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The human cell > Lecture 1 and 2 > Flashcards

Lecture 1 and 2 Flashcards

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1
Q

Define condensation reaction

A

Activated monomers are linked together by the removal of water

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2
Q

What are the three components of a nucleotide?

A

Nitrogen containing base
Deoxyribose (five carbon sugar),
Phosphate group

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3
Q

What carbon is the phosphate and hydroxyl group attached to in a nucleotide?

A

5’ phosphate

3’ hydroxyl

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4
Q

What type of bond forms between nucleotides? What is this called?

A

Covalent bonds
Phosphodiester bonds
(Between hydroxyl and phosphate group)

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5
Q

What is formed by phosphodiester bonds between nucleotides?

A

Sugar-phosphate backbone

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6
Q

How are two polynucleotide chains held together?

A

Hydrogen bonding between the complementary bases

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7
Q

DNA strands are ___parallel

A

Anti

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8
Q

What type of helix do the sugar phosphate backbones wind into?

A

A right handed helix

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9
Q

What is the formula of a phosphate group in a nucleotide?

A

PO4

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10
Q

How far apart are nucleotides in a DNA helix?

A

0.34nm

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11
Q

What distance is between each complete turn of a DNA double helix?

A

3.4nm

10 nucleotides

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12
Q

Why can each strand of DNA act as a template for the synthesis of the other?

A

The two anti-parallel strands are reverse complements of each other

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13
Q

Define transcription

A

The synthesis of RNA from a DNA template

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14
Q

What are the three differences between RNA and DNA?

A

Ribose replaces deoxyribose
Uracil replaces thymine
RNA is single stranded

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15
Q

What are the 4 types of RNA?

A

Messenger
Ribosomal
Transfer
Micro

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16
Q

What does micro RNA do?

A

Regulates expression of mRNA

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17
Q

What protein complex translates mRNA into protein?

A

Ribosomes

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18
Q

How many possible codons are there? How many amino acids?

A

64 codons

20 amino acids (DNA is degenerate)

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19
Q

What are the three stop codons?

A

UAG, UAA, UGA

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20
Q

How are amino acids linked?

A

Condensation reaction in the ribosome forms a peptide bond (between amino group and carboxyl group)

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21
Q

Why do sterioisomers of amino acids exist?

A

Asymmetric alpha carbon

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22
Q

What sterioisomer of amino acids is found in proteins?

A

L- amino acids (not D)

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23
Q

What is pi-pi stacking of aromatic rings?

A

Delocalised electrons generate a weak charge in aromatic side chains

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24
Q

What electrostatic interactions can delocalised electrons in aromatic rings participate in?

A
  • Other aromatic pi-pi stacking

- Cations (side chains of lys, arg, ions and ligands)

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25
What are the 9 classes of proteins?
Enzymes, structural, motility, regulatory, transport, hormonal, receptor, defensive, storage
26
What does it mean that amino acid chains have directionality?
N-terminus (amino acid group) at one end, C-terminus (carboxyl group) at the other
27
What type of bonding is responsible for the local folding of proteins (secondary structure)
Hydrogen bonding
28
Define alpha helix
Coiled form of peptide chain
29
How are alpha helix stabilized?
Regular hydrogen bonds between carbonyls and N-H groups of secondary amides of the peptide bond, 4 amino acids apart
30
How many amino acids are there per turn of the alpha helix?
3.6
31
What are beta sheets comprised of?
Adjacent beta strands, stabilized by regular hydrogen bonds between carbonyls and amides of the peptide backbone
32
What are the features of a beta sheet?
More extended chain than a helix | Alternate R groups point above and below the flat sheet
33
Define tertiary structure of a protein.
The overall 3D shape of a protein
34
What forces stabilize the tertiary structure of a protein?
``` Hydrogen bonds, van der waals forces Disulphide bridges (covalent bond) Salt bridges (ioninc bond) ```
35
What is a monomeric protein?
A protein consisting of only one polypeptide chain
36
Define quaternary structure.
Interaction of two or more polypeptide chains to form a protein complex
37
What name is given to a protein consisting of 2 or more polypeptide chains?
Multimeric protein
38
What is collagen?
The most abundant protein in the human body | 3 stranded coiled-coil
39
Where is collagen found?
Extracellular matrix, connective tissue and muscle
40
What is haemoglobin?
The most abundant protein in red blood cells Tetramer Four iron containing heme groups that carry oxygen around the body
41
Where are fatty acids synthesized?
Mainly in liver and adipose tissue
42
What enzyme synthesizes fatty acids?
Fatty acid synthase
43
What name is given to the methyl end of a fatty acid?
Omega
44
What name is given to the carboxyl end of a fatty acid?
Delta
45
How is acetyl-CoA transported out of the mitochondrial matrix?
As citrate
46
What is the first stage of fatty acid synthesis?
Loading | Acetyl-CoA and malonyl-CoA +ACP +MAT make acetly-ACP and malonyl ACP
47
How many carbon atoms in Acetyl-CoA?
2
48
How many carbon atoms in Malonyl-CoA?
3
49
When does fatty synthesis occur?
In a fed state, high blood glucose (high insulin)
50
What process occurs after loading during fatty acid synthesis?
Elongation
51
What enzyme works on acetyl-ACP and malonyl-ACP? What reducing agent is used?
Ketosynthase | No reducing agent
52
What type of reaction occurs when ketosynthase catalyses acetyl-ACP and malonyl-ACP?
Condensation
53
What is the product of the first condensation reaction during fatty acid synthesis?
beta-ketoacyl and CO2
54
What is the next step after condensation during fatty acid synthesis?
Reduction
55
What enzyme is used to reduce beta-ketoacyl? What is the reducing agent?
Ketoreductase | NADPH
56
What is the product when ketoreductase reacts with beta-ketoacyl in the presence of NADPH?
B-hydroxyacyl
57
What is the next step, after reduction 1, in fatty acid synthesis?
Dehydration
58
What enzyme is used to dehydrate beta-hydroxyacyl? What reducing agent is used?
Dehydratase | No reducing agent
59
What is the product of dehydratase and beta-hydroxyacyl?
beta-enoyl and H2O
60
What is the final step of fatty acid synthesis before the cycle repeats?
Enoylreductase reduces beta-enoyl using NADPH to form acyl (Cn+2)
61
How many cycles does fatty acid synthase under go?
7
62
What is formed by fatty acid synthase after 7 cycles?
Palmitate
63
What enzyme removes ACP at the end of 7 cycles of fatty acid synthesis?
Thioesterase
64
How many carbons are there in palmitate?
16
65
How many carbon atoms are there in stearic acid?
18
66
What is an 18 carbon fatty acid with one double bond in the middle called?
Oleic acid
67
What enzyme can make oleic acid from stearic acid?
Desaturase
68
How many malonyl/acetly-CoA, NADPH and ATP are used in the synthesis of palmitate?
7 14 NADPH 7ATP
69
Where is ATP used in fatty acid synthesis?
Synthesis of malonly-CoA
70
How is linoleic acid different from oleic acid?
linoleic acid is polyunsaturated, 2nd double bond is 6C from omega end (Omega-6 FA)
71
What is alpha-linolenic aicd?
3 double bonds, one 3C from omega end (Omega 3-FA)
72
Why is omega 3 and omega 6 essential fatty acids?
They must be obtained from diet | We do not have desaturase to remove hydrogen from 3rd or 6th carbon
73
Where are fatty acids stored?
In triglycerides in adipose tissue
74
How do fatty acids change fluidity and permeability of membranes?
Saturated and unsaturated fatty acids pack differently
75
What enzyme converts omega 6/3 into membrane lipids?
Phospholipase
76
Name an important derivative of omega 6 (linoleic acid)
Arachidonic acid
77
Name an important derivative of omega 3 (alpha linolenic acid)
Eicosapentaenoic acid
78
What enzymes convert omega 3/6 into their important derivatives?
Elongases, desaturases
79
What are arachidonic acid and eicosapentaenoic acid used for?
Paracrines
80
Name some paracrines derived from essential fatty acids.
Leukotrienes, prostoglandins, thromboxanes
81
What are these paracrines effects?
Mediators of inflammation, pain, fever, immunosuppression, clotting, vasoconstriction, air way constriction
82
How many x more efficient is triglyceride than glycogen?
6x energy store
83
What is the structure of a triglyceride?
glycerol head, ester bond between 3 fatty acid tails
84
Why can triglycerides store more energy per mass as opposed to glycogen?
They're anhydrous- they contain no H2O
85
What is the sugar found in ATP?
Deoxyribose
86
What is the adinosine part of ATP made of?
Adenine | deoxyribose
87
What bonds are between the phosphate groups of ATP?
Phosphoanhydride bond
88
Other than energy, what is the citric acid a source for?
Precursors for important biological molecules
89
What is the first enzyme involved in glycogen catabolism?
Glycogen phosphorylase and phosphate
90
What is the product of the first step of glycogen catabolism?
Glucose-1-phosphate (and the rest of the glycogen molecule)
91
What enzyme acts on glucose-1-phosphate during glycogen catabolism?
Phosphoglucomutase
92
What does is the product when phosphoglucomutase acts on glucose-1-phosphate?
Glucose-6-phosphate, which can then enter glycolysis

The human cell (10 decks)

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