Structure of Genes and RNA Flashcards
When does gene expression occur?
It occurs when a product is created from a gene
What are genes?
Segments of DNA within a larger DNA molecule
What does the base sequence do to the product?
The base sequence within a gene contains the information needed to make the product
How does gene expression begin?
It begins with the transfer of the information from the gene to an RNA molecule
What is transcription?
The process of procuring an RNA molecule with a base sequence similar to that within the gene
What are transcripts?
The RNA produced by transcription
What genes are transcribed?
All genes that are expressed are transcribed
What are the final products in SOME genes?
An RNA molecule
What are the RNA molecules produced from those genes called?
Non-coding RNAs/transcripts
What do non-coding RNAs/transcripts do?
They DO NOT code for a polypeptide
For many genes, what is RNA considered to be?
An intermediate product used to create a particular polypeptide
What is the base sequence of the intermediate RNA used for?
The base sequence of the RNA is used to produce a polypeptide with a specific amino acid sequence
What is translation?
Using the base sequence of an RNA to produce a polypeptide
In bacteria, how are transcription and translation occurring?
Transcription and translation are occurring at the same time at the same location within the cell
In eukaryotic cells, how are transcription and translation occurring?
Transcription occurs within the nucleus, where DNA is located.
The RNA is transferred from the nucleus to the cytoplasm of the cell.
Translation of the RNA occurs within the cytoplasm
A gene has two regions. What are those regions used for?
- One contains a base sequence that is transcribed into RNA
- The other contains a base sequence that is not
What kind of sequences are found in the transcribed region?
The coding sequence, which is the base sequence used to create the product
Terminator/terminating sequence
Introns
What are introns?
Base sequences found within the transcribed regions of many eukaryotic genes that interrupt the coding sequence of these genes.
They are transcribed, but they are removed after transcription.
How many strands are transcribed to create RNA?
Only one of two strands
What is the name of the strand being transcribed?
Template strand
Antisense strand
What is the name of the strand that is not being transcribed?
Non-template strand
Coding strand
Sense strand
What is the relationship between the TEMPLATE strand sequence and the RNA sequence transcribed from it?
They are complementary to each other
What is the relationship between the CODING strand sequence and the RNA sequence transcribed from it?
They are similar. Basically the same, but in the coding strand, each T is changed into a U.
What is the promoter?
A region of a gene that is not transcribed.
It acts to regulate the transcription of the transcribed region.
What is RNA polymerase?
An enzyme that synthesizes RNA
In eukaryotic cells, what proteins can bind to the promoter? What is the result?
Transcription factors bind to the promoter to either aid or inhibit the activity of RNA pol
What are general transcription factors?
Proteins that are necessary for the binding of RNA pol to the promoter
What are general transcription factors involved in?
They are always involved in transcription
Transcription cannot occur without general transcription factors
What are regulatory transcription factors?
Proteins that regulate the rate of transcription
What are the two types of regulatory transcription factors?
Activators and repressors
What are activators?
They increase the rate of transcription, increasing the amount of product created
What are repressors?
Decrease the rate of transcription, decreasing the amount of product created
What sequences do activators bind to?
Enhancer sequences
What sequences do repressors bind to?
Silencer sequences
How are individual ribonucleotides linked?
They are linked by phosphodiester bonds to form a strand
What are the the different types of RNA?
mRNA (messenger)
tRNA (transfer)
rRNA (ribosomal)
snRNA (small nuclear)
With the exception of mRNA, what are the different types of RNAs considered to be?
Non-coding RNAs
What can be done to only mRNA?
Only mRNA is translated into a polypeptide
Which RNAs are found in both prokaryotic and eukaryotic cells?
tRNA, rRNA, and mRNA
Which RNA is found ONLY in eukaryotic cells?
snRNA
What is the role of snRNA?
It has a role in the removal of introns from RNA and in the splicing together of the remaining portions of the RNA
