From DNA to Proteins: How cells read the genome Flashcards
Gene Expression
Process where cells read out the instructions (nucleotide sequence) in their genes
What is the first step in gene expression?
Transcription
Portions of __________ are transcribed into RNA
DNA sequence
Transcription
Cells copy the nucleotide sequence of the gene into RNA molecule
RNA differs from DNA by containing _______ instead of thymine (T) in DNA (RNA has all the other bases like A, C, & G)
Uracil (U)
RNA
Is a linear polymer made of four different nucleotides (bases) linked together by phosphodiester bonds
The formation in genes that are expressed/ copied into RNA are done through the __________ since RNA is like DNA & can form complentary base pairs with A & U
Nucleotide Sequence
The structure of RNA is a large ________ molecule
Single - Stranded
Since RNA is a single-stranded molecule it can _______ into a variety of shapes
Fold up
_________ produces RNA that is complentary to one strand of DNA
Transcription
What is the process of transcription?
Begins by opening up a small portion of the DNA molecule & one of the two strands of the DNA molecule is used a template for making (synthesis) of RNA
The __________ of the RNA is based on the base pairing with the __________
Nucleotide sequence, the DNA template strand
What enzyme forms the RNA strand in transcription?
RNA polymerase
RNA transcript
The RNA chain that is produced by transcription
___________ is similar to RNA transcription
DNA replication
How does DNA replication differ from RNA transcription?
The RNA strand is removed from the complentary DNA strand (which allow DNA to re-form its double-helix structure)
Why is RNA only a single - stranded molecule?
Because its only transcribed from one DNA strand
RNA polymerase
Forms the RNA molecule (like DNA polymerase make DNA)
The _______ unzips the DNA strand & forms the RNA molecule in the 5’ to 3’ direction
RNA polymerase
Since RNA is _______ from DNA once its synthesis means that many RNA copies can come from the same gene (The synthesis of the next RNA is started before the first RNA is completed)
Removed
Unlike DNA polymerase in DNA replication, RNA polymerase can __________________
Start an RNA chain without a primer & doesnt proofread itself
Messenger RNA (mRNAs)
The RNA molecules that were formed by genes & also synthesis proteins (carry genetic information from the gene to make proteins)
_____________ refers to the process by which the information (the nucleotide sequence) of DNA is converted into a product either as proteins or RNA
Gene Expression
If the final product is a ________ then gene expression includes both transcription & translation
Proteins
If the final product is _________ then gene expression just requires transcription
RNA
When translating the nucleotide sequence into proteins, _________ & ________ are used
Ribosomal RNA (rRNAs) & Transfer RNA (tRNAs)
Ribosomal RNA (rRNAs)
Form the structural & catalytic core of the ribosomes which translate mRNAs into proteins
Transfer RNA (tRNAs)
Act as adaptors that select specific amino acids & hold them in place on a ribosome for their incorption into proteins
Signals in ______ tell the RNA polymerase where to _______ & _______ transcription
DNA, start & stop
To begin transcription ____________ have to be able to recognize the start of a gene & bind to that place
RNA polymerase
How does RNA polymerase recognize the transcription site in bacteria?
The RNA polymerase collide with the DNA molecule & weakly attach itself to move along the DNA strand till it finds a promter & once it finds the promoter it binds tightly to it & start transcription in front of the promoter
Promoter (start site)
Contains a specific sequence of nucleotides thats the starting point for RNA synthesis
What happens when the RNA polymerse finds the promoter?
- The RNA polymerase opens up the double - helix in front of the promoter where one of the two DNA strands acts as a template for complentary base - paring with the RNA formed by the RNA polymerase
- The RNA polymerase continues to make the RNA molecule till it reaches a second singal spot which is the terminator spot (stop site) where the the polymerase stops & releases the RNA strand
Bacteria promoter (start site) & the terminators (stop site) have ___________ that are recognize by the RNA polymerase (like AUG)
Specific nucleotides sequence
The _______ in bacteria is responsible for finding the promoter sequence in DNA & once it finds the promoter it binds to the DNA strand keeping it open
Sigma Factor
Since the RNA polymerase can only form the RNA molecule in the ____ to _____ direction it usuallly chooses the DNA strand that is in the 3’ to 5’ direction
5’ to 3’