Genes and Proteins: Chapter 15 Lecture Review

These flashcards cover the vocabulary and key concepts of Chapter 15, focusing on genetic codes, transcription in prokaryotes and eukaryotes, RNA processing, and translation mechanisms.

Central dogma of molecular biology

The overarching process by which DNA leads to specific traits by directing the synthesis of mRNA and protein ($ext{Genotype} <br /> ightarrow ext{Phenotype}$).

Transcription

The first step of the central dogma where an enzyme synthesizes an RNA strand based on a DNA template.

Messenger RNA (mRNA)

A type of RNA that carries genetic instructions from the DNA in the nucleus to the ribosomes in the cytoplasm.

Translation

The process by which the genetic code in mRNA is read by a ribosome to synthesize a polypeptide.

Codon

A nonoverlapping, three-nucleotide sequence that codes for a single specific amino acid.

Reading frame

The specific grouping of nucleotides in sets of three that determines how the genetic code is read; for example, $ext{THECATATETHERAT}$.

RNA Polymerase

An enzyme that separates DNA strands and assembles an RNA strand in the $5' <br /> ightarrow 3'$ direction without requiring a primer.

Core enzyme (Prokaryotic)

The portion of the prokaryotic RNA polymerase consisting of subunits $ext{α, α, β, and β'}$.

Sigma ($σ$) subunit

A subunit involved only in the initiation of prokaryotic transcription that identifying the location for RNA polymerase to bind.

Holoenzyme

The complete prokaryotic RNA polymerase complex containing all five subunits ($ext{α, α, β, β', and σ}$).

Promoter

A DNA sequence that includes the transcription start point and upstream regulatory sequences determining when a gene will be transcribed.

$-10$ consensus sequence

A conserved prokaryotic promoter sequence, $ext{TATAAT}$, that is identified by the $σ$ subunit.

Rho-dependent termination

A termination process controlled by the Rho protein, which follows RNA polymerase and causes it to release the mRNA when the polymerase stalls.

Rho-independent (Intrinsic) termination

Termination triggered by a GC-rich region forming a hairpin in the RNA, followed by a U-rich region weakly associated with the DNA template.

TATA box

A eukaryotic promoter consensus sequence located around the $-25$ region with the sequence $ext{TATAAA}$.

Basal transcription factors

A complex of factors (designated $ext{TFII}$ plus letters $ext{A-J}$) that help recruit RNA polymerase II to eukaryotic promoters.

TFIID

A specific basal transcription factor that contains a TATA-binding protein ($ext{TBP}$).

FACT protein complex

A complex that facilitates transcription by temporarily pulling histones away from the DNA.

Polyadenylation signal

The RNA sequence $ext{AAUAAA}$ which signals proteins to cut the pre-mRNA free from the RNA polymerase II.

5' cap

A modified guanine nucleotide ($ext{7-methylguanosine}$) added to the $5'$ end to protect mRNA and help the ribosome identify it.

Poly-A tail

A stretch of $50-250$ adenines added to the $3'$ end of mRNA to protect it from degradation.

Introns

Noncoding segments of a nucleic acid that lie between coding sequences and are removed during RNA processing.

Exons

The sequences of eukaryotic nucleic acids that are eventually expressed after splicing, including UTRs.

snRNPs (Small nuclear ribonucleoproteins)

Particles made of snRNA and protein that recognize splice sites at the ends of introns.

Spliceosome

A large complex formed by snRNPs and other proteins that removes introns and splices exons together.

A site (Aminoacyl-tRNA binding site)

The binding site on a ribosome that holds the tRNA carrying the next amino acid for the growing polypeptide.

Aminoacyl-tRNA synthetase

An enzyme that uses ATP hydrolysis to join the correct amino acid to the $3'$ end of its corresponding tRNA.

Shine-Dalgarno sequence

A sequence located upstream of the start codon in prokaryotic mRNA that helps the ribosome attach.

Kozak's rules

The rules determining the correct start codon in eukaryotes based on the nucleotides surrounding the first $ext{AUG}$.

Signal peptide

A sequence of about $20$ amino acids near the amino terminal end that targets a ribosome to the rough endoplasmic reticulum ($ext{RER}$).