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💚OCR BIOLOGY A LEVEL > Chapter 3// Biological molecules > Flashcards

Chapter 3// Biological molecules Flashcards

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1
Q

Polar molecule

A

A molecule w regions of negative charge and positive charge

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2
Q

Solution

A

A liquid (solvent) w dissolved solids,liquids or gases (solutes)

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3
Q

Cohesion 💧

A

A property of water in which water molecules are attracted to each other by hydrogen bonding, allowing the molecules to move together

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4
Q

Adhesion 💦

A

A property of water in which water molecules are attracted to surfaces such as the walls of cells,vessels or tubes

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5
Q

What 3 types of carbohydrates are there and which one of them is not sweet tasting?

A

Monosaccharides, disaccharides + polysaccharides

Polysaccharides r not sweet to taste

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6
Q

What type of molecule is a monosaccharide

A

simple sugars : monosaccharides

single, soluble molecule that’s sweet to taste 🍬🍬🍬🍬

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7
Q

Describe the structure of a monosaccharide

A

Monosaccharides have NO glycosidic bonds and exist as a single ring shape or as a straight chain

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8
Q

Give 3 examples of monosaccharides

A

Hexoses (6C) e.g. Glucose,fructose,galactose 🍎🥭🍑

Pentoses (5C) e.g.
Ribose, Deoxyribose 🧬

Trioses (3C) e.g.
Glyceraldehyde

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9
Q

What type of molecule is a disaccharide

A

Complex sugars : disaccharide

Are 2 molecules covalently joined which r soluble and sweet to taste 🍰🍰🍰

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10
Q

Describe the structure of a disaccharide

A

Disaccharides have a single glycosidic bond and there structure is two rings joined

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11
Q

Give 3 examples of a disaccharide

A

Sucrose 🍬

Maltose 🍭

Lactose🥛

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12
Q

What type of molecule is a polysaccharide

A

Complex carbohydrates : polysaccharides

Are many molecules covalently joined to each other

Polysaccharides r insoluble + NOT sweet

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13
Q

Describe the structure of a polysaccharide

A

Polysaccharides have many glycosidic bonds and exist as long chains which may be branched + coiled, making them v compact

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14
Q

Covalent bond

A

A strong chemical bond formed by sharing one or more e- between two atoms, creating a molecule

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15
Q

Glycosidic bond

A

A covalent bond formed when two carbohydrate molecules are joined together by a condensation reaction

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16
Q

Monomer

A

A single small molecule that may combine w other monomers to build up larger molecules called polymers

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17
Q

Polymer

A

A large molecule built up from many similar monomers joined together by covalent bonds to form a chain or branched chain

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18
Q

Condensation

A

A chemical reaction where 2 molecules r joined together w a covalent bond forming a larger molecule and releasing 1 molecule of water 💧

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19
Q

Hydrolysis

A

A chemical reaction where the covalent bond between 2 molecules is broken w the addition of a water molecule, separating the 2 molecules

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20
Q

Give 3 examples of monosaccharides + there function

A

Glucose (6C) = source of energy as easily hydrolysed; transported in the blood of animals

Ribose (5C) = part of all types of RNA + ATP molecules, so it’s an important part of protein synthesis

Deoxyribose (5C) = part of DNA for inherited information

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21
Q

Explain how hydrogen bonds form between water molecules

A

Oxygen and hydrogen share electrons unequally when they bond.

The oxygen has a slight -ve charge and the hydrogen atoms have a slight +ve charge.

This polarity means water molecules r attracted to each other cuz the slightly +ve pole around the hydrogen atoms bonds to the slightly -ve pole of the oxygen atoms— forming a HYDROGEN BOND

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22
Q

Explain why water is a polar molecule

A

Because the oxygen draws e- from the hydrogen atoms this results in unequal sharing of electrons in bonds so

The oxygen has a slight -ve charge 💔

And the hydrogen has a slight +ve charge💚

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23
Q

What elements make up carbohydrates ?

A

C, H + O

🥖🥞🥔🥐🍞🥯

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24
Q

What elements make up lipids?

A

C, H + O

🧀🍳🥑🥥🍮

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25
Q

What elements make up proteins?

A

C, H, O, N + S

🥩🍖🍗🥓🌭

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26
Q

What elements make up nucleic acids?

A

C, H, O, N + Phosphorus

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27
Q

Function of glucose (6C) in organisms

A

Glucose (6C monosaccharide) = source of energy as easily hydrolysed; transported in the blood of animals

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28
Q

Function of ribose (5C) in organisms

A

Ribose (5C monosaccharide) = part of all types of RNA + ATP molecules, so it’s an important part of protein synthesis

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29
Q

Function of deoxyribose (5C) in organisms

A

Deoxyribose (5C monosaccharide) = part of DNA for inherited information

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30
Q

Function of maltose in organisms

A

Maltose (disaccharide) = energy store in plants

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31
Q

Function of sucrose in organisms

*bonus if u name monosaccharides it’s made of

A

Sucrose (disaccharide made of glucose+ fructose)

= energy storage in some plants transported in phloem

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32
Q

Function of lactose in organisms

*bonus if u name monosaccharides it’s made of

A

Lactose (disaccharide made of glucose+ galactose)

= the sugar found in milk provides nutrients for young mammals 🦙🐈🦘

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33
Q

Important features of monosaccharides

A

Small + soluble

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34
Q

Important features of polysaccharides

A

Large complex molecules which are stable + insoluble

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35
Q

Function of starch+ glycogen in organisms

A

Starch + glycogen (polysaccharides)
= energy storage in plants (starch)
energy storage in animals (glycogen)

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36
Q

Function of cellulose in organisms

A

Cellulose (polysaccharide)

= structural + v strong so forms main component in plant cell walls

37
Q

Which properties of water make it an important component of the blood

A
  • high specific heat capacity + high latent heat of vaporisation= hard to heat so maintains optimum body temp for reaction
  • good solvent = important molecules such as glucose can dissolve n be carried in the blood + most biological reactions take place in solution
  • water is a reactant in loads of important chemical reactions (hydrolysis reactions)
38
Q

Difference between high specific heat capacity vs. High latent heat of vaporisation

A

High specific heat capacity is the energy required to heat water (raise its temp) = important as water is hard to heat meaning it maintains optimum temp for reactions
Whereas
High latent heat of vaporisation is the energy required for a substance to change state= important as water acts as a coolant, it takes a lot of energy to change state so e.g. when sweat evaporates it cool skin

39
Q

Give 2 reasons why the high specific heat capacity of water is beneficial to organisms

A

water doesn’t experience rapid temperature changes which means

  • it acts as a good stable habitat for organisms to live in
  • it acts as a coolant in the blood, keeping a constant body temp
40
Q

Meaning of coolant

A

Used to remove heat from something

41
Q

What is a indirect energy source + give an example

A

An indirect energy source is one that can be stored n broken down to release energy
E.g. GLYCOGEN

N.b. Glucose is a DIRECT energy source= used straight away not stored

42
Q

What sugar is present in RNA nucleotides?

A

RIBOSE (a pentose monosaccharide)

43
Q

What is the difference between ribose n deoxyribose?

A

Deoxyribose lacks 1 oxygen atom whereas ribose has it

44
Q

What monosaccharides make up the disaccharide maltose

A

Alpha glucose + alpha glucose

Maltose is found in germinating seeds

45
Q

What monosaccharides make up the disaccharide sucrose

A

Alpha glucose + fructose

Sucrose is found in sugar cane

46
Q

What monosaccharides make up the disaccharide lactose

A

Alpha glucose + beta galactose

Lactose is found in milk

47
Q

What is a polysaccharide

A

Large polymers formed of many monosaccharides held together by glycosidic bonds formed thru condensation reactions

48
Q

What is the difference between amylose and amylopectin

A

Both are starch molecules however amylose has only 1,4 glycosidic bonds whereas amylopectin has 1,4 and 1,6 glycosidic bonds

49
Q

In amylopectin, how often do 1,6 glycosidic bonds form ?

A

In amylopectin 1,6 glycosidic bonds form once every 25 glucose subunits

50
Q

Both glycogen and amylopectin are storage molecules, however why is glycogen arguably better?

A

Glycogen forms more branches than amylopectin, meaning it’s more compact so less space is needed for it to be stored

51
Q

Give 3 similarities between amylopectin and glycogen

A
  • both insoluble
  • 1,4 + 1,6 glycosidic bonds
  • both branched
  • both compact
52
Q

Why is glycogen easily broken down in the body ?

A

Because glycogen, as a result of branching, has many free ends where glucose molecules can be added or removed = this speeds up storing + releasing glucose molecules required by the cell

53
Q

What glucose is glycogen made of ?

A

Glycogen is a polymer of alpha glucose molecules

54
Q

What glucose is cellulose made of ?

A

Cellulose is a polymer of beta glucose molecules

55
Q

How are microfibrils, macrofibrils and fibres formed in a cellulose molecule

A

H bonds form between the adjacent cellulose chains forming MICROFIBRILS which combine together to form MACROFIBRILS which combine to make FIBRE

These fibres r strong 💪 + insoluble which is why cellulose forms the main component of cell walls

56
Q

Describes how beta glucose molecules r joined together in cellulose

A

Cellulose is made from beta glucose molecules joined together by condensation reactions to form glycosidic bonds. However, alternate beta glucose molecules r inverted cuz otherwise the hydroxyl (-OH) groups r too far apart to react. Because of this cellulose is a straight chain w many -OH groups on the outside

57
Q

How are triglycerides formed?

A

Triglycerides form from ESTERIFICATION = a condensation reaction between fatty acids + glycerol forming an ester link/bond between each molecule and 3 molecules of water (one molecule for each ester link)

58
Q

What’s the difference between a saturated vs. unsaturated fat

A

Saturated fats have NO C=C DOUBLE BONDS

Whereas unsaturated fats have one or more C=C DOUBLE BONDS ( the presence of double bonds causes the molecule to kink/bend meaning they can’t pack closely together so they’re usually oils not fats)

59
Q

What is a monounsaturated fat

A

A unsaturated fat with only one double bond between carbon atoms

60
Q

What is a polyunsaturated fat

A

A unsaturated fat w more than one double bond between carbon atoms

61
Q

What are phospholipids

A

They’re modified triglycerides which contain phosphorus along w C,H + O

one of the fatty acids in a triglyceride is replaced w a PHOSPHATE
(phosphate ions r -ve so dissolve in water)
this phosphate joins w the glycerol creating a HYDROPHILLIC END (charged heads)

the remaining 2 fatty acids form the HYDROPHOBIC ENDS (non-polar tails)

62
Q

What are sterols?

A

Steroid alcohols = a type of lipid

4C ring structure

HYDROPHILLIC hydroxyl (-OH) group = polar end which dissolves in water

Rest of molecule hydrophobic

63
Q

Where is cholesterol manufactured in the body?

A

Cholesterol is manufactured in the liver + intestines

64
Q

What is cholesterol and name 4 of its functions

A

Cholesterol is a sterol= a lipid 4C ring structure steroid alcohol w a -OH HYDROPHILLIC group

Important role in:

🧀producing vitamin D

🧀producing steroid hormones

🧀producing bile

🧀providing STABILITY TO CELL MEMBRANES

65
Q

Name roles of lipids due to their non-polar nature

A
  • membrane formation + creation of hydrophobic barriers
  • hormone production
  • electrical insulation necessary for impulse transmission
  • waterproofing e.g. birds feathers + plant leaves
66
Q

Lipids, esp. triglycerides play an important role in long-term energy storage which provides :

A
  • thermal insulation to reduce heat loss e.g. in penguins
  • cushioning to protect vital organs such as heart + kidneys
  • buoyancy for aquatic animals like whales
67
Q

How does one test for lipids?

A

EMULSION TEST = mix lipid sample w an organic solvent e.g. ethanol, next add water and shake. If a white emulsion forms a layer on top it indicates the presence of a lipid

If it remains clear = test negative

68
Q

R group (residual group)

A

A side chain that acts as a functional group as it helps to determine the internal bonds + the shape/function of the polypeptide

69
Q

Peptide bond

A

A covalent bond that forms when 2 amino acids r joined by a condensation reaction w the loss of 1 water molecule 💧

70
Q

How can a peptide bond be broken?

A

A peptide bond can be broken by a HYDROLYSIS reaction 💦

71
Q

Polypeptide

A

A polymer of amino acids each joined to the other by a peptide bond

72
Q

Dipeptide

A

2 amino acids held together by a peptide bond

73
Q

Amino acids all have the same general structure, what is it?

A
  • a carboxyl group (-COOH)
  • an amino group (-NH2)

__ all attached to a carbon atom__

+ an R group (residual/variable group) which is unique to each individual amino acid

74
Q

What is the smallest amino acid + what is it’s r group?

A

Glycine

It’s r group is a hydrogen atom

75
Q

All amino acids contain the elements _ _ _ _ and some contain _

A

All amino acids contain the elements
Carbon, oxygen, hydrogen + nitrogen

+ some contain SULFUR

76
Q

Explain what is involved in the primary structure of a protein 🔴

A

🔴
The primary structure is the sequence in which the amino acids r joined=
•only involves PEPTIDE BONDS•

> this sequence influences how the polypeptide folds to give its final shape

77
Q

Explain what is involved in the secondary structure of a protein 🔵

A

🔵
In the secondary structure polypeptide chain don’t remain flat, they coil=
•as a result of HYDROGEN BONDING•

> where/how the H bonds form depends on the amino acid sequence of the protein

Either
ALPHA HELIX
Or
BETA PLEATED SHEETS

78
Q

In secondary structure how do the H bonds form in an alpha helix

A

In alpha helix the H bonds form between amino acids in one part of the chain to those a little further down the chain

79
Q

In secondary structure how do the H bonds form in beta pleated sheets

A

In beta pleated sheets the H bonds connect to the adjacent pleated sheet

80
Q

Explain what is involved in the tertiary structure of a protein 🌕

A

🌕
In the tertiary structure folding of the protein into its final shape occurs thru interactions between R groups

These interactions include:
⚠️hydrogen bonds= these r the weakest of the bonds formed

⚠️ hydrophobic/hydrophillic interactions= weak interactions between polar + non-polar R groups

⚠️ionic bonds= these r stronger than H bonds n form between oppositely charged R groups

⚠️disulfide bonds= covalent + the strongest bonds, only form between R groups that contain sulfur atoms

81
Q

Not all proteins have QUATERNARY STRUCTURE, but which ones do ?

A

Proteins that r made of more than one polypeptide chain have QUATERNARY STRUCTURE

82
Q

Conjugated proteins

A

Conjugated proteins r GLOBULAR proteins which contain a non-protein component called a PROSTHETIC group

83
Q

What are proteins without prosthetic groups called

A

Proteins without prosthetic groups r called SIMPLE PROTEINS

84
Q

Give an example of a prosthetic group

A

HAEM prosthetic group found in the conjugated protein haemoglobin

85
Q

What happens to the RNA molecules after protein synthesis?

A

After protein synthesis the RNA molecules are degraded in the cytoplasm

The phosphodiester bonds r hydrolysed + the RNA nucleotides r released and reused

86
Q

Properties of ATP

A
  • small= moves easily into + out of cells
  • water soluble = energy requiring processes happen in aqueous environments
  • releases energy in small quantities
  • easily regenerated = can be recharged w energy
87
Q

What is meant by the phrase ‘ATP contains bonds between phosphates w intermediate energy’

A

Bonds w intermediate energy between phosphates means the energy is large enough to be useful for cellular reactions but not so large that energy is wasted as heat

88
Q

What enzyme catalyses the formation of peptide bonds (found in ribosomes)

A

Peptidyl transferase

89
Q

What is the difference between ATP and DNA

A

In ATP the base is always adenine and it has 3 phosphate groups instead of one

💚OCR BIOLOGY A LEVEL (11 decks)

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