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A-level biology OCR > 2.1.2 Biological molecules > Flashcards

2.1.2 Biological molecules Flashcards

(73 cards)

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1
Q

Draw a diagram to show hydrogen bonding between two water molecules

A

image in file

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2
Q

What kind of molecule is water

A

polar

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3
Q

When do hydrogen bonds form?

A

Slightly negative oxygen of one molecule comes close to a slightly positively charged hydrogen in another molecule

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4
Q

Why does water have an unsually high boiling point

A

Lots of energy needed to break many hydrogen bonds

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5
Q

Benefits of ice being less dense than water

A

creates an insulating barrier for aquatic animals under water, habitat for animals such as polar bears

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6
Q

Explain cohesion as a property of water

A

Creates a high surface tension for insects to walk on

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7
Q

Explain the adhesion property of water molecules

A

waters attraction to other molecules/surfaces

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8
Q

Explain the solvent property of water molecules

A

allows mineral ions to be transported around plants and animals

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9
Q

Explain the transport medium property of water molecules

A

Allows transport of soluble substances around the body

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10
Q

Explain the cooling mechanism property of water molecules

A

evaporating water takes heat away from the body

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11
Q

Explain the HSHC of water & why this is good

A

means: need lots of energy to heat water up by one degree
good because: stable temperature, enzymes can work at optimum, gases remain soluble for aquatic organisms

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12
Q

Explain the HLHV of water & why this is good

A

means: lots of enrgy to change water from liquid to gas
good because:prevents big temperature changes in environments

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13
Q

Explain the capillary action property of water & why this is good

A

Allows water to move up narrow vessels,

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14
Q

When does a condenstaion reaction occcur?

A

When a water molecule is removed to form a covalent bond

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15
Q

When does a hydrolysis reaction occur?

A

When a water molecule is added to break a covalent bond

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16
Q

Give the chemical elements that make up the following:
-carbohydrates
-lipids
-proteins
-nucleic acids

A

Carbohydrates=C,H,O
Lipids=C,H,O
Proteins=C,H,O,N,S
Nucleic acids=C,H,O,N,P

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17
Q

Define a monosaccharide and give 3 common examples

A

one unit of sugar
examples: glucose,galactose,fructose

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18
Q

Define a disaccharide

A

made of 2 monosaccharide molecules joined together

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19
Q

Define a polysaccharide and give an example

A

long chain of monosaccharides such as starch

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20
Q

Draw the structure of alpha and beta glucose

A

Diagram in 📂

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21
Q

2 properties of glucose

A

-hexose sugar
-reducing sugar

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22
Q

Draw the structure of ribose

A

diagram in 📂

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23
Q

What kind of sugar is ribose? Where can it be found?

A

pentose sugar found in RNA

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24
Q

glycosidic bond btwn…

A

carbohydrates

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25
peptide bond btwn...
amino acids
26
ester bond btwn...
fatty acids and glycerol
27
phosphodiester bond btwn...
nucleotides in nucleic acids
28
disulphide bonds btwn...
sulfur atoms in cysteine amino acids
29
maltose is...
alpha glucose + alpha glucose
30
lactose is...
beta glucose + galactose
31
sucrose is made of..
alpha glucose + fructose
32
what two polysaccharides is starch made of?
amylose and amylopectin
33
Fill in the gaps: both don't ___________ therefore don't effect the __________ _________
dissolve, water potential
34
bonding in amylose? what structure does it appear as?
alpha 1,4 glcyosdic bonds, coiled structure
35
bonding in amylopectin?
1,4 and 1,6 glycosidic bonds
36
what do the bonds in amylopectin create and why is this good?
Create: branches Good because: allows hydrolysis of ends by enzyme to create monisaccharides available for aerobic respiration
37
bonds in glycogen?
alpha 1,4 and 1,6 glycosidic bonds
38
properties of glycogen?
won't affect wp, compact, branched ends which can be hydrolyzed by enzymes to create alpha glucoses again
39
where are starch and glycogen stored?
starch=plants glycogen=mammalian livers
40
cellulose is formed from.... cellulose will _____________ every _______ to form ________ ________________ ____
beta glucose rotate,180 degreees, 1,4 glycosidic bonds
41
how do beta glucose molecules form beta pleated sheets? they provide....
hydrogen bonds can form cross links to form bundles called microfibrils a high tensile strength
42
draw and label the general structure of an amino acid
diagram in 📂
43
what is different btwn the 2o different amino acids?
the r group
44
explain dipeptide bonds
bond btwn 2 amino acids, water molecule released
45
draw 2 glycines forming a peptide bond
diagram in 📂
46
define primary protein structure
sequence of amino acids bonded by peptide bonds
47
define secondary protein structure
folding of polypeptide chain held in place by hydrogen bonds: alpha helix or beta pleated sheets
48
defne tertiary structure of a protein
-further folding of polypeptide chain -held in place with hydrogen bonds,disulphide bridges, ionic bonds -hydrophobic r groups orientate towards the center of the protein, hydrophillic ones outside
49
define quarternary structure
more than 1 polypeptide chain
50
describe fibrous proteins
-strong so provide structural roles - e.g keratin so more disulphide bridges within the keratin, the stronger (hair) - insoluble in water due to lots of amino acids with hydrophobic r groups -V strong bcz many cross bridges btwn polypeptide chains
51
2 fibrous proteins (not keratin)
elastin=alveoli - recoils after being deformed collagen=skin - flexible but doesn't strech
52
properties of globular proteins
-compact, 3d globular shape - soluble in water bcz amibo acids w/hydrophobic r groups in center of protein -conjugated proteins have a prosthetic r group
53
what's a prosthetic group? found in what protein?
non-polypeptide component tightly bound to a protein - conjugated protein
54
3 main globular proteins
insulin=specific fixed shape haemoglobin (conjugated) = can change shape catalase (conjugated) = specific fixed shape
55
give biological uses of the following cations: Ca2+ K+ Na+ H+ NH4+
Ca2+ - muscle contraction, bohr effect K+ - nerve impulses Na+ - nerve impulses, selective reabsorption H+ - translocation,photosynthesis, respiration, co-enzymes NH4+ - nitrogen cycle
56
give biological uses of the following anions: - NO3- - HCO3- - Cl- - PO4)^3- - OH-
- NO3- nitrogen cycle - HCO3- bohr effect - Cl- bohr effect - PO4)^3- DNA, RNA, ATP, phospholipids - OH- photosynthesis
57
biuret test 4 proteins
blue solution turns purple if protein is present
58
benedicts test for reducing and non-reducing ugars
reducing: heat sample w/benedicts non-reducing: heat sample w/benedicts, no change then heat w/hcl & add an excess of NaOH -Heat sample w/benedicts
59
why do we add HCl in benedicts? why add NaOH?
-HCl breaks glycosidic bond in non-reducing sugar to give two reducing sugars - TO NEUTRALIZE THE ACID
60
Reducing sugar exxamples
glucose, lactose, galactose, ffructose
61
non reducing sugar to know?
sucrose
62
emulsion test?
-few drops ethanol -shake -pour over water -lipids present = white emulsion should form
63
How to caibrate a calorimeter
-fill cuvette w/distilled water (blank) -put inside calorimeter + close lid - press cal button to set to zero -set red filter -measure absorbance
64
PEQ: Describe how the concentration of a reducing sugar can be measured uing a calorimeter (7pnts)
1)serial dilution 2)benedicts test 4 both types of sugars on KNOWN + UNKNOWN CONCS 3)filter precipitate 4)use calorimeter to determine absorbance 5) plot a calibration curve 6) high glucose conc = low absorbance 7)read graph to find unknown conc
65
how to do thin layer paper chromatography
- sample on pencil line (on,dry x 10) -stationary paper= dried layer of silica gel on chromatogram - only handle edges to avoid contamination - place sample in solvent and allow it 2 travel up - solvent MUST be below pencil line otherwise sample will dissolve - lighter ones travel higher - to see amino acids, spray w/ninhydrin=purple -draw solvent front
66
RF formula
sample distance/solvent distance
67
Tiglyceride structure? bonds? condensation or hydrolysis?
3 fatty acids + glycerol, joined w/ester bonds condensation
68
draw a gglycerol and a faty acid(gg-get it😏)
diagram in 📂
69
difference in saturated vs unsaturated fatty acids
can't li close 2 another unsaturated triglyceride=less dense substance
70
phospholipid structure?
2 fatty acids, 1 phosphate, 1 glycerol - fatty acids non-polar and hydrophobic - phosphate group is polar and hydrophilic
71
triglyceride function?
-storing enrgy bcz release water when broken down -insoluble so don't affect water potential -make hormones -waterproofing -buouyancy -forming insulation layers -protective layers around organs -myelin sheath -aids fat absorption; fat soluble molecules
72
function of chloesterol
- 4 carbon ring structure - regulate fluidity
73
temperature effect of cholesterol on membranes
- low temp, cholesterol increases fluidity - high temp, cholesterol decreases fluidity

A-level biology OCR (14 decks)

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