Chapter 17 Terms Flashcards
genes
The information found in DNA is stored in specific regions of chromosomes called genes
gene expression
the process by which DNA is converted into RNA and proteins, involves two stages:
- transcription
- translation
transcription
The conversion of DNA into RNA
translation
the process by which mRNA is converted into polypeptides
messenger RNA
Required for protein synthesis
- contains the code for proteins
transfer RNA
carries amino acids to ribosomes during protein synthesis
ribosomal RNA
Required for protein synthesis
- major component of ribosomes
primary transcript (pre-mRNA)
The initial mRNA (primary transcript) produced in eukaryotes undergoes processing inside the nucleus prior to being translated
mature mRNA
pre-RNA is processed into mature mRNA prior to translation
RNA polymerase
The main enzyme that carries out transcription
-Eukaryotes have three different RNA polymerases (one for mRNA, one for tRNA, and one for rRNA) while bacteria only have one RNA polymerase that make all three forms of RNA
template strand
Only one of the two DNA strands is used for transcription. This is called the template strand
codon
The nucleotide sequence of mRNA is read as three nucleotides units called codons
anti-codon
At one end of the tRNA is an anticodon on the other end (the anticodon base-pairs with a complementary codon on mRNA)
reading frame
a result of mutated genes
-Codons must be read in the correct reading frame
frame shift
A shift in the reading frame lead to mutated proteins (frame shift mutation)
promoter
RNA attaches and initiates transcription at a special DNA sequences called promoters that are found “upstream” of the gene that will be transcribed
transcription: initiation, elongation, termination
RNA polymerase carries out transcription in three main steps:
–Initiation - RNA polymerase recognizes and binds to a special DNA sequence located upstream of a gene called a promoter
RNA polymerase then separates double stranded DNA forming a transcription bubble
–Elongation - RNA polymerase adds RNA nucleotides that are complementary to the DNA template strand in the 5’ to 3’ direction
–Termination - RNA transcript is released from DNA template and RNA polymerase detaches from DNA
TATA box
In eukaryotes: transcription factors must first bind to a specific sequence in the promoter called the TATA box
transcription initiation complex
The completed assembly of transcription factors and RNA polymerase II bound to a promote
terminator sequence
In bacteria, the polymerase stops transcription at the end of the terminator sequence and the mRNA can be translated without further modification
polyadenylation
In eukaryotes, RNA polymerase II transcribes the polyadenylation signal sequence (AAUAAA); the pre-RNA transcript is released 10–35 nucleotides past this polyadenylation sequence
RNA processing
The pre-mRNA made during eukaryotic transcription is modified by enzymes prior to leaving the nucleus and being translated
5’ cap
The 5’ end receives a 5’ cap made of a modified guanine nucleotides
poly A tail
The 3’ end receives a poly A tail made of 50-250 adenine nucleotides
