(P) Management of Genetic Information Part 2 (module-based) Flashcards
It is the rules that specify how the nucleotide sequence of an mRNA is translated into the amino acid sequence of a polypeptide.
genetic code
T or F. The nucleotide sequence is read as triplets called anticodons.
F (codons)
Identify which of the following are the stop codons.
A. AUG, GUA
B. UGA, UAA, UAG
C. UAA, UGA, AUG
B
T or F. In mitochondrial genomes, some codons have distinct assignments compared to the nuclear genetic code.
T
It is a run of codons that starts with ATG and ends with a termination codon, TGA, TAA or TAG.
open reading frame (OPF)
T or F. In order for translation to proceed, this must be available:
an “ initiator” tRNA carrying the first amino acid in the protein, which is almost always
methionine (Met)
T
T or F. Translation in eukaryotes begins by the formation of a 30S initiation complex (30S ribosomal subunit + mRNA + initiation factors + fMET tRNA). The 30S subunit binds to the Shine Dalgarno sequence where the start codon is located.
F (prokaryotes)
In the first step, the aminoacyl-tRNA binds to the A site on the ribosome, tRNA is delivered to the site by?
elongation factors
Peptide bond formation is catalyzed by?
peptidyl transferase
Defined as changes that take place to the sequence of nucleotides on the DNA molecule other than genetic recombination.
“ Gene mutations
T or F. Gene mutations can arise due to natural reasons, such as errors in the replication process, and these mutations are known as spontaneous mutations.
T
Mutations can also arise from external factors called ______, giving rise to induced mutations.
mutagens
This kind of substitutions involve the replacement of a purine or pyrimidine base with another base of the same category. For instance, adenine, a purine, might be substituted with guanine, another purine.
transition
This substitutions entail the replacement of a purine with a pyrimidine, or vice versa. For instance, a pyrimidine like cytosine could be replaced by adenine, a purine.
transversion
no change in the protein sequence
silent mutations
change the amino acid sequence
missense mutations
create what is known as a stop codon
nonsense mutation
Insertions and deletions in protein coding sequences lead to what are known as
frameshift mutation
is crucial for the faithful transmission of genetic information, and cells have evolved intricate mechanisms to repair DNA damage.
DNA integrity
Identify what DNA repair mechanism is shown:
- In DNA, the bases may undergo modifications due to processes like deamination or
alkylation, resulting in damaged bases. - Such damage leads to the creation of an “abasic site” or “AP site” in the DNA
structure. - In bacteria like E. coli, a specialized DNA glycosylase recognizes and removes the
damaged base from the AP site. - Subsequently, an AP endonuclease removes the AP site along with nearby
nucleotides, creating a gap in the DNA strand. - DNA polymerase I then fills this gap by synthesizing a new DNA strand, and the
process is finalized by DNA ligase sealing the repaired strand.
Base Excision repair
Identify what DNA repair mechanism is shown:
- In cases like UV-induced DNA damage, certain nucleotides may become damaged,
forming dimers. - E. coli employs proteins UvrA, UvrB, and UvrC to recognize and remove these
damaged nucleotides. - Similar to base excision repair, DNA polymerase I and DNA ligase collaborate to fill
the gap and seal the repaired DNA strand. - In yeast, similar repair proteins are denoted as RADxx (RAD stands for radiation),
such as RAD3, RAD10, and others.
Nucleotide excision repair
Identify what DNA repair mechanism is shown:
- Mismatch repair corrects errors that may occur during DNA replication, involving
the mispairing of bases. - A distinguishing feature of this repair process is the recognition of the correct base
for repair. - In E. coli, the Dam methylase methylates adenines within specific GATC sequences.
- After DNA replication, the template strand contains methylated adenines, while the
newly synthesized strand lacks this methylation. - Hence, the template strand and the newly synthesized strand can be differentiated,
allowing the mismatch repair system to target and correct the mismatched bases.
mismatch repair
play a pivotal role in preserving the genetic integrity of organisms, ensuring accurate transmission of genetic information and safeguarding against mutations and potential health risks.
DNA repair mechanisms
