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BIOLOGY > 1A - Biological molecules > Flashcards

1A - Biological molecules Flashcards

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AP® Biology flashcards Biology 101 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
Q

How does one test for starch

A

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

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26
Q

where is energy stored in animals

A

glycogen

animals store excess glucose as glycogen

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27
Q

describe glycogen

A

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

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28
Q

describe cellulose

A

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

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29
Q

what is a triglyceride

A

a type of lipid

one molecule of glycerine with three fatty acids attached

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30
Q

what does hydrophobic mean

A

they repel water

31
Q

describe fatty acid molecules

A

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
Q

how are triglycerides formed

A

condensation reaction

33
Q

describe how triglycerides are formed

A

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
Q

what are the two types of fatty acids

A

saturated and unsaturated

difference is in their hydrocarbon tails (r group)

35
Q

describe saturated fatty acids

A

don’t have any double bonds between their carbon atoms
the fatty acid is saturated with hydrogen

“saturated hydrocarbon tail”

36
Q

describe unsaturated fatty acids

A

have at least one double bond between carbon atoms, which cause chain to kink

“unsaturated hydrocarbon tail”

37
Q

what are phospholipids

A

lipids in cell membranes

38
Q

describe phospholipids

A

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
Q

what is hydrophilic

A

attracts water

40
Q

TRIGLYCERIDES

what is their main use

A

energy storage molecules

41
Q

TRIGLYCERIDES

how are the long hydrocarbon tails good for energy storage

A

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
Q

TRIGLYCERIDES

how is their insolubility good for energy storage

A

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
Q

PHOSPHOLIPIDS

what is their function

A

make up the bilayer of cell membranes

44
Q

PHOSPHOLIPIDS

more on function

A

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
Q

PRACTICAL

emulsion test for lipids

A

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
Q

what are the monomers of proteins

A

amino acids

47
Q

how is a dipeptide formed

A

when two amino acids join together

48
Q

how is a polypeptide formed

A

when more than two amino acids join together

49
Q

what are proteins made up of

A

one or more polypeptide

50
Q

what is the amino acid general structure

A

A carboxyl group (COOH) , an aminé or amino group (NH2) and an R group(variable)

51
Q

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

A

Glycine

52
Q

how are polypeptides formed

A

condensation reaction

bonds formed are called peptide bonds

53
Q

describe primary structure of proteins

A

this is the sequence of amino acids in the polypeptide chain

54
Q

describe the secondary structure of proteins

A

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
Q

describe tertiary structure of protein

A

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
Q

different bonds in the tertiary structure of protein

A 
hydrogen bonds
ionic bonds (attractions between negative and positive charges)

Disulphides bonds - whenever two molecules of the amino acid CYSTEINE come close together

57
Q

explain disulfide bridges

A

the sulfur atom in one cysteine bonds to the sulfur atom in another cysteine.

58
Q

describe quaternary structure of protein

A

some proteins are made of several different polypeptide chains held by bonds
this structure is the way they are assembled together

59
Q

name four examples of proteins

A

enzymes
antibodies
transport proteins
structural proteins

60
Q

how are enzymes specialised

A

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
Q

how are antibodies specialised

A

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
Q

how are transport proteins specialised

A

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
Q

how are structural proteins specialised

A

they are physically strong
consists of long polypeptide chains lying parallel to eachother with cross links between
include keratin and collagen

64
Q

PRACTICAL

biuret rest for proteins

A

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
Q

what’s an enzyme

A

enzymes speed up chemical reactions by acting as a biological catalysts without being used up

66
Q

what do enzymes do

A

lower the activation energy of a reaction

often causing reactions to happen at a lower temp

67
Q

what is a enzyme-substrate complex

A

when a substrate first into the enzymes active site

68
Q

why does the enzyme-substrate complex lower activation energy

A

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
Q

Why is the lock and key model of the enzyme not fully correct

A

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
Q

explain temperatures effect on enzymes

A

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
Q

explain ph effect on enzyme

A

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
Q

how does enzyme concentration effect rate of reaction

A

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
Q

how does substrate concentration effect the r of r

A

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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