Lecture 9

Question 1

Polymers

Answer 1

built from monomers

long molecules consisting of many similar building blocks (monomers)

Question 2

Synthesis and breakdown of polymers

Answer 2

condensation reaction- synthesis

hydrolysis- breakdown

Question 3

Condensation reaction

Answer 3

occurs when two monomers bond together through the loss of a small molecule (usually water)

Question 4

Hydrolysis reaction

Answer 4

polymers are disassembled to monomers, a reaction that is essentially the reverse of condensation

Question 5

Structure of amino acids

Answer 5

an amino group and a carboxyl group and a varying R group side chain

Question 6

Amino acid side chains

Answer 6

non-polar side chains- hydrophobic
polar side chains- hydrophilic
electrically charged side chains- hydrophilic

Question 7

Peptide bonds

Answer 7

each amino acid has a different side chain

amino acids are linked together by peptide bonds

the two ends of the polypeptide chains are chemically distinct

the N terminus is capped by an amino group

the C terminus by a carboxyl group

Question 8

Protein structure and function

Answer 8

a functional protein consist of one or more polypeptides twisted, folded and coiled into a unique shape

the sequence of amino acids determines a proteins three dimensional shape

a proteins structure is determined by its function

Question 9

Primary protein structure

Answer 9

sequence of amino acids
- determined by inherited genetic information

Question 10

Secondary protein structure

Answer 10

the coils and folds of secondary structure due to hydrogen bonds between repeating constituents of polypeptide backbone (C-N)

alpha helixes or beta pleated sheets

Question 11

Tertiary protein structure

Answer 11

hydrogen bonding
van der Waals interactions
ionic bonds
disulphide bonds
results from interactions between side chains

• determined by R groups

Question 12

Quaternary protein structure

Answer 12

aggregation of two or more polypeptide chains into one functional macromolecule

Question 13

Structure determining techniques

Answer 13

x-ray crystallography
to determine a proteins structure

bioinformatics uses computer programs to determine protein structure from amino acid sequences

many virus capsids are more or less spherical protein assemblies

Question 14

Bioinformatics

Answer 14

uses computer programs to predict protein structure from amino acid sequences

Question 15

Protein functions include

Answer 15

-structural support
-storage
-transport
-cellular communications
-movement
-defence against foreign molecules

Question 16

Enzymatic proteins

Answer 16

function:
selective acceleration of chemical reactions
example:
digestive enzymes catalyse hydrolysis of food molecules

Question 17

Defensive proteins

Answer 17

function:
protection against disease
example:
antibodies

Question 18

Storage proteins

Answer 18

function:
storage of amino acids
example:
casein is the major source of amino acid for baby mammals (protein of milk)

Question 19

Transport proteins

Answer 19

function:
transport of substances
examples:
haemoglobin

Question 20

Hormonal proteins

Answer 20

function:
coordination of an organisms activities
example:
insulin

Question 21

Receptor proteins

Answer 21

function:
response of cell to chemical stimuli
example:
receptors built into the membrane of a nerve cell detect signalling molecules released by other nerve cells

Question 22

Contractile and motor proteins

Answer 22

function:
movement
example:
motor proteins are responsible for the undulations of cilia and flagella

Question 23

structural proteins

Answer 23

function:
support
example:
keratin is the protein of hair, horns feathers etc

Question 24

Properties of lipids

Answer 24

lipids are large biological molecules that do not form polymers

little or no affinity for water

hydrophobic because they consist of mostly hydrocarbons which form non polar covalent bonds

Question 25

functions of lipids

Answer 25

the major function is energy storage

store their fat in adipose cells

adipose tissue also cushions vital organs and insulates the body

steroids are lipids characterised by a carbon skeleton consisting of four fused rings

cholesterol is used in the plasma membranes

Question 26

fats and fatty acids

Answer 26

fats are constructed from two types of smaller molecules:
glycerol and fatty acids

Question 27

Glycerol

Answer 27

a three carbon alcohol with a hydroxyl group attached to each carbon

Question 28

general structure of phospholipids

Answer 28

2 hydrophobic fatty acid tails joined to a hydrophilic head containing glycerol, phosphate and a polar group such as choline

Question 29

Carbohydrates

Answer 29

serve as fuel and building materials

include sugars and polymers of sugars

simplest carbohydrates are monosaccharides

carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks

Question 30

Monosaccharides

Answer 30

have molecular formulas that are usually multiples of CH2O
glucose is the most common

Question 31

isomers

Answer 31

same formula but a different arrangement

monosaccharides differ in arrangements of groups around one or two carbon atoms

these small differences make only minor changes but can be detected by enzymes and other proteins so have biological effects

Question 32

formation of a disaccharide

Answer 32

a disaccharide is formed when a dehydration reaction joins two monosaccharides

this covalent bond is called a glycosidic linkage

Question 33

Polysaccharides

Answer 33

polymers of sugars

they have storage and structural roles

the structure and function of a polysaccharide are determined by its sugar monomers and positions of glycosidic linkages

Question 34

Starch

Answer 34

a storage polysaccharide of plants, consisting of entirely glucose monomers

plants store surplus starch as granules within chloroplasts

Question 35

Glycogen

Answer 35

a storage polysaccharide in animals

humans and other animals store glycogen mainly in the liver and muscle cells

hydrolysis of glycogen releases glucose into a useable form in the body

Question 36

cellulose

Answer 36

a major component of tough wall of plant cells

a polymer of beta glucose
- each molecule is flipped for strength and rigidity

Question 37

Structure of cellulose

Answer 37

1. polymers with beta glucose are straight (unbranched)
2. unbranched cellulose molecules are held together by hydrogen bonds between OH groups on parallel strands
3. parallel cellulose molecules held together this way are grouped into microfibrils