Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > 2.1.2: Biological molecules > Flashcards

2.1.2: Biological molecules Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Ionic bond description and strength

A

Ionic bonds are more likely to be broken by pH and temperature changes
The electrons are transferred
They form positive and negative ions, held together by attraction of opposite charges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Covalent bond description and strength

A

Strongest of the bonds and not easily broken.
The atoms share a pair of electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Hydrogen bond description and strength

A

Strongest of the attractions but weaker than covalent bons
They are easily broken by pH and temperature changes
The polar oxygen of one molecule is attracted to the polar hydrogen of another due to uneven distribution of electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What charger are anions and what charge are cations?

A

Cations are positive
Anions are negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define a monomer and give examples

A

A monomer is a small unit that can be reacted with other molecules to form a polymer

Examples: monosaccharides, nucleotide, amino acids and fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define a polymer and give examples

A

A large molecule made up of a chain of repeating units from many monomers

Examples: Starch, DNA double helix, polypeptide and triglyceride

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe polymerisation

A

The joining of repeating units (monomers) into a long chain (polymers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe a condensation reaction

A

A reaction that occurs when two molecules are joined together with the removal of water

A monomer forming a polymer is a condesation reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe what macromolecules are

A

Large molecules with a relatively high molecular mass and must have a stable structure to ensure it can meet its function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe a hydrolysis reaction

A

A reaction that occurs when a molecule is split into two smaller molecules, with the addition of water, breaking the covalent bond between two monomers.

A polymer being brokwn down into two monomers is a hydrolysis reaction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What type of bond forms between two monosaccharides in carbohydrates?

A

A glycosidic bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What type of bond forms between 2 amino acids in proteins?

A

A peptide bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of bond forms between nucleotides in nucleic acids?

A

Phosphodiester bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Name a polymer formed by monosaccharides?

A

A polysaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name a polymer formed formed by amino acids?

A

Polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name a polymer formed by nucleotides?

A

Polynucleotide (nucleic acid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name a polymer formed by fatty acids + glycerol

A

Lipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Example of polysaccharides found in plants and polysaccharides found in animals?

A

Plant: Starch and cellulose
Animal: Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Give 2 examples of proteins

A

Enzymes and antibiotics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give 2 examples of nucleic acid

A

DNA and RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Properties of water- Good metabolite

A

Water is a good metabolite
* It is released in condensation reactions
* It is used in hydrolysis reactions to break bonds
* It is used in photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Properties of water- Good solvent

A

Water is the solvent where metabolic reactions occur
* As water is a polar molecule many ions (e.g. sodium chloride) and covalently bonded polar substances (e.g. glucose) will dissolve in it as water molecules will bind to solute molecules

  • This allows chemical reactions to occur in cells (cytoplasm is 70-95% water)
  • And, this allows metabolites (ions and molecules) to be transported efficiently
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Properties of water- High Specific Heat Capacity

A

Water has a high specific heat capacity relative to the size of the molecule
* A large amount of thermal energy required to raise the temperature of 1kg of that substance by 1°C
* Due to many intermolecular hydrogen bonds which take a lot of energy to break or build
* So, water has a stable temperaturaature
* So, water is a buffer keeping temperature stable and preventing sudden change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Properties of water- Large latent heat of vaporisation

A

Relatively large latent heat of vaporisation
* To change state (from liquid to gas) a large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate
* So, as water evaporates, lots of energy is taken with it causing a cooling effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Properties of water- Strong cohesion and adhesion

A

Strong cohesion
* Hydrogen bonds between water molecules allows for strong cohesion between water molecules
* Enabling surface tension where a body of water meets the air, these hydrogen bonds occur between the top layer of water molecules to create a sort of film on the body of water

Strong adhesion
* Water is also able to hydrogen bond to other molecules, such as cellulose, which is known as adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Properties of water- Densitity, viscosity, incompressibility, transparency

A

Density
* When water becomes cooler than 4°C it becomes less dense
* So, ice is able to float on water

Viscosity
* Water is viscous so it flows easily

Incompressible
* Water cannot be compressed

Transparent
* Light can be transmitted through water so will not stop light going through anything

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why water is important to living organisms

A
  1. Metabolite- allows for photosynthesis
  2. Solvent- allows substances eg nutrients and ions to be atransported throughout organism
  3. SHC- stable habitats in aquatic environments and maintains optimal temperature for enzyme activity in both prokaryotes and eukaryotes
  4. LHV- cooling effect for living organisms, eg the transpiration from leaves or evaporation of water in sweat on the skin
  5. Cohesion- allows columns of water to move through the xylem of plants and through blood vessels in animals. And allows insects such as pond skaters to float due to surface tension
  6. Adhesion- enables water to move up the xylem due to transpiration
  7. Density- Lakes don’t feeze completely so aquatic organisms aren’t killed as temperature falls. And, allows habitats above water and in water eg, fish and polar bears.
  8. Viscosity- Can move easily up the xylem
  9. Incompressability- keep cells turgid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Structure of a water molecule

A
  • Water is a dipolar molecule
  • Water has an uneven distribution of charge (oxygen is slightly negative and the hydrogens are slightly positive)
  • Between oxygen and hydrogen are strong covalent bonds. These are intramolecular bonds
  • A hydrogen bond is the attraction between the slightly positive hydrogen and slightly negative oxygen. This is an intermolecular bond and individually are weak
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is a monosaccharide?

A

An individual sugar molecule (monomer) that makes up disaccharides and polysaccharides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

3 examples of monosaccharides

A
  1. Glucose
  2. Fructose
  3. Galactose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is a hexose sugar and give examples?

A

A sugar containing 6 carbon atoms
Example: Glucose, galactose and fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is a pentose sugar and give examples?

A

A sugar containing 5 carbon atoms
Examples: Ribose and deoxyribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

In what biological molecules do we find pentose sugars?

A

Nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the difference between α-glucose and β-glucose?

A

The position of the hydroxyl group (OH) on the first carbon atom differs.

α-glucose= OH is below the plane of C
β-glucose= OH is above the plane of C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What type of reaction joins two monosaccharides together?

A

Condensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is a disaccharide?

A

A molecule formed by joining two monosaccharides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Give 3 disaccharides and how they’re formed

A
  1. Glucose + Glucose –> Maltose
  2. Glucose + Fructose –> Sucrose
  3. Glucose + Galactose –> Lacotse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Which disaccharides are reducing sugars?

A

Maltose and lactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Which disaccharide is a non-reducing sugar?

A

Sucrose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is a reducing sugar?

A

A sugar that can lose or donate electrons to other compounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What process breaks the bond between two monosaccharides?

A

Hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How are disaccharides and polysaccharides formed?

A

Disaccharides and polysaccharides are formed when two hydroxyl (-OH) groups (on different saccharides) interact to form a strong covalent bond called the glycosidic bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are polysaccharides?

A

Polysaccharides are polymers of monosaccharides. They’re made of hundreds or thousands of mosaccharides bonded together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Starch:
* What monosaccharide is it made of
* What polysaccharides is it made of
* Is it storage or structural
* Is it plant or animal

A

Monosaccharide-α-glucose
Polysaccharides- Amylose and amlyopectin
Store or structural- Energy store
Plant or animal- Plants in starch grains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Structure of amylose

A

Amylose (10 - 30% of starch)
* Unbranched helix-shaped chain with 1,4 glycosidic bonds between α-glucose molecules
* The helix shape enables it to be more compact allowing more storage in a smaller space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Structure of amylopectin

A

Amylopectin (70 - 90% of starch)
* 1,4 glycosidic bonds between α-glucose molecules but also 1,6 glycosidic bonds form between glucose molecules creating a branched molecule
* Hydrolysed easily due to branches
* The branches increase surface area for enzymes to hydrolyse glycosidic bonds, releasing glucose quickly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Glycogen
* What monosaccharide is it made of
* Is it storage or structural
* Is it plant or animal

A

Monosaccharide- Alpha glucose
Plant or animal- Animal (in liver and muscle cells)
Store or structural- Energy store

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Structure of glycogen

A
  • 1,4 glycosidic bonds between α-glucose molecules and 1,6 glycosidic bonds between glucose molecules creating a branched molecule
  • HIGHLY branched so hydrolysed the easiest as there is more access points for enzymes
  • Branches increase surface area for enzymes to hydrolyse glycosidic bonds, releasing glucose quickly.
48
Q

Cellulose
* What monosaccharide is it made of
* Is it storage or structural
* Is it plant or animal

A

Monosaccharide- β-glucose
Storage or structural- Structural
Plant or animal- Plant

49
Q

Cellulose structure

A
  • Made up of long chains of β-glucose joined together by 1,4 glycosidic bonds with alternating β-glucose molecules are flipped/turned upside down so it forms straight lines
  • many hydrogen bonds form between the long chains forming microfibrils
  • These microfibrils join to form fibres which cross over each other in the cell walls
  • So, it has high tensile strength
50
Q

What chemical elements make up carbohydrates?

A
  • Carbon
  • Hydrogen
  • Oxygen
51
Q

What chemical elements make up lipids

A
  • Carbon
  • Hydrogen
  • Oxygen
52
Q

What chemical elements make up proteins?

A
  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Sulfur
53
Q

What chemical elements make up Nucleic acids?

A
  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
54
Q

Role of Ca 2+

A
  • Muscle contraction
  • Nerve impulse transmission
55
Q

Role of Na+

A
  • Nerve impulse transmission
  • Kidney function
56
Q

Role of K+ ions

A
  • Nerve impulse opening
  • Stomatal opening
57
Q

Role of H+ ions

A
  • Catalysis of reactions
  • pH determination
58
Q

Role of NH4 + (ammonium) ions

A
  • Production of nitrate ions by baceria
59
Q

Role of nitrate ions (NO3 -)

A
  • Nitrogen supply to plants for amino acid and protein formation
60
Q

Role of hydrogen carbonate ions (HCO3 -) ions

A
  • Maintenance of blood pH
61
Q

Role of Cl- ions

A
  • Balance positive charge of sodium and potassium ions in cells
62
Q

Role of phosphate (PO4 3-) ions

A
  • Cell membrane formation
  • Nucleic acid and ATP formation
  • Bone formation
63
Q

Role of hydroxide (OH-) ions

A
  • Catalysis of reactions
  • pH determination
64
Q

What is a reducing sugar?

A
  • Reducing sugars include all monosaccharides and some disaccharides such as maltose and lactose.
  • Reducing sugars can donate electrons or reduce another molecule or chemical
  • Examples: Galactose, glucose, fructose, maltose
65
Q

What types of compounds do non-reducing sugars include?

A

Non-reducing sugars include some disaccharides such as sucrose and all polysaccharides.

66
Q

Steps to find out whether a sample contains a reducing sugar

A
  1. Place 2 cm3 of your food sample into a test tube.
  2. Add an equal volume of Benedict’s reagent (so it is in excess).
  3. Heat the mixture in a gently boiling water bath for 5 minutes at 80 °C.
  4. If a reducing sugar is present, the mixture will change from a blue solution to a brick red precipitate.
67
Q

Interpretation of the results of Benedict’s test

A

The concentration of reducing sugar determines the colour of this mixture:

Blue - This indicates no reducing sugar is present.
Green - This indicates a low concentration.
Orange - This indicates a medium concentration.
Brick-red - This indicates a high concentration.

A positive result will form a brick red precipitate, however the colour seen is a mixture of the precipitate and the blue Benedict’s reagent.

68
Q

Why is sucrose a non-reducing sugar?

A

Reducing sugars can donate electrons to the Cu 2+ in Benedict’s solution, turning it a coloured precipitate of Cu+ ions.
The position of the glycosidic bond in sucrose prevents it from donating its electrons.

69
Q

Steps to find out whether a sample contains a non-reducing sugar:

A
  1. Carry out the test for reducing sugars, and if the result is negative, continue with the next steps.
  2. Add 2 cm3 of the food sample to 2 cm3 of dilute hydrochloric acid.
  3. Heat the mixture in a gently boiling water bath for 5 minutes (the acid will hydrolyse disaccharides into monosaccharides).
  4. Neutralise the mixture by adding sodium hydrogencarbonate solution.
  5. Retest this mixture using the test for reducing sugars.
  6. If non-reducing sugars were present, the mixture will change from a blue solution to a brick red precipitate.
70
Q

What must you do with a non-reducing sugar before testing with Benedict’s?

A

A non-reducing sugar will give a negative result (blue solution) for the reducing sugars test.
To test for these types of sugars, you must first hydrolyse them into their monosaccharide components.

71
Q

Steps to test for starch

A

The iodine test is used to detect the presence of starch:
1. Add a few drops of iodine dissolved in potassium iodide solution to the sample
2. If the solution changes from yellow brown to ble/black then starch is present

72
Q

What are reagent strips?

A

Reagent test strips can be used to test for the presence of reducing sugars
An advantage is that, with the use of a colour-coded chart, the concentration of the sugar can be determined.

73
Q

Steps to using a colorimeter to test for concentration of an unknown sample.

A
  1. Switch the colorimeter on and leave to stabilise for 5 minutes.
  2. Select the red filter (for Benedict’s – use a complementary colour to starting
    solution) on the colorimeter. If using Benedict’s, centrifuge the solution or allow to sit to precipitate out the copper solid.
  3. Set the colorimeter to zero using a cuvette ¾ filled with distilled water.
  4. Ensure the cuvette is placed into the colorimeter so the light passes through the clear
    sides.
  5. Make sure the slides are clean and there are no bubbles in the solution.
  6. Using a pipette, fill the cuvette ¾ with the sample.
  7. Place in the colorimeter and read the absorbance of light.
  8. Less light is absorbed by the solution in a paler solution, so there is a greater
    transmission for a paler solution.
74
Q

How are lipids different from proteins and carbohydrates?

A

Lipids are not polymers

75
Q

Are lipids polar?

A

No, lipids are non-polar

76
Q

What type of molecule are lipids?

A

Lipids are large complex molecules called macromolecules

77
Q

What are triglycerides?

A
  • Triglycerides are non-polar, hydrophobic molecules
  • The monomers that make up triglycerides are glycerol and 3 fatty acids
  • Glycerol is an alcohol
  • Fatty acids are caboxylic acids (so they consist of a carboxyl group (-COOH) with a hydrocarbon chain attatched
78
Q

How can the fatty acids vary?

A
  • Length of the hydrocarbon chain (R group)
  • The fatty acid chain (R group) may be saturated (mainly in animal fat) or unsaturated (mainly vegetable oils, although there are exceptions e.g. coconut and palm oil)
79
Q

Describe the formation of trigylcerides

A
  • The hydroxyl groups (OH) of the glycerol and the fatty acid interact
  • This leads to the formation of 3 water molecules and bonds between the fatty acids and the glycerol molecule
  • These are called ester bonds
  • The reaction is called esterification which is an example of a condensation reaction
80
Q

What happens when a triglyceride is broken down?

A
  • 3 water molecules need to be supplied to reverse the reaction that formed the triflyceride
  • In the breakdown, the ester bond needs to be broken
  • This is an example of a hydrolysis reaction
81
Q

What are saturated fatty acids?

A
  • Fatty acid chains that have no carbon carbon double bonds
  • All the carbon atoms form the maximum number of bonds with hydrogen atoms
82
Q

What are unsaturated fatty acids?

A
  • A fatty acid with carbon-carbon double bonds
  • Monounsaturated= only 1 C-C double bond
  • Polyunsaturated= 2 or more C-C double bonds
83
Q

What is the effect of carbon carbon double bonds in fatty acids?

A

The presence of double bonds causes the molecule to kink or bend.
So, they cannor pack so closely together
This makes them liquid at room temperature, so they are oils nor fats

84
Q

What are phospholipids?

A
  • Phospholipids are a type of lipid, therefore they are formed from the monomers glycerol and fatty acids
  • Unlike triglycerides, there are only two fatty acids bonded to a glycerol molecule in a phospholipid as one has been replaced by a phosphate ion (PO4 3-)
  • As the phosphate is polar it is soluble in water (hydrophilic)
  • The fatty acid ‘tails’ are non-polar and therefore insoluble in water (hydrophobic)
85
Q

How does the structure of phospholipids effect its function?

A
  • Phospholipids are amphipathic (they have both hydrophobic and hydrophilic parts)
  • So, they form a layer on the surface of water (phosphate heads in water and fatty acid tails sticking out of water)
  • So they are called surface active agents (surfactants)
  • Also, they form a bilayer in water with all they hydrophobic tails pointing towards the centre, protected by the hydrophillic head
  • So, they can seperate 2 aqueous environments (eg inside a cell and outside the cell as a cell membrane)
86
Q

What elements do phospholipids contain and where are they found?

A
  • They contains carbon, hydrogen, oxygen and phosphorus
  • Inorganic phosphate ions are found in the cytoplasm of every cell
87
Q

What are sterols

A
  • Sterols are a type of lipid found in cells
  • They’re not fats or oils
  • They are complex alchol molecules
  • They have a 4 carbon ring structure with a hydroxyl group at one end
  • They have dual hydrophobic/hydrophilic characteristics
  • The OH- group is polar and so hydrophilic and the rest of the molecule is hydrophobic
88
Q

What is cholestrol?

A
  • Cholestrol is a sterol
  • So, has hydrophobic and hydrophilic regions
89
Q

Where is cholestrol found?

A
  • Found in the cell membrane of eukaryotic cells
  • As their chemical structure allows them to exist in the bilayer of the membrane
90
Q

Where are molecules of cholestrol synthesised?

A
  • Synthesised in the liver and transported via the blood
91
Q

What is the function of cholestrol?

A

Cholesterol affects the fluidity and permeability of the cell membrane
* It disrupts the close-packing of phospholipids, making the membrane more ridgid
* It acts as a barrier, fitting in the spaces between phospholipids. This prevents water-soluble substances from diffusing across the membrane

92
Q

Function of lipids

A

These occur due to their polar nature
* Membrane formation and the creation of hydrophobic barriers
* Hormone production
* Electrical Insulation necessary for impulse transmission
* Waterproofing eg, birds feathers and on plant leaves

They are also important in long-term energy storage. They’re stored under the skin and around vital organs providing:
* Thermal insulation to reduce heat loss
* Cushioning to protect vital organs
* Boyancy for aquatic animals

93
Q

How to test for lipids

A
  1. Place your food sample in a test tube.
  2. Add 2 cm3 of ethanol.
  3. Shake.
  4. Add 2 cm3 of distilled water.
  5. If lipids are present, a milky white emulsion will appear. (As lipids are not soluble in water)
94
Q

What are peptides?
What do proteins consist of?

A

Peptides are polymers made up of amoni acid molecules (the monomers).
Proteins consist of one or more polypeptides arranged as complex macromelecules

95
Q

What is an amino acid?

A

Amino acids are the monomers of polypeptides
* There are 20 amino acids found in proteins common to all living organisms

The general structure of all amino acids is a central carbon atom bonded to:
* An amine group -NH2
* A carboxylic acid group -COOH
* A hydrogen atom
* An R group (a variable group) (which is how each amino acid differs and why amino acid properties differ)

96
Q

How are peptides synthesised?

A

Amino acids join when the amine and carboxylic acid groups connected to the central carbon atoms react
* The hydroxyl group in the carboxylic acid group of 1 amino acid reacts with a hydrogen in the amine group of another amino acid
* This forms a peptide bond between the 2 amino acids
* And, water is produced (so it is a condensation reaction)
* This produces a dipepetide

97
Q

When is a polypeptide formed?

A

When many amino acids are joined together by peptide bonds a polypeptide is formed.

98
Q

What are the levels of protein structure?

A
  1. Primary
  2. Secondary
  3. Tertiary
  4. Quaternary
99
Q

What is the primary structure of proteins and what determines it?

A
  • The sequence of amino acids bonded by covalent peptide bonds makes up the primary structure
  • The DNA of a cell determines the primary structure of a protein by instructing the cell to add certain amino acids in specific quantities in a certain sequence. This affects the shape and therefore the function of the protein

The primary structure is specific for each protein (one alteration in the sequence of amino acids can affect the function of the protein)

100
Q

What is the secondary structure of an amino acid?

A

The secondary structure of a protein occurs when the weak negatively charged nitrogen and oxygen atoms interact with the weak positively charged hydrogen atoms to form hydrogen bonds

There are two shapes that can form within proteins due to the hydrogen bonds:
* α-helix
* β-pleated sheet

The secondary structure only relates to hydrogen bonds forming between the amino group and the carboxyl group (the ‘protein backbone’)

101
Q

When does the α-helix shape occur in a protein?

A

The α-helix shape occurs when the hydrogen bonds form between every fourth peptide bond (between the oxygen of the carboxyl group and the hydrogen of the amine group)

102
Q

When does the β-pleated sheet occur in proteins?

A

The β-pleated sheet shape forms when the protein folds so that two parts of the polypeptide chain are parallel to each other enabling hydrogen bonds to form between parallel peptide bonds

103
Q

What is the tertiary structure of a protein?

A

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

  • As the coiling or folding of proteins into their secondary structures bring R-groups of different amino acids closer together, so they’re close enough to interact
  • So, additional bonds form between the R groups (side chains) as further folding occurs
104
Q

What are the interaactions that occur between the R-groups in the tertiary structures of proteins?

A
  • Hydrophobic and hydrophilic interactions- Weal interarctions between polar and non-polar R-groups
  • Hydrogen bonds- The weakest of the bonds formed
  • Ionic bonds- These are stronger than hydrogen bonds and form between oppositely charged R-groups
  • Disulfide bridges/ disulfie bonds- These are covalent bonds and are the strongest, but they only form between R-groups that contain sulfur atoms
105
Q

What is quaternary structure of proteins and what are the interactions within the structure?

A

Quarternary structure exists in proteins that have** two or more** polypeptide chains working together as a functional macromolecule

Each polypeptide chain in the quaternary structure is referred to as a subunit of the protein

The interactions between subunits are the same as in the tertiary structur expet they are between** different protein molecules** rather than within one molecule

106
Q

How are peptides broken down?

A

A hydrolysis reaction occurs, using a water molecule to break the peptide bond in order to reform the amine and carboxylic acid groups.
The enzyme protease catalyses the reaction

107
Q

What is the structure of globular proteins?

A
  • Compact, water-soluble and usually spherical in shape
108
Q

When do globular proteins form and what is their orientation?

A

They form when proteins form into their tertiary structures:
* their non-polar hydrophobic R groups are orientated towards the centre of the protein away from the aqueous surroundings and
* their polar hydrophilic R groups orientate themselves on the outside of the protein

109
Q

Why are globular proteins soluble in water and why is this important?

A
  • Their solubility is due to their hydrophilic R-groups being on the outside of the proteins

This is important for the functions of globular proteins in regulating processes in life including:
* chemical reactions
* immunity
* muscle contraction

110
Q

How does the structure of insulin relate to its function?

A
  • Insulin is a globular protein
  • It is a hormone that regulates blood glucose concentration
  • Hormones are transported in the bloodstream so need to be soluble
  • Hormones have to fit specific receptors on the cell-surface membranes to have their effect so need to have precise shapes
111
Q

What are conjugated proteins and how do they compare to simple proteins?

A
  • Conjugated proteins are globular proteins that contain a non-protein component called a prosthetic group
  • Proteins without prosthetic groups are called simple proteins

Example protein that contains a prosthetic group is haemoglobin which contains the prosthetic group haem

112
Q

How does the structure of haemoglobin relate to its function?

A
  • Haemoglobin is the red, oxygen-carrying pigment found in red blood cells
  • It is a quaternary protein made from four polypeptides, two alpha and two beta subunits
  • Each subunit contains a prosthetic haem group
  • The haem group contain ** iron (ii) ions (Fe 2+)**
  • The Fe 2+ are able to combine reversibly with an oxygen molecule- enabling haemoglobin to transport oxygen around the body
113
Q
A

Catalase is an enzyme. Enzymes catalyse reactions and each enzyme is specific to a particular reaction or type of reaction

  • Catalase is a quaternary protein containing four haem prosthetic groups
  • The prosense of iron (ii) ions in the prosthetic groups allow catalse to interact with hydrogen peroxide and speed up its breakdown
  • Hydrogen peroxide is a common byproduct of metabolism but is dammaging to cells and cell comonents if accumalated.
  • Catalase makes sure this doesn’t happen.
114
Q

What are fibrous proteins (their structure)?

A

** Fibrous proteins are formed from long, insoluble molecules. **
* This is due to the presence of a high proportion of amino acids with hydrophobic R-groups in their primary structures
* They contain a limited range of amino acids (with usually small R-groups)
* The amino acid sequence in the primary structure is quite repetitive
* This leads to organised structures

They make strong, long molecules which are not folded into complex three-dimension shapes

115
Q

How does the structure of keratin relate to its function?

A
  • Keratin is a group of fibrous proteins
  • It is found in hair, skin and nails
  • It has a larger proportion of the sulfur-containing amino acid, cysteine
  • So, has many strong disulfide bridges
  • So, forms strong, inflexible and insoluble materials
  • The degree of disulfide bonds determines the flexibility
    Eg, hair contains fewer bonds than nails so is more flexible
116
Q
A
  • Elastin is a fibrous protein found in elastic fibres (along with small protein fibres)
  • They’re found in the walls of blood vessels and in the alveoli of the lungs
  • They give these structures the flexibilty to expand when needsed but also able to return to their normal size
  • It is a quaternary protein made from many stretchy molecules called tropelastin
117
Q

How does the structure of collagen relate to its function?

A
  • Collagen is a fibrous protein
  • It is a connective tissue found in skin, tendons, ligaments and the nervous system
  • All forms of collagen are made up of 3 polypeptides wound together in a long and strong rope-like structure
  • Like rope, collagen has flexibility

Biology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions