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Biology AS > Biological Molecules - Carbohydrates, Lipids and Proteins > Flashcards

Biological Molecules - Carbohydrates, Lipids and Proteins Flashcards

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1
Q
A
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2
Q

Define a monosaccharide

A

The monomer of a carbohydrate

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3
Q

Name 3 monosaccharides

A

Glucose

Fructose

Galactose

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4
Q

What is the structural difference between alpha and beta glucose?

A

The hydroxyl and hydrogen groups on the right of the molecules are flipped

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5
Q

Define a disaccharide

A

A disaccharide consists of 2 monosaccharides bonded with a glycosidic bond

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6
Q

Name 3 examples of disaccharides

A

Maltose

Sucrose

Lactose

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7
Q

What are the monosaccharides of maltose?

A

2 alpha glucose

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8
Q

What are the monosaccharides of sucrose?

A

Glucose and fructose

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9
Q

What are the monosaccharides of lactose?

A

Glucose and galactose

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10
Q

What is a structural polysaccharide found in animals?

A

Chitin

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11
Q

What are 3 examples of polysaccharides?

A

Cellulose

Glycogen

Starch

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12
Q

What are the monosaccharides of cellulose?

A

Chains of beta glucose

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13
Q

What are the monosaccharides of glycogen

A

Chains of alpha glucose

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14
Q

What are the monosaccharides of starch?

A

Chains of alpha glucose

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15
Q

What are 3 examples of hexoses?

A

Glucose

Fructose

Galactose

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16
Q

Define a condensation reaction

A

The process where 2 monomers form a covalent bond and a H20 molecule is lost

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17
Q

Define hydrolysis

A

The process where water is added to a polymer under certain conditions, breaking the covalent bond and releasing the individual monomers

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18
Q

Describe the Benedict’s test for sugars

A
  • add an excess of Benedict’s reagent (blue)
  • Heat in a boiled water bath
  • If the test is positive, a coloured precipitate will form
  • Green (very low), Yellow (low), Orange (medium), Red (high)
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19
Q

What is the structure of glycogen and where is it found?

A

Glycogen consists of multi-branched, short chains of alpha glucose

It is found in animals (liver and muscles) and plants

Insoluble and large

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20
Q

What is the function of glycogen?

A

Storage molecule

Synthesized from alpha glucose when blood sugar levels are too high

Can be easily broken down into an energy source when blood sugar levels are too low

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21
Q

How does the structure of glycogen help its function?

A

Glycosidic bonds are easily broken by water

Multiple branches provide quick breakdown

Low osmotic potential means it doesn’t diffuse in and out of cells and also doesn’t affect the volume of water of cells

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22
Q

What is structure of starch?

A

Starch consists of alpha glucose chains and specific to plants only

The 2 types are amylose (unbranched) and amylopectin (branched)

Forms close spirals and is insoluble

23
Q

What is the function of starch?

A

It is designed for use in respiration and long term storage in plants

Used when there is limited light -> less photosynthesis

Stored in seeds in order for them to grow before they can photosynthesise

24
Q

How does the structure of starch help its function?

A

The long chains wind up tightly

  • efficient storage
  • Monomers can be hydrolyzed for energy use
  • Amylopectin used for shorter term energy release as it is branched
  • Amylose used for longer term energy release as it is unbranched
25
Q

What is the structure of cellulose?

A

Chains of beta glucose, resulting in every other molecule being flipped

Flipped molecules can form hydrogen bonds with the parallel chain below, forming a strong, rigid polymer

26
Q

What is the function of cellulose?

A

To provide structure - it makes up 30% of the cell wall in plants

27
Q

How does the structure of cellulose help its function?

A

The beta glucose linkages gives it a flat a rigid structure which helps it to provide structure throughout different organisms

28
Q

What are the properties of lipids?

A

Double energy:mass ratio than carbohydrates

Insoluble in water but soluble in organic substances

High ratio of H:O so releases water when oxidised

29
Q

What are the functions of lipids?

A

Energy storage molecules

Waterproofing

Insulation

Physical protection

30
Q

What are the major differences between fats and oils?

A

Fats: Solid at 10 - 20 degrees, saturated

Oils: Liquid at room temp , unsaturated

31
Q

What are the 3 types of triglyceride tails?

A
  • Saturated -> no double bonds
  • Unsaturated -> one double bond
  • Polyunsaturated -> multiple double bonds
32
Q

What is the structure of a triglyceride?

A

3 fatty acid tails combined with a glycerol head by an ester bond

33
Q

Define a phospholipid?

A

Similar to lipids except one fatty acid is replaced with a phosphate molecule

34
Q

What is the relationship between phospholipids and water?

A

Phospholipids have a hydrophilic head and a hydrophobic tail

This causes them to form structures such as lipid bilayers in water

35
Q

What are amino acids composed of?

A

Centre alpha C

Solitary H branch

Amino group

Carboxyl group

R (variable) group

36
Q

How many amino acid variations are there?

A

20

37
Q

What feature of amino acids provides indirect evidence for evolution?

A

The same 20 amino acids occur in all living organisms

38
Q

How many structural levels occur in proteins?

A

Proteins can have up to 4 levels of structure

Some only need 3 -> only the large proteins have quaternary structure

39
Q

What is the primary structure of proteins?

A

The synthesis of amino acids into a polypeptide chain

40
Q

What is the secondary structure of proteins?

A

This occurs as H bonds form between the H+ ions and O- ions of the carboxyl group

These bonds are relatively weak but contain enough strength to fold the polypeptide chain into a 3D shape

41
Q

What are 2 examples of shapes formed in secondary structure?

A

Alpha helix

Beta pleated sheet

42
Q

What is the tertiary structure of proteins?

A

Result of further twisting of the secondary structure

Can be complex and is specific to the protein

Plays a significant role in determining the behaviours of the protein

Maintained by 3 types of bonds

43
Q

What are the 3 types of bond that maintain tertiary structure?

A

Disulfide bonds - strong and not easily broken

Ionic bonds - formed between the carboxyl and amino groups that weren’t involved in peptide bonds, weaker than disulfide bonds and easily broken by pH changes

Hydrogen bonds - numerous but easily broken

44
Q

What is the quaternary structure of proteins?

A

Multiple polypeptides bond together eg Haemoglobin

45
Q

If 2 proteins have the same and type of amino acids, why will they have different tertiary structures?

A

The amino acids are in different orders

This means that different hydrogen, ionic and disulfide bonds will form, twisting the polypeptide into a different shape

46
Q

What is the test for lipids?

A

The Emulsion Test

Add ethanol to the sample in a 5:2 ratio of ethanol:sample

If lipids are present, a white emulsion will form

47
Q

What are the types of proteins?

A

Fibrous proteins eg collagen

Globular proteins eg enzymes

48
Q

What is the function of a fibrous protein?

A

Fibrous proteins have structural functions eg collagen is found in tendons (joining muscles to bones)

49
Q

What is the function of a globular protein?

A

Globular proteins perform metabolic functions eg enzymes catalyse digestion

50
Q

How are the structures of fibrous and globular proteins different?

A

Fibrous proteins have a quaternary structure with 2 other polypeptide chains

Globular proteins only have a tertiary structure, not quaternary

51
Q

Describe the structure of collagen and how it is formed

A

Primary Structure -> coiled chain

Secondary Structure -> tightly coiled into an alpha helix

Tertiary Structure -> also an alpha helix

Quaternary Structure -> 3 double coiled polypeptide chains wound together

52
Q

What is the tertiary structure of haemoglobin?

A

2 alpha helices and 2 beta pleated sheets

53
Q
A

Biology AS (17 decks)

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