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Biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

how does hydrogen bonding occur in water

A

the slightly negatively charged oxygen atom attracts the slightly positively charged hydrogen atoms

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2
Q

why is water a good solvent

A

water is polar so the slightly positive oxygen atom will be attracted to negative ions and the slightly negative hydrogen atoms will be attracted to positive ions, as most substances in biological reactions are ionic

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3
Q

why is water a good coolant

A

it has a high latent heat of vaporisation meaning it takes a lot of energy to break hydrogen bonds between molecules, cools surface of skin

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4
Q

why is water cohesive and what does this mean

A

cohesion is the attraction of molecules to the same type of molecule, this helps water to flow making it great for transporting substances like in the transpiration stream

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5
Q

why does water have a high heat capacity and why is this a benefit

A

it takes a lot of energy to raise the temperature by 1oc as hydrogen bonds can absorb a lot of energy, makes it a good habitat as temperature of water doesn’t fluctuate too much

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6
Q

why does water have a lower density when said and how is this a benefit

A

molecules are held further apart in a lattice structure as each water molecules forms four hydrogen bonds , this means in freezing conditions ice forms an insulation layer on top of water preventing it from freezing

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7
Q

what are macromolecules

A

complex molecules with a large molecular mass, proteins, lipids, carbohydrates

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8
Q

what is a monomer

A

small, basic molecular units, amino acids, monosaccharides

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8
Q

what is a polymer

A

large complex molecules made up of small repeating units (monomers) joined together

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9
Q

What reaction can breakdown polymers and how dos this happen

A

hydrolysis- breaks a bond using a water molecules

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10
Q

what reaction can form a polymer and how does this happen

A

condensation- forms a chemical bond and releases a molecule of water

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11
Q

what chemicals make up carbohydrates

A

C,H and O

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12
Q

What chemicals make up lipids

A

C,H and O

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13
Q

What chemicals make up proteins

A

C,H,O, N and S

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14
Q

What chemicals make up nucleic acids

A

C,H,O,N and P

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15
Q

what are the two types of monosaccharides that make up carbohydrates

A

glucose and ribose

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16
Q

describe or draw the structure of alpha glucose

A

Ch2OH at top, 5 carbon atoms and an oxygen in top right, H above OH attached to right carbon

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17
Q

describe or draw the structure of beta glucose

A

CH2OH at top, % carbon atoms and O in top right, Oh above H on right carbon

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18
Q

What is the structure of ribose

A

O at top, CH2OH attached to top left carbon, pentagon shape, pentose sugar

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19
Q

what is the difference between a hexose sugar and a pentose sugar

A

hexose has an extra carbon atom

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20
Q

what are monosaccharides joined together by

A

glycosidic bonds

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21
Q

how are glycosidic bonds made and broken

A

condensation and hydrolysis

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22
Q

What is sucrose and what is it made up of

A

disaccharide- alpha mucose and fructose

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23
Q

what is lactose and what is it made up of

A

disaccharide- galactose and either alpha or beta glucose

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24
Q

what is maltose and what is it made up of

A

disaccharide- two alpha glucose molecules

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25
Q

What is starch and describe its structure

A

main energy storage molecule in plants, insoluble in water, mixture if two polysaccharides of alpha glucose (amylopectin and amylose)

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26
Q

Give the structure of amylose

A

long, unbranched chain of a glucose, coiled, compact so can fit more in a small space

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27
Q

Give the structure of amylopectin

A

long, branched chain of a glucose, allow glycosidic bonds to be broke down easily, glucose can be released quickly

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28
Q

What is glycogen and describe its structure

A

main energy storage in animals, made of a glucose, very branched, can be released quickly, very compact

29
Q

What is cellulose and describe its structure

A

major component of cell wall in plants, long unbranched chains of b glucose, linked by hydrogen bonds, form microfibrils, means strong, structural support

30
Q

What is the structure of a triglyceride

A

one molecule of glycerol with three fatty acid tails attached to it by ester bonds

31
Q

how are triglycerides synthesised and broken down

A

esterification and hydrolysis

32
Q

what is the structure of a phospholipid

A

a phosphate group, molecule of glycerol and two fatty acid tails

33
Q

what is the structure and properties of fatty acid tails

A

made out of hydrocarbons, hydrophobic, insoluble in water

34
Q

what is a saturated fatty acid

A

no double bonds ‘saturated with hydrogen

35
Q

what is an unsaturated fatty acid

A

double bonds between at least one carbon

36
Q

Give the structure of cholesterol

A

hydroxyl group attached to hydrocarbon rings with a hydrocarbon tail

37
Q

What is the function of triglycerides and how does their structure support this

A

mainly energy storage in animals and plants, long hydrocarbon tails containing lots of chemical energy, insoluble (form droplets) so they don’t cause water to enter cells via osmosis

38
Q

What is the function of phospholipids and how does their structure support this

A

found in cell membranes of E and P cells, make up bilayer, hydrophilic heads and hydrophobic tails which face inwards so water soluble substances can’t pass through easily, helps control what enters and leaves the cell

39
Q

What is the function of cholesterol and how does its structure support this

A

regulates fluidity of membrane, has a small flattened shape so can fit between phospholipids, bind to tails in high temps so they pack together making membrane less fluid, opposite in low temps

40
Q

What is the general structure of an amino acid

A

amine group, carbon, carboxyl; group with a variable group attached above or below central carbon and a hydrogen opposite the variable group

41
Q

what are amino acids joined together by

A

pptide bonds

42
Q

how are peptide bonds made and broken

A

condensation and hydrolysis

43
Q

describe the primary structure of a protein

A

sequence of amino acids in the polypeptide chain

44
Q

describe the secondary structure of a protein

A

hydrogen bonds form causing the coil into an alpha helix or fold into a beta pleated sheet

45
Q

Describe the tertiary structure of a protein

A

ionic bonds form between negatively charged and positively charged R variable groups, disulfide bonds between sulphur atoms in cysteine, hydrophobic and hydrophilic interactions cause hydrophilic R groups tone push to outside, hydrogen bonds form between slightly positive H atoms in R groups and slightly negatively charged atoms in other R groups

46
Q

Describe the quaternary structure of a protein

A

for proteins made up of more than one polypeptide chain , creates a 3D structure, example is haemoglobin

47
Q

Describe the structure, function and give some examples of globular proteins

A

round and compact, soluble, haemoglobin, insulin amylase, transport

48
Q

Describe the structure, function and give examples of fibrous proteins

A

tough, rope-shaped, in soluble, structure, collagen (found in connective tissue’s), keratin (found in skin and nails), elastin (found in skin and large blood vessels)

49
Q

what is a conjugated protein and give an example

A

it is a protein with a non-protein group attached called a prosthetic group, each of the four polypeptide chains in haemoglobin have a prosthetic group called ham which contains iron

50
Q

What cation is involved in the transmission of nerve impulses and release of insulin from the pancreas, acts as a cofactor for many enzymes e.g blood plotters, important in bone formation

A

calcium (Ca2+)

51
Q

What cation is important for generating nerve impulses for muscle contraction and regulating fluid balance in body

A

Sodium (Na+)

52
Q

What cation is important for generating nerve impulses for muscle contraction and regulating fluid balance in body. Activates essential enzymes needed for photosynthesis in plant cells

A

Potassium (K+)

53
Q

what cation affects pH of substances, important for photosynthesis reactions that occur in thylakoids and respiration reactions occurring in the inner membrane of the mitochondria

A

Hydrogen (H+)

54
Q

What cation is absorbed from the soil by plants and is an important source of nitrogen

A

Ammonium (NH4+)

55
Q

What anion is absorbed from the soil by plants and is an important source of nitrogen

A

nitrate (NO3-)

56
Q

What anion is important in acting as a buffer for blood pH

A

hydrogencarbonate (HCO3-)

57
Q

What important anion is used in the chloride shift to help maintain pH of blood and acts as a cofactor. of the enzyme amylase, also involved in some nerve impulses

A

chloride (Cl-)

58
Q

What anion is important in photosynthesis and respiration, needed for synthesis of biological molecules such as ATP and phospholipids

A

Phosphate (PO43-)

59
Q

What anion is important in affecting the pH of substances

A

hydroxide (OH-)

60
Q

what is the test for proteins, how is it carried out and what would a positive test result in

A

biuret test, add NaOH and copper sulphate, turns from blue-purple

61
Q

what is the test for starch, how is out carried out and what would a positive test result in

A

iodine test, add iodine, solution turns fro. orange to blue /black

62
Q

what is the test for lipids, how is it carried out and what would a positive test result in

A

emulsion test, shake in ethanol and pour into water, if present the solution will turn milky

63
Q

what is the test for reducing sugars, how is it carried out and what would a positive test result look like

A

add Benedict’s solution, heat in a water bath, will form a coloured precipitate green-yellow-orange-brick red (( the further the colour change the higher the conc if no reducing sugar is present then solution remains blue

64
Q

what types of sugars are reducing

A

monosaccharides and maltose/lactose

65
Q

what is the test for non-reducing g sugars, how is it carried out and what would a positive result look like

A

carry out Benedict’s test first the using a new sample add HCl and heat in a water bath, then neutralise with NaOH and carry out Benedict’s test, same results as reducing sugar

66
Q

how do you use a calorimeter

A

do a Benedict’s test on each solution and remove any precipitate that forms,
switch calorimeter on and allow 5 mins to stabilise
use red filter
add distilled water to cuvette and place inside with the light passing through the clear sides, calibrate machine to zero
use pipette to transfer sample of solution into a clean cuvette
put cuvette in calorimeter and record absorption, relate for remaining solutions

67
Q

what is the mobile phase in chromatography

A

where the molecules can move, a liquid solvent like water or ethanol

68
Q

what is the stationary phase In chromatography

A

where the molecules can’t move, e.g thin layer of solid

69
Q

how do you calculate the Rf value

A

distance moved by solute/distance moved by solvent

70
Q
A

Biology (25 decks)

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