Biomolecules 2.1.2

Question 1

Describe the structure of a water molecule

Answer 1

An oxygen atom covalently bonded to 2 hydrogen atoms. It is a non-linear shape.

Question 2

Name the bond that can link two water molecules together

Answer 2

Hydrogen bond

Question 3

Explain what a hydrogen bond is, which types of atoms it can join together and where they occur in biology

Answer 3

A hydrogen bond is a weak interaction that can occur whenever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen

Question 4

Draw two water molecules and draw and label the bond that links them together

Answer 4

https://o.quizlet.com/jf-cS-7cwA0rs7MGdF-Ptg.jpg

Question 5

Define the term ‘Polar’

Answer 5

Has 2 poles, one slightly positive the other slightly negative

Question 6

Explain why water is a polar molecule

Answer 6

Water is a polar molecule because the oxygen atom is more attractive to electrons than hydrogen so pulls the shared electrons towards it. This causes the Oxygen to be slightly negative and the Hydrogens to be positive.

Question 7

Define the term “electronegativity” and “dipole”

Answer 7

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
A dipole is a molecule in which a concentration of positive electric charge is separated from a concentration of negative charge

Question 8

List the roles water plays in life (at least 5)

Answer 8

Solvent, transport medium, habitat, reactant, thermal stability

Question 9

Explain why the polar nature of water allows it to be a useful solvent

Answer 9

Solvent: Dissolves polar and charged molecules as charges interact with polar water molecules which cluster around them keeping them apart

Question 10

Explain why the polar nature of water allows it to be a useful transport medium

Answer 10

Transport medium: Liquid over large temp. range as H bonds require lots of energy to break. It dissolves many molecules

Question 11

Explain why the polar nature of water allows it to be a useful coolant

Answer 11

Coolant: High specific heat capacity as H bonds require lots of energy to break

Question 12

Explain why the polar nature of water allows it to be a useful habitat

Answer 12

Habitat: Maintains a constant temp. due to energy required to break H bonds

Question 13

Define the terms “hydrophilic” and “hydrophobic”

Answer 13

Hydrophilic: The physical property of a molecule that is attracted to water
Hydrophobic: The physical property of a molecule that is repelled by water

Question 14

Define the terms “cohesion” and “adhesion”.

Answer 14

Cohesion: Water molecules attracted to one another
Adhesion: Water molecules attracted to other substances

Question 15

Describe any other properties (not related to its polar nature) water has that makes it useful for life

Answer 15

Transparent to light - plants growing under water can get light for photosynthesis and aquatic animals can see underwater

Question 16

List examples of how water is used from across the whole diversity of life (prokaryotes and eukaryotes; plants, animals and fungi; unicellular and multicellular organisms).

Answer 16

Supports - keeping plant cells turgid, the hydrostatic skeletons of earthworms
Lubrication - Joints such as elbow called 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 17

Using the “polar nature of water” explain the 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.

Answer 17

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 18

Define the term “monomer”

Answer 18

Monomer: Individual molecules that make up a polymer

Question 19

Define the term polymer

Answer 19

Polymer: Long-chain molecules composed of linked (bonded) multiple individual molecules (monomers) in a repeating pattern

Question 20

Define the term macromolecule

Answer 20

Macromolecule: Large complex molecules with large molecular masses

Question 21

Define the terms “dimer” and “oligomer”

Answer 21

Dimer: a molecule consisting of two identical molecules linked together
Oligomer: a polymer whose molecules consist of relatively few repeating units

Question 22

Define the term “hydrolysis reaction”

Hydrolysis reaction: the breakdown of a molecule into two smaller molecules requiring the addition of a water molecule (opposite to condensation)

Answer 22

Hydrolysis reaction: the breakdown of a molecule into two smaller molecules requiring the addition of a water molecule (opposite to condensation)

Question 23

Define the term “condensation reaction”

Answer 23

Condensation reaction: a reaction between two molecules to form a larger molecule and the release of a water molecule. (opposite to hydrolysis)

Question 24

Define the term “metabolism”

Answer 24

Metabolism: the chemical processes that occur within a living organism in order to maintain life

Question 25

Define the term 'catabolic reaction'

Answer 25

Catabolic reaction: reactions of metabolism that break molecules down into smaller units. These reactions release energy.

Question 26

Define the term 'anabolic reaction'

Answer 26

Anabolic reaction: reactions of metabolism that construct molecules from smaller units. These reactions require energy from the hydrolysis of ATP.

Question 27

List the 4 main categories of biological molecule.

Answer 27

Carbohydrates, Lipids, Proteins, Nucleic acids

Question 28

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule, whether or not the macromolecule is a polymer, the name of the bond that links the building blocks together, the name of the reaction that joins the building blocks together, the name of the reaction that breaks the macromolecule apart, examples of the functions of the molecules and the elements that make up the molecules for carbohydrates

Answer 28

Carbohydrates: monosaccharides, disaccharides, polysaccharides, they are polymers, glycosidic bond, condensation reaction, hydrolysis, respiration-cell wall-cell signalling etc.

Question 29

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule, whether or not the macromolecule is a polymer, the name of the bond that links the building blocks together, the name of the reaction that joins the building blocks together, the name of the reaction that breaks the macromolecule apart, examples of the functions of the molecules and the elements that make up the molecules for LIPIDS

Answer 29

Lipids: fatty acids and glycerol, (monoglyceride, diglyceride) and triglyceride, not a polymer, ester bond, condensation, hydrolysis, source of energy-membrane structure-hormones etc.

Question 30

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule, whether or not the macromolecule is a polymer, the name of the bond that links the building blocks together, the name of the reaction that joins the building blocks together, the name of the reaction that breaks the macromolecule apart, examples of the functions of the molecules and the elements that make up the molecules for PROTEINS

Answer 30

Proteins: amino acids, dipeptide, polypeptide, they are polymers, peptide bond, condensation, hydrolysis, transport molecules-enzymes-antibodies etc.

Question 31

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule, whether or not the macromolecule is a polymer, the name of the bond that links the building blocks together, the name of the reaction that joins the building blocks together, the name of the reaction that breaks the macromolecule apart, examples of the functions of the molecules and the elements that make up the molecules for NUCLEIC ACIDS

Answer 31

Nucleic acids: nucleotides, dinucleotide, polynucleotide, they are polymers, phosphodiester bond, condensation, hydrolysis, genetic material-protein synthesis etc.

Question 32

Define the terms "single bond" and "double bond"

Answer 32

single bond: a chemical bond in which one pair of electrons is shared between two atoms double bond: a chemical bond in which two pairs of electrons are shared between two atoms

Question 33

State the elements present in carbohydrates

Answer 33

Carbon, Hydrogen and Oxygen

Question 34

Monosaccharides

Answer 34

glucose fructose galactose

Question 35

Disaccharide

Answer 35

Maltose Sucrose Lactose

Question 36

Polysaccharide

Answer 36

Starch Glycogen Cellulose Chitin

Question 37

Maltose

Answer 37

alpha glucose + alpha glucose

Question 38

Sucrose

Answer 38

glucose + fructose

Question 39

Lactose

Answer 39

galactose + glucose

Question 40

Starch

Answer 40

polymer of glucose Main storage carbohydrate in plants- insoluble good storage Made of Amylopectin and Amylose Amylose by hydrogen bonding for a helix which is compact and therefore good for storage Amylopectin has many protruding ends (glucose molecules) which can be hydrolysed rapidly – allows rapid release of glucose to provide energy via respiration.

Question 41

glycogen

Answer 41

polymer of alpha glucose main storage polysaccharide of animal and fungal cells Similar structure to amylopectin but has many more branches and the branches are shorter. Glycogen is even more compact than amylopectin The structure of glycogen allows faster hydrolysis than starch which is important as animals may need emergency glucose faster than plants.

Question 42

cellulose

Answer 42

Polymer of beta glucose Structural polysaccharide in plants Long unbranched chains of glucose linked by β-1,4-glycosidic bonds. The individual chains are then linked to each other by hydrogen bonds. These are formed into strong microfibrils.

Question 43

chitin

Answer 43

Polymer of glucosamine Structural polysaccharide found in hard exoskeletons of all arthropods Made of glucosamine units (glucose + amino acid) and is linked by β-1,4-glycosidic bonds. The presence of the amino group causes even more hydrogen bonding between the chains than in cellulose. Chitin is therefore an extremely resilient and tough polysaccharide.,

Question 44

State the general formula of carbohydrates

Answer 44

(CH2O)n

Question 45

Define the term "monosaccharide", "disaccharide" and "polysaccharide"

Answer 45

Monosaccharide: A single sugar molecule

Question 46

Define the term "disaccharide"

Answer 46

Disaccharide: A molecule comprised of two monosaccharides joined by a glycosidic bond

Question 47

Define the term "polysaccharide"

Answer 47

Polysaccharide: A polymer made of many sugar (monosaccharides) monomers

Question 48

Define the term "pentose sugar" and "hexose sugar"

Answer 48

Pentose - a monosaccharide composed of 5 carbons Hexose - a monosaccharide composed of 6 carbons

Question 49

Define the term "triose sugar" and name an example

Answer 49

Triose - monosaccharide composed of 3 carbons E.g. glyceraldehyde

Question 50

Describe what is meant by a "furanose ring" and a "pyranose ring"

Answer 50

Furanose ring - 5 membered ring e.g. fructose Pyranose ring - 6 membered ring e.g. glucose

Question 51

Define the term "isomer"

Answer 51

Molecules with the same molecular formulae but different structural formulae (same atoms but arranged differently)

Question 52

Describe the difference between alpha- and beta-glucose

Answer 52

The hydrogen and hydroxyl groups on carbon 1 are reversed.

Question 53

Describe the differences between alpha glucose and ribose

Answer 53

Glucose is pyranose but ribose is furanose Glucose used in starch and glycogen Ribose used in RNA

Question 54

List 3 examples of disaccharides and for each state which monosaccharides they are composed of

Answer 54

Sucrose - alpha-glucose and fructose Maltose - two alpha-glucose Lactose - alpha-glucose and galactose

Question 55

State the properties and functions of Fructose

Answer 55

Fructose - hexose sugar commonly found in fruit

Question 56

State the properties and functions of Glucose

Answer 56

Glucose - monosaccharide used in respiration and to make polymers such as starch

Question 57

State the properties and functions of Maltose

Answer 57

Maltose - found in barley

Question 58

State the properties and functions of Sucrose

Answer 58

Sucrose - found in sugar cane and beet

Question 59

State the properties and functions of Glactose

Answer 59

Galactose - another hexose sugar

Question 60

State the properties and functions of Lactose

Answer 60

Lactose - found in milk

Question 61

Explain why alpha-glucose links together to form starch whereas beta-glucose links together to form cellulose

Answer 61

Due to the arrangement of the hydrogen and hydroxyl groups on carbon-1... The 1-4 glycosidic bonds using alpha mean all the monomers are the same way up, but with beta each is rotated 180° from the last.

Question 62

List the two different polysaccharides that make up starch.

Answer 62

Amylose (1-4 bonds only) and Amylopectin (mainly 1-4 but some 1-6)

Question 63

Describe the structure of a cellulose fibre

Answer 63

Several cellulose molecules produce a microfibil Several microfibrils hydrogen bonded together produce a macrofibril Macrofibrils are laid down in layers to form cell wall etc.

Question 64

Describe and explain the properties and functions of starch, glycogen and cellulose

Answer 64

Starch: Coils into helix, amylase unbranched and amylopectin branched. Compact and insoluble so ideal for storage - food store in plants Glycogen: More branched than amylopectin, coils into helix. Compact and insoluble so ideal for storage - animals and fungi Cellulose - Unbranched, does not form helix - forms layers of fibres to give great strength to cell wall

Question 65

State the elements present in lipids (and the additional element needed to make phospholipids)

Answer 65

Carbon, Hydrogen and Oxygen Phophorus

Question 66

State the 3 categories of lipids (or lipid derived molecules)

Answer 66

Triglycerides, Steroids and Phosopholipids

Question 67

Basic structure of a triglyceride

Answer 67

3 fatty acids joined to a glycerol

Question 68

show the difference between saturated, monounsaturated and polyunsaturated fatty acids/triglycerides.

Answer 68

Unsaturated fatty acids have kinks in the chain due to the double bonds (1 for mono, several for poly)

Question 69

Explain why saturated triglycerides tend to be solid (fats) at room temperature whereas unsaturated triglycerides tend to be liquid (oils).

Answer 69

Saturated fatty acids can pack more tightly as do not have kinks and therefore have higher melting points than unsaturated which are more spread out so melt at lower temperatures.

Question 70

State the difference between the triglycerides found in non-fish animals and those in plants and fish.

Answer 70

Plant and fish triglycerides tend to be unsaturated whereas other animal fats tend to be saturated