Chapter 13: RNA and Protein Synthesis

RNA

What is RNA?

• RNA (Ribonucleic Acid)– How is RNA physically different from DNA?

• 1. Single strand not a double• 2. Contains Ribose and not deoxyribose• 3. Uracil replaces thymine as nitrogen base

– DNA is the “masterplan”– RNA are the “blueprints” for protein synthesis

What are the functions of RNA?

• 3 Main Functions– Messenger RNA

• Carries the assembly information for each protein

– Ribosomal RNA• Assembles the proteins from the instructions given

– Transfer RNA• Takes amino acids to the proteins that need them

What is RNA Synthesis?• Transcription

– Synthesis of RNA molecule from a DNA pattern– Creation of RNA– Complementary strand of DNA sequence

• Same as the DNA sequence hence the same bases except for uracil

– RNA Polymerase• Enzyme• Binds to DNA• Pulls DNA apart• 1 strand used to make complementary strand

• Promoters– Tell RNA where to bind– Looks for specific sequences to bind to

Chapter 13: RNA and Protein Synthesis

Ribosomes and Protein Synthesis

Genetic Code

• What are amino acids?– Building blocks of protein– Long chains of polypeptides created out of them– 9 “essential” amino acids

• Proteins– Made up of different combos of amino acids– Shape and function all determined by what amino acid

goes in it

Genetic Code• What is Genetic Code?– Combo of the 4 bases (A,C,G,U)– 3 bases in a row makes an amino acid

• 3 letter combos called “codons”• Some amino acids have multiple codons• Read from the center to the outside• 64 different codons

– Used to create protein• Every protein will begin with AUG (methionine)• Certain codons will mark end of protein

Codon Table

Translation• Process of converting amino acids to proteins• Takes place in cytoplasm• Step 1: Transfer RNA– tRNA brings amino acids to ribosome based on pattern– Also brings the anti-codon (complementary strand)

• Step 2: Joining Amino Acids– Peptide bonds form between 1st and 2nd acid– Breaks the bond between the amino acid and tRNA

• Step 3: Chain Grows– Goes until it hits a stop codon

Chapter 13: RNA and Protein Synthesis

Mutations

Types of Mutations• What is a mutation?– Change in the genetic material

• Gene Mutations– Occurs during replication– Changes are passed on in cell division

• Daughter cells will have mutation

– 1. Substitutions• One base (A,C,G,U) is changed in sequence• Sometimes there is no change (Example)

– 2. Insertions• Adding a base to the sequence (Example)

– 3. Deletions• Taking away a base from sequence (Example)

Examples• 1. Substitutions

Examples

• 2 and 3. Insertions and Deletions

Type of Mutations• Chromosomal Mutations– 1. Deletions

• Removal of entire chromosome

– 2. Duplication• Copy of chromosome made and added

– 3. Inversion• Swapping of chromosomal positions

– 4. Translocation• Total movement of chromosome

Examples

Chapter 13: RNA and Protein Synthesis

Gene Regulation

Prokaryotic Gene Regulation

• How do they regulate genes?– Through controlling transcription– Operons

• Group of genes that can be regulated together• Lac Operon

– Responsible for breaking down bonds when lactose is present– Lactose found in dairy products

Prokaryotic Gene Regulation

• Role of Promoters and Operators– Promoters

• Place where RNA polymerase binds• Allows for transcription

– Operators• Place where Lac repressor binds to DNA

– These are how transcription is regulated– Lac repressor will keep things from happening when

needed

Hox Genes

• Role of Hox Genes– Controls the formation of the body– Tells body parts where to go in development– Also tells the body when it needs to develop– Humans have them