Topic 3 Flashcards
(22 cards)
What are the 3 components of nucleotides?
The 3 parts are a nitrogenous base, phosphate group and sugar.
1).What are the bonds between sugars and phosphate groups called? 2). What are the bonds between nitrogenous bases called? Are these bonds covalent or non covalent?
1) These bonds are called phospodiester bonds. These are covalent bonds.
2). These bonds are hydrogen bonds. These are non covalent bonds.
What are the nitrogenous bases in DNA and how much hydrogen bonds do these pairs have?
DNA has Adenine, thymine, cytosine and guanine. G-C have 3 hydrogen bonds and A- T has 2.
What are the nitrogenous bases in RNA and how much hydrogen bonds do these pairs have?
The nitrgogenous bases in RNA are, Adenine, Uracil, cytosine and guanine. G-C has 3 hydrogen bonds and A-U has 2 hydrogen bonds.
1) Which way are nucleotides added in transcription? 2) Which way are RNA polymers are added in transcription? 3)Which way is the template strand read?
1) 5’ to 3’ end
2) 5’ to 3’ end
3) 3’ to 5’ end
1) Which way is RNAP read? 2) Which way does RNAP read the template?
1) 3’ to 5’
2) 3’ to 5’
What is the 5’ methyl cap? What does it protect mRNA from?
The 5’ methyl cap is a guanine nucleotide at the 5’ end with an extra methyl group. It protects mRNA from nucleases.
What componenet puts the 5’ methyl cap on?
RNA guanylyltransferase and with help of triphosphatase and methyltransferase.
Whats a 3’ Poly A tail?
This is a chain of adenine nucleotides at the 3’ end of mRNA. It protects mRNA from degradtion and helps it exit the nucleus.
What is the process of adding on the 3’ Poly A tail?
Poly A polymerase puts on the polyA tail. Before this addition, CPSD cleaves mRNA.
What is the process of going from DNA to mature mRNA?
1.__________ makes transcript of gene it wants. (_______)
2. ________ must be spliced out
3. _______ and _______ tail must be added for stability and protection.
4. __________ finds the ribosome
1) POLYMERASE makes transcript of gene it wants. (RNA)
2.INTRONS must be spliced out
3.5’ CAP and 3’ POLY A TAIL must be added for stability and protection.
4.MATURE MRNA finds the ribsome
Define the template and non template strand.
Template strand: the DNA strand that is transcribed. AKA non coding strand. Read 3’ to 5’ by RNAP
Non template strand: the DNA strand that is not transcribed. Non template strand is always the same as mRNA strand.
What information is needed to determine template strand?
You need to know the direction that RNAP is reading (always 3’ to 5’) and where the promoter is.
Define promoter sequence
The promoter sequence recruits RNA polymerase and tells it where the transcription of a gene should begin.
Define terminator sequence
The terminator sequence tells RNA polymerase where the transcription of a gene should end.
What needs to be sliced out before reaching ribosome? What mechanism carries this function out?
Introns must be spliced out before reaching ribosome. The spliceosome is used to splice.
What is snRNP and its function?
snRNP are small nuclear ribonuclear protiens. These proteins base pair with intron start sequences and cleave it there.
Describe exon skipping.
Exon skipping is when the cell blocks out intron cut sequences and stiches the exons together. Some exons are left out of final product.
Where does RNA splicing occur?
RNA splicing occurs in the nucleus.
Explain alternative splicing.
Alternative splicing allows a single gene to produce multiple protein variants.
What are 3 steps of RNA synthesis- Transcription
1) Initiaton
2) Elongation
3) Termination
