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Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

Test for reducing sugars

A
  1. add benedicts reagant to a sample solution in a test tube
  2. heat the test tube in a water bath or beaker of water thats has been brought to a boil
  3. If a reducing sugar is present, the colour will change from blue to yellow/orange (some present) and to brown/brick red (lots present)
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2
Q

Test for non reducing sugars

A
  1. Add dilute hydrochloric acid to the sample and heat in water bath that is boiling
  2. Neutralise solution with sodium hydrogencarbonate
  3. Carry out benedicts test as usual
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3
Q

Why is water important to life

A

Provides a medium for metabollic reactions to take place
Makes 71% of earths surface
Universal solvent - transport
Habitat for life
Involved in chemical reactions

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4
Q

Properties of water

A

Polar
High specific heat capacity
High latent heat of vaporisation
Hydrogen bonds

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5
Q

Why is water being polar so helpful?

A

Can act as a solvent:
- Many ions and covalently bonded substances will dissolve in it
- Which allows chemical reactions to occur as substances can move more freely

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6
Q

What is high specific heat capacity and why is it useful in water?

A

Amount of thermal energy required to increase 1kg of waters temperature by 1 degree celcius
High in water as it has many hydrogen bonds
- Useful as it helps organisms to regulate their temperatures
- Provides suitable habitats

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7
Q

What is high latent heat of vaporisation and why is it useful in water?

A
  • The amount of energy required to change state
  • Water has high latent heat of vaporisation due to many hydrogen bonds, meaning it would take a lot energy to change waters state
  • Useful as it can be used by organisms to lose great amounts of heat for example sweating or transpiration from leaves
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8
Q

Cohesion

A

Cohesion is the bond between two of the same molecules
in water this hydrogen bonds between one another
- This allows collums of water to move through the xylem of plants and blood vessels in animals
- This also enables surface tension where a body of water meets air, these bonds occur between the top layer of water molecules to create a film on the body of water - allows pond skaters

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9
Q

What are monosaccharides

A

Subunit of polysaccharides
Simplest form of a carbohydrate

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10
Q

Example of a monosaccharide

A

Glucose
Galactose
Fructose

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11
Q

Difference between Alpha glucose and Beta glucose

A

Alpha glucose’s OH group is on the lower plane of Carbon 4 whilst Betas is at the higher
A for ants - lower
B for bees - higher

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12
Q

What are Disaccharides?

A

Two monosaccharides

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13
Q

Example of a disaccharide

A

Glucose + Galactose = Lactose
Fructose + Glucose = Sucrose
Glucose + Glucose = Maltose

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14
Q

Ribose and Deoxyribose

A

Pentose sugars
Ribose = RNA nucleotides
Deoxyribose = DNA nucleotides
Deoxyribose is the same as ribose except it is missing an oxygen atom on Carbon 2

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15
Q

The glycosidic bond

A

Formed by a condensation reaction - loss of water to join molecules
Can be broken down by hydrolysis - addition of water

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16
Q

What are Polysaccharides?

A

Multiple monosaccharides joined by glycosidic bonds

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17
Q

Examples of polysaccharides

A

Animals: Glycogen
Plants: Starch - amylose and amylopectin
Plants: cellulose

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18
Q

What is the structure and function of glycogen

A

1-4 and 1-6 glycosidic bonds - alpha glucose
Storage of carbohydrates in animals
branched molecule - compact
- more energy held in a small amount of space
Insoluble - does not affect water potential

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19
Q

Structure and function of amylose

A

1-4 glycosidic bonds
Unbranched
insoluble - does not affect water potential

20
Q

Amylopectin

A

1,4 and 1,6 glycosidic bonds between alpha glucose molecules
Branched molecule
Insoluble - does not affect water potential
Storage of plants

21
Q

Structure and function of Cellulose

A
  • Long chains of B glucose joined by 1,4 glycosidic bonds
  • B glucose is an isomer of A glucose so in order to form the 1,4 glycosidic bonds consecutive B glucose molecules must be flipped
  • Many hydrogen bonds to form fibrils
  • Used for structural strength of cell wall
22
Q

what is the structure of an amino acid?

A

Amine group - NH2
A Carbon atom
A Hydrogen atom
R group
Carboxyl group - COOH

23
Q

How many amino acids are there

A

20 found in proteins common to all living organisms

24
Q

What are proteins?

A

polypeptide chains of amino acids

25
Q

What are peptide bonds?

A

Condensation reaction which joins two amino acids
Can be broken down by hydrolysis

26
Q

How many levels of structure are there and what are they?

A

Four:
Primary
Secondary
Tertiary
Quaternary

27
Q

Primary structure of protein

A

Sequence of amino acids joined by covalent peptide bonds

28
Q

Secondary structure of a protein

A

Hydrogen bonding between r groups on amino acids
Creates the 3D shape of protein
Can form a Alpha helix and Beta sheet

29
Q

Tertiary structure of a protein

A

Additional bonds of the protein structure:
- Ionic
- Disulphide
- Weak hydrophobic interactions

30
Q

Quaternary structure of a protein

A

Multiple polypetide chains joined together

31
Q

Globular Proteins

A

Compact, roughly spherical and soluble
Form a spherical shape when folding into their tertiary structure:
- non polar hydrophobic R groups are orientated towards their center
- Polar hydrophillic R groups orientate themselves on the outside of the protein

32
Q

Cations

A

Calcium ions (Ca2+)
Potassium (K+)
Sodium ions (Na+)
Hydrogen ions (H+)
Ammonia (NH4+)

33
Q

How does water act as a solvent?

A

Polar molecules can dissolve in water
The polar properties allows water to attract both negative and positive solutes.
This allows molecules to be transported in the body.

34
Q

Water as a transport medium

A

As polar subtances can be dissolved in water they are easily transported, either in the blood of animals or xylem of plants.
Water is transported in the xylem due to transpiration - this occurs due to cohesion of water molecules

35
Q

Water as a coolant

A

High specific heat capacity meaning it takes lots of energy to change the temperature of water
This is useful as internal temperatures of plants and animals should remain relatively constant.
Water also has high latent heat of vaporisation meaning it takes lots of energy to change the state of water to gas.

36
Q

Water as a habitat

A

Water buffers temperature means it provides a stable environment, in terms of temperature for aquatic organisms
Cohesion provides surface tension to water. This enables small invertebrates to move and live on the surface, providing them a habitat away from predators within water.
Ice is less dense then water creating an insulating layer on the surface

37
Q

Properties of lipids?

A

Macromolecules
Non polar - hydrophobic
Insoluble in water
Dissolve in organic solvents such as ethanol
Made up of fatty acids and glycerol

38
Q

Triglyceride structure

A

1 glycerol
3 fatty acid chains
Glycerol is joined with fatty acids by condensation reactions between them known as an ester bond

39
Q

Saturated fatty acids vs Unsaturated

A

Saturated - no double bonds only single between carbons - fully saturated with hydrogen
Unsaturated - double bonds between carbons

40
Q

Properties of triglycerides

A
  1. Can transfer energy due to large ratio of energy storing carbon-hydrogen bonds, the breakdown of these release energy
  2. Due to the high ratio of hydrogen to oxygen atoms they can act as a metabolic water source. This is because they can release water when oxidised
  3. As lipids are large, hydrophobic molecules they are insoluble in water. This means they will not affect the water potential and osmosis.
  4. Low in mass meaning lots can be stored in an animal without it increasing the mass and preventing movement
41
Q

Structure of Phospholipids

A
  • Made of a glycerol molecule, two fatty acid chains and a phosphate group
  • Two fatty acids also bond to the glycerol via two condensation reactions, resulting in two ester bonds
  • One saturated and one unsaturated train
42
Q

Properties of phospholipids

A
  • Hydrophilic head of a phospholipid can attract with water as it is charged
  • Due to the phosphate being charged, it repels other fats
  • The fatty acid chain is not charged. It is known as the hydrophobic tail and repels water but will mix with fats
  • Polar
43
Q

How do phospholipids form the phospholipid bilayer

A

Hydrophilic heads on outside of bilayer as they can interact with water and polar molecules
Hydrophobic tails align inside of bilayer

44
Q

Cholesterol

A

Sterols
Have 4 carbon rings
Hydroxyl group at one end
Hydrophilic and hydrophobic ends

45
Q

How does cholesterol affect the phospholibid bilayer

A

Impact fluidity
Reduce the fluidity of membranes at high temperatures
Increase fluidity at low temperatures

46
Q
A

Biology (9 decks)

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