PPT# 4 Notes: Mutations and Regulation Name_______________________ Date______________Per._______ I. Making Mistakes Mutations = _________________in the genetic material (mistakes) Several types: 1. Gene mutations = mutation to a single __________________ 2. Chromosomal mutations = mutations to the whole _______________________ 1. GENE Mutations Point mutations – involve changes to one or a few nucleotides; affect a _____________________ in the DNA sequence Examples of Point Mutations a) Substitutions - one nucleotide base is _____________________ for another Ex: AGGUC changed to ACGUC The dog bit the cat changed to… The dog bit the __________. Affects ___________ amino acid – ______________ damage! (but can still be bad! (sickle cell anemia for example)) b) Insertion: one nucleotide ________________ …AAU CGC GGG… becomes …ACA UCG CGG… c) Deletion: one nucleotide _________________ …AAU CGC GGG… becomes …AAU GCC GGG THESE can be very ____________!!! Because they are Frameshift Mutations Frameshift mutations – adding or deleting a nucleotide causing a ________________ of codons. AUG GCC UAC CGA… AUU GGC CUA CCG A… Or AUG GCC UAC CGA AGG CCU ACC GA… It’s like this…frameshifting. The cat ate the fat rat. Tec ata tet hef atr at… Or The dog ran and bit the cow. The edo gra nan dbi tth eco w. These can totally ____________a whole gene!!! (depending on where it occurs) 2. Chromosomal Mutations Involves changes in the number or structure of the entire ______________________. There are: a) Deletions – _____________ of part of the chromosome b) Duplications – ________________ copies of part of the chromosome is made c) Inversions – ___________________ the direction of some of the chromosome d) Translocations – part breaks off and ___________________ to another chromosome 3) Polyploidy: an organism has an _____________ set of chromosomes. Lethal or harmful to ________________ Ex: Most die as embryos or fetuses; defects in nearly all organs. Plants that are polyploid are often ________________ and _________________!! Ex: (bananas, strawberries, pumpkins, other fruits/veggies) Luckily… Most mutations are ________________ – have little or no affect on the organism Others are ________________ (disorders, cancer, etc.) But, they are the source of genetic ________________ though!! Help things adapt. II. Gene Regulation 1. DNA and RNA polymerase and other enzymes also “_________________” the DNA and RNA to fix mutations if possible. 2. Repressors are proteins that bind to specific genes on chromosomes ________________ transcription of a gene until conditions are such that the gene is needed. 3.Other types of proteins can _____________________ transcription if necessary. III. Differentiation A life starts with ___________ cell. They have to “know” to ______________ (differentiate) ___________ genes control differentiation – they are the master control gene! If __________________, problems arise – you can grow legs instead of antennae on fruit flies!! The control genes are ____________________ in all animals – they took an eye gene and put it in the leg gene of a fruit fly and grew an eye on the fruit fly’s leg! This is where _________________ cell research comes in!!! CRITICAL THINKING: DNA AND SUN EXPOSURE Analyzing processes can help you understand how a complex system works. When you analyze, you break something down into its parts. You examine how each part contributes to the functioning of the whole. Once you understand how the parts are related you should be able to explain the process to someone else. It is now common knowledge that exposure to the ultraviolet rays (UVR) of the sun can lead to several types of skin cancer and to premature aging of the skin. The intensity of the ultraviolet rays actually alters and breaks certain sections of the DNA strand; thus mutations occur. To repair the structural damage done by the sun, a group of proteins, ultraviolet radiation A, B, and C (better known as Uvr A,B, C) work together with adenosine triphosphate (ATP). In this process, the UVr ABC proteins attach to the ends of DNA molecules and move along the strand like a zipper. As the proteins advance, they unwind the coiled DNA one section at a time. Once a section of DNA is unwound, it is accessible for repair by another protein, Uvr D. The Uvr D protein cuts out the sundamaged area, and DNA polymerases create a new section of DNA and insert it into the strand. The energy for this process is derived from, the energu-storing molecule ATP. The more often people are exposed to the ultraviolet rays of the sun, the harder it is for their Uvr proteins to repair their DNA. The results of one study suggest that reduced repair of DNA can lead directly to the development of basal cell carcinoma (BCC), a fatal skin cancer. The ability of DNA to repair itself declines normally with age. This means that, in terms of DNA repair, a teenager who spends a lot of time in the sun is as likely to develop BCC as a person in their 60s! APPLICATION: Write a complete sentence to each question. 1. How does ultraviolet light damage the DNA of skin cells? 2. What chemical compounds help to repair the damage done to the DNA strands? 3. Describe the process by which these compounds repair the DNA. 4. What two factors contribute to the development of Basal Cell Carcinoma? 5. Why is this information important ? 6. Summarize this information in 3 sentences. Electromagnetic radiation exists in a range of wavelengths, which are cut into major divisions for our convenience. Ultraviolet B radiation, harmful to living organisms, represents a small portion of the spectrum, from 290 to 320 nanometer wavelengths. (Illustration by Robert Simmon)