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chapter 3 - biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the composition of the body’s biological molecules

A

70% water
30% chemicals - carbohydrates, lipids, proteins and nucleic acids

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2
Q

what are the monomers of
lipids:
proteins:
carbohydrates:

A

lipids: fatty acid and glycerol
proteins: amino acids
carbohydrates: glucose

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3
Q

define organic chemistry

A

the study of chemical reactions that involve carbon

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4
Q

what happens in a condensation reaction?

A

a water molecule is released,
a new covalent bond is formed
a larger molecule is formed
(monomers linked)

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5
Q

what happens in a hydrolysis reaction?

A

a water molecule is used
a covalent bond is broken
smaller molecules are formed
(polymer split into monomers)

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6
Q

how many bonds can carbon atoms form?

A

4

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7
Q

how many bonds can nitrogen form?

A

3

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8
Q

how many bonds can oxygen form?

A

2

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9
Q

how many bonds can hydrogen form?

A

1

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10
Q

what elements are present in the biological molecules:
1. carbohydrates
2. lipids
3. proteins
4. nucleic acids

A
  1. carbohydrates - carbon, hydrogen and oxygen (usually in the ratio C6H12O6)
  2. lipids - carbon, hydrogen and oxygen
  3. proteins - carbon, hydrogen, oxygen, nitrogen and sulfur
  4. nucleic acids - carbon, hydrogen, oxygen, nitrogen and phosphorus
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11
Q

what is the difference between a cation and an anion?

A

cations - the atom loses electrons creating a positive ion

anion - the atom gains electrons creating a negative ion

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12
Q

what abnormal properties do hydrogen bonds give ice?

A

less dense than water - hydrogen bonds hold molecules apart

higher boiling point - strong hydrogen bonds, 2 bonds per molecule

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13
Q

define “high latent heat of vaporisation”
and why is it important that water possesses this?

A

large amount of energy to vaporise

efficient cooling mechanism

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14
Q

define “high specific heat capacity”
and why is it important that water has this?

A

large amount of energy required to raise temp of one unit of substance by 1degrees
thermally stable for aquatic organisms

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15
Q

what are the 7 properties of water molecules and why are they important

A

high latent heat of vaporisation - efficient cooling mechanism

high specific heat capacity - thermally stable for aquatic organisms

ice is less dense than water due to hydrogen bonds - insulator, reflects light, habitat for algae underneath, provides habitat for animals living on ice

efficient solvent (due to polarity) medium for enzyme controlled reactions

cohesion/adhesion - helps transpiration stream in plants

surface tension - habitat for invertebrates

transparent - allows light for photosynthesis

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16
Q

define cohesion and adhesion in water molecules

A

cohesion - attraction to water molecules

adhesion - attraction to other molecules

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17
Q

why is water an effective solvent

A

due to the polarity of the molecules

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18
Q

what are the main four functions of carbohydrates (give examples)

A

energy source - glucose in respiration
energy store - starch, glycogen
structure - cellulose
form part of larger molecules - nucleic acids or glycolipids

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19
Q

what three elements are carbohydrates made of?

A

hydrogen, oxygen and carbon

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20
Q

what are monosaccharides and what are some examples

A

simple sugars
eg. glucose, fructose, galactose, ribose

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21
Q

what are disaccharides and what are some examples

A

“double sugars” formed from 2 monosaccharides.
eg. maltose, sucrose and lactose

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22
Q

what are polysaccharides and what are some examples

A

large molecules made of many monosaccharides.
eg, starch, glycogen, cellulose

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23
Q

what are the properties of monosaccharides and what are the 3 main types

A

have between 3 and 6 carbon atoms,
are soluble in water
are sweet tasting

TRIOSE - 3 carbons
PENTOSE - 5 carbons
HEXOSE - 6 carbons (most common)

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24
Q

what are the properties of glucose and what are its possible structures?

A
  • major energy source for most cells
  • highly soluble
  • main form in which carbohydrates are transported around the body of animals

structure
straight chain or ring

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25
Q

what is the difference between alpha and beta glucose structure?

A

the position of the -OH and H groups on carbon 1

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26
Q

what are the 2 isomers of glucose and what are their properties

A

fructose - very soluble
main sugar in fruits and nectar
sweeter than glucose

galactose - not as soluble as glucose
important in production of glycolipids and glycoproteins

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27
Q

what are the 3 main disaccharides, what are their monomers?
and what are they joined by

A

maltose - glucose + glucose
sucrose - glucose + fructose
lactose - glucose + galactose

joined by glycosidic linkage

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28
Q

what is the polysaccharide starch composed of?

A

amylose and amylopectin
(alpha glucose with 1-4 glycosidic bonds and a coiled structure)

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29
Q

what shared features do the polysaccharides starch and glycogen have

A

both energy storage molecules

are insoluble (don’t affect water potential of cell)

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30
Q

what makes up cellulose fibres

A

50-100 beta glucose molecules cross link via hydrogen bonds to form bundles of MICROFIBRILS
microfibrils cross link to form MACROFIBRILS,
bundles of macrofibrils make up cellulose fibres

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31
Q

what are the structure and function of cellulose cell walls

A
  • provide strength to cells and the whole plant
  • prevents bursting (lysis), keeps cell turgid
  • apoplast - permits passage of water
  • allows cells to grow or change shape
  • reinforced with other substances eg. lignin to be waterproof
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32
Q

how are the long chains of beta glucose molecules that make up cellulose arranged?

A

straight chain, every alternative monomer rotated 180 degrees

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33
Q

what elements are lipids composed of?

A

carbon, hydrogen and oxygen

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34
Q

what is the solubility of lipids like?

A

soluble in organic solvents but not in water

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35
Q

what are 4 examples of lipids

A

triglycerides (fats and oils)
cholesterol
steroid hormones
phospholipids

36
Q

what is the difference between fat and oil

A

fat is solid at room temp
oil is liquid at room temp

37
Q

explain in detail the 8 functions of lipids?
give examples

A

energy source - used when glycogen and starch are depleted

energy store - in adipose tissue, provides more energy per gram than carbohydrates

biological membranes - phospholipid bilayer, cholesterol regulates fluidity

insulation - blubber reduces heat loss (whales + seals). electrical insulation around nerve cells (myelin sheath)

buoyancy - fat is less dense than water - marine animals

physical protection - around vital organs

waterproofing - cuticle on plant leaves, ducks produce an oil to waterproof their feathers

vitamin D, bile and steroid hormone production

38
Q

what are triglycerides composed of?

A

a glycerol and 3 fatty acids

39
Q

what is the difference between the structure of saturated and unsaturated fatty acids

A

saturated = straight chain, unsaturated = bent tail

40
Q

what group do all fatty acids have at one end?

A

carboxyl group

41
Q

formula for saturated fatty acids:

A

CnH(2n+1)COOH

42
Q

what are the two types of unsaturated fatty acids and how do they differ?

A

cis - both hydrogen atoms bonded to the double bond of carbon from the same side - bent
trans - one hydrogen atom bonded to each side of the double carbon bond - straight structure

43
Q

what is the structure of phospholipids like compared to a triglyceride?

A

similar structure but one fatty acid is replaced by a phosphate group

44
Q

would an organism living in a cold environment have more saturated or unsaturated fatty acids?
why?

A

more unsaturated as can’t pack as tightly together due to bent structure - membrane remains more fluid

45
Q

4 facts about cholesterol

and where are they placed for their function

A
  1. NOT formed from glycerol/ fatty acids
  2. 4 carbon rings
  3. small, narrow molecule
  4. hydrophobic

fit between phospholipid tails in membrane, regulates membrane fluidity and strength

46
Q

2 facts and 3 examples of steroid hormones

A
  1. made from cholesterol
  2. lipophilic- can pass through phospholipid bilayer
  3. testosterone
  4. oestrogen
  5. progesterone
47
Q

how do you remember the difference in structure between alpha and beta glucose?

A

ABBA = OH group in Alpha Below
OH group in Beta Above carbon 1

48
Q

define isomer of a molecule

A

same chemical formula, different structure

49
Q

what is the difference between amylose and amylopectin (in starch)

A

amylopectin has side branches with 1-6, glycosidic bonds

50
Q

when is beta glucose used as monomers
when is alpha glucose used as monomers

A

beta = structural - cellulose
alpha = energy - starch and glycogen

51
Q

what is the difference between structural vs energy carbohydrates?

A

structural - has hydrogen bonds (important for strength), straight chain structure, every alternative molecule flipped 180degrees.

energy - no hydrogen bonds, coiled structure

52
Q

what are the 4 carbohydrate structures you need to know and draw?

A

ribose
deoxyribose
alpha glucose
beta glucose

53
Q

what is the structural difference between ribose and deoxyribose

A

deoxyribose does not have the oxygen on carbon 2

54
Q

what are ribose and deoxyribose found?

A

ribose = RNA
deoxyribose = DNA

55
Q

how many water molecules are produced in the formation of a triglyceride molecule (lipids)

A

3 water molecules

56
Q

why is glycogen such a good energy storage molecule?

A
  1. insoluble - doesn’t affect water potential of cell
  2. easily and quickly hydrolysed - releasing energy for functions
  3. lots of side branches (1-6, glycosidic bonds) - enzymes can attach
  4. very compact shape - high energy content for its mass
57
Q

what molecule is produced when glycogen is hydrolysed?

A

Alpha glucose

58
Q

what is the difference between the functional groups of glucose and fructose molecules

A

fructose = ketone functional group (C=O)
glucose = aldehyde functional group (CHO)

59
Q

why can bacteria not break down the carbohydrate agarose?

A

because the bacteria doesn’t contain the correct enzymes to digest agarose,
agarose does not have complimentary shape to the active site on bacteria

60
Q

suggest the purpose of a control test alongside your experiment
eg. an experiment without the presence of the substance you are investigating

A

to ensure that the positive result is due to the independent variable you are testing and not another factor
to ensure the reliability of the experiment

61
Q

suggest 2 ways in which reliability of an experiment can be improved

A
  1. repeat the experiment
  2. test the samples more than once for each category
62
Q

what bonds are formed during the condensation of lipids?

A

ester bonds

63
Q

what bonds are formed during the condensation of proteins

A

peptide bonds

64
Q

what bonds are formed during the condensation of sugars/ carbohydrates

A

glycosidic bonds

65
Q

what tissue is composed of lipids

A

adipose tissue

66
Q

Define heteropolysaccharide

A

A polysaccharide containing multiple different monosaccharides

67
Q

Define heteropolysaccharide

A

A polysaccharide containing multiple different monosaccharides

68
Q

what are some examples in which hydrogen bonds are found in biological molecules (5)

A
  • water
  • between cellulose fibres
  • adjacent collagen chains
  • proteins - secondary, tertiary and quaternary structure
  • strands of/ bases in DNA
69
Q

what are the roles of cholesterol in living organisms (5)

A

1.regulate plasma membrane fluidity
2.converted to steroid hormones
3.producing vitamin D
4.making bile (salts)
5.waterproofing the skin

70
Q

what are ways that the molecular structure of cholesterol is similar to that of a carbohydrate

A

contains carbon, oxygen and hydrogen
has OH/ hydroxyl groups
has a six membered ring/ hex

71
Q

what 2 molecules combine with cholesterol to form LDLs (low density lipoprotein)

A

saturated lipids/ fats/ triglycerides
proteins / polypeptides

72
Q

suggest why diets with high red meat are associated with high blood cholesterol

A

red meat contains large amounts of saturated fat/ fatty acids
which leads to an increased number of LDLs

73
Q

list some of the differences between the structures of glycogen and cellulose

A

G: no hydrogen bonding
C: hydrogen bonding

G: 1,4- + 1-6 glycosidic bonds
C: 1,4 glycosidic bonds ONLY

G: branched
C: unbranched - linear

G: no fibres/fibrils
C: fibres/fibrils

G: granules
C: no granules

74
Q

how is collagen’s structure similar to that of haemoglobin

A

collagen has amino acid chain/ sequence, peptide bonds, helix/helical

3 bonds / interactions from hydrophobic & hydrophilic, ionic, hydrogen, disulfide

quaternary structure; more than one polypeptide / subunit

75
Q

how do sodium and hydrogen ions help a cut plant live longer

A

sodium regulates water potential
hydrogen regulates pH

76
Q

why is glucose easily transported into the blood stream

A

its soluble in water

77
Q

how can you estimate glucose concentration without a colorimeter?

A

carry out benedict’s test, allow precipitate to form and sink to the bottom. filter the solution and weigh the mass of solid precipitate

78
Q

what is the difference between DNA and RNA

A

DNA contains deoxyribose
RNA contains ribose

DNA contains: Thymine, Adenine, Cytosine and guanine

RNA contains Adenine, Cytosine, Guanine and Uracil

79
Q

define molecule

A

what is produced when 2 or more atoms chemically bond together

80
Q

which type of glucose molecule makes up structural carbohydrates and which makes up energy source carbohydrates

A

alpha = energy = starch and glycogen
beta = structural = cellulose

81
Q

why does benedict’s solution turn red when heated with a reducing sugar

A

because the blue cu2+ ions are reduced to brick-red cu+ ions
therefore the higher reducing sugar concentration, the more red precipitate formed

82
Q

how do you use the benedict’s test for non-reducing sugars?

A

boil the sugar with hydrochloric acid first,
then neutralise with a base
then the sugar will react with the benedict’s solution as the sugar has been hydrolysed by the acid to reducing sugar monomers

83
Q

what is the alternative way to benedict’s solution for testing for reducing sugars?
what is the advantage for this method

A

reagent strips
with the use of a colour-coded chart, the concentration of glucose can be calculated

84
Q

what are the 3 basic components of a biosensor

A
  1. molecular recognition - a protein or single strand of DNA is immobilised to a surface. This will interact with, or bind to, the specific molecule in question
  2. transduction - this interaction causes a change in the transducer. The transducer detects a change and produces a response. e.g. an electric current on a glucose testing machine
  3. display - this then produces a visible qualitative or quantitative signal such as colour on a test strip or readings on a machine
85
Q

why do the presence of saturated and unsaturated fatty acids cause fats to be solid and oils to be liquid

A

saturated fatty acids - the carbon-to-carbon double bond causes the molecule to kink or bend and can therefore not pack together as tightly. making them liquid at room temperature and described as oils rather than fats

86
Q

What would be the results for tests of starch and sucrose
Biurets:
Benedict’s:
Iodine in potassium iodide:

A

Blue
Blue
Blue-black

87
Q

What property of water is the main factor enabling homeotherms (endotherms) to adapt to a range of environments

A

High heat of vaporisation

biology (22 decks)

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