Regulation of gene expression Flashcards Preview

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Flashcards in Regulation of gene expression Deck (16):

How much of our genome is transcribed?

About 80%

Very little of this actually codes for protein 


Describe the mitochondrial genome?

13 protein-coding genes

24 RNA-coding genes


Describe the difference between heterochromatin and euchromatin?

Heterochromatin: dark bands on chromosome, A and T rich, few active genes, closed conformation

Euchromatin: light bands on chromosome, C and G rich, 80% active genes, open conformation 

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Describe the different types of primary transcripts that can result from gene transcription?

rRNAs and tRNAs > further processing

mRNAs > proteins 

Other non-coding RNAs > further processing 

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Describe the RNA splicing of protein-coding genes?

snRNPs bind to splice and branch sites on RNA > spliceosome forms > cleavage > introns removed 

Spliceosome: large ribonucleoprotein complex that splices primary trasncripts to remove introns 

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Describe how a single gene can produce a complex array of different protein products?

Each gene can have multiple start sites for transcription/promoter regions 

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At which points of gene expression can regulation occur?

Open conformation of chromatin


Post-transcriptional processing

mRNA degradation


Post-translational processing

Protein degradation

Protein targeting and transport 


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How can histone proteins be aletered, and what effect can this have on the DNA that they are associated with?

Can be chemically modified, e.g. acetylation, methylation

Can cause DNA to wind more or less tightly 


How does chromatin remodelling occur?

Chemical modification to histones and DNA

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Describe how chromatin is remodelled via DNA methylation?

A large proportion of cytosines are in CG adjacent pairs (CpG), and are methylated

This pattern is passed to daughter cells during replication 

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Where are CpG island usually found in genes?

Associated with 5' region

Often surround promoters of genes 

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Describe how methylation and acetylation differ between euchromatin and heterochromatin?

Euchromatin: active; hypomethylation, hyperacetylation

Heterochromatin: silent; hypermethylation, hypoacetylation

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Describe the post-transcriptional regulation of gene expression?

Alternative splicing of exons > different combinations create different proteins

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Describe how long non-coding RNAs can regulate gene expression?

Can acts as:

Scaffold (bring in other transcription factors)
Guide (guide transcription factors or RNA polymerase)
Enhancer (bring enhancer close to region)

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Describe how siRNAs can regulate gene expression?

siRNAs produced in short double stranded format > interact with RISC > binds and degrades mRNA

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Describe how miRNAs can regulate gene expression?

miRNAs bind RISC > bind mRNA > translation repressed (mechanism unclear)

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