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Biology A Level AQA > Biological molecules > Flashcards

Biological molecules Flashcards

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1
Q

How many bonds does carbon like to make

A

4 bonds

  • So can join to make complex molecules of different sizes
  • called the ‘backbone’ for organic e.g. sugars
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2
Q

What 4 molecules are found in all living things

A

1 carbohydrates = sugars
2 lipids = fats
3 proteins = amino acid
4 nucleic acids = DNA

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3
Q

What 3 things make up carbohydrates

A

Carbon
Hydrogen
Oxygen

The same as lipids but arranged differently

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4
Q

What 3 things make up lipids

A

Carbon
Hydrogen
Oxygen

The same as carbohydrates but arranged differently

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5
Q

What 5 things make up proteins

A 
Carbon 
Hydrogen 
Oxygen 
Nitrogen 
Sulphur
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6
Q

What 5 things make up nucleic acids

A 
Carbon 
Hydrogen 
Oxygen 
Nitrogen 
Phosphorus (usually just 1 in the molecule)
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7
Q

What does a polymer have?

A

A repeating pattern

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8
Q

What does saccharide mean

A

Sugar

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9
Q

Carbohydrates ➡️ monomer ➡️ monosaccharides

➡️polymers ➡️ polysaccharides

A

➡️

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10
Q

Proteins ➡️ monomers ➡️ amino acids

➡️ polymers ➡️polypeptides

A

➡️

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11
Q

Nucleic acid ➡️ monomer ➡️ nucleotides

➡️polymers ➡️ polynucleotides

A

➡️

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12
Q

Lipids ➡️monomers ➡️ glycerol + fatty acids = a triglicerol
➡️polymers ➡️ diglycerides, triglycerides
not composed of lots of monomers repeating itself

A

➡️

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13
Q

Monomer + monomer =

What is the + reaction called

A

Polymer

Through condensation reaction

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14
Q

What is a condensation reaction

A

A reaction that occurs when 2 molecules combine to form a more complex molecule with the removal of water

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15
Q

What is hydrolysis reaction

And why is it needed

A

Needed to break down polymers e.g. when eating food

Hydrolysis - it requires water in order to break the bond between the monomers

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16
Q

What are condensation reactions needed for

A

Metabolic rate

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17
Q

Carbohydrates are a source and store of energy, what are their function in plants

A

Structural function to make the plant cell walls rigid

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18
Q

What are simple carbohydrates called

A

Monosaccharides (mono =1) sugars
Disaccharides (di =2)
Polysaccharides (poly = many)

General formula = (CH2O)n

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19
Q

What is a molecular formula

A

The number of atoms in a formula

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20
Q

The molecule formula + general formula =

A

C3H6O3

The number of C and O are always the same
H is always double the C and O

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21
Q

What does hexose mean

A

Means 6 carbons in their ring

E.g. gluctose, fructose, galactose

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22
Q

Glucose

A

Is the main source of energy in respiration

Glucose + O2 ➡️ CO2 + H2O + ATO ➡️ energy

Is the building block for larger carbohydrates ( there are 2 types of glucose)

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23
Q

Glucose + spiral structure =

A

Amylose

Part of starch

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24
Q

Glucose have 4 well adaptations that make them useful

A
  1. Glucose can transport in/out of cells easily through carrier proteins
  2. Small in size - easily transported + soluble in water so can travel through the blood stream in this way
  3. Less reactive - breakdowns are controlled by enzymes - therefore enzymes control the rate of respiration because can only breakdown by passing through an enzyme (the catalyst )
  4. Different structural forms = called isomers (have the same chemical formula but different arrangement of atoms in space)
    (Double bonds mean the arrangement can’t change)
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25
Q

There are 2 isomers in glucose, what are they

A

α - glucose

β-glucose

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26
Q

What is the difference between α-glucose and B-glucose

A

Need diagrams!,!!!

The hydroxy (-OH) is at top for α, bottom for B

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27
Q

What is both alpha-glucose and B-glucose have in common

A

Both are polysaccharides

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28
Q

Why is a ribose called a pentose sugar

A

Because is has 5 carbon atoms

Found in ribonucleic acid and ATP

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29
Q

What is the definition of a disaccharide

A

Sugars that are composed of 2 monosaccharides joined together in a condensation reaction

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30
Q

Alpha-glucose + B-glucose =

A

+ is a condensation reaction
= maltose (found in germinating seeds as more complex carbohydrates + are broken down for energy)
- The seed needs energy so breaks down large carbohydrates to disaccharides (smaller units) (maltose molecules used for energy)

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31
Q

Alpha-glucose + fructose =

A

= sucrose – transported in the phloem to provide sugars to other parts of the plant
(Photosynthesis happens in the leaf = makes sugars called sucrose respiration plus other functions – sucrose travels through the plant through phloem tissue)

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32
Q

Alpha glucose + galactose =

A

+ means condensation reaction

= lactose (Mammal milk to provide energy for its young)

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33
Q

2 monosaccharides =

And what is the bond called

A

A disaccharide

The bond is called a glycosidic bond

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34
Q

What does a condensation reaction create

A

A water molecule

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35
Q

Diagram of CH2OH - the number order of carbon atoms goes clockwise

A

Diagram

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36
Q

Glycosidic bond

A

Between 2 monosaccharides by a condensation reaction therefore the maltose bond is between carbon 1 and carbon 4 so it’s called a 1,4 glycosidic bond

37
Q

Hydrolysis of glycosidic bond

A

Breaking down disaccharides through hydrolysis reaction to 2 monosaccharides equals requires water – give the H2O back to the right that was taken from it in the condensation reaction

38
Q

Examples of polysaccharides

A

Bread, rice, pasta

Needs to have more than 10 monosaccharides in a chain
If the chain has less than 10 monosaccharides it is called a oligosaccharides

39
Q

Polysaccharides properties

A 
They are not:
Not sweet tasting
Not soluble
Not sugars
Have lots of variety because they can change the monosaccharides which changes the whole structure e.g. alpha/B-glucose

Can change how it is bonded together e.g. 1,4 glycosidic bond = amylose (but a 1,4 + 1,6 = glycosidic bond = amylopectin)

40
Q

Alpha glucose = main source of energy in respiration

What is the formula for this

A

Glucose +02 ➡️ CO2 +H20+ATP (energy)

41
Q

Excess chemical energy equals stored in cells by forming polysaccharides of alpha glucose in long chains

Why is alpha glucose well designed for this?

A

Alpha glucose polysaccharide = are compact so ca store a lot of energy in a small space

42
Q

What is the problem with too much water getting into the cell

A

It can burst and die (cytolysis) because it can’t dissolve the water the water

Polysaccharides are large so don’t diffuse out of the cell or we would lose them quickly (can’t fit through carrier proteins)

43
Q

Why are polysaccharides easily hydrolysis to alpha glucose when energy is needed

A

Because enzymes can easily access the end of the polysaccharide to release energy

44
Q

Starch

A

Starch is found in plants The polysaccharide energy that is stored is called starch

Starch is found in photosynthesising cells (in leaves) + storage cells in seeds/storage organs

45
Q

What are amyloplasts

A

Special organelles that store starch in compact/dense/insoluble grains

46
Q

Storage organs

A

Contain cells with lots of amyloplasts to ensure the plant always has a sufficient supply of energy

47
Q

Photosynthesis

A

Making starch to store as energy

48
Q

What two different polysaccharides make up starch

A

Aminos

Amylopecin

49
Q

What are the properties of amalyose

A

– Long chain of alpha glucose

  • Joined by a 1,4 glycogen bond
  • helix shaped = more compact
  • Only has two accessible ends where enzymes can bind to the molecules/clip of the ends to use for respiration therefore only broken down slowly
50
Q

Properties of amylopectin

A
  • has moved branches then amalyose
  • has the occasional 1,6 glycosidic bond as well as 1,4 bonds - this is what creates the branching with more accessible ends to enzymes therefore energy is released quicker - for this alpha glucose respiration
51
Q

What is glycogen

A

The polysaccharides energy store found In animals – because in cells with a high metabolic rate more energy is needed with a higher release rate e.g. liver cells + muscle cells

52
Q

Which glycosidic bond is found more frequently

A

1,6 carbon bond

53
Q

Polysaccharides organisms sample implants, where

A

The cell wall is made from polysaccharides called Celulose
Celulose equal very strong stop plant cells from bursting into much water enters by osmosis (turgid) it swells instead of bursting making the plant stand upright opposed to wilting

54
Q

What is cellulase made from

A

Thousands of B-glucose molecules joined by 1,4 glycosidic bonds

55
Q

Diagram of CH2OH inverted bond + why is this inversion important

A

The inversion stops the cellulase from coiling (like the analyse did) results in a long straight chain in parallel lines

This means we get hydroxyl (– OH) groups that are close in proximity to each other – the hydrogens are close to each other because the close parallel lines

56
Q

Hydrogen bonds

A
  • each individual hydrogen bond is weak because there are thousands of hydrogen bonds the Celulose is very strong overall. This is good because of the swelling that happens in plant cells
57
Q

What makes cellulose strong and rope like

A

The hydrogen bonds that cross-linked the cellulose chain allow the chain to form into strong rope like fibres

58
Q

What is the difference between macrofibres and microfibres

A 
Microfibres bundle together to form large fibres called macrofibres
Macro fibres (Cellulose) create the strong plant cell wall
59
Q

Cellulose is the most abundant material on Earth what is it difficult for most animals to do

A

Not easily digested food because very hard to break down by hydrolysis - because most animals lack the Cellulose enzyme needed to break down the 1,4 glycosidic bonds between B-glucose molecules

-Sam herbivores have symbiotic bacteria in the gut to produce the enzyme

60
Q

Even though humans can’t digest cellulase why is it important

A

Keep the digestive system healthy

61
Q

What is a chitin structure

A

Structural polysaccharide

Can be found in fungi, insects, plants

Use to strengthen the cell walls and fungi

Strengthen exoskeleton and insects

Is waterproof to prevent water loss from body

62
Q

How are chitins similar to cellulose

A

Composed of many B- glucose molecules

Joint with 1,4 glycosidic bonds - inverted molecules therefore chains are strengthened with H cross-links

63
Q

Differences of chitins to cellulose

A

Chitins also contain acetylamine groups bonded to carbon 2 of the B-glucose monosaccharides

64
Q

Glucose + acetylamine =

A

N-acetylglucoseamine

65
Q

Lipids organic molecules with two main types what are they called

A

1) triglycerides - Provide energy e.g. butter

2) phospholipids - structural role in cell membrane

66
Q

What are lipids mostly composed

A

Carbon +hydrogen +oxygen
Need diagram of hydrocarbon chain
A large complex macromolecules but not polymers because they are not made up of individual monomers that can be broken down (instead a long chain)

67
Q

What do triglycerides look like

A

One molecule of glycerol + 3 fatty acids

get diagram

68
Q

Glycerol look like

A

Organic alcohol ➡️ 3 hydroxyl (– OH) groups

69
Q

What does a fatty acid molecule look like

A

Organic acids ➡️ carboxyl (– COOH) groups - joined to a hydrocarbon tail = type of carboxylic acid

70
Q

Do they use the letter R to represent

A

Rest of the hydrocarbons in the chain

71
Q

How does triglyceride form

A 
Condensation reactions (Ester Bonding) 
H2O added during reaction
72
Q

Definition of an ester bond

A

The covalent bond is formed by a condensation reaction between the -OH group and the carboxylic acid and the -OH group of an alcohol

73
Q

Triglycerides saturated or unsaturated what does this mean

A

The different states depend on the presence of a carbon double bond to the fatty acid tail.
No double bond in the hydrocarbon chain = saturated
A double bond in the hydrocarbon chain = monounsaturated (one carbon -carbon double bond)
Many double bonds = polyunsaturated (more than one double bond)
They’re known as fats and oils
fats = solid at room temperature
oils = liquid room temperature

74
Q

What does an unsaturated double bond make the fatty acid tail do

A

Bend
The bending pushes the molecules further part then the saturated molecules - because of the gaps between the unsaturated molecule is the intermolecular forces are weaker - therefore they are liquid form at room temperature

75
Q

Grid of types of fatty acids

A

Grid

76
Q

What else can triglycerides be broken down into

A

Glucose +fatty acids and use for respiration (just like glucose)

Can produce lots of energy because lots of carbon hydrogen bonds can be broken down

Produces a good amount of water from respiration (as a waste product)

77
Q

Why is triglycerides an excellent for energy storage (6):

A

1) provide the most energy per unit of mass of any storage molecule (reduces the mass we would have to carry around if we only use sugar as energy)
2) large nonpolar molecules = don’t dissolve in water therefore don’t affect the osmosis balance of the cell (don’t overload yourself with water until it bursts)
3) what is repel water so aquatic animals produce it on the fur
4) facts as thermal installation
5) that’s protect internal organs e.g. kidneys
6) that’s less dense than water so help aquatic animals float

78
Q

In a phospholipid what is 1 fat fatty acid replaced with

A

1 phosphate molecule

79
Q

What type of reaction does phosphate joy to make a phospholipid

A

Condensation reaction between hydroxyl (– OH) groups on phosphoric acid +glycerol
(Ester bond + extra H2O molecule)

80
Q

What is a hydrophilic molecules

A

A molecule that is attracted to water due to having a charge

81
Q

What is the hydrophobic molecules

A

A molecule that is repelled by water due to not having a charge

82
Q

What happens to the hydrogen ions when a phospholipid is surrounded by water

A

The hydrogen irons disassociate from the phosphoric acid. This is because once the hydrogens are lost it becomes negatively charged meaning the phospholipids heads and now hydrophilic

83
Q

If the fatty acid tales are nonpolar and not charged what does this mean

A

The molecule is hydrophobic

84
Q

Because of phospholipids head is hydrophilic and it’s fatty acid tales are hydrophobic what does this mean

A

The phospholipids will form a layer on the water because the hydrophilic head will attract water but the hydrophobic tail will repell it
(Find diagram)

85
Q

What is a micell

A

A layer of Phospholipids made of a monolayer (heads on the outside tales on the inside squeezing out of the water)

(find diagram)

86
Q

What is a bilayer

A

Form from phospholipids (the heads facing out the tail facing in)
An integral part of all membranes in a cell

87
Q

Why is the phospholipid bilayer so important

A

1) The membrane stays stable because the tails I never exposed to the water (keep their shape tight)
2) Because it’s a barrier it controls the substance in/out of the cell
3) It is electrical insulation ➡️ prevents ions from leaving
4) The middle area is a non-aquatic environment ➡️ forces water to outside the barrier ➡️ therefore things dissolve in water cannot get through the barrier ➡️ therefore only small non-polar molecules can pass through the membrane (e.g. oxygen/carbon dioxide) ➡️ this is important for respiration because its partially permeable to control what enters/leaves the cell

88
Q

Why can’t ions get through the phospholipid bilayer

A

Because ions that dissolve in water cannot get through because they attract water because of their charge

Biology A Level AQA (2 decks)

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