B1-Biological molecules Flashcards

1
Q

What is a monosaccharide?

A

A carbohydrate monomer

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2
Q

3 important polysaccharides:

A

-Starch
- Glycogen
- Cellulose

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3
Q

What is the monomer of starch?

A

Alpha Glucose

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4
Q

What is the monomer of glycogen?

A

Alpha glucose

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5
Q

What is the monomer of cellulose?

A

Beta glucose

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6
Q

Where is starch found & what is the function?

A

Plants
- Storage of glucose released from photosynthesis.

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7
Q

Where is glycogen found & what is the function?

A

Animals & fungi
- Storage (liver + muscles)

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8
Q

Where is cellulose found & what is the function?

A

Plants
- Plant cell walls

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9
Q

What bonds are present in starch?

A

-1-4 glycosidic bonds
-1-6 glycosidic bonds

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10
Q

What bonds are present in glycogen?

A

-1-4 glycosidic bonds
-1-6 glycosidic bonds

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11
Q

What bonds are present in cellulose?

A

1-4 glycosidic bonds

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12
Q

How the structure of starch relates to its function [3]:

A

-Branched for faster hydrolysis by enzymes due to a larger surface area
-Insoluble due to large molecules, stops plant bursting due to osmosis
-Helical (helix-shape), more compact and more resistant to digestion.

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13
Q

How the structure of glycogen relates to its function [2]:

A

-Very branched, faster hydrolysis which releases glucose more quickly, allows respiration during exercise
-Insoluble so no osmotic effect

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14
Q

How the structure of cellulose relates to its function [2]:

A

-Forms microfibrils, long, unbranched chains of glucose joined by hydrogen bonds which provide strength + support
-Compact, occupies a small space

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15
Q

3 important monosaccharides/reducing sugars:

A

-Glucose
-Fructose
-Galactose

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16
Q

What two monosaccharides form the disaccharide maltose?

A

-Two alpha glucose

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17
Q

What two monosaccharides form the disaccharide sucrose?

A

-Glucose
-Fructose

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18
Q

What two monosaccharides form the disaccharide lactose?

A

-Glucose
-Galactose

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19
Q

What chemical reaction joins two monosaccharides?

A

A condensation reaction

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20
Q

What type of bond forms between two monosaccharides?

A

A glycosidic bond

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21
Q

Test for reducing sugars? (test & outcome for positive result)

A

Benedict’s solution + heat.
Turns brick red with presence

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22
Q

Test for non-reducing sugar? (test & outcome for positive result)

A

Benedict’s first- failed. New solution- add hydrochloric acid + heat (boil). Cool + add an alkali to NEUTRALISE. Add Benedict’s + heat again.
Turns brick red after hydrolysing with presence.

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23
Q

Test for starch (test & outcome for positive result)

A

Add iodine
Turns blue/black with presence of starch.

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24
Q

Test for lipids (test & outcome for positive result)

A

Add ethanol + mix/shake. Add distilled water
Milky emulsion forms with presence of lipid.

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25
Two types of lipids?
-Triglyceride -Phospholipids
26
Function of triglycerides [4]:
-Storage molecule for energy -Insulation -Protection -Waterproof waxy cuticle
27
What type things form a triglyceride?
Glycerol + Fatty Acids
28
What bonds form between glycerol and fatty acids?
Ester bonds
29
What is the cell membrane made of?
A phospholipid bilayer
30
Structure of phospholipids [2]:
-Glycerol 'backbone' + ester bonds -only two fatty acids present, one is replaced by a phosphate group
31
What does the phospholipid bilayer consist of?
-A hydrophillic phosphate head (soluble in water- faces towards water- outwards) -A hydrophobic fatty acid tail (insoluble in water- faces away from water- inwards)
32
Where are unsaturated lipids mainly found?
Vegetable/olive oil
33
Where are saturated lipids mainly found?
Animal fats
34
What is the monomer of protein?
Amino acids
35
How do you test for proteins?
-Biuret test -Dark purple=positive result
36
Basic structure of amimo acid:
H o l ll H2N---C---C l l R oH
37
What type of bond forms between two amino acids?
Peptide bond
38
Primary structure of a protein: 3
-Unique polypeptide sequence of amino acids -Bonded by covalent peptide bonds -Long, straight, continuous chain
39
Secondary structure of a protein [3]:
-The folding/coiling of a polypeptide chain -Hydrogen bonds formed -Folded into either: An alpha helix A beta pleated sheet
40
Tertiary structure of a protein [3]:
-Chain often folds again and twists -Forms any complex 3D shape based on function -Strong hydrogen, ionic, and disulfide bonds
41
Quaternary structure of a protein [1]:
-Proteins made from more than one peptide e.g. haemoglobin
42
What term is used to describe the different structures of a-glucose and B-glucose?
Isomer(ism)
43
What type of protein is an enzyme?
Globular
44
5 stages in the induced fit model of an enzyme
1. Enzymes have SPECIFIC TERTIARY STRUCTURES 2. The substrate is CoMPLEMETARY to the active site & binds to the active site of the enzyme. The active site is a specific sequence of amino acids 3. When the substrate binds to the active site, it forms an ENZYME-SUBSTRATE CoMPLEX. 4. The active site changes shape slightly to accomodate the substrate so breaks/forms bonds. 5. A product is formed and released from the enzyme
45
How does the temperature affect the rate of enzyme activity?
-At lower temps, molecules move slower, as they have less kinetic energy therefore the frequency of collisions between substrates and enzymes decreases. Less complexes form. They also collide more slowly, making it less likely to form/break bonds. -At higher temps, there is more kinetic energy, so more successful collisions, so more E-S complexes form.
46
How does the pH affect the rate of enzyme activity?
-Enzymes denature at extremes -Hydrogen and ionic bonds hold enzyme together -Above + below optimum, acidic + alkaline solutions can break bonds. -This alters the shape of the active site, meaning the E-S complex forms slower/less easily. -Complete denaturation occurs when the E-S complex no longer forms at all.
47
What is a competitive inhibitor?
-Compete with the substrate for the active site -The substrate cannot bind to the active site -Less E-S complexes form -Slows rate of reaction
48
What is a non-competitive inhibitor?
-Binds to the enzyme at an alternative active site -Alters the shape of the active site -Prevents substrate from binding Less E-S complexes form
49
What does DNA stand for?
Deoxyribose Nucleic Acid
50
2 types of nucleic acids?
-DNA -RNA
51
What is the monomer of a DNA polymer?
Nucleotide
52
What three things make up a DNA nucleotide?
-Deoxyribose sugar (pentose sugar- 5 carbon) -Phosphate group Nitrogenous base
53
'A' nitrogenous base
Adenine
54
'T' nitrogenous base (DNA only)
Thymine
55
'C' nitrogenous base
Cytosine
56
'G' nitrogenous base
Guanine
57
'U' nitrogenous base (RNA only)
Uracil
58
What two scientists were involved in discovering the structure of DNA (the double-helix)
Crick and Watson (1953)
59
What bonds occur between the sugar and phosphate group?
Phosphodiester bonds via condensation reaction.
60
What bonds occur between the two complementary base strands?
Hydrogen bonds
61
Differences between DNA and RNA? [5]
-DNA is double stranded, RNA is single stranded -DNA has thymine, RNA has uracil -DNA has deoxyribose sugar, RNA has ribose sugar -only one type of DNA, 3 types of RNA -DNA is much longer than RNA
62
Similarities between DNA and RNA?
-Both have phosphate group -Both have nitrogenous bases -Both have phosphodiester bonds between the phosphate and sugar -Both have polymers of nucleotides -Both pentase sugar (5 carbons)
63
True or false: Starch contains only the elements carbon, hydrogen and oxygen
True
64
True or false: Glycogen contains only the elements carbon, hydrogen and oxygen
True
65
True or false: Deoxyribose contains only the elements carbon, hydrogen and oxygen
True
66
True or false: DNA helicase contains only the elements carbon, hydrogen and oxygen
False
67
True or false: Starch is made from amino acid monomers
False
68
True or false: Glycogen is made from amino acid monomers
false
69
True or false: Deoxyribose is made from amino acid monomers
false
70
True or false: DNA helicase is made from amino acid monomers
true
71
True or false: Starch is found in both plants and animal cells
False
72
True or false: Glycogen is found in both plants and animal cells
False
73
True or false: Deoxyribose is found in both plants and animal cells
True
74
True or false: DNA helicase is found in both plants and animal cells
True
75
What are the four DNA nitrogenous bases?
- Adenine - Thymine - Guanine - Cytosine
76
Which DNA base pairs are complementary with each other?
Adenine-Thymine Cytosine-Guanine
77
What base pair does RNA have that is different to DNA?
Uracil instead of Thymine
78
At what point in the cell cycle does semi-conservative DNA replication occur?
During the 'S' phase (synthesis)
79
Why is DNA replication semi-conservative?
Half of the strands in a new DNA molecule are from the original DNA molecule.
80
DNA replication steps (6):
- DNA helicase breaks hydrogen bonds between bases - Helix unwinds to form 2 single strands - Each original strand acts as a template to a new strand - Free-floating DNA nucleotides are drawn to the exposed complementary bases - The complementary base pairings form new hydrogen bonds between the bases - Condensation reactions form new phosphodiester bonds between the nucleotides (this is catalysed by DNA polymerase_
81
What does the enzyme DNA helicase do during semi-conservative DNA?
'unzips'/unwinds the double-helix to form two strands
82
Six properties of water:
- High surface tension - Cohesive - High latent heat of vaporisation - Good solvent - High specific heat capacity - A metabolite
83
Why does water have a high surface tension?
It has hydrogen bonds
84
Why is water cohesive?
The hydrogen bonds support the transpiration stream
85
Example of how water has a high latent heat of vaporisation?
Eg when you sweat, creates a cooling effect
86
Why must water be a good solvent?
For the transport of substances
87
Why must water have a high specific heat capacity?
To resist changed in temperature- eg useful for aquatic life
88
Why is water a metabolite?
It is involved in chemical reactions like condensation and hydrolysis reactions
89
What is ATP? (3 points)
- An energy- carrying molecule - A type of nucleic acid A phosphorylated nucleotide
90
What does ATP break into during hydrolysis when energy is released for cellular work (eg mitosis, active transport) ?
ADP + Pi (inorganic phosphate)
91
What enzyme catalyses the hydrolysis of ATP?
ATP hydrolase
92
What is an inorganic ion?
A charged particle that contains no carbon
93
Four examples of inorganic compounds:
Sodium ions Hydrogen ions Phosphate ions Iron ions
94
What are sodium ions used for?
Cotransport of glucose and amino acids
95
What are hydrogen ions used for?
Helps control the pH in digestion (the more H+ ions, the lower the pH)
96
What are phosphate ions used for?
Found in DNA, RNA, ATP & phospholipids
97
Where are iron ions found?
In haemoglobin