Unit V Molecular Genetics Part III Transcriptio n

Unit V: Molecular Genetics

Part III: Transcriptio n&

RNA • Polymer of nucleotides • Just like DNA • Composed of a 5 -carbon sugar, phosphate & nitrogenous base • Just like DNA • Unlike DNA… • Ribose sugar (rather than deoxyribose) • Uses the base uracil (rather than thymine)

Different Types of • m. RNA (messenger. RNA): • Takes information from DNA in the nucleus to the ribosomes in the cytoplasm • r. RNA (ribosomal RNA): • Makeup ribosomes along with protein • Ribosomes synthesize

Transcriptio n

Transcription • Process of producing an m. RNA molecule based on the

RNA Polymerase • Enzyme involved in the synthesis of RNA • RNA polymerase binds to the DNA • Separates the two strands of the double helix

m. RNA • Sequence made is complementary to the DNA sequence DNA contain m. RNA contains Guanine (G) Cytosine (C) Thymine (T) Adenine (A) Uracil (U) Cytosine (C) Guanine (G)

THINK!! • What is the complementary m. RNA sequence for the following DNA sequence? TAC TTG GGC TCC

Cellular Location of Transcription • Eukaryotes • Occurs in the nucleus • After m. RNA made, it is transported to the

Process of Transcription • Involves 3 steps: 1. RNA polymerase binding and initiation 2. Elongation of m. RNA

Genetic Code

Ribosomes • Once m. RNA is made and in the cytoplasm • The ribosomes attach • They decode the m. RNA 3 nucleotides at a time

THINK!! • Use the chart to identify the amino acid for each of the codons 1. CAG 2. AAU 3. UUG 4. AUG (start codon)

Properties of Genetic Code • Genetic code is redundant • Most amino acids have more than one codon • Code has start & stop signals

Translatio n

Translation • Decoding of an m. RNA message into a polypeptide chain • Proteins are polymers of

t. RNA • Single stranded RNA molecule • That is folded into a 2 dimensional clover shaped molecule • Amino acid is attached to one end of the t. RNA

THINK • If m. RNA has the following sequence: GGC. What is the anticodon

Ribosomes • Site where translation takes place • Composed of protein & r. RNA • Ribosomes contain 2 sites • A site: where

Process of Translation • Involves 3 steps: 1. Initiation 2. Elongation 3. Termination

Initiation • Brings together m. RNA & t. RNA bearing the first amino

Elongation • Amino acids added one by one • m. RNA codon forms bonds • With anticodon of incoming t. RNA at the A site

Termination • Translation continues until the stop codon reaches the A site of the ribosome • This triggers termination of translation

Answer Questions in Note Guide https: //www. youtube. com/watch? v=h 5 m. Jb. P 23 Buo