Week 1 Textbook Reading

Question 1

polymer

Answer 1

long molecule made by covalently linking multiple identical or similar subunits (monomers).

Question 2

subunit

Answer 2

A monomer that forms part of a larger molecule, such as an amino acid in a protein or a nucleotide in a nucleic acid

Can also refer to a complete molecule that forms part of a larger molecule

Many proteins, for example, are composed of multiple polypeptide chains, each of which is called a protein subunit.

Question 3

how do neutrons affect cells?

Answer 3

-contribute to the structural stability of the nucleus
-change in neutrons can cause the nucleus to disintegrate by radioactive decay
-neutrons don’t alter the chemical properties of atom

Question 4

what does an element’s chemical reactivity depend on?

Answer 4

the degree that its outer electron shell is filled

Question 5

electronegativity

Answer 5

tendency of an atom to attract electrons

Question 6

bond strength

Answer 6

measured by the amount of energy that must be supplied to break the bond

Question 7

hydrogen bond

Answer 7

-H attracted to N, O, F
-weaker than covalent bonds
-hydrophilic- water loving
-hydrophobic- water fearing

Question 8

why is water a liquid at room temp?

Answer 8

interlocking hydrogen bonds allows water to be a liquid at room temp and gives it a high BP and surface tension

Question 9

electrostatic attraction

Answer 9

ionic bonds that hold together the ions in a salt crystal
-strongest when atoms involved are fully charged

Question 10

van der Waals

Answer 10

These weak attractions occur in all types of molecules and are nonpolar and can’t form ionic or hydrogen bonds

Question 11

buffer

Answer 11

Buffer→ mixtures of weak acids and bases that maintain proton concentrations at about pH 7 by releasing protons (acids) or taking them up (bases) whenever the pH changes

Question 12

polymers of sugars

Answer 12

Polysaccharides and oligosaccharides

Question 13

polymers of fatty acids

Answer 13

fats and membrane lipids

Question 14

polymers of nucleotides

Answer 14

nucleic acids

Question 15

Oligosaccharides:

Answer 15

contain a smaller number of sugar subunits (e.g. disaccharides only have 2)

Question 16

Polysaccharides:

Answer 16

e.g. glycogen and starch can have 1000s of sugar monomers

Question 17

how are sugars energy sources and subunits of polysaccharides

Answer 17

Monosaccharides are the simplest sugars with the general formula (CH2O)n

Because of this formula, sugars and the larger molecules made from them are called carbohydrates

Question 18

describe monosaccharides and the bonds they can form

Answer 18

Monosaccharides can be linked by covalent bonds—called glycosidic bonds—to form larger carbohydrates.

2 monosaccharides linked together make a disaccharide, such as sucrose, which is composed of a glucose and a fructose unit.

Larger sugar polymers range from the oligosaccharides, which typically contain 2 to 10 monosaccharide subunits (monomers), all the way up to giant polysaccharides, which can contain hundreds or thousands of subunits

Question 19

isomers

Answer 19

Sets of molecules with the same chemical formula but different structures are called isomers

Question 20

condensation rxn

Answer 20

Condensation reaction is when a bond is formed between an -OH group on one sugar and an -OH group on another

**(reverse of hydrolysis)

Question 21

difference between hydrolysis and condensation rxn

Answer 21

The bonds created by condensation rxns can be broken by the reverse process of hydrolysis, in which a molecule of water is consumed

condensation is the opp of hydrolysis rxns

Question 22

why are hydrolysis rxns energetically favourable

Answer 22

break down larger molecules into smaller subunits

Question 23

why are condensation rxns energetically unfavourable

Answer 23

synthesize large molecules from smaller subunits

Question 24

glycogen

Answer 24

Cells use simpler polys. composed of only glucose units (glycogen) in animals and starch in plants as long term stores of glucose, held in reserve for energy production

Question 25

glycoproteins

Answer 25

Smaller polys. can be linked to proteins to form glycoproteins or to lipids to form glycolipids

Question 26

structure of a fatty acid molecule

Answer 26

Fatty acid chains are components of cell membranes Fatty acid molecule, has 2 distinct regions One is long hydrocarbon chain, which’s hydrophobic and not very reactive chemically Other is a carboxyl (COOH) group, which behaves as an acid (carboxylic acid) In aq solution, it’s ionized(-COO^-) extremely hydrophilic and chemically reactive

Question 27

amphipathic

Answer 27

Molecules that are both hydrophobic and hydrophilic are amphipathic

Question 28

saturated tail

Answer 28

Some fatty acids have saturated tails→ containing the max possible number of hydrogens and therefore has no double bonds between its carbon atoms

Question 29

unsaturated tail

Answer 29

Others have unsaturated tails → with one or more double bonds along their length

Question 30

how are fatty acids stored

Answer 30

Fatty acids are stored in the cytoplasm of cells in the form of fat droplets composed of triacylglycerol molecules- compounds made of 3 fatty acid chains covalently joined to a glycerol molecule

Question 31

Phospholipids→

Answer 31

constructed from fatty acids and glycerol However glycerol is joined to 2 fatty acid chains, rather than 3 as in triacylglycerols

Question 32

peptide bond vs. polypeptide

Answer 32

Covalent bond b/w 2 adjacent amino acids in a protein chain is called a peptide bond and the resulting chain of amino acids is a polypeptide

Question 33

how are peptide bonds formed

Answer 33

Peptide bonds are formed by condensation rxns that link one amino acid to the next

Question 34

noncovalent bonds

Answer 34

-specify the precise shape of a macromolecule -allow a macromolecule to bind other selected molecules -can also stabilize associations b/w any 2 macromolecules, as long as their surfaces match closely

Question 35

Amines

Answer 35

Amines in water combine with an H+ ion to become positively charged

Question 36

amides

Answer 36

Amides are formed by combining an acid and an amine Unlike amines, amides are uncharged in water

Question 37

ring formation in sugars and fatty acids

Answer 37

In aqueous sol, the aldehyde or ketone group of a sugar molecule tends to react with a hydroxyl group of the same molecule, thereby closing the molecule into a ring

Question 38

isomers (monosaccharides)

Answer 38

When monosaccharides differ only in the spatial arrangement of atoms

Question 39

a and B(beta) Links

Answer 39

The hydroxyl group on the carbon that carries the aldehyde or ketone can rapidly change from one position to the other -2 positions called a and B

Question 40

Disaccharides

Answer 40

When the carbon that carries the aldehyde or the ketone can react with any hydroxyl group on a second sugar molecule

Question 41

Oligosaccharides vs. polysaccharides

Answer 41

Oligo→ short chains Polysacc→ long chains

Question 42

fatty acids

Answer 42

All have a carboxyl group at one end and a long hydrocarbon tail at the other

Question 43

triacylglycerols

Answer 43

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

Question 44

carboxyl group

Answer 44

If free, the carboxyl group of a fatty acid will be ionized More often it is linked to other groups to form either esters or amides

Question 45

how do photosynthetic organisms use sunlight to synthesize organic molecules

Answer 45

Photosynthesis converts the electromagnetic energy in sunlight into chemical bond energy in cells In the 1st stage, energy from sunlight is captured and temporarily stored as chemical-bond energy in specialized molecules called activated carriers In the 2nd stage, activated carriers are used to help drive a carbon-fixation process, in which sugars are made from CO2 gas This way, photosynthesis generates an essential source of stored chemical-bond energy and other organic materials

Question 46

how do cells get energy

Answer 46

-by the oxidation of organic molecules -Oxidation→ extraction of chemical energy from food molecules takes place through a process of gradual oxidation -The complex process by which food molecules are broken down in this way to produce energy is known as cell respiration

Question 47

oxidation

Answer 47

Oxidation→ the addition of oxygen atoms to a molecule; the removal of electrons from an atom

Question 48

reduction

Answer 48

Reduction→ the addition of electrons to an atom

Question 49

how is a polar covalent bond formed?

Answer 49

When a carbon atom becomes covalently bonded to an atom with a strong affinity for electrons, it gives up more than its equal share of electrons to form a polar covalent bond

Question 50

how does carbon gain partial positive and negative charges

Answer 50

The positive charge of the carbon nucleus now slightly exceeds the negative charge of its electrons→ C atom gains a partial positive charge and is oxidized When the carbon atom in a C-H bond has more than its share of electrons; it gains a partial negative charge and is reduced

Question 51

true or false: an individual enzyme can make an energetically unfavorable rxn occur

Answer 51

false Even though an individual enzyme can accelerate an energetically favourable rxn, it can’t force an energetically unfavourable rxn to occur

Question 52

activation energy

Answer 52

Activation energy→ when a molecule requires a boost over an energy barrier before it can undergo a chemical rxn that moves it to a lower-energy (more stable) state

Question 53

what do enzyme-catalyzed rxns depend on?

Answer 53

Enzyme-catalyzed reactions depend on rapid molecular collisions For 2 molecules to interact, they must first collide

Question 54

what do noncovalent interactions allow?

Answer 54

Noncovalent interactions allow enzymes to bind specific molecules 1st step is the binding of the substrate Once this occurs, the substrate must stay bound to the enzyme long enough for the chemistry to occur