Macromolecules

what are monosaccarides

simplest form of carbs

the positioning of what structural component of a monosaccaride differentiates ketones and aldoses

the carbonyl group

what is C=O

carbonyl group

whats an asymmetric carbon

carbon bonded to 4 different elements

where is the carbonyl group in aldoses

at end of carbon skeleton

where is the carbonyl group in ketones

within the carbon skeleton

examples of aldoses

glyceraldehyde, ribose, glucose, galactose

examples of ketoses

dihydroxyacetone, ribulose, fructose

what is starch

to store excess glucose produced during photosynthesis

where is starch

within plastids, as granules

examples of starch

potato tubers, grains, rice, wheat, corn

where is glycogen stored

liver and muscles

how does amylose and amylopectin differ

amylose has alpha glucoses with 1-4 bondages

amylopectin has alpha glucoses with 1-4 bondages with a 1-6 bond at branches

what is cellulose used for

providing strength to the plant cell wall

what holds microfibrils of β glucoses together in cellulose

hydrogen bonds

example of microfibrils of cellulose contructured material

cotton

what is the most abundant chemical compound

cellulose

what does “cellulose is an insoluble fiber” mean

most animals do not digest it because our enzymes are mostly built for hydrolyzing alpha glucose bonds not beta glucoses

when it passes through the digestive system, it abrades the lining, stimulating mucus production (good effect)

what is chitin for

building the exoskeleton in anthropods

what chemical allows chitin to harden in crabs

calcium carbonate

what is the cell wall made of in fungi vs plants

chitin for fungi, cellulose for plants

are lipids polar or non polar

non polar

what are triacylglycerols made of

one glycerol, three glycerides

what is an ester bond

bond between carbonyl group and hydroxyl group

difference between carbonyl group and carboxyl group

carboxyl = one of the R groups in carbonyl is OH

which has more H, saturated or unsaturated fats?

saturated

why are polysaccarides a better form of storage for plants compared to animals

polysaccarides require bulkier storage (starch), and plants don’t move
animals move so they perfer storing energy in fats

what is adipose tissue

contains fat storing cells: adipocytes

shrinks to store more fat

how are phospholipids differentiated

the phosphate group can bond to different compounds, like choline

whats the difference between a fatty acid and a phospholipid

the 3rd hydroxyl group of the glycerol is bonded to a phosphate group

hydroxyl group

O-H

what is a steroid

organic compound with 4 fused rings

where do steroids come from

diet or liver

what does cholesterol do

core building block for cells, hormones, and vitamins
ex: builds and maintains the outer structure and fluidity of every cell

what do enzymes do

catalysts, not consumed

describe amino acid structure

what is the amine group end of a polypeptide called

N-terminus

what is the carboxyl group end of a polypeptide called

C-terminus

name all 9 essential amino acids

Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine

name all 11 non essential amino acids

Alanine, asparagine, aspartic acid, glutamic acid, serine, arginine, cysteine, glutamine, glycine, proline, tyrosine

which amino acids have non polar side chains and are hydrophobic

Glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, and proline

which amino acids have polar side chains and are hydrophilic

Serine, threonine, cysteine, asparagine, glutamine, and tyrosine

which amino acids have negatively charged side chains and are hydrophilic

Aspartic acid (aspartate) and glutamic acid (glutamate)

which amino acids have positively charged side chains and are hydrophilic

Lysine, arginine, and histidine

How are macromolecules constructed?

By linking organic monomers (subunits) into polymers; macromolecules make up the vast majority of a cell's dry mass

Name the monomer → polymer pairs for the three main macromolecule classes

Sugars → polysaccharides; amino acids → proteins (polypeptides); nucleotides → nucleic acids (DNA and RNA)

Which reaction joins monomers into a polymer, and which breaks the polymer apart?

Condensation (dehydration) reaction joins them and releases H2O; hydrolysis breaks them by adding H2O

What determines the unique function of a protein, RNA, or DNA polymer?

The specific sequence of its subunits (which in turn determines how it folds)

Why are polymer chains flexible?

Most single covalent bonds between subunits allow the atoms to rotate, so the chain can twist into an unlimited number of shapes

What is a conformation?

One specific three-dimensional shape that a polymer chain adopts

What makes a polymer chain adopt one particular conformation?

Weak noncovalent bonds between different regions of the chain constrain its free movement

Name the four weak noncovalent bonds/forces that help fold macromolecules

Hydrogen bonds, electrostatic attractions, van der Waals attractions, and the hydrophobic force

Why do weak noncovalent bonds still give macromolecules specific binding?

Each is individually weak (thermal energy can break it), but many acting together give strong, highly specific binding between macromolecules or to selected small molecules

What fraction of a cell's dry mass is protein?

About half

Give an example of a protein that works as an enzyme

Ribulose bisphosphate carboxylase (Rubisco)

Why are proteins the most diverse and versatile macromolecules?

They are built from 20 types of amino acids and can have thousands of functions (e.g. enzymes)

Are lipids true polymers of a repeating monomer like polysaccharides, proteins, and nucleic acids?

No. Lipids are not built as long polymers of one repeating monomer, so they are usually not counted among the three macromolecule polymer classes

What is the general formula for a monosaccharide, and an example?

(CH2O)n; for example glucose is C6H12O6

How many carbons do trioses, pentoses, and hexoses have?

3, 5, and 6 respectively

Give a triose, pentose, and hexose for aldoses and ketoses

Aldoses: glyceraldehyde (triose), ribose (pentose), glucose/galactose (hexoses); Ketoses: dihydroxyacetone (triose), ribulose (pentose), fructose (hexose)

What is the relationship between D-glucose and L-glucose?

They are mirror-image isomers (enantiomers); D-glucose is the natural and abundant form

What bond links monosaccharides into oligosaccharides and polysaccharides?

Glycosidic bond, formed by a condensation reaction

What is the difference between an oligosaccharide and a polysaccharide?

An oligosaccharide is a short chain of sugars; a polysaccharide is a long chain

Which linkage is found in starch and glycogen versus cellulose?

Starch and glycogen: alpha-glucose (1-4 with 1-6 branches); cellulose: beta-glucose (1-4)

How does glycogen compare structurally with amylopectin?

Both are alpha-glucose polymers with 1-4 chains and 1-6 branches, but glycogen is more extensively branched

What is chitin a polymer of?

A linear polymer of the sugar derivative N-acetylglucosamine

What is the main energy role of sugars in the cell?

Sugars are a primary source of chemical energy and can be joined into oligosaccharides or polysaccharides

What is the essential function of fatty acids in cells?

To form lipid molecules that assemble into sheet-like cell membranes (they are also a richer energy source than sugars)

Describe the structure of a fatty acid

A carboxyl group head attached to a long hydrocarbon tail

Give an example of a saturated and an unsaturated fatty acid

Saturated: palmitic acid (hydrocarbon tail is saturated); Unsaturated: oleic acid

Compare the energy in fat and carbohydrate per gram

Fat stores roughly twice the energy per gram of carbohydrate (about 9 vs 4 kcal per g)

Why do unsaturated fatty acids stay liquid at room temperature?

Cis double bonds put kinks in the hydrocarbon tails so they cannot pack tightly

What bonds join the fatty acids to glycerol in a triacylglycerol?

Ester bonds between the glycerol hydroxyls and the fatty acid carboxyl groups

What does amphipathic mean for a phospholipid?

It has a hydrophilic head (phosphate group) and hydrophobic fatty acid tails, so in water it self-assembles into a lipid bilayer

How many fatty acids does a phospholipid have?

Two fatty acids plus a phosphate group attached to glycerol

Describe the general structure of an amino acid

A central (alpha) carbon bonded to an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a variable side chain (R group)

How many types of amino acids are used to build proteins?

20

What is a peptide bond and how is it formed?

A covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of the next, formed by a condensation reaction that releases water

Which end of a polypeptide is synthesized first?

The N-terminus (amino end); the chain grows toward the C-terminus

Which amino acid forms covalent disulfide bonds?

Cysteine (S-S bonds between side chains)

Which amino acid has no D and L forms and why?

Glycine; its side chain is H so its alpha carbon is not asymmetric

Which optical isomer of amino acids is found in proteins, and where is a D form used?

L forms are in proteins; D-serine is used in the brain

Where do nonpolar amino acid side chains tend to end up in a folded protein in water?

Clustered in the interior, driven by the hydrophobic force

What are nucleic acids built from?

Long chains of nucleotides joined by phosphodiester bonds

What is a nucleotide made of?

A nitrogenous base + a five-carbon sugar + a phosphate group

What is a nucleoside?

A nitrogenous base + a five-carbon sugar (no phosphate)

Name the nitrogenous bases in DNA and RNA

DNA: adenine, guanine, cytosine, thymine; RNA: adenine, guanine, cytosine, uracil

Name the nucleosides

Adenosine, guanosine, cytidine, deoxythymidine, uridine

Which bases are pyrimidines and what is their structure?

Cytosine, thymine, uracil; a single six-membered ring

Which bases are purines and what is their structure?

Adenine and guanine; a five-membered ring fused to a six-membered ring

Are adenosine and adenine the same thing?

No. Adenine is the purine base; adenosine is the nucleoside (adenine + ribose)

What bond links nucleotides in a nucleic acid?

A phosphodiester bond between the phosphate attached to the sugar of one nucleotide and the hydroxyl group on the sugar of the next nucleotide

What are the sugars in DNA and RNA?

DNA: deoxyribose; RNA: ribose

What is the role of DNA?

Long-term repository of hereditary information

Why is DNA suited for long-term storage?

It is a more stable hydrogen-bonded double helix (and its sugar lacks the 2' hydroxyl of ribose)

What is the role of RNA?

Transient carrier of molecular instructions

What is the structure of ATP?

Adenine + ribose + three phosphates

What bonds link the three phosphates of ATP and what happens when they break?

Phosphoanhydride bonds; breaking them releases free energy

Which bases pair in DNA and how many hydrogen bonds link each pair?

A-T with 2 hydrogen bonds; G-C with 3 hydrogen bonds

Which of the following is NOT a ketose? A. Dihydroxyacetone B. Ribulose C. Fructose D. Galactose

D. Galactose is an aldose; its carbonyl group is at the end of the carbon skeleton