure (ex: cholesterol, testosterone)

What bonds connect amino acids?

peptide bonds

R groups, or side chains, are the variable chemical groups attached to the alpha-carbon of amino acids that define their unique properties (size, charge, polarity, and hydrophobicity).

There are 20: categorized primarily into nonpolar, polar uncharged, positively charged (basic), and negatively charged (acidic) groups.

What are the basic (positively charged) side chains?

lysine, arginine, histidine

What are the acidic (negatively charged) side chains?

aspartic acid, glutamic acid

What are the uncharged polar side chains?

asparagine, glutamine, serine, threonine, tyrosine

What are the non polar side chains?

Glycine, Alanine, Valine, Leucine, Isoleucine, Methionine, Cysteine, Phenylalanine, Tryptophan, Proline

What bond can form between two cysteine side chains?

disulfide bond

What bond links nucleotides? and how are they produced?

phosphodiester bonds produced by RNA or DNA Polymerase

What is the structural difference between DNA and RNA?

DNA is double stranded and RNA is single stranded.

DNA uses deoxyribose sugar and thymine (T), whereas RNA uses ribose sugar and uracil (U)

Both DNA and RNA are synthesized/transcribed in the 5' to 3' direction

DNA polymerase and RNA polymerase read the template strand in the 3' to 5' direction.

What percent of the bacterial cell is chemical?

30%

The 30% chemical of the bacterial cell is made up of what?

inorganic ions (1%)

small molecules (3%)

phospholipids (2%)

DNA (1%)

RNA (6%)

protein (15%)

polysaccharide (2%)

What are the 4 classes of macromolecules and what are their roles in the cell?

1) polysaccharides (sugars) - energy source/subunit

2) fats/oils (fatty acids) - form cell membranes, steroids,

3) proteins (amino acids) - enzymes

4) nucleic acid (nucleotides)- DNA/RNA, ATP, cyclic AMP, coenzyme A (CoA)

What are the building blocks of these molecules ?

1) sugars

2) fatty acids

3) amino acids

4) nucleic acid

How do these macromolecules form?

1) Condensation/ dehydration reaction of two monosaccharides produces one disaccharide with a glycosidic bond.

disaccharides - maltose, lactose, sucrose.

2) Fatty acids are stored as energy reserves (fats/oils) through an ester linkage to glycerol to form triacylglycerols.

3) Peptide bonds connect amino acids to form proteins.

4) Nucleotides are linked by phosphodiester bonds which are produced by DNA or RNA polymerases.

Does the synthesis of macromolecules require or release energy?

Biological polymers are broken down through hydrolysis reactions which require energy input.

What are the roles of covalent vs non covalent interactions in the formation of molecules and structures in the cell?

Covalent bonds are strong enough to survive conditions within the cells.

Noncolvalent bonds are how molecules interact with one another.