BIOL 213 1st Edition Lecture 18 Outline of Last Lecture I. All cells of the same organism contain the same DNAa. Cloning II. Gene expression regulationa. Early stage and late stageb. Transcription regulation is most commonIII. Regulatory proteins in transcription regulationa. Activators or repressorsb. DNA-binding motifsIV. Gene regulation in bacteria and virusesa. Operoni. Negative or positive feedback loopii. Ex: CAP and lac repressorV. Gene regulation in eukaryotesa. More complex than prokaryotesb. Activators and enhancersc. Chromatin structure can be transmitted to next generations and can be altered so that transcription can happenVI. Transcriptional network motifsOutline of Current Lecture These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.I. Somatic cells and gametesII. The five basic types of genetic change that contribute to evolutiona. Mutation within a geneb. Gene duplicationc. Gene deletiond. Exon shufflinge. Horizontal gene transferIII. Gene duplicationa. Gene familiesIV. Genome duplicationV. Exon shuffling can result in the appearance of eukaryotic genesVI. Transposable elements can change genes by inserting new coding sequencesa. Can transpose exonsVII. Horizontal gene transfera. Plasmids VIII. The human genomeIX. Comparative genomics X. Overview a. Gene duplicationb. Exon shufflingc. Transposable elementsd. Horizontal gene transferCurrent LectureI. Somatic cells and gametesa. Somatic cells are body cells – everything but gametesb. Gametes are egg and spermc. Mutationsi. A mutation in a somatic cell will only affect that one organism1. It won’t be passed onto its descendantsii. A mutation in a gamete cell will affect that cell and all of its descendantsd. Stem cellsi. These have the potential to become any type of cellii. Embryonic stem cells can become any type of cell – no limitationsiii. There are some stem cells that can only become one of a few kinds of cells1. Ex: those found in blood can only become cells that are found in bloodII. The five basic types of genetic change that contribute to evolutiona. Mutation within a genei. Point mutationii. One base pair is mismatched during replication and is not repaired1. Changes a single nucleotide2. Deletes one or more nucleotides3. Duplicates one or more nucleotidesiii. Because most of DNA isn’t coding DNA, a large amount of these point mutations don’t lead to any change in protein sequence1. These are called silent or neutral mutationsiv. The number of silent mutations can be used to help determine how closely related two things are1. If they have a lot of the same silent mutations, it’s safe to assume that they’re closely related and diverged from each other not too long ago2. As opposed to two organisms who have very few of the same point mutations – it is more likely that they diverged a long time agob. Gene duplicationc. Gene deletiond. Exon shufflingi. Two or more genes can be shuffled so that a third, new hybrid gene is createdii. Seen in recombination of chromosomesiii. If recombination is unequal, it can lead to the creation of new genese. Horizontal gene transferi. Genes are transferred from one cell to another ii. Seen in prokaryotes; almost never in eukaryotes1. Only low-level eukaryotes like single celled amoebas do thisIII. Gene duplicationa. This can five rise to gene families i. Multiple genes that are descendants from the same gene all code for verysimilar, but slightly different proteinsb. When a gene is duplicated, each copy has the chance to accumulate its own mutationsi. The duplicated gene doesn’t always evolve though, it can also:ii. Be lostiii. Become a pseudogene1. It looks like a gene, but the promoter is so dysfunctional that the gene will never be transcribedc. This causes the two copies to eventually become different from each otherd. These genes can be duplicated and their copies can be mutated to create even more genese. After millions of years, a lot of these duplications can lead to gene familiesi. Lots of genes that descended from one genef. They are similar enough so that they are almost the same gene, but different enough so that they have different functionsg. Many gene duplications are created from errors in homologous recombinationi. If the chromosomes are not aligned equally, this will lead to unequal crossing-overii. One chromosome will get duplicates of some genes while the other will lose those genesiii. This can happen several more times to the same chromosome, resulting in a lot of duplications  gene family1. Over the course of several generationsh. Example of a gene family: the globin gene familyi. Globin carries oxygenii. More advanced animals have four globin proteins of two types1. 2 α-globins2. 2 β-globinsiii. These four interact so that the hemoglobin molecule can bind to four oxygen molecules at onceiv. The α- and β-globins are a result of duplicationv. The original globin gene duplicated and the copies mutated into the two kinds of globins found today1. Another kind of globin was also a result of this duplication: a second β-globin that is only found in fetusesa. This β-globin has a higher affinity for oxygenb. This is good because the fetus doesn’t get as much oxygen as individuals do because it essentially has to breathe through its mom2. There are several different genes that code for α- and β-globin, so the different globins aren’t all exactly alikevi. The genes for α- and β-globins are on different chromosomes1. α-globin on chromosome 162. β-globin on chromosome 113. There is a β-globin gene family on chromosome 11a. 5 different genes leads to different subtypes of β-globin:b. .ε codes for fetal β-globin c. . γG codes for fetal β-globind. . γA codes for fetal β-globin e. δ codes for a minor form of β-globin that’s only found in primates f. β codes for adult β-globin4. The β-globin proteins are more specialized because there are more proteins to do the same amount of workIV. Genome duplicationa. Sometimes, an organism’s entire genome can be duplicatedi. This is extremely rare in vertebrates, but seen commonly in plantsb. A duplicated genome means the organism has 2 chromosomes from mom and 2 from dadi. Versus the normal 1 from eachc. This means it has twice as much DNA, which will code for twice as many proteins,which will make the cell biggerd. This is useful in crops because we can make them