topic one - biological molecules - mr hedditch Flashcards
1
Q
4 important ways of water to living organisms?
A
chemical reactions
hydrolysis reaction
excretion
photosynthesis
2
Q
draw a water molecule?
A
2-H positive 1-O negative
3
Q
draw hydrogen bonding?
A
4-H positive 2-O negative lines between bonds
4
Q
what happens in hydrogen bonding?
A
oxygen attracts hydrogen bond as it is negative and hydrogen is positive
there is a weak link between the bonds showing that it can be easily broken
5
Q
what does the ‘delta’ sign mean?
A
indicates a slight change
6
Q
why is having a high boiling point and high specific heat capacity good and bad (water)?
A
good - keeps the heat/temp stable and cools down slowly
bad - needs large amount of energy to increase the temp of water
7
Q
why does ice float on water and how is this useful?
A
it floats on water because ice is more dense than water
it useful because things don’t sink e.g. polar bears living in the arctic
8
Q
why is water a good solvent for molecules?
A
waters polarity allows it to dissolve both ionic bonds and other polar molecules
9
Q
what is cohesion and what does it create?
A
water molecules sticking together
this creates surface tension at the water surface
10
Q
what is cohesion useful for?
A
plant transport
11
Q
give examples of 4 biological molecules?
A
carbohydrates
proteins
liquids
nucleic acid
12
Q
define ‘monomers’
A
small, basic molecules that are the building blocks for larger molecules
13
Q
define ‘polymer’
A
large complex molecules made of many monomers joined together
14
Q
what type of reaction are polymers joined together by?
A
a condensation reaction
15
Q
what bond is made when polymers form?
A
a covalent bond
16
Q
how are polymers broken down into polymers?
A
through a hydrolysis reaction
17
Q
state three roles carbohydrates has towards organisms?
A
acts as an energy source for respiration e.g. glucose
acts as an energy store e.g. starch
structure role e.g. cellulose in plant cell walls
18
Q
what does saccharide mean?
A
a sugar
19
Q
define ‘monosaccharide’ + example
A
a simple sugar made up of one bond e.g. glucose
20
Q
define ‘disaccharide’ + example
A
a sugar composed of two monosaccharides e.g. lactose
21
Q
define ‘polysaccharide’ + example
A
a complex carbohydrate e.g. starch
22
Q
define ‘ribose’
A
a monosaccharide formed from five carbon atoms - pentose sugar
23
Q
what is the difference between glucose alpha & beta?
A
in Alpha-glucose H is Above and the OH is below however in the Beta-glucose H is Below and the OH is above
24
Q
state three of glucose’s functions?
A
readily respired to release energy
small molecule - enter cells easily by diffusion
soluble - easily transported around organism
25
draw alpha-glucose
diagram
26
draw beta-glucose
diagram
27
what is a glyosidic bond?
the bond formed between to monosaccharides
28
what is starch a polymer of?
alpha-glucose
29
is starch insoluble in water? if so why?
no, because it consists of two polymers
30
starch is made up of two types of molecules, what are they?
amylose
| amylopectin
31
define 'amylose' and state how much amylose is in starch?
it's a simple poly-(1,4) alpha-glucose, it's a straight
chain molecule
it makes up 80% of starch
32
what shape does the amylose chain curl up into?
a helix shape
33
define 'amylopectin' and state how much amylopectin is in starch?
it's a poly -(1,4) alpha-glucose and makes up 4% of starch
34
amylopectin gives a more open structure than amylose, suggest why?
it has more ends and can be hydrolysed more quickly than amylose by amylase enzymes
35
what is sucrose made up of?
alpha-glucose and fructose
36
what is maltose made up of?
two alpha-glucose's
37
what is lactose made up of?
galactose and alpha-glucose
38
draw maltose
diagram - check with diagram sheet in book
| make sure H2O is on the side
39
draw sucrose
diagram - check with diagram sheet in book
| make sure H2O is on the side
40
draw lactose
diagram - check with diagram sheet in book
alpha should be flipped
make sure H2O is on the side
41
lipids are a varied and diverse group of substances
| that share characteristics, state these?
containing carbon, hydrogen & oxygen
the proportion of oxygen to carbon and
hydrogen is smaller than in carbohydrates
they are insoluble in water (non-polar molecule)
they are soluble in organic solvents such as
alcohols and acetone
42
what are the main group of lipids, and what is it?
triglycerides, it fats and oils
43
state the uses of lipids?
energy source (for respiration)/energy store
thermal insulation e.g. blubber in polar animals
electrical insulation e.g. around the axon of
neurones
biological membranes
hormones
waterproofing
protection e.g. reducing transpiration from
leaves; vital organs in animal
44
difference between fats and oils?
fats are solid at room temp
oils are liquid
fats are saturated
oil are unsaturated
45
what's does a triglyceride molecule consist of & how is it formed?
a triglyceride molecule consists of a glycerol molecule,
and three fatty acid chains
the fatty acids are joined to the glycerol molecule by
ester bonds formed by condensation reactions.
46
what's a glycerol made of?
glycerol is a 3-carbon molecule with 3 –OH groups
47
define 'fatty acids' and explain the bonds?
fatty acids are a long chain of hydrocarbons with a carboxyl group at one end
unsaturated - double bonds
saturated - single bond
48
why are triglyceride insoluble in water?
triglycerides are insoluble in water (hydrophobic)
| because they are non-polar molecules
49
state the main role of a triglyceride?
to store energy for later use
50
draw diagrams to show the structure of a glycerol
molecule, and a fatty acid chain that is 8 C-atoms
long
check biology book
51
where is amylose, amylopectin, glycogen & cellulose found in?
amylose - plants
amylopectin - plants
glycogen - animals
cellulose - plants
52
what is amylose, amylopectin, glycogen & cellulose found as?
amylose - grains
amylopectin - grains
glycogen - granules
cellulose - fibre
53
what is the functions of amylose, amylopectin, glycogen & cellulose?
amylose - energy store
amylopectin - energy store
glycogen - energy store
cellulose - structural support
54
what are the basic monomer units for amylose, amylopectin, glycogen & cellulose?
amylose - alpha-glucose
amylopectin - beta-glucose
glycogen - alpha-glucose
cellulose - beta-glucose
55
what are the types of bonds between monomers for amylose, amylopectin, glycogen & cellulose?
amylose - glycosidic bond (1,4)
amylopectin - glycosidic bond (1,4 + 1,6)
glycogen - glycosidic bond (1,4 + 1,6)
cellulose - glycosidic bond (1,4)
56
what are the types of chains for amylose, amylopectin, glycogen & cellulose?
amylose - unbranched & curls to helix
amylopectin - long, few branches
glycogen - short, lots of branches
cellulose - chains of long unbranched monomers
57
describe the structure of phospholipids?
consists of a glycerol molecule, a phosphate group & two fatty acids
58
apart from a phosphate group and two fatty acids, which other component makes up a phosphide molecule?
glycerol
59
elements found in lipids?
carbon, hydrogen, oxygen
60
name the class of hormones made of cholesterol molecules?
steroid hormones
61
what is the role of cholesterol in plasma membrane?
regulates how fluid it is & forms the basis of steroid hormones
62
which property of phosphide molecules makes them well suited to their role in plasma membrane?
some are hydrophobic & some are hydrophilic
63
which elements do proteins contain?
carbon, hydrogen, oxygen and sometimes nitrogen
64
name the importance's of proteins?
structure - collagen, muscle mass
enzymes - catalyse a range of reactions
transport - membrane carriers
65
define 'amino acids' name some of the common structures?
are monomers that form dipeptides & protein
common structures are:
a central carbon atom
a side chain or R-group
66
draw an amino acid?
check with book
67
what is the R-group, which is the simplest amino acid and what kind of atom is the R-group?
the R-group gives each amino acid unique properties which make it different from the other amino acids, the simplest amino acid is glycine and the R-group is made from a hydrogen atom
68
how many amino acids are there?
20
69
how are dipeptides formed and what happens in this process?
through a condensation reaction between two amino acids
the water molecule is eliminated and a peptide bond is formed
70
how can a dipeptide bond broken?
by adding water (hydrolysis)
71
define 'polypeptides' and where does it take place?
long chains of amino acids joined together by peptide bonds
takes place in the ribosomes
72
define what is meant by a 'primary structure of proteins'?
is the specific sequence of amino acids in a polypeptide chain
73
define what is meant by a 'secondary structure of proteins'?
the coiling or folding of the polypeptide chain due to the formation of the hydrogen bonds
74
what are the two main three-dimensional shapes formed from the secondary structure?
alpha helix
| beta pleated sheets
75
define 'alpha helix'?
the H on the –NH group are attracted to the O on the –CO group
the H is slightly positive and the O is slightly negative
a hydrogen bond forms between these two atoms
the polypeptide chain coils up into a helical shape
76
define what is meant by 'tertiary structure of a protein'?
overall 3D shape of a protein molecule
77
name the four types of bonding involved in tertiary structure?
hydrogen bonds
ionic bonds
disulphide bonds
hydrophobic and hydrophilic interactions
78
state the two main 3D proteins formed in the tertiary structure?
fibrous e.g. collagen
| globular e.g. haemoglobin
79
define the 'quaternary structure?
the way that two or more polypeptide subunits are arranged to give a final specific shape e.g. insulin, collagen & haemoglobin
80
what shape are globular protein and why?
globular proteins are round in shape and compact
because of the tendency of hydrophobic R-groups to cluster on the inside of the molecule while the hydrophilic R-groups stay on the outside
81
examples of globular proteins?
haemoglobin
pepsin
insulin
82
what is haemoglobin?
haemoglobin is a globular transport protein. It binds
| with oxygen in the lungs to form oxyhaemoglobin
83
what do haemoglobin consists of?
consists of four polypeptide sub-units
two are an identical pair called alpha-chains, and two are a different identical pair called beta-chains disulphide bonds hold the chains together
84
what does each subunit contain?
each subunit contains a haem group - an inorganic iron ion (Fe2+)
85
what are proteins with prosthetic group called and what is a prosthetic group?
proteins which have a prosthetic group are called conjugated protein
permanent parts of a protein molecule but are not made of amino acids are called prosthetic groups
86
define pepsin?
a digestive enzyme found in the stomach
87
define insulin?
a hormone secreted by the pancreas. It is essential in the regulation of blood glucose levels
88
define a fibrous protein?
are tough and rope-shaped, they are insoluble, unreactive and mechanically strong – essential
properties for structural role
89
state the three examples of fibrous protein?
collagen
keratin
elastin
90
define the structure collagen and where its found?
consists of three polypeptide chains, each in
the shape of a helix (NOT an alpha-helix though)
these three chains are wound around each other
to form a rope-like structure, held in place by hydrogen bonds
```
in connective tissues:
skin
bone
teeth
walls of blood vessels
etc.
```
91
define keratin and give examples of where its found?
as keratin is insoluble it provides a waterproof barrier
and helps stop pathogens entering the body
```
found in
nails
hair/fur
claws
horns
hooves
scales
feathers
```
92
define what elastin is and does?
it is elastic – it stretches as tissues
expand and then recoils to allows the tissue to return
to its original shape
93
what is denaturation in proteins?
It loses its shape permanently (tertiary structure is
| damaged). This means the protein will no longer function properly
94
what causes denatured proteins?
heat – increased kinetic energy breaks hydrogen bonds and disrupts hydrophobic interactions
acids/bases – H+ or OH-ions break hydrogen bonds
between polar R-groups and break ionic bonds
heavy metal ions – react with disulphide bonds to
form solid
95
what are inorganic ions?
ions are atoms or molecules with an electrical charge Inorganic ions do not contain carbon atom
96
what are positive and negative ions called?
positive - cathode
| negative - anode
97
what are the key inorganic positive ions in biological molecules?
```
calcium ions (Ca2+), sodium ions (Na+), potassium ions (K+), hydrogen ions (H+), ammonium ions
(NH4+)
```
98
what are the key inorganic negative ions in biological molecules?
nitrate (NO3–), hydrogen carbonate (HCO3–), chloride (Cl-), phosphate (PO43–), hydroxide, (OH)
99
steps of chromatography?
there are two components of chromatography:
stationary phase - the chromatography paper (made
If cellulose) or TLC plate
mobile phase - a liquid solvent water for polar molecules ethanol for non-polar molecules
the mobile phase moves up the stationary phase
the different molecules in the the mixture moves at different speeds up the paper depending on there solubility, polarity and size
the paper/plate is removed from the solvent when the solvent front is roughly at the top
the pattern of spots made by the different molecules is called a chromatogram
100
what is chromatography is used for?
used to separate out molecules in a mixture
101
what the two main types of chromatography?
paper chromatography
| thin - layer chromatography (TLC)
102
application of TLC?
monitor the process of chemical reactions
urinalysis- testing for banned drugs in spots
testing the purity of drugs
testing foods for contamination
103
state the six qualitative tests?
monitor the process of chemical reactions
urinalysis- testing for banned drugs in spots
testing the purity of drugs
testing foods for contamination
104
postive results for starch?
brick red
105
postive result for protein?
forms a cloudy red precipitate
106
postive result for lipids?
black
107
postive results for reducing sugars?
lilac
108
state the 10 stages of determining glucose?
Label five boiling tubes 0.1%, 0.5%, 1.0%, 1.5% and 2.0%
glucose (mass (g) per volume (dm3)).
2. Using a clean syringe, add 5cm3 Benedict’s reagent to each
tube (Benedict’s must be in excess so that all of the sugar
reacts)
3. Add 0.5cm3 of each of the glucose solutions to the labelled
boiling tubes, using a clean syringe each time.
4. Stir each with a clean dry glass rod.
5. Heat all the boiling tubes into a water bath at 80°C for ten
minutes.
6. Carefully remove the tubes from the water and allow to cool.
7. Remove the precipitate, using filtration or a centrifuge
8. Pipette the remaining liquid (supernatant) into clean
cuvettes before placing in the colorimeter (no fingerprints!)
9. Put a red filter into the colorimeter (as sample is blue)
10. Take one colorimeter reading for each cuvette. Remember
to calibrate the colorimeter (set it to 100% transmission)
between each reading using a cuvette of water – a “blank”
109
what can quantitative tests tell us?
whether a solution contains a certain type of molecule, but not how much is present
110
what can the benedicts test us?
the Benedict’s test can give us an idea of whether a solution contains no reducing sugars, a small amount or a large quantity, based on the degree of colour change
111
What are the limitations of qualitative testing?
only gives you a yes or no result, it doesn’t give you a numerical value
112
Why did you use water as a control in each of your tests?
because distilled water doesn’t contain anything – won’t affect the outcome of tests
113
What would you need to do if you wanted to test a solid
| substance?
grind substance and add distilled water to add fluidity
114
What is meant by a “reducing sugar”?
include all monosaccharides and disaccharides and they are known as reducing sugars because they can give electrons to other molecules
115
Why must you check there is no reducing sugar in a sample before testing for the presence of a non-reducing sugar?
because non reducing sugars don’t change the colour of the solution – this has led to sugar breakdown to monosaccharides by hydrolysis
116
# Define the following terms:
a) Reduction
b) Emulsion
c) Precipitate
the gaining of electrons
two or more liquids in which one is present as droplets
causing a solid to settle out of a solution
117
Why would a solution of amino acids give a negative result for the Biuret test?
when there no peptide bonds
118
Why do lipids form an emulsion in water?
lipids are insoluble in water and soluble in ethanol then added to H20 something tiny dispersed droplets in water
