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Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

Describe the emulsion test?

A
  1. Dissolve potential lipid solution in ethanol
  2. Give it a shake
  3. Mix in boiling water
  4. Positive= milky lipid layer forms
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2
Q

What bond between amino acids will result in a positive biuret test?

A

Peptide bonds between amino acids to form a polypeptide chain
If amino acids free result will not be positive

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3
Q

What is the result for a positive Biuret test?
(What does it test)

A

If protein is present solution will change from blue to violet
Solution will only change colour if the amino acids are joined by phosphodiester bonds

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4
Q

What does a white, milky emulsion in the emulsion test show?

A

Presence of a lipid

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5
Q

Types of monosaccharide reducing sugars?

A

Glucose
Fructose
Galactose

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6
Q

Types of disaccharide reducing sugars?

A

Lactose
Maltose

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7
Q

Example of a non-reducing sugar

A

Sucrose

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8
Q

What is used to test for starch in food testing?

A

Potassium iodide

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9
Q

What is the positive result from test for starch ? (Potassium iodide)

A

Change from orange to blue-black

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10
Q

Which is the following describes Benedict’s solution?
Clear purple liquid
Brick red precipitate
Milky white emulsion
Clear blue liquid

A

Clear blue liquid

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11
Q

What are colorimetry and biosensors used for?

A

Used to work out concentrations in solution

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12
Q

What are biosensors made of?

A

Biological elements and a physicochemical detector

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13
Q

Biosensors produce …….. signals from ……… responses

A

Electrical
Biological

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14
Q

Describe the properties of water?

A

High heat capacity
Important metabolite
Good solvent
Polar (oxygen slightly negatively charged, hydrogen slightly positive in water )

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15
Q

Waters high heat capacity is caused by what?

A

Hydrogen bonding between water molecules

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16
Q

Why is water a good metabolite?

A

It is used or formed in many metabolic reactions, such as condensation and hydrolysis reactions
ATP + H2O = ADP + Pi + free energy is the equation for hydrolysis reaction
Bond broken

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17
Q

Which of the following is an example of a polymer ?
Starch
Nucleotide
Monosaccharide
Amino acid

A

Starch

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18
Q

What bond is formed to make polymers?

A

Covalent bonds between monomers

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19
Q

What does the hydrolysis of lipids produce?

A

Fatty acids and monoglycerides
Absorbed by cells by diffusion or through protein channels

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20
Q

Properties of glycogen?

A

Glycogen is the main energy storage material in animals
Glycogen is highly branched molecule
Glycogen is formed by condensation of alpha- glucose

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21
Q

What are the two types of starch?

A

Amylopectin (branched)
Amylose (unbranched)

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22
Q

What is starch made out of ?

A

Alpha- glucose polysaccharides

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23
Q

Cellulose chains are linked together by ………. Bonds to form strong fibres called …….

A

Hydrogen
Microfibrils

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24
Q

How are the structure of cellulose and glycogen different?

A
  • glycogen has a branched structure and forms coils, whereas cellulose is straight chain
  • glycogen has both 1,4- and 1,6- glycosidic bonds
  • cellulose just has 1,4- glycosidic bonds
  • cellulose is made from beta-glucose monomers, whereas glycogen is made up of alpha-glucose monomers
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25
Q

How does glycogen act as an energy source?

A
  • glycogen can be hydrolysed to glucose
  • the glucose could then be used to release energy through the process of respiration
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26
Q

Name the monomer maltose is made from?

A

Glucose

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27
Q

Explain how starch is adapted to its function in the cells of plants?

A

-Starch is insoluble in water, so can be stored without affecting cells. Water potential.
-Starch is helical in shape, making it compact for storage.
-Starch is a large molecule, so is unable to leave the cell. 

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28
Q

Why must polymers in food be hydrolysed in the body?

A

Monomers are easier to transport than polymers

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29
Q

Benedict reagent is added to a sugar solution. There is no change in a blue solution is observed. After boiling in HCL and neutralising with sodium hydrogen carbonate, more Benedict reagent is added. An orange/red precipitate is formed.
What can be concluded from these experiments?

A

A non-reducing, disaccharide is present

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30
Q

X is a polymer of beta – glucose found in plants. X is the most abundant natural polymer. X cannot be broken down by human digestive enzymes. What is X?

A

Cellulose

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31
Q

What are triglycerides made out of?

A

One molecule of glycerol
Three molecules of fatty acid (fatty acids have long tails made of hydro carbons with 4–36, carbon atoms)

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32
Q

What are triglycerides?

A

Triglycerides are a type of lipid that are mainly used as energy storage molecules

33
Q

How are triglycerides formed (which reaction)?

A

Condensation of one molecule of glycerol and three molecules of fatty acid.

Three molecules of water are released per triglyceride formed

34
Q

What bond is formed between glycerol and a fatty acid chain?

A

Ester Bond

35
Q

Why do triglycerides repel water?

A

The structure is called lipid micelle
Triglycerides soluble in water, but the fatty acid tails are hydrophobic.
This means that the sales water potential is not affected by triglycerides
If it didn’t repel water, water would enter cell through osmosis causing cells to swell

36
Q

What is the structure of a phospholipid?

A

Phosphate group, Hydrophilic
Glycerol backbone
2 Fatty acid chains, hydrophobic

37
Q

What does hydrophobic and hydrophilic mean?

A

Hydrophobic – cannot interact with water.
Hydrophilic-can interact with water

38
Q

Define saturated?

A

Contains the greatest possible number of hydrogen atoms and has no double or triple bonds between carbon atoms

39
Q

What is the difference between saturated and unsaturated fatty acids?

A

Hydrocarbon tails.
Unsaturated fatty acids have one or more double bond between carbon atoms in the hydrocarbon chain.
E.g. Cooking oil

40
Q

Why do unsaturated fats remain liquid at room temperature?

A

Double bond kink the carbon chain, so unsaturated fats cannot pack together tightly

41
Q

What type of bonds are found in saturated fatty acids?

A

Single bonds between carbon atoms only

42
Q

How are polypeptides formed?

A

Condensation reactions of many amino acids

43
Q

What monomers are bonded together to form polypeptides?

A

Amino acids

44
Q

What are the two common secondary structures of proteins?

A

Alpha – helix
Beta – pleated sheet

45
Q

Which bonds formed between the amino acids hold the secondary structure in place?

A

Hydrogen bonds

46
Q

What are the other bonds in the tertiary structure of a protein?

A

Ionic bonds –
Charged amino acids can form relatively strong ionic bonds with other charged amino acids.
Disulphide bridges, –
They are known as S – S bond
These are covalent bonds set up within proteins containing cystine amino acids (sulphate)

47
Q

Property of hydrogen bonds? (Strength)

A

Hydrogen bonds are relatively weak, but when there are many that overall stability of the tertiary structure increases

48
Q

Which of the statements about the tertiary structure of proteins are true?
- Weak and strong interactions hold together, the 3-D structure
- Interactions that hold together, 3-D structure, a rule, strong
- Interactions between our groups form the 3-D tertiary structure
- Interactions between carboxyl group forms the 3-D structure.
- if a polypeptide loses its 3-D shape it will remain functional.
- If a polypeptide loses its 3-D shape it may not be functional.
- Ionic bonds between amino acids are quite rare.
- Ionic bonds between amino acids are quite common

A
  • weak and strong interactions hold together the 3-D structure.
  • interactions between our groups form the 3-D structure.
  • If a polypeptide loses its 3-D shape, it may not be functional.
  • Ionic bonds between amino acids are quite rare
49
Q

Which structure involves multiple 3-D polypeptide in one complex structure?

A

Quaternary

50
Q

Name, three common examples of quaternary proteins:

A

Insulin
Collagen.
Haemoglobin

51
Q

Can be a proteins are insoluble in:

A

Water

52
Q

Define a conjugated protein?

A

A conjugated protein is a specific type of globular protein that contains a prosthetic group

53
Q

What is haemoglobin?

A

Conjugated protein?
That carries oxygen around in the blood of animals

54
Q

Define a prosthetic group?

A

Prosthetic group is a non-protein part of a protein
E.g. haem group in haemoglobin

55
Q

What are the structures of a fibrous protein?

A

Long and narrow.
Insoluble in water (unlike globular proteins)

56
Q

What are the functions of fibrous proteins?

A

Structural, support to cells

57
Q

Name examples of fibrous proteins:

A
  • collagen
    Roughly 30% of the protein in your body is collagen (ligaments, tendons, muscles, cartilage, bone and skin).
  • keratin
    Crucial to maintaining the structure of horns, claws, hooves, hair and skin
  • elastin
    Is found in connective tissue and allows our skin to return to its normal appearance after being pinched
58
Q

Unlike globular, proteins, fibre proteins are:

A

Insoluble in water

59
Q

What is the main function of triglycerides?

A

Energy storage

60
Q

Who is the statement true or false?
“Carbohydrates contain less energy per gram than lipids“

A

True

61
Q

Is the statement true or false?
“The cells water potential decreases as the amount of triglycerides increase “

A

False

62
Q

A sample is boiled in a test tube with ethanol. The samples then shaken and left to stand. The solution inside is then poured into a tube containing distilled water.
What would be observed, if there is lipid present in the tube?

A

a white milky layer

63
Q

How many amino acids are common in organisms?

A

20

64
Q

Which amino acid does not have carbon in its R group?

A

Glycine

65
Q

What what molecule is released as a byproduct when the amino-terminal of one amino acid reacts with the carboxyl-terminal or another amino acid?

A

Water

66
Q

What colour shows a positive result in the direct test for proteins?

A

Violet

67
Q

The following sentence describes which structure?
Many, relatively weak hydrogen bonds, hold the beta – pleated sheets in a stable fold.

A

Secondary

68
Q

The following sentence describes which structure?
Changing the nucleotide sequence of the proteins gene could change the amino acid sequence

A

Primary

69
Q

What interactions are most important in protein tertiary structure?

A

Ionic bonds
Disulphide bridges

70
Q

How do enzymes speed up the rate of biological reactions?

A

They bind to reactants and promote collisions or bond breaking.
They act as a catalyst provide a reaction route with a lower activation energy

71
Q

“Increasing the temperature of an enzyme catalyst reaction will always increase the rate of reaction because there is a higher chance of collision having the activation energy. “
Is this true or false?

A

False

72
Q

What sort of inhibitor binds to the active site and has a similar structure to the normal substrate of the enzyme?

A

Competitive

73
Q

Which of the following anions is commonly found in fertilisers?
Chloride ions.
Hydrocarbonate ions.
Nitrate ions.
Hydroxide ions

A

Nitrate ions

74
Q

Name anions

A

Phosphate
hydrocarbonate ions,
hydroxide ions,
chloride ions

75
Q

Which of these are important uses of water in the cell?
What is a good solvent
Water allows the cell to cool down.
Water provided structure.
Water is a reactant.

A

Water is a good solvent.
Water provide structure.
Water is a reactant

76
Q

What is polar. Which atom (S) hold S) the partial negative charge?

A

O

77
Q

What type of interactions is the most common in water?

A

Hydrogen bonding

78
Q

Which of the following properties of water explains why sweating helps with body temperature regulation?
High heat capacity
High heat of evaporation.
Cohesive proper
Good solvent.
Good metabolite

A

High heat of evaporation

79
Q

What property of water allows plants to transport water from their roots to their leaves via the transpiration stream?

A

Cohesive properties

Biology (9 decks)

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