Biological Molecules - Proteins and water

Question 1

What are the monomers for proteins

Answer 1

Amino acids

Question 2

What elements are amino acids made of

Answer 2

Hydrogen
Carbon
Oxygen
Nitrogen
Sometimes sulfur (will be in r group)

Question 3

What groups make up an amino acid

Answer 3

NH2
COOH
R

Question 4

What group determines the properties of an amino acid

Answer 4

The R group as it is different in each one

Question 5

How many naturally occurring amino acids are there

Answer 5

20-22

Question 6

What will form when two amino acids condense

Answer 6

A dipeptide

Question 7

What bond forms between a dipeptide

Answer 7

A peptide bonds

Question 8

What two molecules need to be joined together

Answer 8

Carbon and nitrogen

Question 9

What is a long chain of amino acids called

Answer 9

Polypeptide

Question 10

What 2 types of proteins are there

Answer 10

-globular proteins
-fibrous proteins

Question 11

What is a globular protein

Answer 11

Shape is important to function
Found in cell membranes and has a metabolic function
Eg enzymes and transport of oxygen via haemoglobin

Question 12

What are fibrous proteins

Answer 12

Structural function eg support to muscles
Function depends on properties
Eg insolubility, strength and flexibility
Eg elastin found in tissues and collagen in tendons

Question 13

How do you test for proteins

Answer 13

-2cm3 of solution to test tube
-equal vol of potassium hydroxide
-few drops copper sulphate
-blue to purple colour change indicates presence of protein

Question 14

What is the primary structure of a protein

Answer 14

The series/sequence of amino acids that form the polypeptide chain

Question 15

What does the primary structure determine

Answer 15

Shape and function eg properties and active site

Question 16

What is the secondary structure

Answer 16

The twisting of the polypeptide chain to form a helix shape
A-helix - is the most common linked by hydrogen bonds
Beta pleated sheet - less common groups on both sides

Question 17

What is the tertiary structure

Answer 17

The infolding of the a-helices and chains into a compact structure with additional bonds forming
-disulfide bridges
-hydrogen
-ionic

Question 18

What 3 types of bond forms in the tertiary structure

Answer 18

Disulfide bridges- strongest and not easily broken
Ionic bonds- formed between carboxyl and amino group weaker than disulfide bridges
Hydrogen bonds- weakest and numerous

Question 19

How is the 3d shape important

Answer 19

Determines how the protein functions and its ability to recognise and be recognised by other molecules

Question 20

What is the quaternary structure of proteins

Answer 20

Multiple polypeptide chains combining together and are linked in various ways

Question 21

What can sometimes be apart of the quaternary structure

Answer 21

None protein groups (prosthetic groups)

Question 22

Give an example of a prosthetic group

Answer 22

Iron in the haem group of haemoglobin

Question 23

What is the form of fibrous proteins

Answer 23

Long chains that run parallel to one and other and are linked by cross chains to form stable molecules
Twisted into a rope structure with 3 helixes

Question 24

why is water an important biological molecule

Answer 24

it acts as a metabolite

Question 24

what is the structure of water

Answer 24

one atom of oxygen and two atoms of hydrogen

Question 25

What are the properties of water

Answer 25

-solvent-polar molecule many ions (e.g. sodium chloride) and covalently bonded polar substances (e.g. glucose) will dissolve in it This allows chemical reactions to occur within cells -metabolite- transported easily due to polar nature -high specific heat capacity- Provides suitable habitats Is able to maintain a constant temperature as water is able to absorb a lot of heat without big temperature fluctuations This is vital in maintaining temperatures that are optimal for enzyme activity Water in blood plasma is also vital in transferring heat around the body, helping to maintain a fairly constant temperature -high latent heat of vaporisation- only a little water is required to evaporate for the organism to lose a great amount of heat thus providing a cooling effect -cohesion- water molecules allows for strong cohesion between water molecules This allows columns of water to move through the xylem of plants and through blood vessels in animals This also enables surface tension where a body of water meets the air, these hydrogen bonds occur between the top layer of water molecules to create a sort of film on the body of water (this is what allows insects such as pond skaters to float)

Question 26

Explain five properties that make water important for organisms.

Answer 26

-metabolite in condensation reactions or hydrolysis/photosynthesis/respiration -solvent so metabolic reactions can occur -high heat capacity so buffers changes in temp -large latent heat of vapuristaion so provides a cooling effect -cohesion bwt water molecules so supports columns of water in plants -cohesion bwt water molecules so produces tension supporting small organisms