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Biological Molecules Flashcards

Biological elements, water, carbohydrates, testing for carbohydrates, lipids, structure of proteins, types of proteins, nucleic acids, DNA replication and the genetic code, protein synthesis, ATP.

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AP® Biology flashcards Biology 101 flashcards
1
Q

How does hydrogen bonding occur between water molecules?

A

Water is a polar molecule the positive and negative regions of the molecule attract eachother and form hydrogen bonds.

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2
Q

What does ‘water has adhesive properties’ mean? And give an example.

A

Water molecules are attracted to other materials.

For example when you wash your hands and the water doesn’t run straight off.

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3
Q

What does it mean when water has ‘cohesive properties’? And give an example.

A

Cohesive properties means that it moves as one mass because the molecuels are attracted to eachother.

Example of when this occurs is when you drink water usinf a straw, it is also how plants are able to draw up water up their roots.

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4
Q

Give some examples of roles of water in living organisms:

A

Transport medium
Coolant
Habitat
Solvent

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5
Q

Describe water’s role as a solvent.

A

Many of the solutes in an organism can be dissolved in water as it is a polar molecule.
Acts as a medium for chemical reactions and helps transport dissolved compoumds in and out of the cell.

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6
Q

Describe water’s role as a transport medium.

A

Cohesion of water molecules - molecules will stick together when water is transported.
Adhesion of water molecules- water can rise up a narrow tube against the force of gravity.

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7
Q

Decribe water’s role as a coolant.

A

Helps to buffer temperature changes during chemical reactions because of the large amount of energy requires to overcome hydrogen bonding this is important as enzymes are only active in a narrow temperature range.

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8
Q

Describe water’s role as a habitat.

A

Water is stable which means it does not chnahe temperature or become a gas easily therefore providing a constant environment.
Because ice forms on the surface thsi forms an insulating layer for the water below this means that aquatix animals can survive freezing temperatures.
Surface tension is strong enough to inhabit small insects such as pondskaters.

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9
Q

What happens when glucose undergoes a condensation reaction?

A

Condensation reaction is a process to turn 2 glucose monosaccharides into a disaccharide.
In the reaction 2 hydrogen atoms and an oxygen atom are removed to make water.
A covalent bond is formed between the two glucose molecules called the 1 4 glycosidic bond.

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10
Q

What is a hydrolysis reaction and what is it used for? Name an example.

A

This is a reverse reaction to the condensation reaction.
In this reaction water molecules are added to break the glycosidic bonds.
This reaction is used to release glucose for respiration so starch or glycogen undergo hyrdrolysis.

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11
Q

What chemical elements does carbohydrates include?

A

C H and O

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12
Q

What chemical elements does lipids include?

A

C H and O

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13
Q

What chemical elements does proteins include?

A

C, H, O, N and S

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14
Q

What chemical elements does nucleic acid include?

A

C, H, O, N and P

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15
Q

Describe the ring structure of glucose and ribose?

A

Glucose is a hexose monosaccharide which means it is composed of 6 carbons.

Ribose is a pentose monosaccharide because it is composed of 5 carbon atoms.

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16
Q

Give some properties of glucose

A

Polar

Soluble

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17
Q

What are the 2 types of glucose?

A

Alpha and beta

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18
Q

What is the structural difference between an alpha and beta glucose?

A

The OH hydroxyl group are in opposite positions.

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19
Q

How is a disaccharide formed? Give an example of a product formed.

A

Condensation reaction takes place. 2 alpha glucose molecules are side by side and the hydroxyl groups react when this happens 2 hydrogen atoms and an oxygen atom are removed from the glucose monomers to form a water molecule. A 1 4 glycosidic bond is formed between the 2 glucose molecules. An example of a product formed form this reaction is maltose {disaccharide}.

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20
Q

How are polysaccharides broken?

A

The 1 4 glycosidic bonds break via a hydrolysis reaction. Water molecules are added and the reaction is catalysed by enzymes. This is the reverse of a condensation reaction.

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21
Q

What is starch made up of?

A

Amylose and Amylopectin

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22
Q

Describe the structure of Amylose.

A

Formed by alpha glucose molecules
Connected by 1 4 glycosidic bonds.
Long chain of glucose twists to form helix further stabilised by hydrogen bonding.

This makes amylose more compact and much less soluble.

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23
Q

Describe the structure of amylopectin.

A

Made of alpha glucose molecules bonded with 1 4 glycosidic bonds.
Has a branched structure.
Glycosidic bonds are formed in condensation reactions between carbon 1 and 6on 2 glucose molecules.
1-6 branching points occur approximately once every 25 glucose subunits.

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24
Q

Describe the structure of glycogen.

A

Has more branches than amylopectin which means it is more compact and less space is needed for it to be stored.

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25
Q

Describe the structure of cellulose.

A

Made up of beta glucose molecules.
Alternate beta glucose molecules are turned upside down.
Straight chain molecule is formed called cellulose.

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26
Q

How does glycogen’s structure help it to carry out it’s function?

A

The branches means that it is more compact and less space is needed for it to be stored.
There are many free ends where glucose molecules can be added or removed.
This speeds up the processes of storing or releasing glucose molecules required by the cell.

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27
Q

How does the structure of cellulose help to carry out it’s function?

A

Cellulose makes up cell walls in plant cells.
Cellulose molecules make hydrogen bonds with each other making microfibrils which combine to form fibres, these fibres are strong and insoluble and are used to make cell walls. It is very hard to break down.

28
Q

How does the structure of starch help it to carry out it’s function?

A

Starch is compact which makes it easier for storage and it is much less soluble. Has a branched stricture which means it is easier for it to meet the demands of the cell by releasing glucose and storing it in order for it to be used in respiration.

29
Q

How does the structure and properties of glucose helps it to carry out its function?

A

Glucose is soluble in water this is important because it means glucose can be dissolved in the cytosol of the cell.

30
Q

Describe the structure of a triglyceride .

A

Combining one glycerol molecule with 3 fatty acids.

31
Q

Describe the structure of a phospholipid.

A

Modified triglycerides and contain the element phosphorus.

One of the fatty acids in the triglyceride molecule is replaced with a phosphate group to make a phospholipid.

32
Q

What is an unsaturated fatty acid?

A

Fatty acids with double bonds.

33
Q

What is a saturated fatty acid?

A

Fatty acids with single bonds.

34
Q

Why are some fatty acids liquid at room temperature?

A

The presence of double bonds causes the molecule to kink or bend so they cannot pack closely together.

35
Q

What is esterification?

A

The hydroxyl groups react leading to the formation of 3 water molecules and the formation of ester bonds. This is the synthesis of triglycerides.

36
Q

How are triglycerides broken down?

A

The ester binds are broken through the process of hydrolysis.
3 water molecules are supplied to reverse the reaction that formed the triglyceride.

37
Q

What is a function of a phospholipid?

A

Key role in forming cell membranes

38
Q

What parts of a phospholipid is hydrophilic and hydrophobic?

A

Hydrophilic- the charged heads are attracted to water.

Hydrophobic- non-polar tails are repelled by water.

39
Q

Name some biological functions of lipids:

A 
Buoyancy {animals e.g. whales}.
Cushioning to protect vital organs.
Thermal insulation to reduce heat loss.
Hormone production.
Membrane formation 
Creation of hydrophobic barriers.
Waterproofing (in birds feathers sand plant leaves).
Electrical insulation important for impulse transmission.
40
Q

What is the general structure of an amino acid?

A

R group (variables group).
Hydrogen group.
Carboxylic acid group.
Amino group

41
Q

What bonds are amino acids in a chain linked by?

A

Peptide bonds

42
Q

Describe the synthesis of peptide bonds.

A

Undergoes condensation reaction.
The hydroxyl in the carboxylic group of one amino acid reacts with a hydrogen in the amine group of another amino acid.
A peptide bond is formed and water is produced.

43
Q

Describe the breakdown of peptide bonds.

A

Hydrolysis reaction occurs.
Reaction is catalysed by protease.
A water molecule is supplied to break down the peptide bond reforming the amino group and the carboxylic acid group.

44
Q

What are the levels of protein structure?

A

Primary
Secondary
Tertiary
Quaternary

45
Q

What is the primary structure of proteins?

A

This is the sequence in which the amino acids are joined directed by information in the DNA. This determines the ultimate shape and function fo the protein.

46
Q

What is the secondary structure of proteins?

A

The oxygen hydrogen and nitrogen atoms of the basic repeating structure fo the amino acids react.
Hydrogen bonds may form within the amino acid chain pulling it into a coil shape called an alpha helix.

47
Q

What is the tertiary structure of proteins?

A

This is the folding of the protein into its final shape.

Often includes sections of secondary structure.

48
Q

What are the interactions that can occur between R-groups?

A

Hydrophobic/Hydrophilic interactions (weak interactions between polar and non-polar R groups.

Hydrogen bonds (weakest bonds formed).

Ionic bonds (stronger than hydrogen bonds form between oppositely charged R groups.

Disulphides bonds (covalent and strongest bonds, only form between R groups that contain sulphur atoms).

49
Q

What is the quaternary structure of proteins?

A

Contains number of individual polypeptide chains linked in various ways.
Interactions between different subunits in different protein molecules.

50
Q

What is a globular protein?

A

They are compact, water soluble and roughly spherical in shape.
They form when proteins fold into their tertiary structures.

51
Q

What is the function of a globular protein?

A

Essential for regulating many chemical reactions, immunity, muscle contraction.

52
Q

Name an example of a globular protein.

A

Insulin

53
Q

What is the function of insulin.

A

Hormone involved in the regulation of blood glucose concentration.

54
Q

What is a conjugated protein?

A

Globular proteins that contain a prosthetic group.

55
Q

What is a prosthetic group?

A

A non-protein component.

56
Q

Give an example of a prosthetic group.

A

Haem groups (Fe 2+).

57
Q

Name some examples of a conjugated protein?

A

Haemoglobin and catalase

58
Q

Describe the structure and function of haemoglobin.

A

Haemoglobin is the oxygen-carrying pigment found in red blood cells.
Made up of 4 polypeptides.
Quaternary structure protein.
Each subunit contains a prosthetic haem group .

59
Q

Describe the structure and function fo catalase.

A

Is an enzyme that breaks down hydrogen peroxide in the body (it is damaging to cells and if accumulated can damage cells catalase prevents that).
It is a quaternary protein.
Contains 4 haem prosthetic groups
The irom 2 allows to interact with hydrogen peroxide to help speed up its breakdown.

60
Q

What is a fibrous protein?

A

Make strong long molecule that are not folded into complex 3d shapes.
They are long and insoluble molecules.

61
Q

Name some examples of fibrous proteins.

A

Keratin, Elastin and Collagen.

62
Q

Where is keratin found and give properties and function .

A

Found in hair, skin and nails

Strong inflexible and insoluble.
Has many strong disulphides bonds.

63
Q

Where is elastin found and give properties and function.

A

Protein found in elastic fibres in walls of blood vessels, alveoli in the lungs.
Give structures flexibility and return to normal size.

64
Q

Where is collagen found and give properties and function.

A

Connective tissue found in skin, tendons, ligaments, and the nervous system.
Has flexibility,
Rope like structure.

65
Q

Why does water have high specific heat capacity and why is this important?

A

A large amount of energy is required to increase water temperature.

This is important because that means there is thermal stability in aquatic environments and inside organisms.

Biology (4 decks)

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