Chapter 7 Flashcards
(25 cards)
What is Transcription
Information in DNA is transcribed into a complementary RNA copy
What is Translation
Information contained w/in RNA is used to build proteins
What occurs during folding
Folding changes the shape of a polypeptide chain into a functioning protein
What are the three main types of RNA
- MESSENGER RNA (mRNA)
- TRANSFER RNA (tRNA)
- RIBOSOMAL RNA (rRNA)
What is MESSENGER RNA (mRNA)
Used to move information from DNA to the ribosome where it can be translated
what is TRANSFER RNA (tRNA)
Transfers amino acids to ribosomes to build proteins, as dictated by the mRNA template
What is RIBOSOMAL RNA (rRNA)
Structural component of a ribosome
What are Codons and how many are there
-3 base pairs that code for one amino acid
-64 possible codons
-61 specify amino acids called “sense codons” -3 are called “stop codons” – used to stop translation
What is the wobble hypothesis
the 3rd base in a codon can change (wobble), while allowing the codon to still code for the same amino acid
Why does Post-transcriptional Modifications
happen
Pre-mRNA Needs to be modified before it can exit the nucleus to the ribosomes
What modification is Poly(A)tail
Chain of 50-250 adenine nucleotides added to the 3’ end by the enzyme poly-A polymerase
What modification is 5’ cap
7 guanine bases attached to the beginning of the pre- mRNA strand
Characteristics of tRna
-about 70 - 90 nucleotides long
What is an anticodon
found at the tip of one of the double-helical segments is a 3 nucleotide segment that complementary pairs with a codon in an mRNA
What is the Ribosome Structure and Function
carry out protein synthesis by translating mRNA into chains of amino acids
What is Initiation
how the ribosomal subunits bind to mRNA at the 5’cap
What is The Lac Operon
The lac operon is a cluster of 3 genes that code for the proteins involved in lactose metabolism
The 3 main parts of The lac operon
-A promoter – where DNA transcription begins
-An operator – sequence of bases that control transcription
-And the coding regions for the enzymes that metabolize lactose
The trp Operon
Tryptophan is an amino acid used to build proteins
What is each Operon inactivated by
The lac repressor protein is inactivated by lactose, the trp repressor protein is activated in the presence of tryptophan
Transcriptional
DNA is wrapped around histones, thus the gene promoters are not accessible to the proteins for transcription
Nonsense mutation
Change in a single base pair results in a stop code
Missense Mutation
change in a single base or bases result in a new amino acid code
Frameshift Mutation
results in the insertion or deletion of one DNA sequences
