Nucleic Acids Flashcards
1
Q
what are the components of nucleotides
A
phosphate group
Pentose sugar
nitrogenous base
2
Q
which bases are pyrimidine
A
thymine
cytosine
urasil
3
Q
which bases are purine
A
adenine
guanine
4
Q
what does DNA stand for
A
deoxyribonucleic acid
5
Q
what are the functions of DNA
A
carries the genetic code for protein synthesis
replicates in dividing cells
6
Q
the two DNA strands are said to be what
A
antiparallel
7
Q
what are base pairs held together by
A
hydrogen bonds
8
Q
how many hydrogen bonds does G and C have
A
3
9
Q
how many hydrogen bonds does A and T have
A
2
10
Q
what phase does DNA replication take place in
A
interphase
11
Q
conservative replication theory
A
the parent DNA remains unchanged and is copied by the cell creating a new daughter molecule
12
Q
semi conservative replication theory
A
the parent DNA separates into 2 strands. Each strand acts as a template for a new complementary strand. The daughter molecules therefore have one strand of original DNA and one strand of newly synthesised DNA
13
Q
dispersive replication theory
A
the parent DNA breaks into double stranded segments which are copied using new nucleotides.
14
Q
RNA stand for
A
ribonucleic acid
15
Q
mRNA function
A
carries genetic code for specific protein from DNA in nucleus to ribosomes in the cytoplasm
16
Q
tRNA
A
transfers specific amino acids to the ribosome
17
Q
rRNA
A
forms a ribosome. Ribosomes translate the genetic code and join amino acids together to form polypeptides
18
Q
what replaces thymine in RNA
A
urasil
19
Q
how many possible genetic codes are there
A
64
20
Q
what does the sequence of bases determine
A
the sequence of amino acids
21
Q
what is a gene
A
a section of DNA that codes for a specific polypeptide
22
Q
what is a triplet code
A
3 bases that encode each amino acid
23
Q
why are there more triplet codes that amino acids
A
each amino acids has more than one code so the code is degenerate
some triplets do not code for amino acids, these are stop codons which mark the end of translation
24
Q
name the components of ATP
A
3 phosphate groups
ribose sugar
Adenine base
25
what are the 5 uses of ATP
```
active transport
muscle contraction
nerve impulse transmission
bulk transport
synthesis of complex molecules
```
26
purine
a double ringed nitrogenous base
27
pyrimidine
a single ringed nitrogenous base
28
the addition of phosphate to ADP is called
phosphorylation
29
what reaction is the formation of ATP
endergonic
30
what reaction is the hydrolysis of ATP
exergonic
31
why are there more triplet codes than amino acids
each amino acids has more than one code so the code us described as degenerate
stop codons do not code for amino acids as they mark the end of translation
32
differences in DNA and RNA
```
DNA:
deoxyribose sugar
A-T
G-C
2 strands
long
```
```
RNA:
ribose sugar
A-U
G-C
1 strand
short
```
33
what types of RNA are involved in protein synthesis
mRNA and tRNA
34
what two stages are involved in protein synthesis
transcription
| translation
35
transcription
a process that occurs in the nucleus where the genetic code for a specific protein is copied
36
translation
a process occurring at the ribosome where the genetic code is translated into a polypeptide
37
formation of ATP
the enzyme ATP synthase combines ADP and P in a condensation reaction. This requires an input of energy in an endergonic reaction
38
hydrolysis of ATP
the enzyme ATPase hydrolyses the terminal phosphate bonds releasing a small packet of energy in an exergonic reaction, forming ADP and P
39
4 advantages of using ATP over glucose
only one enzyme is needed to release energy
ATP releases small packets of energy when and where it is needed
common source of energy for many reactions
easily transported across membranes
40
why is ATP a universal energy current
it provides energy for many metabolic reactions in all living organisms
41
what 3 stages are involved in translation
initiation
elongation
termination
42
what is a polysome
complex of several ribosomes on the mRNA
43
ATPase
hydrolyses the terminal phosphate bond in ATP releasing a small packet of energy
44
ATPsynthase
combines ADP and P in a condensation reaction
45
DNA helicase
catalyses hydrogen holding together DNA strands
46
DNA polymerase
catalyses condensation reaction between 2 DNA nucleotides
47
RNA polymerase
binds to template strand at the beginning of the sequence and moves down the strand catalysing the reaction between complementary RNA nucleotides
48
endonuclease
cuts DNA at a specific base sequence, removing introns
49
ligase
splices together exons
50
intron
sections of DNA within a gene which do not code for a protein. They are removed after transcription by the enzyme endonuclease
51
exon
sections of DNA within a gene which code for a protein. They are left behind and are spliced together by the enzyme ligase to form the final mature mRNA
52
splicing
joining together of DNA fragments by ligase enzymes
53
where does transcription occur
in the nucleus
54
where does translation occur
at a ribosome
55
what strand codes for amino acids
mRNA
56
what is complimentary to the DNA template strand
mRNA
57
what is complimentary to tRNA
mRNA
58
DNA
a very large stable molecule, found as chromatin in the nucleus and small amounts are found in mitochondria and chloroplasts
59
RNA
a short-lived molecule, found mainly in the cyctoplasm and can also be found in the nucleus
60
does prokaryotic DNA contain introns
no
61
why does mRNA modification take place
because the initial mRNA molecule produced by transcription is longer than than the final mRNA that is translated at the ribosome
62
how many tRNA molecules can bind to the large subunit at the ribosome
2
63
what does the small subunit in the ribosome bind to
mRNA
64
when tRNA attaches to the amino acid in the cytoplasm what is this called and what is required
it requires ATP and is called 'amino acid activation'
65
what does the anti codon on tRNA determine
which amino acid the tRNA molecule will carry
66
what happens at post-translational modification
the polypeptide is transported to the Golgi body in a vesicle where it can be chemically modified by non-proteins
67
what does a carbohydrate and polypeptide make
glycoprotein
68
what does a lipid and a polypeptide make
lipoprotein
69
what does a phosphate and a polypeptide make
phospho-proteins
70
primary structure
order and sequence of amino acids
71
secondary structure
polypeptide chains fold into an a-helix or b-pleated sheet
72
tertiary structure
further folding of secondary structure into a specific 3D shape
73
quarternary structure
2 or more polypeptides chemically bonded together, may have a prosthetic group
74
bonds in secondary structure
peptide and hydrogen
75
bonds in tertiary and quaternary
hydrogen
disulphide
ionic
hydrophobic interactions
76
examples of secondary structure
collagen and keratin
77
examples of tertiary structure
insulin hormone
78
example of quaternary structure
haemoglobin
79
what processes are involved in protein synthesis in order
transcription
pre-mRNA modification
translation
post-translational modification
80
explain the 6 steps involved in DNA replication
1. DNA helicase catalyses the breaking of hydrogen bonds holding together complementary base pairs
2. DNA strands unwind
3. each DNA strand acts as a template
4. free DNA nucleotides align opposite complementary bases
5. DNA polymerase catalyses the condensation reaction between DNA nucleotides, occurring from the 5 prime to 3 prime end
6. Each new DNA molecule is made from an original template strand and a new replicated strand, known as a semi-conservative approach
81
explain the 6 steps in transcription
1. only one strand of DNA is used as a template strand for mRNA
2. DNA helicase breaks hydrogen bonds holding complementary base pairs causing DNA to unwind
3. RNA polymerase binds to the template strand at the beginning of the sequence
4. free RNA nucleotides align opposite complementary base pairs on the template strand
5. RNA polymerase moves along the template strand, catalysing the addition of RNA nucleotides until a stop codon is reached, the strand behind to rewind
6. mRNA leaves via the nuclear pore and travels to the cytoplasm
82
explain the steps involved in translation
1. ribosome attaches to start codon on the mRNA
2. first tRNA binds to 1st attachment site as the anticodon is complementary to a codon on the mRNA forming a codon-anticodon complex with hydrogen bonds
3. a second tRNA bonds to second attachment site
4. ribosomal enzyme catalyses the formation of peptide bonds between adjacent amino acids
5. the tRNA leaves the site and returns to cytoplasm and the next moves down
6. this sequence repeats until a stop codon is reached
7. the ribosome-mRNA-polypeptide complex separates from the ribosome
83
how many rings do purine bases have
2
84
how many rings do pyridimine bases have
1
85
what phase does DNA replication occur in
interphase
86
DNA polymerase catalyses the condensation reaction of phosphate groups and deoxyribose sugars to form what bond
phosphodiester bond
87
percentages of nitrogen in 0 generation
0% light nitrogen
0% intermediate
100% heavy nitrogen
88
percentages of nitrogen in 1st generation
0% light nitrogen
100% intermediate
0% heavy nitrogen
89
percentages of nitrogen in 2nd generation
50% light nitrogen
50% intermediate
0% heavy nitrogen
90
percentages of nitrogen in 3rd generation
75% light nitrogen
25% intermediate
0% heavy nitrogen
91
percentages of nitrogen in 4th generation
87.5% light nitrogen
12.5% intermediate
0% heavy nitrogen
