Nucleic acids Flashcards
1
Q
Is RNA a polymer
A
Yes
2
Q
What is the monomer of RNA
A
A nucleotide
3
Q
What are the 3 components of the nucleotide that makes up RNA
A
- Ribose (pentose sugar)
- A nitrogenous base (A,G,C,U)
- A phosphate group
4
Q
Name 4 differences between RNA and DNA
A
- RNA contains ribose instead of deoxyribose in DNA
- RNA has the base uracil whereas DNA has thymine
- RNA is single stranded whereas DNA is double
- RNA polymer is a relatively short polynucleotide chain whereas DNA is long
5
Q
What are the functions of RNA
A
- Copy and transfer the genetic code from DNA in the nucleus to the ribosomes
- Some RNA also combines with proteins to create ribosomes
6
Q
What are the 3 types of RNA
A
- mRNA (messenger)
-tRNA (transfer)
-rRNA (ribosomal)
7
Q
What is mRNA
A
A copy of a gene from DNA
8
Q
Where is mRNA created
A
In the nucleus
9
Q
Why is mRNA created instead of just having DNA
A
Because DNA is too large to leave the nucleus whereas mRNA is much smaller because it’s only the length of one gene therefore can fit through the nuclear pores
10
Q
Why is mRNA short lived
A
Because once the genetic material has left the nucleus it has a risk of being exposed to enzymes which can hydrolyse the polymers
11
Q
How many bases on mRNA code for one specific amino acid
A
3
12
Q
What is the name of the 3 bases that code for an amino acid
A
A codon
13
Q
Where is tRNA found
A
In the cytoplasm
14
Q
Is tRNA single or double stranded
A
Single
15
Q
What is the shape of mRNA
A
A straight line
16
Q
What is the shape of tRNA
A
Folds in on itself to create a shape that looks like a cloverleaf
17
Q
What type of bonds hold the cloverleaf shape of a tRNA molecule
A
Hydrogen bonds
18
Q
What is the function of tRNA
A
To transfer amino acids
19
Q
At the top of the tRNA molecule there are 3 exposed bases, what is the name for these bases
A
The amino acid attachment site
20
Q
What is the function of rRNA
A
Combines with protein to make ribosomes
21
Q
Differences between the DNA and RNA monomers (x2)
A
- DNA contains the base thymine whereas RNA contains uracil instead
- DNA contains the pentose sugar deoxyribose, whereas RNA contains the pentose sugar ribose
22
Q
What is the function of DNA
A
- Carries genetic code for protein synthesis
23
Q
What is the name of the monomer making up nucleic acid
A
Nucleotides
24
Q
What is the name of the polymer made from nucleotides
A
Polynucleotides
25
What reaction joins nucleotides together to form a polynucleotide
A condensation reaction
26
What is the name of the bond when nucleotides join together via a condensation reaction
phosphodiester bond
27
How many polynucleotides make up DNA
2
28
How many polynucleotides make up RNA
1
29
What are the 3 main components of a nucleotide
- Phosphate group
- Pentose sugar
- Nitrogen-containing base
30
In DNA, what is the name of the pentose sugar
Deoxyribose
31
In DNA, what are the names of the 4 possible nitrogen-containing bases
- Adenine
- Thymine
- Cytosine
- Guanine
32
In RNA, what is the name of the pentose sugar
Ribose
33
In RNA, what are the names of the 4 possible nitrogen-containing bases
- Adenine
- Cytosine
- Guanine
- Uracil
34
What is the proper name for ATP
Adenosine triphosphate
(must remember the osine)
35
What is the name of the pentose sugar in ATP
Ribose
36
What is the name of the nitrogen-containing base in ATP
Adenine
37
In ATP what is the name of the phosphate group
Triphosphate group
38
What type of structure do purine nitrogenous bases have
Double ring
39
What are the 2 nitrogenous bases that are purine bases
- Adenine
- Guanine
40
What type of structure do pyrimidine, nitrogenous bases have
Single ring structure
41
What are the 3 nitrogenous bases that have pyrimidine structures
- Thymine
- Cytosine
- Uracil
42
What type of nitrogenous base is bigger, purine bases or pyrimidine bases
Purine bases are bigger
43
How many hydrogen bonds does the purine base adenine make
2 hydrogen bonds
44
How many hydrogen bonds does the purine base guanine make
3 hydrogen bonds
45
In DNA, what is the ratio of purine bases to pyrimidine bases
1:1
46
What is the name of the structure of DNA
Double helix
47
DNA has a sugar-phosphate backbone, what is it's role in overall DNA function
Gives strength to DNA molecule
48
DNA is composed of 2 chains held together by weak hydrogen bonds, what is this features relation to the overall function
The chains can be separated for transcription (protein synthesis) and replication
49
DNA has a coiled structure why is this useful
Protects the hydrogen bonds therefore reducing corruption of genetic code
50
DNA contains many weak hydrogen bonds what benefit does this have
Make DNA a stable molecule
51
DNA is a long molecule, what impact does this have on the role of DNA
It can store a lot of genetic information (genes)
52
Where is DNA found
Nucleus
53
Where is RNA found
- Nucleus
- Cytoplasm
54
What forms from the hydrolysis of ATP
ADP and Pi
55
What is the enzyme that catalyses the hydrolysis of ATP
ATP hydrolase
56
Is the hydrolysis of ATP an exergonic or endergonic reaction
Exergonic reaction
57
What molecules are required to synthesise ATP
ADP and Pi
58
What is the name of the enzyme that catalyses the synthesis of ATP
ATP synthase
59
Is the synthesis of ATP endergonic or exergonic
Endergonic reaction
60
What is the function of ATP
An immediate source of energy for biological processes
61
Why is it essential that cells have a constant, steady supply of ATP
So the can under go all the chemical reactions in the cell
62
What process makes ATP
Respiration
63
Why is ATP described as an immediate source of energy
Because only one bond has to be hydrolysed to release energy - so very rapid
64
Why is ATP releasing small, manageable amount of energy better than the energy released from glucose
- Less energy is wasted
- Stops cells from overheating since a lot of waste energy is released in the form of heat
- Glucose would release large amounts of energy
65
Why is ATP being a small and soluble molecule beneficial
It can easily be transported around the cell
66
How many bonds in ATP need to be broken/ hydrolysed to release energy, and why is this better than glucose
Only 1 bond needs to be hydrolysed, so is an immediate energy release, whereas glucose would need several bonds to be hydrolysed to release all its energy
67
What does phosphorylation mean in terms of ATP
The inorganic phosphate group can be bonded to new molecule and make that molecule more reactive
68
Why is ATP not being able to pass out of the cell a benefit
So the cell always has an immediate supply of energy whereas glucose can run out
69
When does DNA replication occur in the cell cycle
Before cell division
70
What is the name of the process of DNA replication
Semi-conservative replication
71
What does semi-conservative replication mean
In the daughter DNA one strand is from the parental DNA and one strand is newly synthesised
72
What are the 2 complementary base pairs
- Adenine and thymine
- Cytosine and guanine
73
What are the names of the 2 key enzymes involved in semi-conservative replication
- DNA helicase
- DNA polymerase
74
What is the role of DNA helicase
This enzyme breaks the hydrogen bonds between complementary base pairs between the 2 strands within a double helix
75
What is the first step needed to start the DNA replication process
The DNA double helix needs to unwind using the enzyme DNA helicase by breaking the hydrogen bonds
76
Once the double helix of DNA has separated what do the 2 parental strands now act as
A template
77
Once the 2 strands of DNA have been separated, what does the free floating DNA nucleotides within the nucleus do
They are attracted to their complementary base pairs on the template strands of the parental DNA - but these nucleotides are not attached together yet so still monomers
78
Once the free floating nucleotides that are attracted to the template DNA strand align adjacent to one another, what enzyme catalyses the joining of these adjacent nucleotides
DNA polymerase
79
What is the function of DNA polymerase
To join together adjacent nucleotides
80
What are the names of the DNA replication theories
- Conservative
- Semi-conservative
- Dispersive
81
Explain what the theory semi-conservative replication of DNA is
Each replicated DNA molecule contains one of the original DNA strands and one newly synthesised DNA strand
Conservative one entire original strand
82
Explain what is meant by conservative DNA replication
The original DNA remains intact following DNA replication and the two newly synthesised strands of DNA join together
83
What are the names of the men who conducted the experiment proving semi-conservative DNA replication
- Meselson
- Stahl
84
When Meselson and Stahl carried out their experiment on DNA replication what were the 2 different isotopes of nitrogen that were used, and which is the lighter one
- Nitrogen-14, lighter
- Nitrogen-15, heavier
85
What bacteria did Meselson and Stahl use in their experiment
Ecoli
86
In the first generation of bacterial growth in the Meselson and Stahl experiment, what medium was the ecoli grown in and how was this proven
Grown in nitrogen-15 medium and once placed in a centrifuge the DNA accumulated at the bottom of the tube
87
After the Ecoli had replicated in the nitrogen-15 medium, what did Meselson and Stahl do next
They took the Ecoli out of the nitrgoen-15 medium and placed it in a nitrogen-14 medium
88
In the first generation of Ecoli, placed in the nitrgon-14 medium, what happens when the DNA is centrifuged
There is only one band but it's higher up the tube compared to the Ecoli that only contained nitrogen-15
89
In the 2nd generation of ecoli DNA replication, what happens to the DNA when centrifuged
2 bands are formed
- one in the middle of the tube - 50% DNA is nitrogen-15 and nitrogen-14
- One at the top of the tube- 50% DNA is nitogen-14 and nitrogen-14
90
In the 3rd generation of ecoli DNA replication, what happens to the DNA when centrifuged, what are the %
2 bands form
- one in the middle- 25% DNA is N-15 and N-14
- one thicker band at the top- 75% DNA is N-14 and N-14
91
Name the type of bond between complementary base pairs
Hydrogen bonds
92
Name the type of bond between adjacent nucleotides in a DNA strand
Phosphodiester bonds
93
Describe the structure of DNA (5 marks)
- Polymer of nucleotides
- Each nucleotide formed from deoxyribose, a phosphate group, and an organic base
- Phosphodiester bonds
- Double helix held by hydrogen bonds
- Hydrogen bonds between adenine, thymine and cytosine, guanine
94
Describe how a phosphodiester bond is formed between 2 nucleotides within a DNA molecule (2 marks)
- Condensation reaction
- Between phosphate and deoxyribose
- Catalysed by DNA polymerase
95
Name the protein associated with DNA in a chromosome
HIstone
96
Describe how the separation of the 2 DNA strands in semi-conservative DNA replication (2 marks)
- DNA helicase
- Breaks hydrogen bonds between base pairs / breaks hydrogen bonds between polynucleotide strands
97
Describe the role of DNA polymerase in the semi-conservative replication of DNA (2 marks)
- Joins adjacent DNA nucleotides
- Catalyses condensation reactions
- Phosphodiester bonds
98
Name the 2 scientists who proposed models of the chemical structure of DNA and of DNA replication
Watson and Crick
99
Give 2 features of DNA and explain how each one is important in the semi-conservative replication of DNA ( 2 marks)
- Weak hydrogen bonds between bases allow 2 strands to separate
- 2 strands, so both can act as templates
- Complementary base pairing allows accurate replication
100
Describe the role of 2 names enzymes in the process of semi-conservative replication of DNA (3 marks)
- DNA helicase causes breaking of hydrogen bonds between DNA strands
- DNA polymerase joins the DNA nucleotides
- Forming phosphodiester bonds
101
Describe the function of DNA helicase
Breaking hydrogen bonds between bases
102
Describe the function of DNA polymerase
Joins adjacent nucleotides / forms. phosphodiester bonds
103
Contrast the structures of ATP and a nucleotide found in DNA to give 2 differences (2 marks)
- ATP has ribose and DNA nucleotides has deoxyribose
- ATP has 3 phosphate groups and DNA nucleotide has 1 phosphate group
- ATP- base always adenine and in DNA nucleotide base can be different
104
Define universal, non-overlapping and degenerate (3 marks)
- Universal- The same codon/ triplet always codes for the same amino acid
- Non-overlapping - Each base is only part of one triplet/ codon
- Degenerate - More than one codon/ triplet codes for each amino acid
105
Describe the role of DNA polymerase in the semi-conservative replication of DNA (2 marks)
1. Joins (adjacent DNA) nucleotides;
2. (Catalyses) condensation (reactions);
3. (Catalyses formation of) phosphodiester bonds
(between adjacent nucleotides);
106
Give 2 ways in which the arrangement of prokaryotic DNA is different from the arrangement of the human DNA
1. Circular (as opposed to linear);
2. Not associated with proteins/histones ;
3. Only one molecule/piece of DNA
OR
present as plasmids;
