lecture 5 genetics topic 1

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What type of RNA is in prokaryotes?
mRNA, rRNA and tRNA
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how can genes be regulated by RNA degradation?
5' cap removal, shortening the poly(A) tail, degrading 5' UTR, coding sequence and 3' UTR
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what is the role of the poly(A) tail in eukaryotes?
the proteins that attach to the 3' poly(A) tail interact with cap-binding proteins and thus enhance the binding of the ribosome to the 5'end of the mRNA
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What is RNA splicing?
the removal of introns within a strand of RNA, introns are non-coding sections of DNA
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What is colinearity?
the idea that there is a strict correspondence between the RNA molecule transcribed and the protein produced. This is infact not true, as introns are removed and mRNA is modified in many ways
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What was the experiment that allowed RNA splicing to be discovered?
DNA mixed with complementary RNA and heat to separate DNA strands. Mixture is cooled, and complementary sequences pair. DNA can anneal with its complementary strand or with RNA, the noncoding regions are seen as loops.
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What was the conclusion from the experiment about RNA splicing?
coding sequences in a gene may be uninterrupted by noncoding sequences
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Can one gene produce many proteins, and why?
yes. as alternative splicing leads to varied protein products
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What is the importance of alternative splicing?
it allows a single gene to produce several protein products
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What is the importance of splicing in a fly?
production of Tra protein, depends on gender
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In what gender of fly is the functional Tra protein produced?
female
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How does splicing lead to a male fly?
the upstream 3' splice site is used, the premature stop codon in mRNA is included hence no functional Tra protein produced.
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How does splicing lead to a female fly?
The presence of an Sxl protein means the downstream 3' splice site is used, the termination codon is spliced out with the intron, a functional Tra protein is produced
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What type of RNAs are only found in eukaryotes?
pre-messenger RNA, small nuclear RNA, small nucleolar RNA, small cytoplasmic RNA, microRNA, small interfering RNA, piwi-interacting RNA (pre-mRNA, snRNA, snoRNA, scRNA, miRNA, siRNA, piRNA)
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How can RNA interference regulate gene expression?
Inhibition of translation, transcriptional silencing - altering chromatin structure
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What does RNA interference do?
to impede translation of RNAs
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Can RNA interference occur in bacteria?
yes but it is rare
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How long are small-interfering RNAs and micro RNAs?
22 nucleotides long
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What is the role of siRNAs?
they degrade mRNA
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What is the role of miRNAs?
they inhibit translation of mRNA
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What is RISC?
RNA-induced silencing complex
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What type of RNA can methylate histones and DNA?
microRNAs (miRNAs)
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How can miRNAs inhibit transciption?
they can attach to complementary sequences in DNA and attract methylating enzymes, the DNA or histones become methylated and transcription is inhibited
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How can RNA interference be used by scientists?
can generate siRNAs, to lower expression of genes in a living cell, this helps to understand the role of specific genes
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How can siRNAs be used in cancer prevention?
to lower the expression of target genes
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Card 2

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how can genes be regulated by RNA degradation?

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5' cap removal, shortening the poly(A) tail, degrading 5' UTR, coding sequence and 3' UTR

Card 3

Front

what is the role of the poly(A) tail in eukaryotes?

Back

Preview of the front of card 3

Card 4

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What is RNA splicing?

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Card 5

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What is colinearity?

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