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Biology > AS Booklet 1 - Biological Molecules > Flashcards

AS Booklet 1 - Biological Molecules Flashcards

1
Q

What is a monomer?

A

A monomer is a small unit that from which larger molecules are made eg. a peptide is a monomer, a polypeptide is formed from them

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2
Q

What is a polymer?

A

A polymer is a chain of monomers joined together eg. a polypeptide is formed from a chain of peptides joined together.

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3
Q

What is a condensation reaction?

A

A reaction in which two molecules join together via a chemical bond and involves elimination of a water molecule.

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4
Q

What is a hydrolysis reaction?

A

A reaction in which larger molecules are broken into smaller molecules by the addition of water.

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5
Q

What elements do carbohydrates contain?

A

Carbon, hydrogen and oxygen. The H and O2 are in a ration of 2H:O

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6
Q

What is a monosaccharide and what is it used for?

A

A single sugar used mainly for respiration and growth during formation of larger carbs.

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7
Q

Name three monosaccharides.

A

Glucose, fructose and galactose.

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8
Q

What is the formula of the three monosaccharides?

A

C6H12O6

They all have the same formula but different structures, so they are isomers.

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9
Q

Are the monosaccharides reducing or non-reducing sugars?

A

Reducing sugars, give a brick red precipitate in the Benedict’s test.

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10
Q

Explain the structure of glucose.

A

There are two isomers: alpha and beta glucose.
Alpha glucose has the hydroxide group on the bottom on both sides whereas the beta glucose only has this group on the bottom on the left side.

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11
Q

Name three disaccharides.

A

Maltose, fructose, galactose.

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12
Q

What is a monosaccharide? What are the examples given?

A

A monosaccharide is a single sugar. A monomer of carbohydrates.
Glucose, Fructose, Galactose.

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13
Q

What are the two isomers of glucose?

A

Alpha and beta glucose have the same structure except the hydroxyl group on the right side of Beta glucose is at the top, not the bottom.
The hydroxyl groups of Alpha glucose are both on the bottom.

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14
Q

What is a disaccharide? What are the examples given?

A

A disaccharide is two monosaccharides joined together by a glycosidic bond.
The examples given are maltose, sucrose and lactose.

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15
Q

What are the equations for the disaccharides?

A

Glucose + Glucose = Galactose + Water.
Glucose + Fructose = Sucrose + Water.
Glucose + Galactose = Lactose + Water.
C6H12O6 + C6H12O6 = C12H22O11 + H2O.

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16
Q

What result do monosaccharides give in the Benedict’s test?

A

Positive, brick red precipitate as they are reducing sugar.

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17
Q

How can you hydrolyse something?

A

Boil with dilute HCl or by heating with an enzyme at its optimum pH.

18
Q

What is the method for the unstandardised, qualitative Benedict’s Test for reducing sugars?

A
  1. Take a small volume of sample, place in test tube with same volume of Benedict’s solution.
  2. Heat in water bath at 70 degrees.
  3. Brick red precipitate is a positive result.
  4. If Benedict’s remains blue, no reducing sugar present.
    Doesn’t allow comparison.
19
Q

What is the method for the standardised, semi-quantitative Benedict’s Test?

A

Control Variables- standardised, same volume of sample, Benedict’s solution, temperature and time in water bath.
Resulting colour or volume of precipitate can be used to compare volume of reducing sugar.
Difficult to judge colour as colour is subjective, this is an issue.

20
Q

What is the method for the standardised, quantitative Benedict’s Test?

A

Numerical data obtained, used to compare volume of reducing sugar of different samples objectively.
Same method as semi-quantitative but colour is measured by colorimeter and then plotted on a calibration curve, used to find out unknown quantities of reducing sugar.

21
Q

What is the Benedict’s Test for non-reducing sugar?

A
  1. Carry out Benedict’s test on small sample and confirm negative result.
  2. Hydrolyse another sample of substance by heating with dilute HCl.
  3. Allow to cool.
  4. Neutralise with NaOH.
  5. Add same volume of Benedict’s solution and heat in water bath.
  6. Positive result (brick red precipitate) indicates non-reducing sugar was originally present.

Hydrolysing broke glycosidic bonds between two monosaccharides.

22
Q

What are polysaccharides? What are the three named examples?

A

Polysaccharides are chains of monosaccharides joined together by glycosidic bonds, formed during condensation reactions.

Glycogen, starch and cellulose are polysaccharides.

23
Q

What are the differences between the three names polysaccharides?

A
  • Cellulose is made from Beta Glucose whereas the other two are made from Alpha Glucose.
  • Cellulose and starch are found in plants whereas glycogen is found in animals.
  • Cellulose is not branched, and is in straight chains whereas the other two are branched.
24
Q

What are the similarities between the three polysaccharides?

A
  • Starch and Glycogen are branched, made of Alpha Glucose, used to store Glucose in organisms.
  • Starch and Glycogen are insoluble, therefore osmotically inactive.
25
Q

What are the properties of Starch? Where is it stored?

A
  • Large molecule so can’t cross cell-surface membrane.
  • Insoluble, therefore osmotically inactive.
  • Helical shape so compact storage of Glucose.
  • Branched, so Glucose is released easily for respiration.

In starch grains in the cytoplasm of plant cells.

26
Q

What are the properties of Glycogen?

Where is it stored?

A
  • Insoluble, therefore osmotically inactive.
  • Similar to Starch but has more branches, to be hydrolysed quickly for respiration.

Stored in liver and muscle tissue, so it can be used for respiration and to increase blood sugar levels

27
Q

What are the properties of Cellulose?

Where is it stored?

A
  • Long, straight chains that aid rigidity and shape of the cell.
  • Each Beta Glucose molecule is inverted to the previous (O is on top then bottom
28
Q

What is the test for Starch?

A
  • Add 2-3 drops of Iodine/potassium iodide solution.
  • If starch is present, blue/black precipitate will be produced.
  • No starch present, solution remains orange/yellow.
29
Q

What is the benefit of polysaccharides being branched and osmotically inactive?

A
  • Branched chains makes it easy for single glucose molecules to be broken off for respiration.
  • Being osmotically inactive means lots of this molecule can be in a cell without lowering water potential so lots of glucose can be stored in cells without the risk of the cell bursting.
30
Q

What are the properties of lipids?

What are the two groups of lipid?

A

Lipids contain Carbon, Hydrogen and Oxygen.
Insoluble in water but soluble in alcohol and other organic solvents.
Triglycerides and phospholipids.

31
Q

How is a Triglyceride molecule formed?

A

Three fatty acid chains combined with one glycerol molecule during a condensation reaction (during which three water molecules are lost). There is an ester bond formed between the glycerol and fatty acid chain.

32
Q

What is the structure of a Glycerol molecule?

A 
Three carbons attached to one another. One OH groups attached to each C (three OH groups) and the rest of the bonds are to H.
     H
      |
H--C-- OH
H--C-- OH
H--C-- OH
      |
     H
33
Q

What is the structure of a Fatty Acid molecule?

A

A carbon double-bonded to O, single bonded to R and OH. General formula is R-COOH.
O
||
OH-C-R

34
Q

What is an R Group?

A

An R group is an “R” on a formula which represents a fatty acid chain (fatty acid chains are many carbons attached to each other and hydrogen).
They can be unsaturated (one or more carbon to carbon double bonds) or saturated (no carbon to carbon double bonds).

35
Q

What is the structure of a phospholipid?

A

A glycerol molecule attached to two fatty acid chains and a phosphate group.
Formed through a condensation reaction that forms ester bonds.
The phospholipid has a polar hydrophilic head which contains the phosphate group and a hydrophobic tail (fatty acid chains).

36
Q

What is a phospholipid bilayer?

A

Two layers of phospholipids. The polar hydrophilic heads point outwards and the non-polar hydrophobic heads (fatty acid chains) point towards each other, inwards.

37
Q

What is the role of water in metabolic reactions and as a solvent?

A

Solvent in which metabolic reactions occur.
Metabolite in condensation and hydrolysis reactions, along with others.
Required for photosynthesis.
Metabolic product of respiration used by organisms in dry habitats.

38
Q

What is the role of water in metabolic reactions and as a solvent?

A
  • Solvent in which metabolic reactions occur.
  • Metabolite in condensation and hydrolysis reactions, along with others.
  • Required for photosynthesis.
  • Metabolic product of respiration used by organisms in dry habitats.
39
Q

What is the role of water in metabolic reactions and as a solvent?

A
  • Solvent in which metabolic reactions occur.
  • Metabolite in condensation and hydrolysis reactions, along with others.
  • Required for photosynthesis.
  • Metabolic product of respiration used by organisms in dry habitats.
  • Transports nutrients such as glucose in blood or sucrose (phloem of plants).
  • Removes excretory products (urea, ammonia).
40
Q

What is the role of water in temperature regulation?

A 
• High heat capacity: absorbs large amount of heat energy before rising in temperature. Acts as buffer so minimises heat rise in cells and prevents dangerous fluctuations in aquatic habitats.
• Large latent heat of vaporisation: because energy required to break H bonds = cooling effect through small loss of water via evaporation.
Aids homeostasis (sweat, lots of heat loss but little water loss) and has cooling effect in plants via transpiration.
41
Q

What is the role of water in support?

A

• Internal Support: helps non-woody plants (and hydrostatic skeleton in earthworms) remain rigid in shape due to turgor pressure.
Helps transport from roots to leaves in plants via xylem or phloem due to strong cohesive forces between water molecules (H bonding).
• External Support: Strong cohesive forces between water molecules (H bonding) give surface tension when water meets air so insects can walk/be suspended on/at surface.
Provides buoyancy fro aquatic organisms.

42
Q

What are the inorganic ions and what are their roles?

A
  • Sodium: Co-transport of glucose and amino acids across cell membranes.
  • Iron: Component of haemoglobin (transports O2)
  • Hydrogen: Effects protein structure and enzyme activity as it helps determine pH.
  • Phosphate: Important structural component of DNA, RNA, ATP and ADP.

Biology (17 decks)

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