Biology 1101 Week 6 Notes
Biology 1101 Week 6 Notes BIOLOGY 1101 - 0100
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BIOLOGY 1101 - 0100
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This 10 page Class Notes was uploaded by Alexa Notetaker on Thursday February 18, 2016. The Class Notes belongs to BIOLOGY 1101 - 0100 at Ohio State University taught by Dr. Kristin Smock in Spring 2016. Since its upload, it has received 53 views. For similar materials see Biology in Biology at Ohio State University.
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Date Created: 02/18/16
Biology 1101 Week 6 Notes Gene Expression: • Gene- a segment of DNA that has information on how to make a protein • In the embryo, all genes are turned on o Totipotent- “all powerful” § These cells can be programed to act like any cell in the body o stem cells • As we develop, only some (about 10%) of our genes are expressed in our cells o Differentiation § Cells assume their roles in the body § Only a small fragment will be expressed – through protein synthesis Protein Synthesis: • DNA à RNA (takes DNA info & helps translate to protein) à Proteins • “The Central Dogma” o Transcription: DNA to RNA o Translation: RNA to proteins § Message of RNA is translated to protein in ribosome DNA vs. RNA: • Function: o DNA: Stores RNA_ and protein-encoding info o RNA: Carries protein-encoding info; helps make protains • Form: o DNA: double stranded o RNA: generally single-stranded • Sugar: o DNA: Deoxyribose o RNA: Ribose • Nucleotide bases: o DNA: A-T C-G o RNA: A-U C-G Biology 1101 Week 6 Notes Types of RNA: • Messenger RNA (mRNA): Carries information specific to protein o Tà A ; Gà C ; Aà U ; Cà G o Used in transcription • Transfer RNA (tRNA)- carries specific amino acid to ribosome o Amino acid attached at end o Used in translation Transcription: • Looking at ONE GENE (NOT the entire strand of DNA) o “Gene region” • Copies messages by complementary base pairing • Leaves nucleus • Prokaryotes: ribosomes translate mRNA as soon as transcription is complete o Immediate process • Eukaryotes: mRNA is usually altered o “first draft” that can be cleaned up before final draft is submitted (before it leaves the nucleus) Biology 1101 Week 6 Notes Transcription to Translation: • 3 RNA bases form a codon • each codon refers to a specific amino acid • The Genetic Code links mRNA to protein o mRNA codons specify 20 amino acids o Also start and stop codons o highly conserved among species • Ribosome works like a translator The transfer molecule uses the anti-codon to hook up the proper amino acid to the mRNA Biology 1101 Week 6 Notes • Amino acids form a chemical bond (peptide bond) to form a protein • Proteins are folded in a very specific way Translation: • Protein folding: o Must achieve final functional folding o Errors in folding can lead to illness PRACTICE: Given this Amino Acid sequence: met; trp; stop Find the DNA sequence: • RNA: AUG, UGG, UAA/UAG/UGA DNA: TAC ACC ATT/ATC/ACT Mutations: • Mutations can affect the structure of the protein the gene is coding for o May render the protein dysfunctional Types of Mutations: • Substitution o One base is substituted for another (Example: Aà G) o The amino acid will be different, causing slight change in the protein • Insertion o Frame-shift mutation- One nucleotide is inserted, which then shifts everything down. All of the bases are different, completely changing the resulting protein o Much greater scale of change • Deletion o Taking out a base and shifting everything back. All of the bases are then different, completely changing the resulting protein. o Much greater scale of change. Biology 1101 Week 6 Notes • Mutations can be good, bad or silent o May cause disease o Silent mutation- a substitution mutation that does not change the amino acid that it is coded for (NO change) • Single gene disorder: One single gene is mutated, resulting in the protein product being changed or missing completely • Cracking the Code of Life Biology 1101 Week 6 Notes Single Gene Disorder: Cystic Fibrosis • What is it? o Mutation affects a protein that allows for the transport of salt across the cell membrane o Mucus builds up § Must be physically dislodged (especially in lungs) o Lungs cells are most impacted o Also impacts pancreas and intestine, which impedes digestion (and nutrition) Germline Mutations: • These are of tremendous biological important o Mutations can be passed to the next generation • Mutation creates a new allele in a population DNA and evolutionary relatedness: • We have mapped genome for thousands of species, most of which are bacteria • Human Genome Project o Geneome sizes of different species: § Humans: 3,400 § Newt: 84,000 § Amoeba: 670,00 • Complexity of organism does not reflect genome size DNA and complexity: • No relationship between size of genome and complexity • In humans, genes make up ~2% of DNA o Most DNA does not code for protein § At least 80% of genome serves a separate purpose and some act as a “switch gene” to tell when a gene should turn on/off • A lot of diseases result from mutations in these switch genes • If we understand what these switches are doing, it may lead to better treatment options or a cure. Biology 1101 Week 6 Notes Review of terms: • Eukaryotic cells have a nucleus • Chromosomes are long strands of DNA and associated proteins • A gene is a protein of DNA that codes for a protein • Each gene can have several alleles, or alternative forms (different versions for the same gene) o Example: eye color Prevailing viewpoints: • 1600s: a pre-made human was contained in every sperm cell • Many thought that an offspring’s trait were blended from each parent (“Theory of Blended Inheritance”) o Traits were intermediate of each parent o Example: Dark purple flower + White Flower à Lavender flower Laws of Inheritance: • Mendel worked with the garden pea plant to study how traits were inherited o Easy to grow o Quick to reproduce o Can be cross-pollinated by hand § This allows to control the crossing (mating) of the plants o Had easily observable traits § Seeds were wrinkled/round; color of seeds, etc. • First, Mendel examined traits have two expressions (like tall/short) o Short x short always resulted in short offspring o When Tall plants were crossed, the results were variable § Sometimes tall plants § Sometimes short plants § Sometimes short plants disappeared, then reappeared in future generations • The tall traits seemed to obscure the short trait • The tall trait was “dominant” to the short trait o Allele for “tall” was dominant Biology 1101 Week 6 Notes o Allele for “short” was recessive § Dominant: “T” § Recessive: “t” • Note: Some genes can have hundreds of alleles Law of Segregation: • During meiosis, only one copy of gene is placed in each gamete Biology 1101 Week 6 Notes Laws of Inheritance: • A diploid cell can have two alleles per gene • If those 2 alleles are the same, the individual is homozygous (TT or tt) o “true breeding” • If those 2 alleles are different, the individual is heterozygous (Tt) • Genotypes express the genetic makeup of an individual o Homozygous dominant (TT) o Homozygous recessive (tt) o Heterozygous (Tt) • Phenotypes are outward expression of the individual o Tall o Short • Mendel developed a system to keep track of all his crosses (matings) o Parental generation: P generation o P’s offspring: F1 generation o F1’s offspringà F2 generation o And so on… • Started with a P generation that was TT or tt • Crossed TT with tt, F1 generation was all tall o The reason why they are all tall is because they are all heterozygous (Tt) • Next, he took plants from the F1 generation and set up a monohybrid cross o Monohybrid cross- Mating before two individuals that are heterozygous for one gene o F2: for every 3 tall plants there was one short plant o Phenotypic ratio: 3 tall : 1 short § Must write descriptor of phenotype in ratio • A Punnett Square uses the genotypes of the parents to reveal which alleles the offspring might inherit Biology 1101 Week 6 Notes • In a monohybrid cross, both parents are heterozygous (Tt) for height Punnett Square: • • All three possible genotypes are possible in the F2 gen eration (Genotypic ratio: 1 TT; 2 Tt; 1 tt)
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