Question 1
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Viruses contain either DNA OR RNA
Question 2
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A virus that is composed not of DNA but of RNA is called a [blank_start]retrovirus[blank_end]
Question 3
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Viroids are infectious agents without protein
Question 4
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Prions –are infectious agents with both DNA and RNA
Question 5
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Adenine and guanine are
Question 6
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A nucleoside is formed when a
base is linked to the WHAT carbon of a
deoxyribose (or ribose) molecule
Question 7
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dCMP and dAMP are examples of [blank_start]nucleotides[blank_end]
Answer
-
nucleotides
-
nucleosides
-
proteins
-
nucleic acid
Question 8
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In DNA and RNA, nucleotides are linked by phosphodiester bonds between the [blank_start]5′[blank_end] and 3′ carbons
Question 9
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In all prokaryotes and eukaryotes DNA is double-stranded
Question 10
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Guanine and Cytosine form a base-pair held together by [blank_start]3[blank_end] hydrogen bonds.
Adenine and Thymine form a base-pair held together by [blank_start]2[blank_end] hydrogen bonds.
Question 11
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Most or all cellular DNA is A-DNA
Question 12
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Z-DNA is left handed and A-DNA is right handed
Question 13
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Underwinding generates [blank_start]negative[blank_end] supercoils
Overwinding generates [blank_start]positive[blank_end] supercoils
Question 14
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Single stranded DNA absorbs more UV than double
stranded DNA
Question 15
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UV absorbance rises as DNA
denatures is known as the [blank_start]hyperchromic shift[blank_end]
Question 16
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Tm (The temperature needed to denature
50% of the DNA molecules in a sample) is increased in DNA with high content of AT base-pairs
Question 17
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What are three key structural differences between
DNA and RNA?
Answer
-
RNA has ribose instead of deoxyribose.
-
RNA has deoxyribose instead of ribose
-
RNA contains adenine, cytosine and guanine (like DNA) but has Uracil (U) instead of thymine.
-
RNA contains adenine, cytosine and guanine (like DNA) but has thymine (T) instead of uracil
-
RNA is usually double stranded
-
RNA is usually single stranded
Question 18
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Plasmids carry non-essential genes, e.g. for
antibiotic resistance
Question 19
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Bacterial genomes usually consist of a single, linear chromosome made of double-stranded DNA
Question 20
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Label this image
Answer
-
Heterochromatin
-
Euchromatin
Question 21
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(Length of DNA/ Length of structure DNA packed into) is known as the [blank_start]packing ratio[blank_end]
Question 22
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By mass, the composition of a chromosome at mitosis is
approximately
Answer
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1/2 DNA and 1/2 histone proteins
-
1/3 DNA and 2/3 histone proteins
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1/3 DNA, 1/3 histone proteins and 1/3 non histone proteins
-
1/2 DNA. 1/4 histone proteins and 1/4 non histone proteins
Question 23
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20% of amino acids are arginine or lysine
Question 24
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[blank_start]Condensin[blank_end] is a ring-shaped protein that can anchor the ends of a loop of DNA
Question 25
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[blank_start]topoisomerase II[blank_end] is an enzyme that can remove supercoils from DNA
Question 26
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Acetylation removes positive charge from side-chain and so [blank_start]weakens[blank_end]
interaction between histones and negatively-charged DNA
Question 27
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Eukaryotic chromosomes have 1 origin of replication
Question 28
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In bacterial replication, replication begins at a single AT-rich origin and is
bidirectional
Question 29
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What enzyme carries out transcriptase?
Answer
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Maltase
-
DNA transcriptase
-
RNA
-
RNA polymerase
-
DNA helicase
Question 30
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To synthesise RNA, RNA polymerases require:
Question 31
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RNA polymerase binds to the promoter in the [blank_start]initiation[blank_end] stage
Question 32
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RNA polymerase dissociates from DNA releasing
the new RNA molecule in the [blank_start]transcriptase[blank_end] stage
Question 33
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RNA polymerase moves along the DNA molecule
synthesising an RNA copy in the [blank_start]elongation[blank_end] stage
Question 34
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A [blank_start]consensus[blank_end] sequence is a sequence of DNA having similar structure and function in different organisms.
Question 35
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The holoenzyme carries out elongation but not initiation
Question 36
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Eukaryotic promoters differ from those in bacteria
Question 37
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RNA polymerase [blank_start]I[blank_end] - synthesises rRNA
RNA polymerase [blank_start]III[blank_end] - synthesises tRNA
RNA polymerase [blank_start]II[blank_end] - synthesises mRNA
Answer
-
I
-
ll
-
lll
-
I
-
ll
-
lll
-
I
-
ll
-
lll
Question 38
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RNA polymerase II produces a 1° transcript (aka pre-mRNA)
which is processed in the nucleus to form mRNA. The main processing reactions are
Question 39
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Promoters recognised by RNA polymerase II usually consists of a core promoter that may include a [blank_start]TATA[blank_end] box
Question 40
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RNA polymerases and DNA polymerases share the same mechanism.
Question 41
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By mass, ribosomes have about a 1:2 ratio of rRNA to protein
Question 42
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The size of ribosomes is measured in Svedbergs (S)
- sedimentation rate during centrifugation.
Question 43
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The small subunit on a ribosome catalyses peptide bond formation, the
large subunit binds the mRNA being translated
Question 44
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mRNA is read from
Question 45
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The small (30S) ribosome subunit binds to the ribosome
binding site on the mRNA in E.Coli
Question 46
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There are several ribosome binding sites on mRNA in eukaryotes
Question 47
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A sequence has [blank_start]three[blank_end] possible reading frames depending
on where translation starts from
Question 48
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The region between an initiation codon (AUG) and a
termination codon is an“open-reading frame”
Question 49
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How do amino acids recognise codons?
Adaptor molecules deliver amino acids to the appropriate codons. These adaptors are transfer RNAs
Question 50
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How long are tRNAs?
Answer
-
Large: 220-293 nucleotides long
-
Small: 50-73 nucleotides long
-
Small: 73-90 nucleotides long
-
Large: 320-393 nucleotides long
Question 51
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All tRNAs have an anticodon
Question 52
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All tRNAs have the sequence GCA at their 3' end.
Question 53
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the ability of some bases at 5' end of anticodon to pair with more than one base at 3' end of codon is known as the [blank_start]base wobble[blank_end]
Question 54
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The enzymes that link tRNAs to amino acids are called
Answer
-
aminoakyl-tRNA synthetases.
-
aminoacyl-tRNA synthetases.
-
aminoacyl-rRNA synthetases.
-
aminoakyl-rRNA synthetases.
Question 55
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The classic example of inducible genes are the three genes required for utilisation of lactose by E. coli. These are:
Answer
-
Lac Z gene
-
Lac B gene
-
Lac A gene
-
Lac Y gene
-
Lac T gene
Question 56
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The [blank_start]operator[blank_end] is the binding
site for lac repressor
protein.
Question 57
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The Lac [blank_start]i[blank_end] gene encodes the
Lac repressor protein.
Question 58
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Transcription of the genes of the lac operon is repressed by the lac [blank_start]repressor[blank_end] protein
Question 59
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When lactose is absent, the lac repressor protein binds to the promoter
Question 60
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When the lac repressor protein is bound to the operator,
RNA polymerase can still bind to the promoter but cannot
initiate transcription.
Question 61
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When lactose is present some is
converted into an isomer called
[blank_start]allolactose[blank_end].
Question 62
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Allolactose binds to the lac repressor protein inducing a conformational change so that lac repressor cannot bind to operator.
Question 63
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Lactose breakdown is only necessary if glucose is not available. Therefore when both lactose and glucose are present in environment, lac operon genes only transcribed weakly. This effect is called [blank_start]Catabolite[blank_end] Repression
Question 64
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Removal of catabolite repression requires:
Question 65
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When glucose conc’ is high the cAMP conc’ is low
Question 66
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[blank_start]Monosaccharides[blank_end] are colourless, crystalline solids, water soluble and most are sweet tasting.
Answer
-
Monosaccharides
-
Polysaccharides
-
Oligosaccharides
Question 67
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In general, a molecule with n chiral centres can have [blank_start]2[blank_end]n stereoisomers
Question 68
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[blank_start]Epimers[blank_end]: each of two isomers with different configurations of atoms about one of several asymmetric carbon atoms present