MC fra forelæsningerne Flashcards
Replication of DNA is semiconservative because:
A) Sequence of both strands is conserved
B) One of the strands of each daughter molecule is newly synthesized while the other is unchanged
C) Each daughter molecule is synthesized from old deoxryibonucleotides
B
Genetic code is degenerate because?
A) Not all codons specify an amino acid
B) Most amino acids are encoded by more than one codon
C) Stop codons UAA, UAG and UGA designate chain termination
B
The synthesis of RNA from DNA template catalyzed by:
a) RNA polymerase
b) RNA transcriptase
c) RNA ligase
A
DNA Polymerase
a) Connects DNA template strands to introns
b) Connects polymers to DNA backbone
c) Catalyses the addition of deoxribonucleotide units to a DNA strand
C
Separation of DNA strands during replication is performed by:
a) Specific enzymes, termed polymerase
b) Specific enzymes, termed ligase
c) Specific enzymes, termed helicases
C
DNA polymerase needs a primer to start DNA replication. The primer is:
A) Short stretch of DNA (about five nucleotides) that is complementary to one of the template DNA strands
B) Short stretch of RNA (about five nucleotides) that is complementary to one of the template DNA strands
C) Fragments of DNA (approximately 1000 nucleotides) that is complementary to one of the template DNA strands
B
Replication of DNA is semiconservative because
A) Sequence of both strands is conserved
B) One of the strands of each daugther molecule is newly synthesized while the other is unchanged
C) Each daugter molecule is synthesised from old deoxyribonucleotides
B
Nonhomologous end joining is
a) Means for repairing double strang breaks in DNA that does not depend on ther DNA molecules in the cell
b) Repair of a region of DNA containing a thymine dimer
c) Carried out by photoreactivating enzyme called DNA photolyse
A
Proofreading is DNA repair precess which focuses on:
A) Repairing double strand breaks in DNA
B) Removing and replaycing a stretch of whole DNA around the site of damage
C) Removing incorrect bases during DNA synthesis
C
Telemerase is:
A) Unique structures at the ends of linear chromosomes
B) Short structure forming the prepriming complex
C) A specialized reverse transcriptase that carries its own template
C
Type 1 topoisomease relax supercoiled structures by:
A) Cleavege of one strand of the DNA and rotation it around the other strand
B) Temporary cleavage of DNA double helix directed passage of one DNA double helix throuht another
C) By introducing negative supercoils thruogh coupling to ATP hydrolysis
A
Histone tails
A) Participate in regulation of gene expression
B) Phosphorylate RNA polymerase 1
C) Form a homeodomain that binds DNA
A
Nucleosome
A) Contains 2000 bp of DNA and 2 copies of four histone proteins H2A, H2B, H3 og H4
B) Is a basic unit of DNA packaging
C) Contains 2000 bp of DNA and 8 copies of four histone proteins H2A, H2B, H3 og H4
B
Euchromatin
A) Is densely packed chromatin that is under constant transcription
B) Participates in the active transcription of DNA to mRNA products
C) Consists of nucleosomes that prevent DNA transkription
B
Introns begin and end with the nucleotide sequences
A) GU og AG respectively
B) TA and TAA respectively
C) CAAT and CG respectively
A
Eukaryotic transcription starts when
A) The RNA polymerase recognizes the promotor sequence upstream of the gene
B) Transpriction factor HF2H binds to the basal transpriptions complec
C) The carboxyterminal domain (CTD) of polymerase 2 becomes phosphorylated
C
RNA polymerase 1
A) Is unique because it transcribes only tRNA (poly 3)
B) Transcribes ribosomal RNA (rRNA) genes arranged in tandem repeats
C) Binds TATA like box sequence in promotor region (poly 2) = m-RNA
B
Bacteria regulate their gene expression
A) In responce to change in their growth enviroment
B) Sothat they do not exhaust the nutrients in their growth media
C) Because otherwise there would not be sufficient space in the cell
A
Helix-turn-helix motifs are commonly found in
A) DNA binding proteins
B) Autoinducers
C) RNA polymerases
A
An operin usally consists of
A) Promoter and terminator sequences
B) Activator, inhibitors and structual genes
C) Promoter, operator and structual genes
C
A promotor region
A) Lowers the energy necessary to separate the DNA-RNA hybrid
B) Is necessary for RNA polymerase transcriptional elongation
C) Increases the binding efficiency of the RNA polymerase og the DNA duplex
C
Transcription termination signals can be found:
A) In the transcribed regions of the DNA
B) In the GC-rich palindromes
C) In antibiotics like rifampicin
A
The transcription bubble contains
A) About 17 watson-Crick paired DNA bases
B) A DNA-RNA hybrid
C) The ρ-complex
B