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Biology OCR A Level > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

How does hydrogen bonding occur?

A

There is an uneven distribution of electrons in the O-H covalent bond due to differing electronegativites. Hydrogen bonds are the electrostatic forces of attraction between delta positive H atoms and the lone pair on the delta negative O- atom’s lone pair.

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2
Q

What is a monomer?

A

The smaller unit or units from which larger molecules (polymer) are made.

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3
Q

What is a polymer?

A

A molecule made from a large number of monomers joined together.

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4
Q

What is condensation?

A

A reaction that creates a chemical bond between two molecules and eliminates a water molecule.

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5
Q

What is hydrolysis?

A

A reaction that breaks a chemical bond between two molecules and uses a water molecule.

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6
Q

What is a carbohydrate?

A

An organic compound containing hydrogen and oxygen atoms in a ratio of 2:1.

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7
Q

What is a monosaccharide?

A

A single sugar unit, the monomer from which larger polysaccharides are made.

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8
Q

What two monosaccharides is sucrose made of?

A

Fructose and glucose

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9
Q

What are three most common monosaccharides?

A

Glucose, galactose and fructose

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10
Q

What two monosaccharides is lactose made from?

A

Glucose and galactose

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11
Q

What two monosaccharides is maltose made from?

A

Glucose and glucose

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12
Q

What are the two polysaccharide molecules known as starch?

A

Amylopectin and Amylose

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13
Q

Describe the structure of amylose.

A

Amylose consists of alpha glucose molecules bonded by only 1,4 glycosidic bonds, twisting to form an alpha helix.

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14
Q

Describe the structure of amylopectin.

A

Amylopectin consists of alpha glucose molecules with long chains bonded by 1,4 glycosidic bonds and branches linked by 1,6 glycosidic bonds.

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15
Q

Describe the structure of cellulose.

A

Unbranched chains formed by beta glucose monomers, joined together only by 1,4 glycosidic bonds. Adjacent monomers are in alternation orientations. There are H bonds between neighbouring chains to form microfibrils, macrofibrils and fibre.

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16
Q

What is a triglyceride?

A

Glycerol and three fatty acid chains (hydrophobic hydrocarbon chains)

17
Q

Even though both carbohydrates and lipids are made of the same elements: C,H and O, what is the difference?

A
18
Q

State the bonds formed when a fatty acid combines with glycerol and the name of this reaction.

A
  • Ester
  • Esterification / Condensation
19
Q

What is a saturated fatty acid?

A

A fatty acid with no double bonds between carbon atoms.

20
Q

What is a (poly)unsaturated fatty acid?

A

A fatty acid with one or more doble bonds between carbon atoms. These cause kinks.

21
Q

What is the structure of a phospholipid?

A

A phospholipid is a molecule with two fatty acids and a phosphate group bonded to one molecule of glycerol formed by condensation reactions.

22
Q

What five elements make proteins?

A

Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur

23
Q

What is a peptide bond?

A

A covalent bond between two amino acids formed by a condensation reactions.

24
Q

What is a protein’s primary structure?

A

The order of amino acids

25
Q

What is a conjugated protein?

A

A protein that contains non-protein prosthetic groups, attached by covalent, hydrogen or ionic bonds.

26
Q

What is the chemical test for reducing and non-reducing sugars?

A

Benedict’s test
Blue - Green - Yellow - Orange - Brick Red depending on sugar concentration

27
Q

What is the function of nucleic acids?

A

The storage and transfer of genetic information and synthesis of proteins.

28
Q

Describe the structure of a nucleotide.

A

A nucleotide molecule (can be DNA or RNA) consist of a pentose sugar, a nitrogen containing base and a phosphate group.

29
Q

What are some properties of water that are useful?

A
  • High SHC: Water acts as a buffer against rapid temperature changes e.g functions as an aquatic habitat
  • Ice is less dense than water: Habitat + Insulates water below, prevents aquatic life from freezing
  • High LHV: High energy to evaporate water, Cooling without much water loss, transfer of heat energy
  • Solvent: Carry O2 for transport in the blood so that organisms can respire, Dissolve mineral ions
  • Cohesive: Forms H bonds between water molecules, allows for the transpiration stream to occur
  • High Surface Tension: Acts as a habitat
  • Adhesion: Binds to xylem walls to allow water to move up through capillary action
30
Q

How is the structure of starch relate to its function?

A
  • Insoluble in water, no effect on wo
  • Polymers, too large to diffuse through csm
  • Compact
  • Branched, more exposed free ends for enzymes to act on and hydrolyse, glucose molecules are released faster
31
Q

What is the difference between alpha glucose and beta glucose?

A

The hydroxyl group is in the downwards position for alpha glucose and the upwards position for beta glucose on C1

32
Q

What are the 4 types of bonding in the tertiary structure?

A
  • Hydrogen bonding (easily broken by temperature or pH)
  • Hydrophobic and hydrophilic interactions (often found in the centre)
  • Ionic (Charged R groups on amino acids and broken by changes in pH)
  • Disulfide bridges (Cysteine R group and contains an S atom forms a covalent bond which is relatively strong)
33
Q

Globular Proteins:

A
  • Hydrophilic R groups on external surface, form H bonds, soluble in water
  • Spherical
  • Tertiary structure
  • Specific
  • Temperature sensitive
34
Q

Fibrous:

A
  • Insoluble
  • Flexible
  • Elongated Ropes
35
Q

How are triglycerides adapted for their function?

A
  • Storage of energy content (2x than carbohydrates because of tails)
  • Insoluble so do not affect water potential or release contents in water
36
Q

What is a conjugated protein?

A

A globular protein containing a non-protein group called a prosthetic group

37
Q

Describe haemoglobin.

A

A globular protein made of 4 polypeptide chains (2 alpha and 2 beta) with an iron ion (prosthetic haem group) attached that can bind to O2 reversibly

38
Q

Describe catalase.

A

A globular protein that catalyses the breakdown of H2O2 into oxygen and water

Biology OCR A Level (18 decks)

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