Topic 1 - biological molecules Flashcards
1
Q
where do ionic bonds form?
what happens to the electrons?
A
between oppositely charged ions
the electrons swap
2
Q
what happens in covalent bonding?
A
electrons are shared
3
Q
use of nitrate ions N03-
A
needed in plants for formation of amino acids
4
Q
use of phosphate ions P043-
A
formation of ATP/ADP and DNA/RNA
5
Q
use of chloride ions Cl-
A
needed in nerve impulses and secretory systems
6
Q
use of hydrogen carbonate ions HC03-
A
needed for buffering the blood, prevent it from becoming too acidic
7
Q
use of sodium ions Na+
A
needed in nerve impulses and secretory systems
8
Q
use of calcium ions Ca2+
A
forms calcium pectate for middle lamella (plants)
bone formation and muscle contraction (animals)
9
Q
use of hydrogen ions H+
A
cellular respiration/photosynthesis/pH balance
10
Q
use of magnesium ions Mg2+
A
needed for production of chlorophyll (in plants)
11
Q
why is water a polar molecule?
A
the electrons are held closer to the oxygen
12
Q
what is the result of a differences of charges within a water molecule?
what’s formed? so….
A
hydrogen bonds are formed
molecules ‘stick’ together
13
Q
explain:
water is a polar solvent
A
many substances will dissolve in it
14
Q
explain:
water is adhesive
this is important for…
A
they are attracted to other molecules
important for transport and surface tension
15
Q
explain:
water reaches its maximum density at 4 degrees
A
freezes and becomes ice
ice is less dense so it floats
provides insulation
16
Q
explain:
water is cohesive
A
sticks to other water molecules
important for the movement of water in plants
17
Q
explain:
water is a transport medium
A
can carry substances
(eg in xylem and blood)
18
Q
explain:
water has a high HSC
A
takes a lot of energy to raise 1kg by 1 degree.
energy goes into breaking the bonds and not KE
less temperature fluctuations
more stable environment for organisms
19
Q
explain:
water has a high surface tension
due to…., a high surface tension is formed.
this provides…..
A
due to attraction between water molecules
provides a habitat
20
Q
what is the main use of carbohydrates?
A
store energy
21
Q
what are all carbohydrates made from?
A
carbon/hydrogen/oxygen
22
Q
what’s the general formula for monosaccharides?
A
(CH2O)n
23
Q
molecular formula for triose sugars
A
C3H6O3
24
Q
when are triose sugars important?
A
in the mitochondria when glucose is broken down into triose sugars (during respiration)
25
what is the molecular formula for a pentose sugar?
C5H10O5
26
give examples of pentose sugars
ribose
deoxyribose
27
give molecular formula for hexose sugar
C6H12O6
28
give examples of hexose sugars
(sweet taste)
glucose
fructose
galactose
29
draw ribose
(answer in textbook, page 19)
30
what are the two different isomers of glucose?
alpha glucose
beta glucose
31
draw alpha glucose
page 19 of textbook
32
draw beta glucose
page 19 of textbook
33
what are disaccharides made from?
what type of reaction?
what bonds are formed?
two monosaccharides
condensation reaction
forms glycosidic bonds
34
what two monosaccharides make this disaccharide?
maltose
a glucose + a glucose
35
what two monosaccharides make this disaccharide?
lactose
a glucose + galactose
36
what two monosaccharides make this disaccharide?
sucrose
a glucose + fructose
37
what is Benedict's solution a test for?
reducing sugars
38
substances that react with benedict's are called reducing sugars.
what is the colour change?
blue to orange
39
what is the name for sugars that don't react with benedict's solution?
non-reducing sugars
40
how do you go about testing a non-reducing sugar?
heat with hydrochloric acid (hydrolysis glycosidic bonds)
cool
neutralise with sodium hydrogen carbonate
this produces monosaccharides
41
what are molecules with 3-10 sugar units known as?
oligosaccharides
42
what are polysaccharides?
many monosaccharides (11+)
43
explain how the structure of polysaccharides makes them ideal storage molecules
-compact
-bonds
-solubility
they form very compact molecules so a lot can be stored in one cell
glycosidic binds are easily broken- rapid release of energy
not very soluble in water so have little osmotic effect
44
what is hydrolysis?
hydrolysis is the breaking of glycosidic bonds using a water molecule
45
give example of hydrolysis in the body
digestion in the gut
muscle and liver cells- when carbohydrates are broken down to release energy for respiration
46
what is starch broken down into when needed?
glucose
47
describe the structure of starch
alpha glucose
amylopectin + amylose
amylose (20%)
- straight chain
-1,4 glycosidic bonds
- as it lengthens, it spirals (compact)
amylopectin (80%)
-kinky
-branched
- 1,4 and 1,6 glycosidic bonds
48
what is glycogen used for?
carbohydrate store in animals and fungi
49
describe the structure of glycogen.
similar to amylopectin
1,4 and 1,6 glycosidic bonds
branched molecules
compact
50
describe the structure of cellulose
beta glucose
remains long and straight
1,4 glycosidic bonds
every other monomer is inverted so hydroxyl groups stick out
hydrogen bonds can form
crosslinking
51
use of cellulose
provided structure and support to plants (cell wall)
52
explain why the rate slows in an enzyme reaction
enzyme controlled reactions are often very rapid as substrate gets used up
less substrate = fewer collisions= rate slows
53
give uses of lipids
e… s…
integral part of ….
energy store
integral part of cell membranes
54
what are fats/oils made from?
fatty acids and glycerol- held together with ester bonds
55
what are two ways in which fatty acids can differ?
carbon chain length
whether it's saturated/unsaturated
56
what is the difference between a saturated and an unsaturated fatty acid?
unsaturated has a double carbon bonds
saturated has no double carbon bonds
57
what are
monounsaturated fatty acid
polyunsaturated fatty acid ?
monounsaturated- has one double carbon bond
polyunsaturated- many double carbon bonds
58
what is esterification?
a condensation reaction between the carboxyl group of the fatty acid and a hydroxyl group of the glycerol
(water molecule produced)
59
what happens when lipids are oxidised in respiration?
the bonds are ….. and ….. is produced
the bonds are broken and carbon dioxide and water are produced
60
explain these features of lipids:
waterproofing
insulating
low density
insoluble in water
waterproofs organisms
insulators- (fatty sheath insulates nerves and impulses travel faster) also keeps animals warm
low density- body fat of water animals helps them float
insoluble in water- do not interfere with water based reactions in the cell
61
what is the formula for phosphate ions?
PO43-
62
what is the structure of a phospholipid?
phosphate head, glycerol, two fatty acids- held together with ester bonds
63
describe how the different parts of a phospholipid respond to water.
phosphate head- hydrophilic- dissolves in water
fatty acid tails-hydrophobic- don't dissolve in water
64
where may a phospholipid monolayer form?
at surface between water and air
65
what do all proteins contain?
carbon, hydrogen, oxygen, nitrogen (and some contain sulfur)
66
what are proteins made from?
amino acids
67
what is the general formula for an amino acid?
page 28 (bottom left)
68
what do all amino acids have?
… group
….. group
… group
amino group (NH2)
carboxyl group (COOH)
R group (varies between amino acids- this is where sulfur is found if present)
69
how do amino acids join together?
amino group from one amino acid and carboxyl group from other (join in a condensation reaction)
peptide bond is formed
70
what is a dipeptide?
when two amino acids have joined
71
what is a polypeptide?
when many amino acids have joined together
72
when does a polypeptide become a protein?
when the polypeptide folds/coils or associates with other polypeptide chains
73
what determines the bonds within a protein?
give examples of these bonds
the bonds are determined based on the R group
hydrogen/ionic/disulphide
74
what causes hydrogen bonds in amino acids?
explain what hydrogen bonds' strength is like
oxygen has small negative charge
hydrogen has small positive charge
attracted to each other
hydrogen bonds are weak but if there are a lot of them they have a big effect and hold the amino acid together
75
when do disulfide bonds form in an amino acid?
when two cystine molecules are close
(both contain sulfur)
76
what type of reaction takes place in a disulfide bond?
results in?
oxidation reaction between the two groups, results in a covalent bond knows as a disulfide bond
77
when do ionic bonds form in an amino acid?
what are these known as?
between positive and negative amino acids
salt bridges
78
describe the primary structure of an amino acid
chain of amino acids held together with peptide bonds
79
describe the secondary structure of an amino acid
arrangement of chain into a repeating structure
alpha helix
beta pleated sheet
80
describe the tertiary structure of an amino acid
folding of the chains into a 3D shape, based on the R bonds
bonds hold this structure together
81
describe the quaternary structure of an amino acid
several polypeptide chains interacting
82
describe what fibrous proteins are like
l
p p c
c l
long, parallel polypeptide chains with occasional cross linkages
83
what function do fibrous protein play within an organism?
why are they good for this?
fibrous proteins play a structural role
insoluble in water and very tough
84
describe the structure of collagen
-type of protein
-amino acid sequence
-polypeptides per molecule
-each polypeptide is wound into a ..
-shape
fibrous protein
regular amino acid sequence (every third is glycine)
each molecule has 3 polypeptide chains
each polypeptide is wound into a left-handed helix
long and thin
85
describe the structure of haemoglobin
-type of protein
- number of prosthetic groups
-soluble/insoluble
-shape
-number of polypeptide chains
-role
-amino acid sequence
Globular protein
Regions of a helix and beta pleated sheet
4 prosthetic groups
Soluble
Spherical
4 polypeptide chains
Functional role
Irregular amino acid sequence
86
what are conjugated proteins?
protein molecules joined to a prosthetic group
87
what are glycoproteins?
what does this do?
proteins with a carbohydrate prosthetic group
makes the protein hold onto water- makes them harder to be broken down- and also aids mucus as it has lubricating properties
88
what are lipoproteins?
what does this do?
protein with lipids as a prosthetic group
helps transport cholesterol in the blood
89
what are the three parts of a nucleotide?
pentose sugar
nitrogen-containing base
phosphate group
90
what are the two options for the pentose sugar?
ribose (for RNA)
deoxyribose (for DNA)
91
what's the difference between ribose and deoxyribose?
deoxyribose contains one less oxygen atom than ribose
92
what is the difference between a purine and a pyrimidine?
they have different number of nitrogen-containing rings
purine- has two
pyrimidine- has one
93
how are the sugar, base and phosphate joined?
in a condensation reaction
(this forms a nucleotide)
94
how many phosphate groups does ATP have?
three
95
what happens to ATP when energy is needed?
what breaks off?
what reaction?
catalysed by?
to make?
third phosphate breaks off (in hydrolysis reaction)
catalysed by ATPase
makes ADP
96
what type of reaction is ATP to ADP?
reversible
97
what are nucleic acids made from?
nucleotide polymers
98
what do nucleic acids carry?
information needed to form new cells (DNA)
99
How are nucleotides joined to form a nucleic acid?
type of reaction
held by what (between which parts?)
join in a condensation reaction, they are held together by phosphodiester bonds
(between sugar of one nucleotide and phosphate group of the other)
100
describe the structure of RNA molecules
can f…. OR remain as l….
can fold into complex shapes due to hydrogen bonds or can remain as long molecules
101
what does a purine always pair with?
a pyrimidine
102
how many hydrogen bonds are formed between C and G
3
103
how many hydrogen binds are formed between A and T?
2
104
how many base pairs are there for one complete twist on the helix?
10
105
what are the two strands called? (according to how many C on pentose)
5 prime
3 prime
106
How does semi-conservative replication work?
the DNA unzips and new nucleotides align along each strand
the new double helix contains one original and one new strand
107
what is the difference between N14 and N15?
N15 is heavier
108
Why do some bases in a gene not code for an amino acid?
they are start/stop codons
some parts of the gene are introns
109
how many amino acids are there?
20
110
where does the process of translation happen?
on the ribosome
111
what is the sequence of three bases called?
a codon
112
what is meant by DNA being a triplet code?
DNA is a triplet code therefore, it is read in threes
every 3 bases codes for one amino acid
4x4x4 (there are four bases and it's TRIPLET)
113
what is meant by DNA having a non-overlapping code?
each sequence of three bases is read individually
114
what is meant by DNA having a degenerate code?
if final base changes, (in mutation), it would still produce the same amino acid
115
differences between DNA and RNA
DNA double/two strands, RNA single strand
DNA made from deoxyribose as nucleic acid wheras RNA has ribose
116
where is mRNA formed?
in the nucleus
(on the anti-sense strand)
117
what does ligase do in DNA replication?
ligase joins sections of DNA together, forming phosphodiester bonds between sugar and phosphate
118
mRNA is complementary to the ....
anti sense strand
119
mRNA is the same as the....
(T has become U)
the sense strand
120
what is a start/stop codon?
determines where to start/stop translating
121
what are two important features of tRNA and what are their uses?
amino acid binding site
anticodon- complementary to mRNA's anticodons
122
describe how a quaternary structure is formed after protein synthesis has occurred.
polypeptide folds into either alpha helix or beta pleated sheet
two or more polypeptides join together , held by h bonds or disulphide bridges.
123
what is activation energy?
activation energy is the energy required for a reaction to occur , by making bonds weak and break , increasing number of collisions
124
why is it necessary to investigate the initial rate of reaction when investigating enzymes?
at this point , there should be enough substrates to saturate enzymes.
ensure substrate is not limiting factor.
highest rate- as reaction continues, substrate conc decreases because it is used up in reactions.
125
explain what is meant by the term sustainable.
a resource that can be renewed, it is not finite
it is available to future generations.
126
describe the structure of a globular protein
has tertiary structure
has quaternary structure
hydrophobic on outside of molecule.
