Protein Synthesis

What does replication start with

DNA.

What is made in replication

DNA.

What does transcription start with

DNA.

What is made in transcription

RNA.

What does translation start with

mRNA.

What is made in translation

Protein.

What are 3 differences between DNA and RNA

DNA has thymine; RNA has uracil. DNA is double-stranded; RNA is single-stranded. DNA contains deoxyribose sugar; RNA contains ribose sugar.

What are the three types of RNA

mRNA, rRNA, tRNA.

mRNA

Copy of a gene (code for a polypeptide).

rRNA

Structural component of a ribosome (like a brick in a wall).

tRNA

Carries amino acids to ribosomes during translation.

What is the “language” of a molecule

Monomers.

Which molecules share the same language (include their monomers)

DNA and RNA — both are composed of nucleotides.

Which molecules have a different language (include its monomer)

RNA and protein — RNA is composed of nucleotides, proteins are composed of amino acids.

What is a codon

Every three mRNA nucleotides.

What does a codon code for

One amino acid in the polypeptide.

What are the stop and start codons

Start - AUG (codes for Met), Stop - UAA, UAG, UGA.

What are the 3 steps of transcription

Initiation, elongation, and termination.

Initiation

RNA polymerase binds to a region of DNA called the promoter.

Elongation

RNA polymerase creates RNA by pairing complementary bases.

Termination

RNA polymerase stops creating RNA when it reaches a DNA sequence called the terminator.

What enzyme is used in transcription

RNA polymerase.

What does it do

Binds to the promoter region of DNA and synthesizes a complementary RNA strand from the DNA template.

What are the three things needed for translation

Ribosomes, mRNA, tRNAs.

What is the basic idea behind translation

When tRNA anticodons are complementary to mRNA codons, the ribosome adds an amino acid to a growing polypeptide.

Describe initiation of translation

mRNA binds to the small subunit of the ribosome. The initiator tRNA binds to the start codon of mRNA (AUG) and carries the amino acid Met. The large subunit binds, forming the full ribosome with A-site, P-site, and E-site.

What are the three steps of elongation of translation

Codon recognition, peptide bond formation, and translocation.

Codon recognition

Ribosome matches mRNA codon with tRNA anticodon; new tRNA enters the A-site.

Peptide bond formation

Peptidyl Transferase forms a peptide bond between amino acids; the polypeptide transfers from the P-site tRNA to the A-site tRNA.

Translocation

Ribosome shifts one codon; the empty tRNA exits via the E-site, and the tRNA with the polypeptide moves to the P-site.

What enzyme recharges tRNA with a new amino acid

Aminoacyl tRNA synthetase.

Describe termination of translation

Ribosome reaches a stop codon (UAA, UAG, or UGA). Release factors with anticodons complementary to stop codons enter the A-site. The polypeptide is released. Ribosomal subunits and mRNA separate.