EXAM 3 Stuff

polycistronic mRNA

A single RNA molecule that contains the coding sequences for multiple proteins, typical in prokaryotes.

cistrons

Regions within polycistronic mRNA that encode for individual proteins, each having its own ribosome binding site.

Polypeptide-Encoding Sequences

Sequences of nucleotides in mRNA that encode information for the synthesis of polypeptides.

elongation factors

Essential proteins that facilitate the elongation phase of translation during protein synthesis.

EF-Tu

A prokaryotic elongation factor that delivers aminoacyl-tRNA to the ribosome's A-site.

EF-G

A prokaryotic elongation factor that facilitates the translocation of the ribosome after a peptide bond is formed.

eEF1

A eukaryotic elongation factor that delivers amino acids to the ribosome.

eEF2

A eukaryotic elongation factor that moves the ribosome along the mRNA.

anticodon

A sequence of three nucleotides in tRNA that is complementary to an mRNA codon.

frameshift mutation

A mutation caused by insertions or deletions that alter the reading frame of the genetic code.

missense mutation

A mutation that results in the incorporation of an incorrect amino acid into a protein.

nonsense mutation

A mutation that creates a premature stop codon, truncating the protein.

paracentric inversion

A chromosomal inversion that does not involve the centromere.

pericentric inversion

A chromosomal inversion that includes the centromere of the chromosome.

dicentric bridge

A structure that forms during meiosis or mitosis when chromosomes with two centromeres segregate abnormally.

transposon

A segment of DNA that can move from one location to another in the genome.

Robertsonian translocation

A type of chromosomal rearrangement occurring between two acrocentric chromosomes.

Shine-Dalgarno sequence

A purine-rich consensus sequence in the 5’ UTR of mRNA in bacteria.

release factor

A protein that binds to the ribosome's A site, causing termination of translation.

two-dimensional gel electrophoresis

A technique for separating proteins based on isoelectric point and molecular weight.

FISH

Fluorescent in situ hybridization, a technique used to detect specific DNA sequences in chromosomes.

photolyase

An enzyme encoded by the 'phr' gene that repairs UV-induced DNA damage.

unbalanced translocation

A chromosomal exchange between two chromosomes that is unequal in terms of chromosomal material.

chromatin

The complex of DNA and protein found in eukaryotic cells that condenses to form chromosomes.

turner syndrome

A condition caused by the absence or mutation of an X chromosome.

lac operon

A group of genes in bacteria that are involved in lactose metabolism, regulated by the availability of lactose.

allopolyploid organism

An organism with more than two sets of chromosomes derived from different species, often having high fertility.

mutation rate

Measure of the frequency of mutations in a specific genetic sequence, often rare but significant.

triplet repeat expansion

A mutation characterized by the increased repetition of a specific three base pair DNA sequence.

apurinic site

A site in DNA lacking a purine base, which can lead to mutation if replicated without repair.

deamination

The removal of an amino group from a nucleotide, which can alter base-pairing properties.

alkylating agents

Chemicals that can induce mutations by causing base substitutions in DNA.

nucleotide excision repair

A DNA repair mechanism that removes and replaces damaged sections of DNA.

core nucleosome

A structure made of histone proteins wrapped by DNA, forming the basic unit of chromatin.

λ mutant

A type of lambda phage that can enter the lytic cycle but cannot lysogenize.