RNA Structure and Protein Synthesis Chapter 10, pg

What is RNA? Nucleic acid called Ribonucleic Acid Nucleic acid called Ribonucleic Acid Function - Messenger: takes info from nucleus to ribosome Function - Messenger: takes info from nucleus to ribosome Differs from DNA in 3 ways: Differs from DNA in 3 ways: Has 5-carbon sugar called ribose (has extra Oxygen) Has 5-carbon sugar called ribose (has extra Oxygen) Contains 1 strand of nucleotides Contains 1 strand of nucleotides Has nitrogen base that is different Has nitrogen base that is different Uracel (U) but no thymine (T) Uracel (U) but no thymine (T) U pairs with A U pairs with A

DNA VS RNA- Nucleic acids DNARNA Structure Double Helix Single Strand SugarDeoxyriboseRibose Nitrogen Bases Adenine thymine Cytosine Guanine Adenine Uracil Cytosine Guanine Function Stores and transmits genetic information Messenger: takes info from nucleus to ribosome

Purpose of RNA Helps make proteins Helps make proteins Traits are determined by proteins Traits are determined by proteins Proteins – large molecules made from chains of amino acids Proteins – large molecules made from chains of amino acids 21 different amino acids found in proteins 21 different amino acids found in proteins some proteins are enzymes and promote chemical reactions and others have important structural functions. some proteins are enzymes and promote chemical reactions and others have important structural functions. protein collagen found in skin, ligaments, tendons, and bones. Hair, hemoglobin, and muscles also contain structural proteins. protein collagen found in skin, ligaments, tendons, and bones. Hair, hemoglobin, and muscles also contain structural proteins.

Protein production A protein is made from the instructions of DNA. This process is called gene expression or protein synthesis. A protein is made from the instructions of DNA. This process is called gene expression or protein synthesis. The sequence of nucleotides in each gene determines the string of amino acids in a protein. Protein synthesis consists of two parts: transcription and translation. Protein synthesis consists of two parts: transcription and translation.

Protein Synthesis- Protein Synthesis- 2 Processes 1. Transcription: instructions are transferred from DNA to mRNA. 1. Transcription: instructions are transferred from DNA to mRNA. 2.Translation: – instructions are read and amino acids are put together to build the protein. 2.Translation: – instructions are read and amino acids are put together to build the protein.

3-Types of RNA Messenger RNA (mRNA)- Takes info from nucleus to the ribosome. Contains codon Messenger RNA (mRNA)- Takes info from nucleus to the ribosome. Contains codon Transfer RNA (tRNA) -Brings amino acids with complementary base pairs to the mRna at the ribosome. Contains the anticodon. Transfer RNA (tRNA) -Brings amino acids with complementary base pairs to the mRna at the ribosome. Contains the anticodon. Ribosomal RNA (rRNA) - Makes up one of the subunits of the ribosomes Ribosomal RNA (rRNA) - Makes up one of the subunits of the ribosomes

Transcription Occurs in nucleus. Has 3 main steps. Occurs in nucleus. Has 3 main steps. 1. RNA polymerase, an enzyme, binds to gene’s promoter site (start site) to start process 1. RNA polymerase, an enzyme, binds to gene’s promoter site (start site) to start process 2. RNA polymerase unwinds and separates strands of double helix, exposing DNA nucleotides on each side 2. RNA polymerase unwinds and separates strands of double helix, exposing DNA nucleotides on each side 3. RNA polymerase adds and links complementary RNA nucleotides as it reads the gene. Follows base pairing rules for DNA replication, except A pairs with U in RNA 3. RNA polymerase adds and links complementary RNA nucleotides as it reads the gene. Follows base pairing rules for DNA replication, except A pairs with U in RNA

Transcription cont. RNA polymerase ends process at stop signal at end of gene RNA polymerase ends process at stop signal at end of gene Not all of the DNA is expressed at once. Not all of the DNA is expressed at once. Usually only one gene or a few genes at a time Usually only one gene or a few genes at a time Exons are the part of the mRNA transcript that are EXPRESSED Exons are the part of the mRNA transcript that are EXPRESSED Introns are regions of unused DNA and removed. Introns are regions of unused DNA and removed.

Translation mRNA carries the instructions for making a protein to ribosome. mRNA carries the instructions for making a protein to ribosome. Instructions are read Codons Instructions are read Codons Codons are 3 nucleotide sequences that code for an amino acid, start signal, or stop signal. Codons are 3 nucleotide sequences that code for an amino acid, start signal, or stop signal.

Steps of Translation 1. First the mRNA leaves the nucleus, entering the cytoplasm 2. mRNA attaches to the ribosome 3. tRNA carrying an amino acid matches its anticodon to the codon on mRNA 4. Peptide bonds form between the amino acids 5. tRNA is released from the ribosome 6. Process is repeated along length of mRNA until reaches stop codon, ending synthesis of protein.

21 amino acids needed for life 21 amino acids needed for life Start codon on mRNA always codes AUG and codes for methionine Start codon on mRNA always codes AUG and codes for methionine Easy to remember… …we always start school in AUGust!

Homework Create a DNA and RNA foldable. Create a DNA and RNA foldable. Fold hamburger style. Outside flap have RNA and DNA. Fold hamburger style. Outside flap have RNA and DNA. Inside top flap have a drawing of the Structure of DNA and RNA which can be found in chapters 9 and 10 of book. Inside top flap have a drawing of the Structure of DNA and RNA which can be found in chapters 9 and 10 of book. Inside bottom, draw venn diagram comparing similarities and differences of both molecules. Inside bottom, draw venn diagram comparing similarities and differences of both molecules.