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Biology A-level > Biological molecules > Flashcards

Biological molecules Flashcards

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1
Q

What is a monosacchiride?

A

Single sugar molecule

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2
Q

What is a hexose sugar?

A

Sugars with 6 carbons

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3
Q

Difference between Alpha and Beta glucose…

A

In alpha the OH group is below the H and vice versa

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4
Q

How do monosacchirides join together? What bond is formed?

A

Join via condensation reactions forming a glycosidic bond

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5
Q

Maltose made of

A

2 glucoses

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6
Q

Sucrose made of

A

Glucose + Fructose

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7
Q

Lactose made of

A

Glucose + Galactose

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8
Q

Hydrolysis

A

Breaks disacchirides or polysacchirides down by adding a water molecule

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9
Q

Testing for a reducing sugar

A

Put solution in test tube
Add Bendict’s reagent
Heat in boiled water bath
Produces a coloured precipitate

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10
Q

Colour scale of Benedict’s reagent precipitate from lowest to highest concentration of sugar

A

Blue, Green, Yellow, Orange, Brick-red

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11
Q

Testing for a non-reducing sugar

A

To break down to monosacchirides, add dilute HCl to sample
Heat in water bath that’s been brought to a boil
Neutralise with sodium hydrogencarbonate
Carry out test with Benedict’s Reagent

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12
Q

What is meant by a reducing sugar?

A

Donates electrons to other atoms (reduces them) while it oxidises itself

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13
Q

What polysacchirides is starch a mixture of?

A

Amylose and Amylopectin

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14
Q

What is Amylose?

A

Long, unbranched chain of alpha glucose. 1-4 Glycosidic bonds giving it a coiled structure, this makes it compact so therefore good for storage.

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15
Q

What is Amylopectin?

A

Long, branched chain of alpha glucose. Side braches allow enzymes to break down the molecule to get to 1-4 and 1-6 glycosidic bonds easily, this means glucose can be released easily.

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16
Q

Starch is good for storage because…

A

It’s insoluble in water so doesn’t affect the water potential of the cell

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17
Q

Iodine test for starch

A

Add iodine dissolved in potassium iodide solution to sample.
Colour change from orange-brown to blue-black

18
Q

What is the structure of cellulose?

A

Made up of long, unbranched chains of beta-glucose. Cellulose chains have alternating patterns so that hydrogen can make links between cellulose chains to form strong fibres.

19
Q

Why is cellulose good for plant cells?

A

Provides structural support for plant cells

20
Q

What is glycogen?

A

Main energy storage in humans.

21
Q

What is glycogen’s structure similar to?

A

Amylopectin but with more branches

22
Q

How does the structure of glycogen relate to its function?

A

Branches so that stored glucose can be released quickly - important for energy release in animals
Also a compact molecule which is good for storage.

23
Q

What is a triglyceride? how is it formed?

A

One molecule of glycerol with 3 fatty acids bonded to it
condensation reaction - Ester bond formed between 2 OH groups releasing water

24
Q

What makes lipids insoluble in water?

A

Have long hydrophobic tails

25
Q

What is a phospholipid?

A

Similar to triglyceride but one of the fatty acid molecules is replaced by a phosphate group(hydrophilic)

26
Q

How does the structure of triglycerides relate to their function?

A

Lipids contain more energy than carbohydrates
Insoluble so don’t affect water potential of a cell

27
Q

How does the structure of phospholipids relate to their function?

A

Centre of the bilayer they make up is hydrophobic, so water soluble substances can’t easily pass through it

28
Q

What is the monomer of a protein?

A

Amino acid

29
Q

Dipeptide

A

Two amino acids joined together

30
Q

Polypeptide

A

More than two amino acids joined together - proteins made up of one or more polypeptides

31
Q

How do amino acids link?

A
  • Linked via condensation reactions to form polypeptides
  • bond formed between two amino acids is called a peptide bond
32
Q

Primary Structure of proteins

A

Sequence of amino acids in the polypeptide chain

33
Q

Secondary structure of proteins

A
  • Hydrogen bonds form between amino acids in chain.
  • This makes it coil into an alpha-helix or fold into a beta-pleated sheet
34
Q

Tertiary structure of proteins

A
  • Coiled and folded further
  • Disulfide bridges form when two molecules of amino acid, cysteine, bonds to sulfur atom in the other.
  • For proteins made of a single polypeptide chain, the tertiary structure forms their final 3D structure
35
Q

Quaternary structure of proteins

A
  • Some proteins made of several different polypeptide chains are held together by bonds
  • contain non-protein (prosthetic groups)
36
Q

Biuret’s test for proteins

A
  • Test solution needs to be alkaline, so add sodium hydroxide
  • Add Biuret’s reagent
  • If protein present, solution should go from blue to purple
37
Q

How do amino acids differ?

A

There are 20 amino acids that are common in all organisms and they differ only from their R group

38
Q

Enzymes - structure and functions

A
  • Usually spherical shape due to tight folding of polypeptide chains
  • Soluble and have roles in metabolism and other enzymes synthesise large molecules
39
Q

Antibodies - Structure and functions

A
  • Involved in immune response.
  • Made up of two light polypeptide chains and two heavy polypeptide chains bonded together
40
Q

Transport proteins function

A

Transport molecules and ions across membranes

41
Q

Structural proteins - structure and function

A
  • Physically strong
  • Consist of long polypeptide chains lying parallel to each other with crosslinks between them
  • Include keratin and collagen

Biology A-level (16 decks)

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