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