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BIOLOGY > 1A - Biological molecules > Flashcards

1A - Biological molecules Flashcards

1
Q

what is a polymer

A

large complex molecules composed of long chains of monomers joined together

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2
Q

what is a monomer

A

small basic molecular units

eg. monosaccharides, amino acids and nucleotides

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3
Q

which elements do all carbohydrates contain

A

C, H & O

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4
Q

describe sugar glucose brief

A

HEXOSE SUGAR - a monosaccharide with 6 carbon atoms

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5
Q

three examples of monosaccharides

A

glucose, fructose & galactose

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6
Q

glucose formula

A

C6H12O6

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7
Q

what is an isomer

A

molecules with the same molecular formula as each other but atoms are connected in different way
eg. glucose -Alpha and Beta

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8
Q

What is a 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

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9
Q

How are monosaccharides joined together

A

By condensation reaction

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10
Q

what happens when condensation reaction joins monosaccharides

A

1) a glycosidic bond forms between the two monosaccharides as a molecule of water is released
2) a disaccharide is formed

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11
Q

what sugar is formed by the condensation reaction between glucose molecule and fructose molecule

A

sucrose

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12
Q

what is formed from a glucose and galactose molecule in condensation reaction

A

lactose disaccharide

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13
Q

what is formed by the condensation reaction between two glucose

A

maltose

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14
Q

What reaction breaks polymers apart

A

hydrolysis

- breaks polymers into monomers

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15
Q

How does a hydrolysis reaction work

A

breaks the chemical bond between monomers using a water molecule -( basically the opposite of a condensation reaction)

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16
Q

what are the reducing sugars

A

all monosaccharides and some disaccharides eg.( lactose and maltose)

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17
Q

BENEDICTS TEST FOR SUGAR

reducing sugars

A

1) add BENEDICTS REAGENT (which is blue) to a sample and heat it in a water bath that’s been brought to boil
2) if the test is positive it will form a coloured precipitate (blu/gre/yell/oran/red)
3) higher the concentration of reducing sugar= further colour change
4) more accurate way is to filter the solution and weigh the precipitate

EXTRA- always add benedicts solution in excess so all sugar reacts

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18
Q

BENEDICTS TEST

non reducing sugars

A

(if reducing test is negative there still may be non reducing)

1) turn into monosaccharides by getting a new sample of test solution and adding dilute hydrochloric acid and heating with water bath that’s been brought to boil
2) then neutralise it with sodium hydrogencarbonate and carry out the benedicts test as normal

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19
Q

what is a polysaccharide

A

loads of sugars joined together

formed when more than two monosaccharides are joined by a condensation reaction

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20
Q

Three polysaccharides

A

starch, glycogen and cellulose

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21
Q

where is energy stored in plants

A

cells get energy from glucose and plants store excess glucose as starch

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22
Q

what is starch a mixture of

A

two polysaccharides of alpha glucose

  • amylose
  • amylopectin
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23
Q

describe amylose

A

Long unbranched chain of alpha glucose
angles of glycosidic bonds give it a coiled structure meaning it’s compact and good for storage as it fits more in a small space

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24
Q

describe Amylopectin

A

Long branched chain of alpha glucose
it’s side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily meaning glucose can be released quicker

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25
How does one test for starch
IODINE test 1)add iodine dissolved in potassium iodide solution to the test sample 2)if there is starch present the sample will change form browny orange to blue black
26
where is energy stored in animals
glycogen | animals store excess glucose as glycogen
27
describe glycogen
polysaccharide of alpha glucose similar to amylopectin but has way more branches off it so stored glucose can be released quickly very compact so also good at storing
28
describe cellulose
major component of cell walls long unbranched chains of beta glucose when beta glucose bond they form straight cellulose chains cellulose chains linked together by hydrogen bonds to form strong bonds called microfibrils for structural support
29
what is a triglyceride
a type of lipid | one molecule of glycerine with three fatty acids attached
30
what does hydrophobic mean
they repel water
31
describe fatty acid molecules
long tails made of hydrocarbons the tails are hydrophobic -meaning these tails make lipids insoluble in water all fatty acids have same basic structure but the hydrocarbon tail is what varies
32
how are triglycerides formed
condensation reaction
33
describe how triglycerides are formed
fatty acid joins glycerol molecule ester bond is formed and a molecule of water is released (condensation reaction) this happens twice to form a triglyceride
34
what are the two types of fatty acids
saturated and unsaturated difference is in their hydrocarbon tails (r group)
35
describe saturated fatty acids
don’t have any double bonds between their carbon atoms the fatty acid is saturated with hydrogen “saturated hydrocarbon tail”
36
describe unsaturated fatty acids
have at least one double bond between carbon atoms, which cause chain to kink “unsaturated hydrocarbon tail”
37
what are phospholipids
lipids in cell membranes
38
describe phospholipids
similar to triglycerides but instead one of the fatty acids is replaced by a phosphate group the phosphate group is hydrophilic which is important in cell membrane
39
what is hydrophilic
attracts water
40
TRIGLYCERIDES | what is their main use
energy storage molecules
41
TRIGLYCERIDES | how are the long hydrocarbon tails good for energy storage
the long hydrocarbon tails of the fatty acids contain lots of chemical energy- lots of energy is released when they’re broken down because of these tails lipids contain twice as much energy per gram as carbohydrates
42
TRIGLYCERIDES | how is their insolubility good for energy storage
they’re insoluble so don’t affect water potential of cell and cause water to enter by osmosis triglycerides clump as insoluble droplets as the fatty acid tails are hydrophobic - the tails face inwards shielding from water with there glycerol heads
43
PHOSPHOLIPIDS | what is their function
make up the bilayer of cell membranes
44
PHOSPHOLIPIDS | more on function
their heads are hydrophilic and there tails are hydrophobic so they form double layer with heads facing out towards water on both sides center of bilayer is hydrophobic so water soluble substances can’t easily pass through - therefore membrane acts as a barrier to those substances
45
PRACTICAL | emulsion test for lipids
1) shake the test substance with ethanol for a min so it dissolves then pour into water 2) ant lipid will show up as milky emulsion 3) the more lipid there is the more noticeable the milky colour will be at top
46
what are the monomers of proteins
amino acids
47
how is a dipeptide formed
when two amino acids join together
48
how is a polypeptide formed
when more than two amino acids join together
49
what are proteins made up of
one or more polypeptide
50
what is the amino acid general structure
A carboxyl group (COOH) , an aminé or amino group (NH2) and an R group(variable)
51
what is the only amino acid which doesn’t have carbon in its side group and it’s R group consists of one hydrogen atom
Glycine
52
how are polypeptides formed
condensation reaction | bonds formed are called peptide bonds
53
describe primary structure of proteins
this is the sequence of amino acids in the polypeptide chain
54
describe the secondary structure of proteins
the amino acids in the polypeptide chain form hydrogen bonds between themselves this makes it cool into an alpha helix or fold into a beta pleated sheet
55
describe tertiary structure of protein
the coiled/ folded chains are coiled and folded more more bonds form between different parts of the molecule for proteins made from a single polypeptide chain the tertiary structure is their final 3d structure
56
different bonds in the tertiary structure of protein
``` hydrogen bonds ionic bonds (attractions between negative and positive charges) ``` Disulphides bonds - whenever two molecules of the amino acid CYSTEINE come close together
57
explain disulfide bridges
the sulfur atom in one cysteine bonds to the sulfur atom in another cysteine.
58
describe quaternary structure of protein
some proteins are made of several different polypeptide chains held by bonds this structure is the way they are assembled together
59
name four examples of proteins
enzymes antibodies transport proteins structural proteins
60
how are enzymes specialised
spherical shape due to tight folding polypeptide chains soluble and have roles in metabolism —eg. some enzymes break down large food molecules and other enzymes help to synthesise large molecules
61
how are antibodies specialised
involved in immune system made up of two light polypeptide chains and two heavy bonded together antibodies have variable regions—the amino acid sequences in these regions vary greatly
62
how are transport proteins specialised
present in cell membranes contain hydrophobic and hydrophilic amino acids which causes the protein to fold and form chanel these proteins transport molecules and ions across membranes
63
how are structural proteins specialised
they are physically strong consists of long polypeptide chains lying parallel to eachother with cross links between include keratin and collagen
64
PRACTICAL | biuret rest for proteins
1) test solution needs to be alkaline so first add few drops of sodium hydroxide solution 2) add some copper (ll) sulfate solution if protein present turns PURPLE if not stay blue
65
what’s an enzyme
enzymes speed up chemical reactions by acting as a biological catalysts without being used up
66
what do enzymes do
lower the activation energy of a reaction often causing reactions to happen at a lower temp
67
what is a enzyme-substrate complex
when a substrate first into the enzymes active site
68
why does the enzyme-substrate complex lower activation energy
1) if two Substrate molecules need to be joined being attached to the enzyme hold them close together reducing any repulsion between the two molecules so they can bond more easily 2) If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on the bonds in the substrate, so the substrate molecule breaks up more easily
69
Why is the lock and key model of the enzyme not fully correct
New evidence shows that the enzyme substrate complex changes shape slightly to complete the fit this lock the substrate even more tightly to the enzyme and this is called the INDUCED FIT model
70
explain temperatures effect on enzymes
1) rise in temp=enzymes molecules vibrate more 2) if temp goes above certain point the vibrations break bonds that hold the enzyme in shape 3) active site changes shape= substrate no longer fits 4) denatures
71
explain ph effect on enzyme
ph is above or below optimum ph level= H+ and OH- ions can mess up ionic and hydrogen bonds that hold the enzymes tertiary structure together causing active site to change shape= denature
72
how does enzyme concentration effect rate of reaction
1) more enzymes=more likely a substrate molecule is to collide and form enzyme-substrate complex therefore increasing r of r 2) however if substrate is limited there comes a point where increasing concentration is no longer effective
73
how does substrate concentration effect the r of r
only up to saturation point 1) after saturation point all enzymes active sites are full and adding more substrate will make no difference 2) substrate concentration decreases over time causing rate to decrease

BIOLOGY (20 decks)

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