TEST 2: Gene Expression and Regulation Flashcards
How does DNA store genetic information?
DNA molecule store, genetic information in the sequence of nucleotides
Define gene
A segment of DNA that contains the instructions to build a single protein
Define transcription
The process by which the information contained within a single gene is copied from the DNA to a pre-mRNA strand
Define mRNA processing
MRNA processing converts, the pre-mRNA strand into an mRNA strand
Define translation
The process by which the information of an mRNA strand is used to build a protein
Describe the steps a cell uses to make a protein
DNA, which is built using for DNA nucleotides TAG andC go through transcription which breaks it down into an mRNA strand, which is built using four nucleotides UAG and C.
mRNA processing converts pre-MRNA to mRNA
Then the RNA is translated into a protein, which is built using 20 amino acids
What is the overall purpose of combine processes of transcription, mRNA processing and translation?
To produce a functional protein from gene
What is the purpose of transcription?
To create mRNA copy of a gene DNA sequence to allow genetic information stored in DNA to be used for protein synthesis without damaging the original DNA
Three major steps of transcription
Initiation, elongation, termination
Describe initiation in transcription
- RNA polymerase binds to the promoter region of the gene
- DNA unwinds, exposing the template strength for RNA synthesis
Describe elongation in transcription
- RNA polymerase moves along the DNA template strand
- Complementary RNA nucleotides are added to form a pre-MRNA strand (U instead of T)
- DNA behind the RNA polymerase rewinds back into a double helix
Describe termination in transcription
- RNA polymerase reaches a termination sequence in DNA
-MRNA transcript detach from DNA
Define promoter
Specific DNA sequence that serves as binding site for RNA polymerase, marking the beginning of a gene, where transcription starts
Where is the promoter located?
Before the start site (TATA box)
Define termination sequence
Specific sequence of DNA that signals the end of transcription
Where is a termination sequence located?
At the end of a gene
How does the temp of DNA strand differ from the complementary DNA strand
The complementary strand is the opposite of the template, directionality, base pairing (U)
Purpose of mRNA processing
To prepare the mRNA for export from the nucleus to the cytoplasm, and to ensure that it is properly stabilized for translation into a protein
What occurs during mRNA processing?
5‘ capping
Splicing
Poly a tail add
Define 5’ capping
A modified guanine nucleotides is added to the 5’ end of the pre-mRNA to protect the mRNA and help the ribosome recognize the mRNA for translation
Define splicing
Introns are removed from the pre-mRNA and the exons are joined together to form the mature mRNA
Define poly a tail
A string of adenine nucleotides is added to the 3’ end of the mRNA, which helps stabilize the mRNA and aids a nuclear export and promotes translation initiation
How does pre-mRNA differ from mRNA
Pre-mRNA has both introns and Exons, no cap and tail, and is not functional for translation
mRNA is a functional transcript, ready to leave the nucleus and translate into protein
Define exon
Expressed in the mRNA, present in pre-mRNA and mRNA, contains info to build protein
Define Cap and tail and its purpose
Additional nucleotides added to both ends of mRNA
Allows the mRNA to move through nuclear poor and to buy two ribosome
True or false
MRNA splicing in the addition of the cap and tail are independent processes that are occurring at the same time
Define introN
Intervening non-coding sequence that is present in the pre-RNA but not to mRNA, and does not contain information to build the protein,
but often contains sequences that regularly whether transcription occurs
Purpose of translation
To synthesize a protein based on the information encoded in mRNA
Molecules and structures required for translation
mRNA, ribosome, tRNa
What does mRNA specify?
The amino acid sequence of a protein
What does TRNA do?
Brings a specific amino acid to the ribosome as a protein is being made
Three major steps of translation
Initiation allegation and termination
Define translation initiation
Robo assembles on mRNA at the start codon
Define translation elongation
Ribosome moves along mRNA one codon at a time each step a TRNA with the appropriate anticodon binds to the corresponding codon on the mRNA
Amino acid carried by TRNA is blinded
Define translation termination
Stop codon as encountered releases, polypeptide, and dissembles
Define codon
Sequence of three nucleotides that encodes a specific amino acid or signals the end of protein synthesis
Codon location
Found an mRNA sequence arranged, sequential along the mRNA molecule
Define anticodon
Sequences of three nucleotides that is complementary to a codon on the mRNA and ensures that the correct amino acid is brought to ribosome during translation
Location of anticodon
Located on the TRNA molecule, which is carrying a specific amino acid to the ribosome
What evidence do we have that the same genetic code is used by all organisms
The same set of codons in mRNA codes for the same amino acids in all organisms
