Chapter 10: How Genes Work PDF

Chapter 10: How genes work Prof. Calkins SCB 101 Gene Expression Gene expression: the process by which genes are transcribed into RNA and then translated to make proteins How we get from nucleotides to proteins… to traits/phenotypes Gene Expression Steps Transcript...

Chapter 10: How genes work Prof. Calkins SCB 101 Gene Expression Gene expression: the process by which genes are transcribed into RNA and then translated to make proteins How we get from nucleotides to proteins… to traits/phenotypes Gene Expression Steps Transcription: the first step of gene expression, when information in DNA is converted to information in RNA. Translation: the second step of gene expression, when information in RNA is converted into the order of amino acids in a protein. Transcription Transcription is the production of RNA that will eventually be the blueprint for protein production RNA is different than DNA: Ribose, not deoxyribose Uracil is used instead of thymine. RNA is single-stranded. Three major types of RNA are needed for translation: messenger RNA, transfer RNA, and ribosomal RNA. All RNA is produced via transcription.  RNA produced during Transcription tRNA, mRNA, and rRNA are all needed in the next step of gene expression Translation Translation: the process by which the information in RNA is converted to a new language: amino acid sequences. For this process to occur, the three types of RNA have specific roles: Messenger RNA (mRNA): contains the information that codes for amino acid sequence, read in groups of three nucleotides called codons. Transfer RNA (tRNA): has a group of three nucleotides at one end that will match with the codon on mRNA, called an anticodon. The other end has an attachment for amino acids. Ribosomal RNA (rRNA): forms ribosomes and provides a location for the amino acids to be connected. Translation Recap: What are the building blocks of proteins? a. Carbohydrates b. Nucleic acids c. Amino acids d. lipids The Genetic Code The information contained in the DNA is called the genetic code. The nucleotides are read in groups of three called codons Codons code that code for ONE amino acid Therefore, multiple codons in a row code for a chain of amino acids Each codon codes for only ONE specific amino acid. Every organism on earth uses the same set of codons to code for the same amino acids. There are 61 amino acid coding codons. There are only 20 amino acids found in proteins. Many amino acids are coded for by two or more codons. Gene Expression Video: https:// www.youtube.com/watch? v=8_f-8ISZ164  Sickle Cell disease is when Red Blood Cells have an abnormally shaped hemoglobin (oxygen carrying protein) which causes the cells to be shaped like commas, or sickles This means that sickle cells do not carry oxygen efficiently to the body Red blood cells (RBC) are responsible for carrying oxygen to organs Hemoglobin is the protein found in RBCs that carries the oxygen A person deficient in hemoglobin is considered anemic and RBCs can’t Sickle Cell Disease carry oxygen to organs efficiently  Sickle cell disease results from inheriting a gene that codes for abnormal hemoglobin HbA: normal hemoglobin HbS: abnormal hemoglobin Sickle Cell Disease  Linus Pauling discovered that the cause of a disease could be an alteration in the structure of a protein He argued that because sickle cell disease was inherited, genes must determine the structure of proteins Vernon Ingram was later able to show that they differ in just one Sickle Cell Disease amino acid (the building blocks of proteins)  We know that amino acid chains (proteins) are coded for by the genetic code Therefore, the change in the structure of a protein can be due to a change in ONE NUCLEOTIDE in a sequence This is the case Sickle Cell Disease with sickle cell disease Recap: Proteins are composed of many subunits called amino acids, which are hooked together in a particular sequence. A change of even one small amino acid may result in a dramatically changed, possibly dysfunctional protein. True or false? a. True b. False Recap: Amino acids linked together fold into shapes that are most chemically stable, so the proteins they make up have particular shapes. Why does this matter? a. It actually doesn’t matter because the body can fix its own proteins, so they can do their job. b. If the proteins aren’t the right shape, DNA can’t translate them. c. If the proteins aren’t the right shape, they don’t fit down blood vessels. d. It actually doesn’t matter because DNA will set up the proteins correctly regardless of the amino acids. e. If the proteins aren’t the right shape, they can’t do their job properly