2.1.2abc Biological Molecules - water + principles of biomolecules

Question 1

Draw a water molecule, label the atoms and their charges
on flashcard

Answer 1

hydrogen - slightly +
water - slightly -

Question 2

What is the structre of a water molecule

Answer 2

1 Oxygen atom covalently bonded to 2 hydrogen atoms
- non-linear shape

Question 3

What is the bond linking 2 water molecules together?

Answer 3

Hydrogen bond

Question 4

What is a hydrogen bond and which type of atoms does it join together?

Answer 4

• A weak interaction that occurs whenever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen

Question 5

Where else do hydrogen bonds occur in biology?

Answer 5

DNA
polysaccharides
proteins

Question 6

Draw 2 water molecules and draw and label the bond that links them together
on flashcard

Answer 6

on flashcard

Question 7

Define polar

Answer 7

the presence of unevenly distrubuted charge on 2 poles
one is slightly + and one is slightly -

Question 8

Why is water a polar molcule?

Answer 8

the oxygen (-) atom is more attractive to electrons than hydrogen (+) so pulls the shared electrons towards it,
- causes O to be slightly - and Hs to be slightly positive

Question 9

Define electronegativity

Answer 9

a measure of the tendancy of an atom to attract a bonding pair of electrons

Question 10

Define dipole

Answer 10

a molecule in which a concentration of positive electric charge is seperated from a concentration of negative charge

Question 11

What are the 5 roles water plays in life?

Answer 11

• Solvent
• Transport medium
• Habitat
• Reactant
• Thermal stability

Question 12

Why does the polar nature of water allow it to be used as a solvent?

Answer 12

as water is polar:
-water dissolves polar and charged molcules
- many solutes are polar: amino acids, proteins,nucleic acids
->water acts as medium for chemical
reactions

Question 12

Why does the polar nature of water allow it to be used as a transport medium?

Answer 12

as water is polar:
- cohesion between water molecules= when water moves through body molecules stick together
-adhesion between water molecules and other polar molecules + surfaces
adhesion+cohesion = capillary action
- water moves up narrow tube via gravity

Question 13

Why does the polar nature of water allow it to be used as a coolant?

Answer 13

• high specific heat capacity as H bonds require lots of energy to break
• maintains constant temperature

Question 14

Why does the polar nature of water allow it to be used as a habitat?

Answer 14

-maintains constant temperature due to high energy required to break H bonds
-less dense when it freezes
=survival+reproduce

Question 15

Define hydrophilic

Answer 15

a molecule attracted to water

Question 16

Define hydrophobic

Answer 16

a molecule repelled by water

Question 17

Define cohesion

Answer 17

water molecules attracted to one another

Question 18

Define adhesion

Answer 18

water molecules attracted to other substances

Question 19

Summarise the 5 properties of water

Answer 19

*High specific heat capacity - hydrogen bonds between water molecules absorb lots of energy - good habitat
*High latent heat of evaporation (liq->gas) - good coolant eg sweat evaporates+cools skin
*Very Cohesive (bc polar) - helps water to flow - good transport medium
e.g. water up stems in transpiration stream
*Lower density when solid - water molecules held further apart in ice than in liq water bc each water molecule forms 4 hydrogen bonds = lattice shape
ice less dense than water - insulating layer on top of water (water below doesnt freeze) - habitat
* Good solvent - bc water polar - slightly positive end of water molecule attracted to negative ion and slightly negative end of water molecule attracted to positive ion
= ion surrounded by water = dissolve

Question 20

What are other properties (not polar related) of water that make it useful for life?

Answer 20

transparent
- plants growing underwater can get light for photosynthesis
- aquatic animals can see underwater

Question 21

Give 10 examples of how water is used across the whole diversity of life (prokaryotes+eukaryotes; plants+animals+fungi ; unicellular and multicellular organisms)
S+C

Answer 21

Support - keep plant cells turgid, hydrostatic skeletons of earthworms
Lubrication - joints such as elbow synovial joints have sac of synovial fluid stopping bones rubbing against each other
Bouyancy - Whales couldn’t be so big etc.
Swimming - When something pushes against water there is an equal reactive force propelling forward
Reactions - Photosynthesis, hydrolysis
High surface tension allows organisms to suspend themselves at/on the surface e.g. pond skaters
Ice floats as less dense so insulates water underneath where organisms can survive
Regulating temperature and reaction conditions etc. - sweating as well as high heat capacity

Question 22

Using the “polar nature of water” explain how water can dome above the level of the glass container it is in, the shape of the meniscus in a glass measuring cylinder and capillary action in a narrow glass tube
S+C

Answer 22

Dome: Cohesion between water molecules causing surface tension due to hydrogen bonds

Meniscus: Adhesion to sides of container draws molecules up.

Capillarity: Cohesion between water molecules and adhesion to other molecules explains why water moves up narrow spaces. Important for water in xylem vessels.

Question 23

Define monomer

Answer 23

individual molecules that make up a polymer

Question 24

Define polymer

Answer 24

long chain molecules composed of linked (bonded) multiple individual molecules (monomers) in a repeating pattern

Question 25

Define Macromolecule

Answer 25

large complex molecules with large molecular masses

Question 26

Define Dimer

Answer 26

a molecule made up of 2 identical molecules linked together

Question 27

Define Oligomer

Answer 27

a polymer whose molecules consist of a few repeating units
oligo - ‘few’

Question 28

Define condensation reaction

Answer 28

reaction between smaller molecules to form a larger molecule
- releases 1 water molcule for every 2 molecules joined together

Question 29

Define hydrolysis reaction

Answer 29

breakdown of larger molecules into smaller molecules
- requires addition of water molecule

Question 30

Define metabolism

Answer 30

chemical processes that occur within living organisms to maintain life

Question 31

Define catabolic reaction

Answer 31

reactions of the metabolism that break down larger molecules into smaller units

Question 32

Define anabolic reaction

Answer 32

reactions of the metabolism that build up larger molecules from smaller units

Question 33

What are the 4 main categories of biological molecules

Answer 33

• carbohydrates
• lipids
  -proteins
  -nucleic acids

Question 34

Carbohydrates
- elements?
- building blocks?
- name of dimer?
-name of macromolecule?
-polymer or not?
-bond linking building blocks
-functions?

Answer 34

• C, H, O
• monosaccharides (glucose)
• disaccharides (maltose)
• polydaccharide
  (cellulose,starch, glycogen)
• polymer
• glycosidic bond
  -energy storage and supply, structure in some organisms

Question 35

Lipids
- elements?
- building blocks?
- name of dimer?
-name of macromolecule?
-polymer or not?
-bond linking building blocks
-functions?

Answer 35

• C, H, O
• 3 fatty acids and glycerol
• no dimer
• triglyceride
• not polymer
• ester
• membranes, energy supply, thermal insulation

Question 36

Proteins
- elements?
- building blocks?
- name of dimer?
-name of macromolecule?
-polymer or not?
-bond linking building blocks
-functions?

Answer 36

• C, H , O, N, S
• amino acids
• dipeptide
• polypeptide/protein
• polymer
• peptide
• structure, transport, enzymes, antibodies, some hormones

Question 37

Nucleic Acid
- elements?
- building blocks?
- name of dimer?
-name of macromolecule?
-polymer or not?
-bond linking building blocks
-functions?

Answer 37

• C, H, O, N, P
• nucleotides
• dinucleotide
• nucleic acid (DNA/RNA)
• polymer
• phosphodiester bond
• carry instructions for life

Question 38

Define single bond (covalent)

Answer 38

chemical bond where 2 atoms share 1 pair of electrons

Question 39

Define double bond (covalent)

Answer 39

chemical bond where 2 atoms share 2 pairs of electrons