Central Dogma Big Idea 3: Living systems store, retrieve, transmit, and respond to info essential to life processes.

Essential Knowledge 3A1: DNA, and in some cases RNA, is the primary source of heritable information.

Central Dogma! Protein Synthesis Genetic info flows from nucleotide sequence in a gene to amino acid sequence in a protein

DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM Fig. 5-26-1 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM Figure 5.26 DNA → RNA → protein

DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Fig. 5-26-2 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm via nuclear pore Figure 5.26 DNA → RNA → protein

DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Fig. 5-26-3 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm via nuclear pore Ribosome Figure 5.26 DNA → RNA → protein 3 Synthesis of protein Amino acids Polypeptide

mRNA: Carries info from DNA to ribosome Types of RNA Involved mRNA: Carries info from DNA to ribosome

Types of RNA Involved tRNA: Bind specific amino acids and allow info in the mRNA to be translated into a linear peptide sequence.

rRNA: functional building blocks of ribosomes (site of translation) Types of RNA Involved rRNA: functional building blocks of ribosomes (site of translation)

Types of RNA Involved RNAi:  RNA interference molecules that inhibit gene expression; sometimes destroy mRNA. 2 molecules involved: microRNA and siRNA (small interfering RNA) that regulate gene expression.

Transcription Occurs Here! Translation Occurs Here!

Transcription DNA  mRNA, made by RNA polymerase II RNA polymerase binds on promoter (nucleotide), reads DNA from 3’ to 5’ 3 stages: Initiation,Elongation, Termination

A on DNA complements U on RNA RULE! A on DNA complements U on RNA RNA has no T base!

Initiation Promoters: start RNA synthesis, TATA box is one in eukaryotes Transcription factors: help binding of RNA polymerase Completed assembly called a transcription initiation complex

Several transcription factors must bind to the DNA before RNA Fig. 17-8 1 A eukaryotic promoter includes a TATA box Promoter Template 5 3 3 5 TATA box Start point Template DNA strand 2 Several transcription factors must bind to the DNA before RNA polymerase II can do so. Transcription factors 5 3 3 5 3 Additional transcription factors bind to the DNA along with RNA polymerase II, forming the transcription initiation complex. Figure 17.8 The initiation of transcription at a eukaryotic promoter RNA polymerase II Transcription factors 5 3 3 5 5 RNA transcript Transcription initiation complex

Elongation Transcription progresses at a rate of 40 nucleotides per second in eukaryotes

Termination In bacteria: polymerase stops transcription at end of terminator (nucleotide sequence) In eukaryotes: polymerase continues transcription after pre-mRNA is cut  polymerase eventually falls off DNA

RNA Processing Enzymes modify mRNA Ex: Addition of poly-A tail on 3’ end and a GTP 5’ Cap Helps export mRNA and protect from degrading hydrolytic enzymes

RNA splicing: removes introns (noncoding), joins exons (coding) RNA Processing RNA splicing: removes introns (noncoding), joins exons (coding)

Translation mRNA message gets translated into a protein w/ help of transfer RNA (tRNA)

Occurs at Ribosomes 2 ribosomal subunits (large and small) are made of proteins and ribosomal RNA (rRNA)

Either free floating in cytoplasm Ribosomes Either free floating in cytoplasm

Or Attached to Rough Endoplasmic Reticulum Ribosomes Or Attached to Rough Endoplasmic Reticulum

P Site: holds tRNA that carries growing polypeptide chain A Site: holds next tRNA that will add a. acid to chain E Site: holds exit tRNA that doesn’t have an a. acid Ribosomes

Initiation of Translation mRNA interacts w/ rRNA of ribosome at start codon AUG mRNA is read in triplets called codons, which encodes a specific amino acid. tRNA carries the amino acid to the mRNA and ribosome

Termination of Translation Amino acids join to make a peptide chain Stop codon stops process, release of new peptide chain.

Amino Acid Sequences

mRNA and Transcription Big green thing = RNA polymerase

Protein Synthesis Videos NOVA: DNA Secret of Life

Prokaryotic Protein Synthesis Transcription is coupled to translation of the message. Involves mucho energy and also has initiation, elongation, and termination.

Phenotypes are determined through protein synthesis!