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Biology old > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

how do hydrogen bonds form between water molecules

A

water is polar-oxygen slightly - and hydrogen slightly +
intermolecular forces of attraction between oxygen and hydrogen on opposite molecule

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2
Q

state 5 properties of water

A

high specific latent heat of vaporisation
high specific heat capacity
cohesive
good solvent
lower density when solid

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3
Q

why does ice float and why is this important

A

ice is less dense as h bonds hold molecules in fixed positions further away
insulates water so aquatic organisms can survive

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4
Q

why is high surface tension important for organisms

A

slows water loss due to transpiration in plants
some insects can skim across water surface

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5
Q

why is water an important solvent for organisms

A

dissolves and transports charged particles involved in intra and extracellular reactions

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6
Q

why is high specific heat capacity important for organisms

A

hydrogen bonds can absorb a lot of energy and it takes a lot of energy to heat water
doesnt experience rapid temperature change so good habitat

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7
Q

why is high latent heat of vaporisation important for organisms

A

takes a lot of energy to break hydrogen bonds
good for cooling down organisms

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8
Q

what happens in a condensation reaction

A

chemical bonds formed and a molecule of water

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9
Q

what happens in a hydrolysis reaction

A

water molecule used to break chemical bonds between two molecules

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10
Q

name the elements found in carbohydrates and lipids

A

carbon, hydrogen, oxygen

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11
Q

name the elements found in proteins

A

carbon, hydrogen, oxygen, nitrogen, sulphur

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12
Q

name the elements found in nucleic acids

A

carbon, hydrogen, oxygen, nitrogen, phosphate

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13
Q

describe the properties of alpha glucose

A

small and water soluble-easily transported in bloodstream
complementary shape to enzymes for glycolosis- respiratory substrate

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14
Q

how is maltose formed

A

glucose+glucose

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15
Q

how is sucrose formed

A

glucose+fructose

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16
Q

how is lactose formed

A

glucose+galactose

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17
Q

describe the structure and function of starch

A

insoluble-water does not enter cells by osmosis
large-does not diffuse out of cells
made from amylose and amylopectin

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18
Q

describe the structure of amylose

A

long unbranched chain of alpha glucose
glycosidic bond so has a coiled structure
compact so good for storage

19
Q

describe the structure of amylopectin

A

long branched chain of alpha glucose
side branches allow enzymes that break down molecules to get to glycosidic bonds

20
Q

describe structure and functions of glycogen

A

main storage monomer of alpha glucose
1,4 and 1,6 glycosidic bonds
branched-many terminal ends for hydrolysis
compact-good for storage

21
Q

describe structures and functions of cellulose

A

long unbranched chains of beta glucose-prevents bursting of plant
alternate glucose molecules rotate 180 degrees
h bonds crosslinks between parallel strands form microfibrils-high tensile strength

22
Q

how do triglycerides form

A

condensation reaction between 1 molecule of glycerol and 3 fatty acids form ester bonds

23
Q

contrast saturated and unsaturated fatty acids

A

saturated:
only single bonds
straight chain molecules
higher melting point-solid at room temp
in animal fats
unsaturated:
contain C=C double bonds
kinked molecules
lower melting point
in plant oils

24
Q

describe the structure and function of phospholipids

A

centre of bilayer is hydrophobic so water soluble sentences cant easily pass through

25
Q

describe the structure and function of triglycerides

A

mainly energy store
long hydrocarbon contains lots of chemical energy
insoluble so water doesnt enter cells by osmosis

26
Q

describe the structure and function of cholesterol

A

helps strengthen cell membrane by interacting with phospholipid
small/flat so fit between molecules
bind to hydrophobic tails so membrane more rigid

27
Q

what is the primary structure of a protein

A

sequence of amino acids

28
Q

what is the secondary structure of a protein

A

alpha helix or beta pleated sheets
caused by hydrogen bonds forming between -NH and -CO groups of amino acids

29
Q

what is the tertiary structure

A

bonds between parts of the chain

30
Q

what are the types of bonds in the tertiary structure

A

ionic bonds-attractions between negatively charged and positive R groups
disulfide bonds
hydrophobic interactions-when hydrophobic R groups close together, hydrophilic more likely to be pushed to the outside
hydrogen bonds- weak bonds between slightly positive charged and slightly negative charged atoms

31
Q

define quaternary structure of a protein

A

way polypeptides are assembled

32
Q

describe structure and function of globular proteins

A

spherical and compact
hydrophilic R groups face outwards and hydrophobic R groups face inwards-water soluble

33
Q

describe the structure of heamoglobin

A

globular conjugated proteins with prosthetic group
2 alpha chains and 2 beta chains
water soluble-dissolves in plasma
FE2+ haem groups
tertiary structures change so subsequent oxygen molecules bind

34
Q

describe the structure and function of fibrous proteins

A

can form long chains or fibres
insoluble in water
useful for structure and support

35
Q

what are the functions of collagen

A

component of bones, cartilage, connective tissues and tendons

36
Q

what are the functions of elastin

A

provides elasticity to connective tissue

37
Q

what are the functions of keratin

A

structural components of hair and nails

38
Q

describe how to test for protein samples

A

biuret test
add equal volume of sodium hydroxide to sample
add drops of copper 2 sulfate-swirl to mix
positive result=colour change from blue to purple
negative result=solution stays blue

39
Q

describe how to test for lipid samples

A

dissolve solid sample in ethanol
add an equal volume of water and shake
positive=milky white emulsion

40
Q

describe how to test for reducing sugars

A

add bendicts reagent to sample and heat in water bath
positive=colour change (green, yellow, orange, brick red)

41
Q

describe how to test for non-reducing sugars

A

negative=remains blue
add dilute hydrochloric acid and heat in water bath
neutralise with sodium hydrogencarbonate
carry out benedicts test

42
Q

describe the test for starch

A

add iodine solution
positive=orange-blue black

43
Q

outline the process for paper chromatography

A

use capillary tube to spot solution onto pencil line
place chromatography paper in solvent
allow solvent to run until almost touches other end of paper

Biology old (25 decks)

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