3. Nucleotides And Nucleic Acids Flashcards
(90 cards)
1
Q
DNA and RNA are…
A
Polymers
2
Q
What monomer makes up DNA and RNA
A
Nucleotides
3
Q
3 components of nucleotide
A
• a pentose sugar
• a nitrogen-containing organic base
• a phosphate group
4
Q
Where is the hydrogen on the DNA nucleotide
A
2nd position
5
Q
Nitrogenous bases in DNA nucleotide
A
adenine (A), cytosine(C), guanine(G) or thymine(T)
6
Q
Components of RNA nucleotides
A
A ribose sugar with a hydroxyl (OH) group at the 2’ position o A phosphate group
o One of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or uracil (U)
7
Q
What is the function of the hydroxyl group on the 2nd carbon in RNA nucleotide
A
• makes RNA more susceptible to hydrolysis
• This is why DNA is the storage molecule and RNA is the transport molecule with a shorter molecular lifespan
8
Q
Draw RNA nucleotide
A
9
Q
Draw DNA nucleotide
A
10
Q
Define purine
A
nitrogenous base that has two rings
11
Q
Shape of larger ring in purines
A
Hexagon
12
Q
Shape of smaller ring in purines
A
Pentagon
13
Q
What bases are purine
A
Adenine and guanine
14
Q
Define pyrimidine
A
A nitrogenous base contains only one hexagonal ring
15
Q
What bases are pyrimidine
A
Cytosine
Thymine
Uracil
16
Q
Difference between dna and rna
A
17
Q
How does RNA and DNA form
A
Condensation reaction
18
Q
Where does the condensation reaction occur between nucleotides
A
between the phosphate group of one nucleotide and the pentose sugar of the next nucleotide
19
Q
What type of bond does the condensation reaction form
A
Phosphodiester bonds
20
Q
Draw a polynucleotide
A
21
Q
The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds is known as.
A
The sugar phosphate backbone
22
Q
Use of ATP
A
- anabolic reactions
- metabolic reactions
- muscle contraction
- conduction of nerve impulses
- movement of substances
23
Q
Examples of nucleotides
A
DNA, RNA, ATO
24
Q
ATP is a type of…
A
Nucleic acid
25
Structure of ATP
Three phosphate groups = adenosine
triphosphate(ATP)
26
Adenosine w 1 phosphate group
adenosine monophosphate(AMP)
27
Adenosine with 2 phosphate groups
adenosine diphosphate(ADP)
28
What is adenosine
Nucleoside
29
What is DNA molecules made up of
two polynucleotide strands lying side by side, running in opposite directions
- the strands are said to be antiparallel
30
What are the bonds in the sugar phosphate backbone
Phosphodiester bonds
31
Where does the Phosphodiester bond occur
the 5-carbon of one deoxyribose sugar molecule to the phosphate group from the same nucleotide, which is itself linked by another phosphodiester bond to the 3-carbon of the deoxyribose sugar molecule of the next nucleotide in the strand
32
Where does the Phosphodiester bond occur
the 5-carbon of one deoxyribose sugar molecule to the phosphate group from the same nucleotide, which is itself linked by another phosphodiester bond to the 3-carbon of the deoxyribose sugar molecule of the next nucleotide in the strand
33
What does 3' and 5' mean
Each DNA polynucleotide strand is said to have a 3' end and a 5' end (these numbers relate to which carbon on the pentose sugar could be bonded with another nucleotide)
o As the strands run in opposite directions (they are antiparallel), one is known as the 5' to 3' strand and the other is known as the 3' to 5' strand
34
How are the two antiparallel polynucleotide strands held together
Hydrogen bonds between bases
35
How many hydrogen bonds are formed between A and T
2
36
How many hydrogen bonds between G and C
3
37
DNA shape
Double helix
38
What process Is dna copied via
Semi conservative replication
39
Why is it called semi-conservative replication
- one original strand and one new strand
Each strand acts as a template strand
40
What is the importance of semi-conservative replication
Retaining one original DNA strand ensures there is genetic continuity (i.e. genetic information is conserved) between generations of cells
41
DNA replication steps
- DNA unwinds = catalysed by enzyme gyrase
- DNA unzips into 2 = hydrogen bonds break = catalysed by helicase
- free floating DNA nucleotides combine with complementary bases that are exposed (AT AND CG)
- catalysed by enzyme DNA polymerase = formation of Phosphodiester bonds between nucleotides
42
What direction does dna polymerase work
5’ to 3’
43
Enzyme that breaks hydrogen bonds
Helicase
44
Which enzyme catalyses condensation reaction between deoxyribose sugar and phosphate groups
DNA polymerase
45
How often do mistakes get made in dna replication (mutations)
Very very rarely
46
How would mistakes in dna replication occur
Bases being inserted into the complementary strand in the wrong order
• An extra base being inserted by accident o A base being left out by accident
47
define Gene
Section of dna that codes for a specific protein
48
What is a codon
Triplet on mRNA
49
Anticodon
triplet on tRNA
50
Triplet code
3 bases on DNA = 1 amino acid
51
Some of the triplets code for..
Start and stop
52
Features of the genetic code
Non-overlapping
Degenerate
Universal
53
Mutation
change is DNA sequence = due to an incorrect
sequence in the newly copied strand
54
Start codon
beginning of a gene = signals start of a sequence that codes for a protein
55
Middle of gene
codes for the amino acid
56
‘Stop’ codons
Signals end of sequence
57
Non overlapping
Each base is only read once in which codon it is part of
58
What does degenerate mean
multiple codons can code for the same amino acid
59
What does universal mean
almost every organism uses the same code
o The same triplet codes code for the same amino acids in all living things
o + is why genetic engineering is possible
60
Role of tRNA
tRNA molecules that transfer amino acids possess anticodons which are complementary to the codons on mRNA
61
Stage 1 of protein synthesis
Transcription - DNA is transcribed and an mRNA molecule is produced
62
Stage 2 of protein synthesis
o Translation - mRNA (messenger RNA) is translated and an amino acid sequence is produced
63
Where does transcription occur
Nucleus
64
Similarities = DNA replication and transcription
- DNA unwinds and unzips
- helicase enzymes
- free activated nucleotides
65
Differences = DNA replication and transcription
- only small section of DNA unzips during transcription
- RNA vs DNA free nucleotides
- RNA vs DNA polymerase
66
Why’s transcription necessary for polypeptide synthesis
- DNA transcribed to mRNA
- RNA goes to ribosomes
- DNA is too large to leave nucleus
67
How does transcription occur
- DNA unwinds = catalysed by enzyme gyrase
- DNA unzips into two = hydrogen bonds break = catalysed by helicase
- free floating RNA nucleotides bind to complementary bases on DNA strand = catalysed by RNA polymerase + Phosphodiester bonds are formed between the nucleotides
- strand of mRNA forms + detaches from DNA + leaves nucleus through nuclear pore
- DNA double helix reforms + mRNA molecule travels to ribosome
68
Template strand
RNA nucleotides pair with bases on this strand of the DNA molecule = produce mRNA molecule
69
Where does translation occur
Cytoplasm = ribosomes
70
Translation
- mRNA binds to a specific site on the small subunit of a ribosome
- tRNA molecules carrying the complementary anticodons to the mRNA codon bind using temporary hydrogen bonds.
- tRNA molecules carry an amino acid corresponding to that codon
- As anticodons bind to complementary codons, the amino acids are brought together + peptide bonds form between the amino acids
- forms primary structure of protein coded for by the mRNA
71
What type of sugar does ATP have
Ribose - OH on 2nd and 3rd carbons
72
What type of sugar does DNA have
Deoxyribose = H on 2nd carbon
73
What type of sugar does RNA have
Ribose
74
Is atp recycled
YES
75
Instead of calling them free nucleotides what should we call them
Free, activated nucleotides
76
Is there any diff in helicase between DNA and RNA
YES
77
Why grind the sample?
To break down the cell wall
78
Mix the sample with detergent
It breaks down the cell membrane by dissolving the phospholipids
79
Add salt
Neutralise the charge of DNA so it becomes insoluble by breaking hydrogen bonds between water and DNA
80
Add protease enzyme
Helps to digest histone proteins so your left with just DNA
81
Add layer of ice cold alcohol
Helps DNA precipitate out of solution
82
83
84
85
86
87
88
89
90
