Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > 1. Biological Molecules > Flashcards

1. Biological Molecules Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Water is a ___ molecule

A

Polar/dipolar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain why water is a polar/dipolar molecule

A
  • Pairs of electrons slightly more attracted to oxygen: more protons in its nucleus
  • Oxygen has slightly negative charge, hydrogen has slightly positive charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of bonds form between water molecules?

A

Hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What property of water do hydrogen bonds cause?

A

Cohesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define hydrogen bonds

A

Weak forces of attraction between a slightly negative and slightly positive group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Water is a ___ for all polar molecules

A

Solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why is it biologically important for molecules to be able to dissolve in water?

A
  • Many molecules that are transported around living things are dissolved in water (e.g. in blood)
  • All metabolic reactions in living things happen in solution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What will dissolve in water?

A
  • All polar molecules (e.g. glucose)
  • All ions
  • All ionic molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What won’t dissolve in water (give an example)?

A

Fats (e.g. oils) because they are non-polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Water has a ___ specific heat capacity

A

high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does having a high specific heat capacity mean?

A

Water absorbs/loses a relatively large amount of energy before changing temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Because of its high specific capacity, water acts as a ___

A

buffer against sudden temperature fluctuations/changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Biological importance of water having a high specific heat capacity

A
  • Important for homeostasis - easier to regulate internal temperature because living organisms are mostly water (enzyme activity!)
  • Important for organisms that live in water (aquatic environments have a more stable temp)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Water and latent heat of vaporisation

A

Water has a high latent heat of vaporisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Latent heat of vaporisation is…

A

the amount of energy absorbed before something turns into vapour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Biological significance of water having a high latent heat of vaporisation

A

Can act as a coolant (eg sweat) with little loss of water through evaporation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why does water have a high latent heat of vaporisation

A

Hydrogen bonds need to be broken - this requires energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why does water have a high specific heat capacity

A

Hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Water will stick to other polar molecules - this is known as

A

Adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why is cohesion important in plants?

A

Water column doesn’t break up when water is pulled up the xylem in the transpiration stream - continuous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When does water show surface tension

A

At an air-water surface due to the cohesion between water molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does surface tension do

A

Makes a solid-like surface, explaining why pond skaters can walk on water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Condensation reaction

A

Two monomers joining together to form a polymer and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Hydrolysis reaction

A

A polymer splitting up into monomers - water required as a reactant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What do monosaccharides and disaccharides have in common?

A

They are sugars: sweet-tasting and very soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What general property do polysaccharides share?

A

Insoluble in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How can monosaccharides form disaccharides and polysaccharides?

A

Through condensation reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Examples of monosaccharides

A 
Glucose
Fructose
Galactose
Deoxyribose
Ribose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

General formula of monosaccharides

A

(CH2O)subscript n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is meant by a hexose sugar?

A

Has 6 carbons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Maltose =

A

glucose + glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Sucrose =

A

glucose + fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Lactose =

A

glucose + galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What type of bond forms between the two glucose molecules in maltose?

A

1-4 glycosidic bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What type of glucose is used in maltose?

A

Alpha glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Are all monosaccharides reducing sugars?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Are all disaccharides reducing sugars?

A

No - only some are!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the test for reducing sugars?

A

Benedict’s solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What do reducing sugars act as?

A

Reducing agents (they donate electrons)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

The blue colour in Benedict’s solution is due to…

A

Cu2+ ions

They are soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

The red colour in Benedict’s solution is due to…

A

Cu1+ ions

They are insoluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Test for non-reducing sugars

A
  1. Negative Benedict’s result
  2. Hydrolyse sample to split into monosaccharides: add HCl, heat in water bath, neutralise with hydrogencarbonate
  3. OR add an enzyme
  4. Repeat Benedict’s test - if brick red there is non-reducing sugar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Benedict’s solution practical main point

A

The colour and density of any precipitate formed with Benedict’s solution can be used to indicate the concentration of reducing sugar present in a sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What does a colorimeter measure

A

Percentage transmission (% of light that passes through the solution) and percentage absorbance (% of light that doesn’t get through)

45
Q

Polymers of alpha glucose

A

Starch & glycogen

46
Q

Polymers of beta glucose

A

Cellulose

47
Q

Most glucose molecules join via…

A

1-4 glycosidic bonds, forming a helical chain

48
Q

What’s good about a helical chain

A

It can coil so it’s more compact

49
Q

How do polymers of glucose become branched?

A

1-6 glycosidic bonds

50
Q

Describe starch (storage polysaccharide? structure?)

A
  1. Storage polysaccharide in plants
  2. Polymer wound into a tight coil
  3. Mix of branched (amylopectin) and unbranched (amylose) chains
51
Q

Starch properties

A
  1. Large & insoluble - doesn’t affect water potential, doesn’t easily diffuse out of cells
  2. Helix - compact, lots of glucose can be stored in a small space
  3. Branched - many ends so can be broken down rapidly
52
Q

Glycogen is…

A

A more highly branched polymer of alpha glucose

53
Q

Advantages of a more highly branched molecule

A

More compact and can be broken down even more rapidly (animals are more likely to suddenly need a lot of energy)

54
Q

Cellulose structure

A
  • Long straight chains held close to each other by hydrogen bonds
  • Strong & rigid overall structure
  • Every other glucose molecule is flipped so no helix - only long straight chains
55
Q

Where is cellulose found

A

Storage polysaccharide in plant cell walls

56
Q

Groups of cellulose molecules form…

A

Microfibrils, which are then arranged in parallel groups which form cellulose fibres

57
Q

What are cellulose fibres like?

A

Rigid and strong - giving cell walls their strength

58
Q

What are lipids made of

A

Carbon, hydrogen and oxygen but proportionally less oxygen than carbs

59
Q

Are lipids soluble in water?

A

No - they are non-polar and hydrophobic

60
Q

What are lipids soluble in?

A

Organic solvents e.g. ethanol

61
Q

Opposite of hydrophobic

A

Hydrophilic

62
Q

Most important groups of lipids are…

A

Triglycerides - includes all fats and oils

63
Q

Other types of fats include…

A

Cholesterol, phospholipids, waxes

64
Q

Four different roles of lipids in living organisms

A
  1. Source of energy (often used as an energy store) - lipids have more energy per gram than carbs
  2. Insulation - poor conductor of heat
  3. Protection (around organs esp those outside the ribcage)
  4. Waterproofing - it’s hydrophobic!
65
Q

What is a triglyceride molecule made up of?

A

3 fatty acids and 1 glycerol molecule

66
Q

What does the “n” in fatty acid structural diagrams mean?

A

Number of repeats (of CH2 units)

67
Q

What reaction forms a triglyceride?

A

Condensation

68
Q

What bonds form in a triglyceride after condensation?

A

Ester bonds

69
Q

What 3 properties make triglycerides a good energy storage molecule?

A
  1. Triglycerides have many energy-storing C-H bonds. This makes then an excellent source of energy.
  2. They are also very energy dense (lots of energy per gram) which makes them a good energy store.
  3. Being non polar also means they are insoluble - a useful property in a storage molecule.
70
Q

Lipids vs. glycogen as energy stores

A
  • Glucose can be used immediately in respiration - faster, short-term energy store. More readily available energy. Can be used in aerobic and anaerobic respiration.
  • Lipids can only be used in aerobic respiration - energy is less readily available.
71
Q

Difference between saturated & unsaturated fatty acid

A

Saturated has single bonds only & straight chain & tend to be solid @ room temp, unsaturated contains C=C double bonds (and wherever there is a double bond there’s a kink in the chain) & tend to be liquid @ room temp

72
Q

Monounsaturated vs polyunsaturated

A

Monounsaturated: one C=C double bond
Polyunsaturated: many C=C double bonds

73
Q

Why are unsaturated fats more likely to be liquid @ room temperature?

A

There are kinks in the chain so it’s harder to pack the fatty acid chains into a regular arrangement

74
Q

Phospholipid structure vs triglyceride

A

A fatty acid has been replaced by a phosphate group (so two fatty acids, one glycerol, one phosphate group)

75
Q

The head of a phospholipid molecule is…

A

hydrophilic

76
Q

The tail of a phospholipid is…

A

hydrophobic

77
Q

What do we call a molecule that is part hydrophilic and part hydrophobic?

A

Amphipathic

78
Q

What happens when a phospholipid is in water?

A

Forms a micelle (see Notion for diagram)

79
Q

Describe chemical test for lipids (emulsion test)

A
  1. Mix sample with ethanol - lipid is dissolved
  2. Add water - any previously dissolved lipid in ethanol will come out of solution, forming tiny lipid droplets
  3. The droplets give a white milky appearance
80
Q

Proteins are made of _____ which are joined together by _____

A

Amino acids; Peptide bonds

81
Q

Some proteins contain which element?

A

Sulphur

82
Q

What elements are all proteins made of?

A

C, H, O, N

83
Q

Examples of proteins

A
  1. Keratin & collagen: found in skin, hair, nails & connective tissue
  2. Actin & myosin: found in muscles
  3. Enzymes
  4. Haemoglobin
  5. SOME hormones (e.g. insulin)
  6. Antibodies are made of a protein called immunoglobin
84
Q

Keratin and collagen are examples of…

A

Structural proteins

85
Q

Is immunoglobin soluble or insoluble?

A

Soluble

86
Q

Are enzymes soluble or insoluble?

A

Soluble

87
Q

What are the three parts of an amino acid?

A

Amino group
R group
Carboxyl group

88
Q

Is amino group acidic or basic?

A

Basic

89
Q

Is carboxyl group acidic or basic?

A

Acidic

90
Q

Define primary structure of a protein

A

The order of amino acids in the polypeptide chain (chain of amino acids)

91
Q

Why is primary structure significant?

A
  • It determines the final shape and properties of the molecule
  • A mistake in the order can lead to a change in the molecule’s shape and properties, and therefore stop it carrying out its function
92
Q

Define tertiary structure of a protein

A

The way in which the polypeptide is further twisted and folded to make a 3D shape

93
Q

What bonds hold secondary structure of a protein in place?

A

Hydrogen bonds between the N-H (slightly positive) group on one amino acid and the C=O (slightly negative) group on another

93
Q

Two types of secondary structure

A

Alpha helix

Beta pleated sheet

94
Q

What bonds hold the tertiary structure in place?

A

Disulphide bridges, ionic bonds and hydrogen bonds between the R groups

95
Q

What R groups/amino acids do disulphide bonds form between?

A

Ones with sulphur in them (i.e. cysteine R groups and methionine R groups)

96
Q

Where are ionic bonds in a tertiary structure found?

A

They form between R groups that are charged

97
Q

Where are hydrogen bonds in a tertiary structure found?

A

Weak bonds between R groups with a slight charge

98
Q

What is quaternary structure?

A

When some proteins made up of several polypeptide chains, each with their own tertiary structure, join together to make one larger protein

99
Q

Examples of proteins with quaternary structure

A

Haemoglobin - made of 4 polypeptides joined together

100
Q

Some proteins with a quaternary structure might also have…

A

Prosthetic groups - non-protein parts of the molecule (e.g. in haemoglobin it’s Fe)

101
Q

Biuret test for proteins

A
  1. Add NaOH
  2. Add 1% CuSO4 drop by drop
  3. Allow mixture to stand for 5 min: positive result is blue to violet
102
Q

Role of phospholipids

A

What cell membranes are made of - forms barrier between cell interior & exterior

103
Q

Globular vs fibrous proteins: what type?

A

Globular: usually metabolic (i.e involved in chemical reactions in the body)
Fibrous: structural

104
Q

Globular vs fibrous proteins: solubility

A

Globular: soluble in water
Fibrous: insoluble in water

105
Q

Globular vs fibrous proteins: primary structure

A

Globular: irregular & specific
Fibrous: repetitive sequences

106
Q

Globular vs fibrous proteins: easy/hard to denature?

A

Globular: unstable so relatively easy to denature
Fibrous: stable so much harder to denature

107
Q

Examples of globular proteins

A

Enzymes
Haemoglobin
Hormones

108
Q

Examples of fibrous proteins

A

Keratin
Collagen
Actin
Myosin

Biology (42 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions