Chapter 10 How Proteins are Made
Section 1 – From Genes to Proteins • Gene – A segment of DNA that codes for a specific protein. • RNA – Ribonucleic Acid • A type of nucleic acid (like DNA) • Used, along with DNA, to make proteins.
Section 1 – From Genes to Proteins • 3 Primary Differences of RNA vs. DNA • RNA usually has one strand, DNA has two • RNA has ribose for a sugar, DNA has deoxyribose • RNA uses Uracil instead of Thymine
Section 1 – From Genes to Proteins • Transcription – Transferring information from DNA (the gene) to RNA. • Translation – Transferring information from RNA to make a protein. • Different types of RNA are used for these processes
Section 1 – From Genes to Proteins • Gene Expression (Protein Synthesis) – The entire process (translation and transcription) by which proteins are made.
Section 1 – From Genes to Proteins • TRANSCRIPTION Step 1: RNA polymerase binds to the gene’s promoter (beginning of gene). Step 2: The two DNA strands unwind and separate – DNA helicase does this Step 3: Complementary RNA nucleotides are added by RNA polymerase.
Section 1 – From Genes to Proteins • There are different types of RNA used during Gene Expression • mRNA – Messenger RNA. Carries instructions from gene (DNA) and delivers it to site of translation. • Codons- RNA is written as a series of three-nucleotide sequences. These are called Codons.
Section 1 – From Genes to Proteins • Transfer RNA (tRNA) molecules are single strands of RNA that temporarily carry a specific amino acid on one end. • Anticodon – A three-nucleotide sequence in tRNA that complements a codon (from mRNA) • Work with mRNA to produce amino acids.
Section 1 – From Genes to Proteins • Translation • Step 1: Ribosome attaches to mRNA • Step 2: tRNA carrying amino acid attaches to A site • Step 3: Peptide bond forms between amino acids that have just arrived and those already in protein. • Step 4: tRNA detaches. • Step 5: Repeat 2-4 until protein is complete • Step 6 Ribosome detaches from mRNA.
Section 1 – From Genes to Proteins • Ribosomal RNA (rRNA) - parts of RNA molecules that are part of the structure of ribosomes. • Ribosomes – Structures that assist in the manufacture of proteins.
Section 2 – Gene Regulation and Structure • Gene Regulation – Control of transcription in gene expression • Specifically, when RNA polymerase binds to a gene • Transcription Factors – Arrange RNA Polymerases on the correct area of the promoter
Section 2 – Gene Regulation and Structure • Not all segments of DNA code for proteins • Introns – long segments of nucleotides that have no coding information • Cut out of mRNA by spliceosomes. • Introns = Stay IN the nucleus • Exons – Segments of DNA that are expressed • Exons = Expressed
Section 2 – Gene Regulation and Structure • Mutation – Any change in the nucleotide sequence. • There are a wide variety of mutations.
Section 2 – Gene Regulation and Structure • Point Mutation - a single nucleotide changes • Substitution – one nucleotide replaces another • Frameshift Mutation – Anytime a mutation causes the wrong three-nucleotide sequence to be read. • Insertion – nucleotides are inserted into a gene. • Deletion - segments of a gene are lost