1A Biological Molecules

Question 1

What is a dipole?

Answer 1

a small charge created by uneven distribution of electrons in a covalent bond. Makes a polar molecule.

Question 2

What is a hydrogen bond?

Answer 2

Weak intermolecular bond formed between polar molecules that contain at least one hydrogen atom

Question 3

Properties of water - cohesive. What does this mean and why is it important?

Answer 3

Water molecules stick to each other - important for movement of water through plants

Question 4

Properties of water - adhesive. What does this mean and why is it important?

Answer 4

Water molecules stick to other molecules - important in plant transport and surface tension

Question 5

Properties of water - liquid. What does this mean and why is it important?

Answer 5

Water cannot be compressed - important for hydraulic mechanisms in living organisms

Question 6

Properties of water - polar molecule. What does this mean and why is it important?

Answer 6

Water is polar due to the dipole charges. This makes it a solvent, able to dissolve many different substances

Question 7

Properties of water - high specific heat capacity. What does this mean and why is this important?

Answer 7

It requires a lot of energy to raise the temperature of water. Temperature of large bodies of water remain stable.

Question 8

Properties of water - density. What does this mean and why is it important?

Answer 8

Solid ice is less dense than liquid water - this is unusual and enables ice to float on water, creating an insulating layer for the organisms below

Question 9

Which end of the water molecule is the positive dipole at?

Answer 9

Hydrogen

Question 10

Which end of the water molecule is the negative dipole at?

Answer 10

Oxygen

Question 11

Which element is found in all organic compounds?

Answer 11

Carbon

Question 12

Which elements are found in a carbohydrate molecule?

Answer 12

Carbon, hydrogen and oxygen

Question 13

What are the 3 main groups of carbohydrate?

Answer 13

monosaccharide, disaccharide and polysaccharide

Question 14

Which carbohydrate molecule is used as an energy source?

Answer 14

Glucose

Question 15

Two monosaccharides are joined by which bond?

Answer 15

Glycosidic bond

Question 16

What type of reaction joins 2 monosaccharides together?

Answer 16

Condensation reaction

Question 17

What type of reaction splits a disaccharide molecule?

Answer 17

Hydrolysis reaction

Question 18

Which reagent is used to test for the presence of reducing sugars, such as glucose?

Answer 18

Benedict’s reagent

Question 19

What is the formula for glucose?

Answer 19

C6H12O6

Question 20

Which monosaccharides fuse to make lactose?

Answer 20

Glucose and galactose

Question 21

Which monosaccharides bond to make sucrose?

Answer 21

Glucose and fructose

Question 22

Which monosaccharides bond to make maltose?

Answer 22

Glucose and glucose

Question 23

What is an oligosaccharide?

Answer 23

A polysaccharide made of between 3 and 10 monosaccharides

Question 24

What is a polysaccharide?

Answer 24

A polymer made from monosaccharide base units joined together

Question 25

Why do polysaccharides make good storage molecules?

Answer 25

They are compact, chemically and physically inactive and they are insoluble

Question 26

Which 2 polysaccharides are found in starch?

Answer 26

Amylose and amylopectin

Question 27

Describe the structure of amylose

Answer 27

unbranched, long chains of glucose molecules, joined with 1,4 glycosidic bonds, chain forms a spiral

Question 28

Describe the structure of amylopectin

Answer 28

branched chains of glucose, joined with 1,4 and 1,6 glycosidic bonds

Question 29

How do the structures of amylose and amylopectin relate to their function?

Answer 29

branches of amylopectin are rapidly broken off to provide energy for respiration, amylose is hydrolysed more slowly, providing energy for longer

Question 30

Describe the structure of glycogen

Answer 30

Highly branched glucose chains, joined by 1,4 and 1,6 glycosidic bond

Question 31

How is the structure of glycogen related to the function?

Answer 31

Many branches (more than starch) can rapidly release glucose for respiration, animals need energy more easily than plants

Question 32

Describe the structure of a triglyceride

Answer 32

Three fatty acid chains bonded to one molecule of glycerol

Question 33

What type of reaction joins the fatty acids to the glycerol molecule?

Answer 33

Condensation reaction

Question 34

What type of reaction is used to break a triglyceride?

Answer 34

Hydrolysis reaction

Question 35

Which type of bond joins a glycerol molecule to fatty acids?

Answer 35

Ester bond

Question 36

What is the difference between a saturated and unsaturated fatty acid chain?

Answer 36

Unsaturated fatty acids contain at least one C=C double bond. This makes them "kinked"

Question 37

Which element is present in proteins but not in other organic molecules?

Answer 37

Nitrogen

Question 38

What does the R group of an amino acid represent?

Answer 38

A variable section that is different for every amino acid

Question 39

What are the 3 main parts of an amino acid?

Answer 39

Amine group, carboxyl group and R (variable) group

Question 40

How many different amino acids are there?

Answer 40

20

Question 41

What type of reaction joins together 2 amino acids?

Answer 41

Condensation reaction

Question 42

What type of reaction separates a dipeptide?

Answer 42

Hydrolysis reaction

Question 43

What is the name of the bond that forms between two amino acids?

Answer 43

Peptide bond

Question 44

Which reagent is used to identify the presence of a protein? What does a positive result look like?

Answer 44

Biuret reagent - turns from blue to purple in the presence of peptide bonds

Question 45

Describe the primary structure of a protein

Answer 45

A long chain of amino acids

Question 46

What determines the primary structure of a protein?

Answer 46

The sequence of bases in DNA

Question 47

Describe the two secondary structures of a protein.

Answer 47

Alpha helix - the long chain of amino acids is coiled into a spiral (helix) with hydrogen bonds holding the shape together. Beta pleated sheet - long chains are "folded" into a zig-zag shape, with hydrogen bonds holding the parallel chains together.

Question 48

Describe the tertiary structure of a protein

Answer 48

In tertiary proteins, the chain of amino acids is folded into a 3D shape. Ionic, hydrogen and disulfide bonds hold the structure in place.

Question 49

Describe the quaternary structure of a protein

Answer 49

Multiple polypeptide chains are joined together, each with their own primary, secondary and tertiary structures. Can be globular or fibrous, may have a prosthetic group - a non-amino acid part (e.g. the iron ion in haemoglobin).