cell bio chapter 2

What bonds hold together strands of DNA?

Hydrogen bonds

Hydrogen bonds alone have what type of strength? When multiple hydrogen bonds are present?

Alone, hydrogen bonds are weak but their strength becomes additive when multiple ones occur

Hydrogen bonds can occur between what atoms?

Oxygen and nitrogen

What are van Der Waals forces?

They are the instantaneous dipoles formed as a result of the distribution of electrons on one end of a molecule, which can then induce an instantaneous dipole on the adjacent molecule; they are very weak intermolecular forces

What three characteristics of the water molecule itself are important?

1) it is highly bent, oxygen at one end, hydrogen at the other

2) it is highly polarized

3) all three molecules can form hydrogen bonds

How can the weak van Der Waals forces be maximized?

When two molecules, such as a protein and enzyme, have complimentary surfaces (lock and key) allowing them to form numerous van Der Waals interactions

What is the cause and a ramification of water having a high boiling point?

Water molecules form numerous hydrogen bonds (up to 4) with other water molecules meaning that a lot of energy is needed to break these bonds, as a result, mammals can use water as a heat absorber (sweat) to cool themselves

What does Amphoteric mean?

Capable of acting as an acid or base

What process forms growing polymers?

Dehydration synthesis: process of removing water to form covalent bonds.

What is the opposite process of dehydration synthesis?

Hydrolysis: the process of using energy, enzymes, and water to cleave bonds between polymers.

Ketoses have the carbonyl located where?

Internally as a ketone

Aldoses have the carbonyl located where?

Externally as an aldehyde

What are buffers and what buffer exists in the blood?

Buffers are compounds (weak acid and its conjugate base) that help to resist pH changes. The buffer that exists in the blood is bicarbonate and carbonic acid keeping the blood pH at 7.4

Ester bonds form between what functional groups?

Carboxylic acids and alcohols

Amide bonds form between what functional groups?

Carboxylic acids and amines

What are some common electronegative elements? (i.e. elements that make molecules polar)

Nitrogen, Sulfur, Oxygen, Phosphorus

What is the least abundant macromolecule in the body?

Nucleic acids followed by polysaccharides

What is the most abundant macromolecule in the body?

Proteins

What are the 4 major categories of macromolecules?

Proteins, nucleic acids, polysaccharides, lipids

Proteins, nucleic acids and polysaccharides are polymers, formed from a polymerization term-93reaction of monomers

What are the components of each of the macromolecules?

Proteins are composed of Amino Acids

Nucleic acids are composed of nucleotides

Polysaccharides are composed of sugars

Lipids are composed of fatty acids

What are metabolites?

Molecules who don't truly have a function but rather are parts of a metabolic pathway towards a specific molecule; They are the intermediates in a reaction

What is the remaining class of molecules in an organism?

Molecules of miscellaneous function, often whose purpose is adjust to proteins and the macromolecules

What are the primary functions of carbohydrates?

Stores of chemical energy and durable building materials for biological construction

What is the general formula for a carbohydrate?

(CH2O)n

What are the carbons linked to in a carbohydrate?

Each carbon is linked to a hydroxyl group (OH) and one carbon is a carbonyl C\=O

What are the terms for sugars containing 3 carbons, 4 carbons, etc

3 carbons: trioses

4 carbons: tetroses

5 carbons: pentoses

6 carbons: hexoses

7 carbons: heptoses

If a carbonyl group (ketone) is located internally, what type of sugar is it?

Ketose

e.g. fructose

If a carbonyl group (C\=O) is located at the end of a chain, what type of sugar is it?

Aldose

e.g. glucose

Why are sugars water soluble usually?

They contain many hyroxyl groups

What is the formula for Glyceraldehyde?

When is a molecule deemed to be a stereoisomers or enantiomer?

When a carbon atom is bonded to 4 entirely different groups

What carbon is numbered 1 in a sugar?

The carbon containing the aldehyde group

What are asymmetric carbons?

Carbons that are sites of stereoisomerism i.e. chiral

What is the difference between a D-sugar and L-sugar?

A D sugar has the hydroxyl group of the farthest asymmetrical carbon projecting to the right and an L sugar has the hydroxyl group projecting to the left

What is an asymmetric carbon?

It is one of the internal carbons (not the ends) that is involved with stereoisomerism

What is a pyranose?

A carbon ring consisting of 6 carbons, 5 of which are in a ring counting also of oxygen

Glucose is a pyranose

Why are sugars highly water soluble?

They have a lot of hydroxyl groups

The same Molecules with configurations that cannot be superimposed on one another are said to be this?

Stereoisomers

Which carbon is designated C1 in a sugar?

The carbon containing the aldehyde

C\==O

What are 6 membered rings called?

Pyranoses

What is alpha glucose?

The OH on C1 lies below plane of molecule

What is beta glucose?

The OH on C1 lies above plane of molecule

Sugars can be joined by what type of covalent bond?

Glycosidic bonds (dehydration synthesis between monosaccharides)

What are the common disaccharides?

When only 2 sugar molecules form a bond, what is the resulting molecule called?

Disaccharides

What is the primary function of disaccharides?

Readily available energy stores

Which of the common polysaccharides, glycogen, starch and cellulose, is helical?

Starch

What are oligosaccharides?

Chains of a few sugars

What role do oligosaccharides play?

They are important on the glycolipids and glycoproteins of the plasma membrane

and serve as cellular identifiers, i.e. they are used to distinguish one type of cell from another

The liver contains an insoluble polymer of glucose named what?

Glycogen

Glycogen, starch and cellulose are all similar in this regard:

They are all polymers of glucose

In what form do plants store their energy?

Starch

What two types of polymers comprise starch?

Amylose and Amylopectin

Which one is branched, Amylose or Amylopectin?

Amylose is the unbranched helical molecule whereas Amylopectin is branched (less than glycogen though and more irregular)

What enzyme in animals hydrolyzes starches?

Amylase

What are most of the bonds in glycogen classified as?

alpha (1 → 4) glycosidic bonds

alpha (1 → 6) glycosidic bonds join neighboring strands leading to the branches of glycogen.

What does glycogen look like?

Cellulose differs from starch and glycogen because of this

Cellulose is joined by ß (1 → 4) instead of alpha (1 → 4) linkages

Can animals breakdown cellulose?

No, most animals cannot break down cellulose, which happens to be the most abundant organic material on earth

What is chitin?

Chitin is an unbranched polymer of the sugar N-acetylglucosamine, which is similar in structure to glucose but has an acetyl amino group instead of a hydroxyl group bonded to the second carbon atom of the ring.

What are GAG's?

glycosaminoglycans

a common one is heparin

What are the 2 structural forms of polysaccharides?

Cellulose and GAGs

What are fats?

Glycerol molecule linked to 3 fatty acids

What are fatty acids?

Long unbranched hydrocarbons with a single carboxyl group at one end

What unique feature of fatty acids makes them amphipathic?

They contain a carboxyl group which is hydrophilic and a hydrocarbon chain which is hydrophobic

Which type of fatty acids, saturated vs unsaturated, are liquid at room temp?

Unsaturated since they have double bonds which form kinks and thereby cause them to be able to move more freely.

What bonds form between lipids?

Ester bonds (covalent bond)

How do the presence of double bonds in fatty acids affect their melting point?

The more double bonds, the lower the melting point

What are the three components of a phospholipid?

1) phosphate group

2) Glycerol backbone

3) 2 fatty acids

What extra component is connected to phospholipids?

The head group

What is the structure of a phospholipid?

Which type of double bond is kinked: Cis or trans?

Cis double bonds produce kinks in fatty acids

What characteristic of proteins makes them useful to perform a wide range of tasks?

Their high degree of specificity

Which amino acid does not have any stereoisomers?

Glycine, since its alpha carbon is bonded to two of the same components, two Hydrogens. All other amino acids exist in two forms, D and L handed

The amino acids used in the synthesis of a protein on a ribosome are always this hand

L-amino acid

What type of bonds forms polymers of proteins?

Peptide bonds

What are the 4 classes that amino acids fall under?

1) Polar and charged

2) Polar and uncharged

3) Nonpolar