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DRILL #16. Quote : If you fail to plan, you plan to fail." -- Unknown Agenda: Pedigree Overview Protein Synthesis Warm-up:
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DRILL #16 Quote: If you fail to plan, you plan to fail." -- Unknown Agenda: Pedigree Overview Protein Synthesis Warm-up: Patrick met Patti at the dance. Both of them are heterozygous for their pink body color, which is dominant over a yellow body color. Create a Punnett square to show the possibilities that would result if Patrick and Patti had children.
Patrick met Patti at the dance. Both of them are heterozygous for their pink body color, which is dominant over a yellow body color. Create a Punnett square to show the possibilities that would result if Patrick and Patti had children. P p PP Pp pp Pp Genotypic ratio: 1PP: 2Pp: 1pp Phenotypic ratio: 3 pink: 1 yellow P p
The Link Between Genes and Proteins Slide # 2 • A gene is a portion of DNA that codes for a protein that controls a trait. • Two types of proteins • Structural proteins: determine how we look • EX: Hair & skin pigments; ear lobe shape • Enzymes: determine how we function • Control every chemical reaction in the body • EX: Sucrase breaks down sucrose (table sugar) • 3. DNA (gene) Protein Trait Detached ear lobes Attached ear lobes
Slide # 3 Overview of RNA and Protein Synthesis • Sequence (order) of nitrogen bases of a gene determines the genetic instructions or “genetic code” of an organism. • DNA NEVER leaves the nucleus, but the code (gene) must be read so that proteins can be made. • RNA makes a copy of DNA code of a gene. • One strand of the DNA code is copied by RNA • RNA carries the copied code out of the nucleus to the ribosome. • The ribosome “reads” the code & makes the protein. DNA code
Slide # 4 Comparison of DNA and RNA Nucleotides Structure of RNA Nucleotide • Structure of DNA Nucleotide Nitrogen Bases: adenine, uracil, guanine, & cytosine Nitrogen Bases: adenine, thymine, guanine, & cytosine
Comparison of DNA and RNA Slide # 5 • 3 Main differences between DNA & RNA • Sugar: • DNA: Deoxyribose • RNA: Ribose • Nitrogen Bases: • DNA: A, T, C, G • RNA: A, U, C, G • U = uracil • Number of strands that make up the molecule: • DNA: two strands • RNA: one strand DNA RNA
Types of RNA Slide # 6 mRNA • Messenger RNA = mRNA • Copies instructions from DNA code; carries code out of nucleus to ribosome • 2. Ribosomal RNA = rRNA • Ribosomes are made of protein and RNA • 3. Transfer RNA = tRNA • Carries and transfers a specific amino acid to the amino acid chain assembled by the ribosome • T-shape rRNA tRNA
How Proteins are Made: Protein Synthesis Slide # 7 Step 1: Transcription • Transcription: a single strand of mRNA is copied from DNA in the nucleus • DNA unwinds – sides of ladder separate • An enzyme (RNA polymerase) “reads” DNA bases and makes the RNA strand • If DNA is TACCAGTTT • mRNA will be AUGGUCAAA c. mRNA is removed and DNA strands will join & coil
How Proteins are Made: Protein Synthesis Slide # 8 Step 2: mRNA editing • mRNA editing: cutting and splicing mRNA before it leaves the nucleus • Introns- (intruders--“junk DNA” ) are cut out • Exons- “good DNA” are left • Exons are spliced together to create an edited version of RNA • Edited mRNA is sent out of nucleus to ribosome Introns are removed and exons are spliced together. This is the message that is translated.
How Proteins are Made: Protein Synthesis Slide # 9 Step 3: Translation • How the code is read: • Every 3 bases on mRNA represents a code for an amino acid (building block of protein) • Every 3 bases on mRNA is called a codon. • Amino acids are abbreviated most times by using the first 3 letters of the amino acid’s name. • Met = methonine • Leu = leucine
Reading the Codon Chart Slide # 10 Examples: AUG = Methionine CAU = Histidine UAG = Stop First Position Third Position Try these: GCU: UAC: CUG: UUA: Answers: Alanine Tyrosine Leucine Leucine This chart only works for mRNA codons.
How Proteins are Made: Protein Synthesis Slide # 11 Step 3: Translation • Edited mRNA is sent out of nucleus to ribosome • Ribosome reads the codons on mRNA • Codon on mRNA specifies which tRNA brings in the designated amino acid • Notice the anticodon on tRNA • Anticodon “reads” the codon on mRNA • Ribosome joins the amino acids together with chemical bonds called peptide bonds to build an amino acid chain called a “polypeptide” • DNA (gene) RNA Protein Trait
Translation Slide # 12 Nucleus mRNA Lysine Phenylalanine t RNA Methionine Anticodon Ribosome mRNA Start codon
Translation Slide # 13 Growing polypeptide chain The Polypeptide “Assembly Line” Ribosome tRNA Lysine tRNA mRNA Completing the Polypeptide mRNA Translation direction Ribosome