BIOLOGICAL MOLECULES (2.1.2) Flashcards
1
Q
what is latent heat
A
heat energy needed to change a substance from one state to another , e.g from a liquid to a gas
2
Q
define the term “polar molecule”
A
a molecule that has a slightly positive charge on one side and a slightly negative charge on the other
3
Q
what do water molecules form with other water molecules due to its polarity?
A
hydrogen bonds
4
Q
why does water have a high specific heat capacity?
A
- hydrogen bonds between H2O molecules can absorb a lot of energy
- results in a lot of energy needed to heat it up
- means that water doesn’t experience rapid temperature changes
5
Q
what effect does waters high specific heat capacity have on its function?
A
- makes water a good habitat
- water doesn’t experience rapid temperature changes
- means temperature underwater is more stable than on land
6
Q
why is water cohesive?
A
- due to waters polarity, molecules are attracted to one another and “stick” to each other
7
Q
what’s effect does water’s cohesive nature have on its function?
A
- allows water to flow
- makes water a good transport medium
- helps water be transported up plant stems in transpiration stream
- produces surface tension for small organisms to walk on
8
Q
why is water a good solvent?
A
- due to waters polarity, it can dissolve ionic substances
- waters δ+ side is attracted to the negative ion
- waters δ- side is attracted to the positive ion
- ions get surrounded by H2O molecules and dissolve
9
Q
What can water be used for, due to it being a good solvent
A
- makes it a good reaction medium, since many substances in biological reactions are ionic
- makes it a good transport medium, as it can transport useful substances
- makes it a good habitat, as it contains useful ions
10
Q
why does water have a high latent heat of evaporation?
A
- takes a high amount of energy to break hydrogen bonds between H2O molecules
- this means a lot of energy is needed to change water from a liquid to a gas
11
Q
what affect does water having a high latent heat of evaporation have on its function?
A
- makes water a useful coolant
- used as a thermoregulatory system by organisms
- sweating/transpiring allows heat to be carried away by vapourised h2o molecules
12
Q
why does water have a lower density when solid?
A
- h2o molecules are held further apart in ice than in liquid
- each molecule forms 4 hydrogen bonds with other h2o molecules to form a lattice shape
- allows ice to float on top of water
13
Q
what affect does water having a lower density when solid have on its function?
A
- makes it a good habitat
- ice floats on top of water, forming an insulating layer on top of water
- liquid below and organisms within (e.g. fish) don’t freeze
14
Q
what elements do carbohydrates contain?
A
- Carbon
- Hydrogen
- Oxygen
15
Q
define and state 3 examples of a monosaccharide
A
a monomer
- alpha glucose
- beta glucose
- ribose
16
Q
where is the hydroxyl (OH) group on α-glucose ?
A
- bonded to the bottom right of Carbon 1
H
/
C1
\
OH
17
Q
where is the hydroxyl (OH) group on β-glucose?
A
- bonded to the top right of Carbon 1
OH
/
C1
\
H
18
Q
state the formula of glucose
A
C6 H12 O6
19
Q
what type of monosaccharide is glucose?
A
- a hexose monosaccharide
- has 6 carbons
- is a sugar
20
Q
how is glucose’s structure related to = its function?
A
- it is soluble, so can be easily transported
- it’s chemical bonds contain energy, making it a good energy source
21
Q
what is the chemical formula for Ribose?
A
- C5 H10 O5
22
Q
structural formula of ribose
A
CH2OH O OH
| / \ /
C4 H H C1
/ \ / \ / \
H C3___C2 H
/ \
HO OH
C5H10O5
23
Q
what type of monosaccharide is ribose?
A
- a pentose monosaccharide
- has 5 carbons
- is a sugar
24
Q
what is ribose’s function?
A
- is a the sugar component of RNA molecules
25
how are polysaccharides formed?
- by glycosidic bonds formed during condensation polymerisation
- H atom on one monosaccharide bonds to a OH group on another
- releases H2O, water molecule
H H H H
/ \ / \
C + C ➡️ C C + H2O
\ / \ /
OH HO O
26
what is excess glucose stored as in plants?
- starch
27
what is starch a mixture of?
- 2 polysaccharides of alpha-glucose
- 70% amylose
- 30% amylopectin
28
describe the structure of amylose
- long unbranded chain of alpha-glucose
- has C1 to C4 glycosidic bonds ONLY
- coiled structure, due to angles of bonds
29
what effects does the structure of amylose have on its function?
- good for storage, due to compact structure
- insoluble, so no osmotic effect on cells
- energy not released quickly, since plants have a low metabolic rate
30
why do plants have a low metabolic rate?
- they don’t move
- they don’t regulate their temperature
31
describe the structure of amylopectin
- long branched chain of alpha-glucose
- C1 to C4 glycosidic bonds, SOME C1 to C6 bonds
32
what effects does the structure of amylopectin have on its function?
- side branches (1-6 bonds) allow enzymes to reach glycosodic bonds easier, and therefore release glucose (energy) easier
- insoluble, no osmotic effects
- good for storage, due to coiled/compact structure
33
why is lots of branching not required in plant storage of glucose?
plants have a low metabolic rate, so do not require much energy
34
what is the animal storage of glucose?
glycogen
35
describe the structure of glycogen
- polysaccharide of alpha-glucose
- C1 to C4 bonds
- many C1 - C6 bonds (lots of branching)
36
why does glycogen have lots of branching?
- to allow enzymes that break down molecules to reach glycosidic bonds easier and release glucose (energy)
- more readily available energy
- animals have a higher metabolic rate
37
why do animals require a store that provides more readily available energy (glucose)?
- animals have a higher metabolic rate, due to movement and temperature control
38
what is cellulose’s function?
- present in cell walls of plants
- provides structural support/maintains shape of plant cells
39
describe the structure of cellulose
- polysaccharide of beta-glucose
- every other beta-glucose is rotated 180degrees to form a linear chain
- cellulose chains link together by hydrogen bonds to form microfibrils
40
how are cellulose chains linked together?
- by hydrogen bonds
- forms microfibrils (strong fibres) that provide structural support for the cell
41
how are disaccharides formed?
when 2 monosaccharides join together through condensation polymerisation
42
how is maltose formed [disaccharide]?
when 2 alpha-glucose monosaccharides join together
43
how is sucrose [disaccharide] formed?
when an alpha-glucose and fructose monosaccharide join together
44
how is lactose [disaccharide] formed?
when a galactose and EITHER alpha or beta-glucose join together
45
give 3 examples of disaccharides
- maltose
- sucrose
- lactose
46
which elements do lipids contain?
- Carbon
- Hydrogen
- Oxygen
47
what do lipids dissolve in?
- organic solvents (e.g. chloroform, ethanol)
- NOT water
48
why do lipids not dissolve in water?
- they are non-polar (electrons distributed evenly)
- have no charged groups
- water has nothing to interact with
49
describe the structure of a triglyceride
- a glycerol molecule
- 3 fatty acid chains
- held together by 3 ester bonds
50
how are triglycerides formed?
- condensation reaction, known as esterification
- each fatty acids hydroxyl group (OH) reacts with one of the 3 OH groups on the glycerol
- forms 3 ester bonds and 3 H2O molecules
H O
| ||
H—C-—O—-C—(CH2)nCH3
X3
51
describe the structure of a fatty acid molecule and the effect it has on lipids
- have hydrocarbon tails, which can vary in structure
- these HC tails are hydrophobic, so do not interact with water
- these make lipids insoluble in water
52
describe the structure of saturated fatty acids
- have SINGLE carbon - carbon bonds ONLY
- every carbon atom is saturated with hydrogen
53
what is the general formula for saturated fatty acids?
CnH2n+1 COOH
54
describe the structure of unsaturated fatty acids
- HAVE carbon-carbon double bonds
- C=C causes the chain to kink
- kink means that they have lower boiling points (often liquid at room temp)
55
state a property of fatty acids
- carbon to carbon bonds release a lot of energy when broken
56
57
why are triglycerides a good energy storage?
- fatty acid HC tail contains lots of energy
- contain twice as much energy as carbohydrates
- insoluble, so can be stored inside cells w/out an osmotic effect
58
state the functions of triglycerides
- store of chemical energy
- protection
- waterproofing
- buoyancy (fat layer beneath skin)
59
describe the structure of a phospholipid
- phosphate head
- glycerol molecule
- 2 fatty acid tails
60
why do phospholipids form a bilayer membrane?
- fatty acids and hydrophobic, so face inwards
- phosphate head is hydrophilic, so point outwards on either side of the membrane
61
state the functions of phospholipids
- make up the bilayer within the cell membrane of eukaryotes and prokaryotes
- protection from friction (act as a lubricant)
- electrical insulation
62
how does the membrane act as a barrier?
- centre of bilayer is hydrophobic, due to hydrophobic fatty acid tails
- water soluble substances (e.g ions, polar molecules) cannot easily pass through i
63
describe the structure of cholesterol
- hydroxyl (OH) group (polar)
- hydrocarbon rings
- hydrocarbon tail (both non polar)
64
describe the function of cholesterol
- strengthen cell membrane, fits between phospholipids bilayer (due to small, flat shape)
- needed to form vitamin D
- production of steroid hormones
65
how does cholesterol interact with the cell membranes bilayer?
- bonds to hydrophobic tails of phospholipids
- causes phospholipids to pack closer together
- make membranes less fluid, increasing rigidity
66
describe the structure of an amino acid
- always contains an N-C-C backbone
- amine group (NH2)
- varied R group
- carboxyl group (COOH)
67
what does the R group on an amino acid do?
changes the proteins chemical properties
68
how are polypeptides formed/joined?
- linked by peptide bonds during condensation reactions
- OH group and H on each amino acid forms a molecule of water
69
state the structure of a protein
- large molecules with 4 structural levels
- primary
- secondary
- tertiary
- quaternary
70
describe the primary structure of a protein
- sequence of amino acids in a polypeptide chain
- change in sequence can change the entire structure of the protein
71
describe the secondary structure of a protein
- hydrogen bonds form between -NH and -CO groups (H is δ+, O is slightly δ-)
- peptide forms either alpha helix OR beta pleated sheet
72
describe the tertiary structure of a protein
- chain is folded more
- IONIC BONDS: negatively and positively charged R groups
- DISULFIDE BONDS: between 2 molecules of cysteine (sulfur atoms)
- HYDROPHOBIC, PHILLIC INTERACTIONS: h-phobic clump together, h-phillic pushes to the outside
- HYDROGEN BONDS: between δ+ and δ- atoms in R groups
73
describe the quaternary structure
- occurs if there is more than one polypeptide, final 3D structure
- determined by the tertiary structure
- ionic bonds
- disulfide bonds
- hydrophobic , hydrophilic interactions
- hydrogen bonds
74
describe globular protein structure and properties
- round, compact
- hydrophillic R groups pushed outside (due to TERTIARY structure)
- means they are soluble, so easily transported in fluids
75
state 3 examples of a globular proteins
- haemoglobin
- amylase
- insulin
76
describe haemoglobins structure and function
- globular protein
- conjugated protein: protein with a prosthetic (non-protein) group attached
- each of 4 polypeptide chains have haem prosthetic group
- haem group contains iron, binds to O2.
77
Outline amylase’s structure and function
- enzyme, catalyses breakdown of starch
- digestive system
- globular: tightly folded, active site forms
78
describe insulin’s structure and function
- globular: solubility allows it to be transported in the blood
- hormone, regulated blood sugar
79
describe fibrous proteins structure
- tough, rope shaped, strong
- insoluble
- fairly unreactive
80
state 3 examples of fibrous proteins
- collagen
- keratin
- elastin
81
describe structure and function of collagen
- fibrous protein, strong
- found in animal connective tissues (bone, muscle, skin)
- provides structural support
82
describe keratins structure and function
- supports animal external structure (nails, skin, horns)
- can be flexible (skin)
- can be hard/tough (nails)
83
describe elastin’s structure and function
- found in elastic connective tissues (skin, blood vessels, ligaments)
- elastic: allows tissues to stretch and return to their original shape after
84
What elements do proteins contain
Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
85
What elements do Nucleic acids contain
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphate
