Biological molecules Flashcards

Carbohydrates

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1
Q

What is a polymer?

A

Made from lots of monomers bonded together

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2
Q

What is a monomer?

A

smaller units which can create larger molecules

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3
Q

What are polymers of glucose and nucleotides?

A

Glucose - starch, glycogen and cellulose are its polymers

Nucleotides - DNA and RNA are its polymers

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3
Q

What are monosaccharides, disaccharides and polysaccharides?

A

Monosaccharides - carbohydrates which are monomers (eg. glucose, fructose and galactose)

Disaccharides - carbohydrates which consist of two monomers - (eg sucrose, lactose, maltose)

Polysaccharides - carbohydrates which are polymers (eg. starch, glycogen, cellulose)

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4
Q

What are the two isomers of glucose?

A

Alpha glucose and beta glucose

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5
Q

What are features of disaccharides? and how are they formed?

A

Made from two monosaccharides and joined together by glycosidic bond.

Formed via condensation reaction

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6
Q

What are examples of disaccharide formations?

A

Glucose + glucose -> maltose + water

Glucose + galactose -> lactose + water

Glucose + fructose -> sucrose + water

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7
Q

How is starch formed?

A

Formed via condensation reactions between many glucose monomers (amylose and amylopectin)

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8
Q

Where is starch found and what is its function?

A
  1. Found in plant cells
  2. Insoluble store of glucose
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9
Q

What bond is formed when amylose undergoes condensation reaction?

A

1-4 glycosidic bond

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10
Q

How is glycogen formed? And where is it found?

A

Glycogen forms by many condensation reactions between alpha glucose

Found in muscle and liver cells

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11
Q

What is function of glycogen?

A

It is an insoluble source of glucose.

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12
Q

How is cellulose formed?

A

By many condensation reactions between beta glucose via 1-4 glycosidic bonds

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13
Q

What is the function of cellulose and where is it found?

A

Cellulose provides strength to plant cell walls and is found in cell walls of plants

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14
Q

What are fibrils?

A

Long straight chains which lie parallel and are held together by hydrogen bonds

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15
Q

How does structure of starch help function?

A

Helix is compact to fit a lot of glucose in small spaces

Branched structure increases surface area allowing for rapid hydrolysis back to glucose

Insoluble so doesn’t affect water potential

16
Q

How does structure of glycogen help function?

A

Branched structure increases surface area allowing for rapid hydrolysis back to glucose

Insoluble so doesn’t affect water potential

17
Q

How does structure of cellulose help function?

A

Insoluble in water so does not affect water potential

Many hydrogen bonds provide strength

18
Q

What are the two types of lipids and what do they consist of?

A

Triglycerides - consist of 3 fatty acid molecules and 1 glycerol molecule

Phospholipids - consist of one glycerol molecule, 2 fatty acid molecules and a phosphate group - attached to the glycerol

19
Q

What happens when the two fatty acid molecules bond to a glycerol molecule (phospholipid)?

A

Two fatty acids bond to glycerol molecule via condensation reaction leading to two ester bonds

20
Q

How are triglycerides formed?

A

Formed via condensation reaction between molecules, forming an ester bond

21
Q

What is emulsion test for lipids?

A
  1. Take sample and dissolve in ethanol
  2. Add distilled water
  3. If lipid is present a white emulsion forms
22
Q

What are properties of triglycerides?

A

Large ratio between number of carbon-hydrogen bonds to the number of carbon atoms, so a lot of energy is stored.

High ratio of hydrogen to oxygen atoms, so triglycerides can be a metabolic water source and release water when oxidised.

Triglycerides are insoluble so do not affect water potential

Triglycerides have a low mass meaning they do not affect mass and prevent movement.

23
Q

What are properties of phospholipids?

A

Hydrophilic head of a phospholipid can attract water as it is charged - repels fats

Hydrophilic tail (fatty acid chain) is not charged and mixes with fats but repels lipids

Form phospholipid bilayer membrane structure which makes up plasma membrane around cells

24
Q

What happens when two amino acids join via a condensation reaction?

A

A peptide bond is formed and a water molecule is released

25
Q

What are two amino acids joined called?

A

A dipeptide

26
Q

What are primary and secondary structures of a protein?

A

Primary structure - the order of the amino acids in polypeptide chain

Secondary structure: Sequence of amino acids causes part of protein molecule to bend into a helix shape or fold into beta plated sheets

  • Held together by hydrogen bonds, which are between C=O group of carboxylic group of one amino acid and the H in the amine group of another.
27
Q

What are tertiary and quaternary structures of a protein?

A

Tertiary structure: Further folding of secondary structure which forms a unique 3D shape.

Held together by ionic, hydrogen and disulphide bonds.

Quaternary structure: protein made up of one polypeptide chain

If a protein denatures, ionic and hydrogen bonds in secondary and tertiary structures break - so unique shape is lost

28
Q

What is benedict’s test of reducing sugars?

A
  1. Add benedict’s reagent to test tube
  2. Heat
  3. Colour change from blue to brick red (more red the more concentration of reducing sugar)
29
Q

What is test for non reducing sugars:

A
  1. Do benedict’s test and stays negative
  2. Boil with acid then neutralise with alkali
  3. Heat with benedict’s and it becomes red/orange
30
Q

What is the test for starch?

A
  1. Add a few drops of iodine to sample
  2. If starch is present colour will change from brown to blue black
31
Q

What is biuret test?

A
  1. Add sample to distilled water and biuret solution
  2. Shake solution
  3. Colour change from blue to purple
32
Q

Why is water a dipolar molecule?

A

Water is slightly positive and slightly negative, as hydrogen atoms are slightly positive and oxygen atoms are slightly negative

33
Q

What are five key properties of water?

A

It is a metabolite - important in condensation and hydrolysis reactions

Important solvent for reactions to occur

High heat capacity which buffers temperature

Has large latent heat of vaporisation - provides cooling effect with loss of water via evaporation

Strong cohesion between molecules supports water columns

34
Q

Why is water a good solvent?

A

Contains slightly positive and negative charges meaning negative and positive ions are attracted to water - hydrophilic

35
Q

What is a dipole?

A

An unequal distribution of charges

36
Q
A