Gen Micro CH13 SG (Altura)

Components of a nucleotide

A nitrogenous base, a five-carbon sugar, and a phosphate group.

Bases in DNA vs. RNA

DNA: Adenine, Thymine, Cytosine, Guanine. RNA: Adenine, Uracil, Cytosine, Guanine.

Key differences between DNA and RNA

DNA has deoxyribose, thymine, double strands; RNA has ribose, uracil, single strand.

Bond joining nucleotides in the same strand

Phosphodiester bond.

Bond stabilizing a nucleotide base pair

Hydrogen bond.

Replication fork

Y-shaped region where parent DNA strands unwind and new strands synthesize.

Origin of replication (ori)

Specific sequence on a chromosome where DNA replication begins.

Enzyme unwinding DNA during replication

DNA helicase.

Enzyme synthesizing DNA during replication

DNA polymerase.

Enzyme removing RNA primers during replication

DNA polymerase I (in bacteria).

Transcription

Process of synthesizing an RNA molecule from a DNA template.

Non-protein products encoded by genes

Functional RNA molecules, such as rRNA, tRNA, and snRNA.

Transcribed and translated region of a gene

Coding region (or open reading frame).

Leader region of an RNA transcript

The 5' untranslated region (5' UTR) located upstream of the coding sequence.

Shine-Dalgarno sequence

Ribosomal binding site in bacterial mRNA upstream of the start codon.

Role of mRNA in protein synthesis

Carries genetic instructions from DNA to the ribosome for protein synthesis.

Role of rRNA in protein synthesis

Forms the structural/catalytic core of the ribosome to synthesize proteins.

Role of tRNA in protein synthesis

Delivers specific amino acids to the ribosome based on mRNA codons.

Components of the 70S ribosome

A 30S small subunit and a 50S large subunit.

Promoter

DNA sequence where RNA polymerase binds to initiate transcription.

Consensus sequence in a promoter

Conserved nucleotide sequence (e.g., -10 and -35 elements) recognized by RNA polymerase.

Components of RNA polymerase holoenzyme

Core RNA polymerase enzyme (α₂ββ'ω) and a sigma (σ) factor.

Factor-dependent vs. factor-independent transcription termination

Factor-dependent uses Rho protein; independent forms a hairpin loop. Both stop transcription.

Initiator codon sequence and encoded amino acid

AUG; encodes N-formylmethionine (fMet) in bacteria and Methionine in eukaryotes.

Bacterial translation initiation process

30S subunit binds Shine-Dalgarno sequence; fMet-tRNA binds AUG; 50S subunit joins.

Translation

Process of decoding mRNA sequence to synthesize a polypeptide chain.

Number of termination (stop) codons

Three (UAA, UAG, UGA).

Polysome

Complex of multiple ribosomes translating a single mRNA molecule simultaneously.

Translocation vs. Secretion

Translocation moves proteins across a membrane; secretion releases proteins outside cell.

Sec system and taxa using it

General secretion pathway translocating unfolded proteins; used by Bacteria and Archaea.