1a biological molecules Flashcards
1
Q
what are most carbohydrates
A
polymers
2
Q
polymers
A
large, complex molecules composed of long chains of monomers joined together
3
Q
monomers
A
small basic molecular units
4
Q
examples of monomers
A
-monosaccharides
- amino acids
- nucleotides
5
Q
what are carbohydrates made up off
A
monosaccharides
6
Q
which elements do all carbohydrates contain
A
Carbon, Hydrogen, and Oxygen
7
Q
which monomer are carbohydrates made off
A
monosaccharides
8
Q
what is glucose
A
a hexose sugar
9
Q
what is a hexose sugar
A
a monosaccharide with six carbon atoms in each molecule
10
Q
two types of glucose
A
alpha and beta
11
Q
what are alpha and beta glucose
A
isomers
12
Q
isomers
A
molecules with the same molecular formula but the atoms connected in a different way
13
Q
where is the OH group on alpha glucose
A
bottom right
14
Q
where is the OH group on beta glucose
A
top right
15
Q
condensation reaction
A
when two molecules join together with the formation of a new chemical bond and a water molecule is released when the bond is formed
16
Q
how are monosaccharides joined together
A
by condensation reactions
17
Q
glycosidic bond
A
forms between two monosaccharides and a molecule of water is released
18
Q
when is a disaccharide formed
A
when two monosaccharides join together
19
Q
glucose + glucose
A
maltose
20
Q
glucose + fructose
A
sucrose
21
Q
glucose + galactose
A
lactose
22
Q
how can polymers be broken down into monomers
A
hydrolysis reactions
23
Q
hydrolysis reaction
A
when the chemical bond between monomers is broken using a water molecule
24
Q
how can carbohydrates be broken down into monosaccharides
A
using hydrolysis reactions
25
sugar
general term for monosaccharides and disaccharides
26
how can all sugars be classified
as reducing or non reducing
27
what is the test for sugars
benedicts reagent
28
reducing sugars
all monosaccharides and some disaccharides
29
test for reducing sugars
1. add benedicts reagent (blue) to a sample and heat it in a water bath thats been brought to a boil
2. if the test is positive it will form a coloured precipitate
30
precipitate
solid particles suspended in a solution
31
how does the concentration of reducing sugars effect the colour of the solution
the higher the concentration, the further the colour change goes. blue-green-yellow-orange-brick red
32
what is a more accurate way to compare the amount of reducing sugars in different solutions
filter the solution and weigh the precipitate
33
what could still be present if there are none reducing sugars present
non-reducing sugars
34
how do you test for non-reducing sugars
1. first you have to break them down into monosaccharides by adding dilute hydrochloric acid and carefully heating it in a water bath that has been brought to a boil
2. you then neutralise it with sodium hydrogen carbonate
3. then carry out the benedict's test as you would for a reducing sugar
35
when is a polysaccharide formed
when more than two monosaccharides are joined together by condensation reactions
36
what are three examples of polysaccharides
starch
glycogen
cellulose
37
where do cells get energy from
glucose
38
what do plants store extra glucose as
starch
39
what happens when a plant needs more glucose for energy
it breaks down starch to release the glucose
40
starch
a mixture of two polysaccharides of alpha glucose - amylose and amylopectin
41
amylose
a long unbranched chain of alpha glucose
- the angles of the glycosidic bonds give it a coiled structure, almost like a cylinder
- this makes it compact, so its really good for storage because you can fit more into a small space
42
amylopectin
long branched chains of alpha glucose
- its side branches allow the enzymes to break down the molecule to get at the glycosidic bonds easily this means that the glucose can be released quickly
43
solubility of starch
insoluble in water and doesn't affect water potential so it doesn't cause water to enter cells by osmosis, which would make them swell. this makes it good for storage.
44
test for starch
iodine test
45
iodine test
add iodine dissolved in potassium iodide solution to the test sample
if there is starch present, the sample changes from browny-orange to a dark blue-black colour
46
where do animal cells get energy from
glucose
47
what do animal cells store excess glucose as
glycogen
48
what is glycogen
another polysaccharide of alpha glucose
49
structure of glycogen
similar to amylopectin except it has loads more side branches coming off it. loads of branches means that stored glucose can be released quickly, which is important for energy release in animals
- also very compact so good for storage
50
cellulose
made of long, unbranched chains of beta-glucose
51
what happens when beta glucose molecules bond
they form straight cellulose chains
52
how are the cellulose chains linked together and what do they form
by hydrogen bonds to form strong fibres called microfibrils
53
why does cellulose form strong fibres
to provide structural support for cells
54
what is a triglyceride
a molecule of glycerol with three fatty acids attached to iit
55
what is a fatty acids tail made from
hydrocarbons
56
what are the tails
hydrophobic
57
hydrophobic
they repel water molecules
58
what do the hydrophobic tails do
make lipids insoluble in water
59
what varies with fatty acids
the hydrocarbon tail
60
how are triglycerides formed
condensation reactions
61
how does a glycerol molecule join to a fatty acid
an ester bond is formed and a molecule of water is released
62
how many condensation reactions are used to make 1 triglyceride
3
63
how man kinds of fatty acids are there
2
64
what are the two kinds of fatty acids
saturated and unsaturated
65
what is the difference between a saturated and unsaturated fatty acid
their hydrocarbon tails
66
saturated fatty acids
dont have any double bonds between their carbon atoms. the fatty acid is saturated with hydrogen
67
unsaturated fatty acids
have at least one double bond between carbon atoms, which causes the chain to kink
68
what are the lipids found in cell membranes
phospholipids
69
difference between phospholipids and triglycerides
one of the fatty acid molecules is replaced by a phosphate group
70
how does the phosphate group react to water
hydrophilic
71
hydrophilic
attracts water
72
what are triglycerides mainly used for
energy storage molecules
73
why are triglycerides good energy storage molecules
- the long hydrocarbon tails of fatty acids contain lots of chemical energy and a load of energy is released when they are broken down. becasue of these tails lipids contain twice as much energy per gram as carbohydrates
- theyre insoluble, so they dont affect the water potential of the cell and cause water to enter the cell through osmosis which would make them swell.
- they clump together as insoluble droplets in cells because the fatty acid tails are hydrophobic, the tails face inwards, shielding themselves from water with their glycerol heads
74
what do phospholipids make up
the bilayer of cell membranes
75
role of cell membranes
control what enters and leaves a cell
76
why are phospholipids good bilayers in cell membranes
- their heads are hydrophilic and their tails are hydrophobic, so they form a double layer with their heads facing out towards the water on either side
- the centre of the bilayer is hydrophobic, so the water soluble substances cant easily pass through it - the membrane acts like a barrier to those substances
77
what is the test for lipids
emulsion test
78
emulsion test
1. shake the test substance with ethanol for about a minute so that it dissolves, then pour the solution into water
2. any lipid will show up as a milky emulsion
3. the more lipid there is, the more noticeable the milky colour will be
79
what are proteins made form
long chains of amino acids
80
what is the monomer of proteins
amino acids
81
what is a dipeptide
when two amino acids join together
82
what is a polypeptide
when two or more amino acids join together
83
what is a protein
one or more polypeptides
84
what do different amino acids have
different variable groups
85
what is the general structure of an amino acid
a carboxyl group
- an amine group or amino group
- an R group (variable side group
86
what do all living things share
a bank of only 20 amino acids
87
what is the only difference between the 20 amino acids
what makes up their R group
88
how are polypeptides formed
condensation reactions
89
how are amino acids linked togehter
condensation reactions to form polypeptides. a molecule of water is released during the reaction
90
what is the name of the bond formed between amino acids
peptide bonds
91
when are peptide bonds broken
during digestion
92
what are the 4 different strucutres a protein can have
- primary
- secondary
- tertiary
- quaternary
93
primary structure
the sequence of amino acids in the polypeptide chain
94
secondary structure
- polypeptide chain doesnt remail flat and straight
- hydrogen bonds form between the amino acids in the chain
- causes it to automatically coil into an alpha helix or fold into a beta pleated sheet
95
tertiary structure
- the coiled or folded chain of amino acids is often coiled and folded further
- more bonds form between different parts of the polypeptide chain (including hydrogen and ionic bonds)
- disulfide bridges also form whenever two molecules of the amino acid cysteine come close together (the sulfur atom in one cysteine bonds to the sulfer atom in the other
- for proteins made from a single polypeptide chain, the tertiary structure forms their final 3D structure
96
quaternary structure
- proteins made of several polypeptide chains held together with bonds
- final structure for proteins made of more than one polypeptide chain
97
protein functions
- enzymes
- antibodies
- transport proteins
- structural proteins
98
proteins - enzymes
- spherical in shape due to tight folding of polypeptide chains
- soluble
- have roles in metabolism, break down large food molecules
- can synthesise large molecules
99
proteins - antibodies
- involved in the immune response
- made from two short polypeptide chains and two long polypeptide chains bonded together
- have variable regions
- amino acid sequences in these regions vary greatly
100
transport proteins
- present in cell membranes
- contain hydrophobic and hydrophilic amino acids which causes the proteins to fold up and form a channel
- transport molecules and ions across membranes
101
structural proteins
- physically strong
- made of long polypeptide chains laying parallel to eachother with cross-links between them
- include keratin and collagen
102
test for proteins
biuret test
103
biuret test
1. test solution must be alkaline so you first add a few drops of sodium hydroxide solution
2. then you add some copper(II) sulfate solution
- if protein is present the solution turns purple
- if there is no protein present, the solution will stay bluee
104
how do enzymes speed up chemical reactions
by acting as biological catalysts
105
what kind of reactions do enzymes catalyse
metabolic reactions both at a cellular level and for the organism as a whole
106
what can enzyme effect
the structures in an organism as well as functions
107
enzyme action can be...
intracellular and extracellular
108
intracellular
within cells
109
extracellular
outside cells
110
what are enzymes
proteins
111
what do enzymes have
an active site, which has a specific shape
112
active site
the part of the enzyme where the substrate molecules bind to
113
why are enzymes highly specific
due to their tertiary structure
114
activation energy
the amount of energy required to start a chemical reaction
115
how is activation energy often provided
as heat
116
how do enzymes effect activation energy
they lower it, allowing reactions to take place at a lower temperature
117
how do enzymes effect rate of reaction
speeds it up
118
enzyme- substrate complex
when a substrate first into the enzymes active site
this is what lowers activation energy
119
why does an enzyme substrate complex lower activation energies
if two substrate molecules need to be joined being attatched to the enzyme holds them together, reducing any repulsion between the molecules so they can bond more easily
120
lock and key model
the substrate fits into the enzyme in the same way a key fits into a lock
121
what is the name of the new model of enzyme-substrate complex
induced fit
122
what does the induced fit model help to explain
why enzymes are so specific and only bond to one particular substrate
123
how does the induced fit model work
the substrate doesnt only have to be the right shape to fit the active site, but has to make the active sit change shape in the right way
124
why are enzymes very specific
they only catalyse one reaction because only one complementary substrate will fit into the active site
125
what determines the active site shape
the enzymes tertiary structure
126
what does each different enzyme have
a different tertiary structure and therefore a different active site
127
what happens if the substrate shape doesnt match the active site
an enzyme-substrate complex wont be formed and the reaction wont be catalysed
128
what happens if the tertiary structure is altered
the shape of the active site will change which means the substrate wont fit into the active site, an enzyme-substrate complex wont be formed and the enzyme will no longer be able to carry out its function
129
how can the tertiary structure be altered
by changes in pH or temperature
130
what is the primary structure of a protein determined by
a gene, if a mutation occurs in that gene, it could change the tertiary structure of the enzyme produced
131
temperature effect on enzyme activity
the rise in temperature makes the enzymes molecules vibrate more
if the temp goes above a certain level this vibration breaks some of the bonds that hold the enzyme in shape
the active site changes shape and the enzyme and substrate no longer fit together
at this point the enzyme is denatured and no longer functions as a catalyst
132
pH effect of enzyme activity
enzymes have an optimum pH
if not at optimumm pH it can mess up the ionic and hydrogen bonds that hold the enzymes tertiary structure in place. this makes the active site change shape, so the enzyme is denatured
133
enzyme concentration affects on rate of reaction
the more enzyme molecules there are in a solution the more likely a substrate molecule is to collide with one and form an enzyme- substrate complex so increasing the concentration of the enzyme increases the rate of reaction
but if the amount of substrate is limited there comes a point where there is more than enough enzyme molecules to deal with all the available substrate, so adding more enzyme has no further effect
134
substrate concentration of rate of reaction
the higher the substrate concentration the faster the reaction, more substrate mean a collision between substrate and enzyme is more likely and so more active sites will be used. this is only true up until a saturation point though after that there are so many substrate molecules that the enzymes have filled all there active sites and therefore there is no difference
decreases with time during a reaction so if no other variables are changed rate of reaction will decrease over time aswell
135
what is a competitive inhibitor
molecules that have a similar shape to that of the substrate molecules
136
what do competitive inhibitors do
they compete with the substrate molecules to bind to the active site but no reaction takes place.
instead they block the active site so no substrate molecules can fit in
137
what happens if there is a high conc. of competitive inhibitors
they will take up nearly all of the active sites and hardly any of the substrate will get to the enzume
138
what happens if there is a higher conc. of substrates then competitive inhibitors
the chances of substrates getting to an active site before inhibitor increases therefore rate of reaction will increase
139
what is a non-competitive inhibitor
moleucles that bind to the enzyme away from the active site
140
what do non-competitive inhibitor do
changes the shape on the active site so substrate molecules can no longer bind to it as they are a different shape
141
what happens when you increase the conc. of substrate with a non-competitive inhibitor
wont make any difference to the reaction rate. enzyme activity will still be inhibited
142
what are the two ways to measure the rate of an enzyme controlled reaction
1. measuring how fast the product of the reaction is made
2. measure how fast the substrate is broken down
143
how are the results of enzyme-controlled reactions usually shown
in line graphs
