GENE EXPRESSION. Amoeba Sisters video 3pk9YVo. Individuality & Mutations

Transcription

1 Amoeba Sisters video 3pk9YVo GENE EXPRESSION Individuality & Mutations Complete video handout 2/1/9/0/ /video_recap_of_muta tions_by_amoeba_sisters.pdf

2 I. Are all genes turned on in all cells? The answer is NO! Every body cell contains your DNA (genetic make-up) Cells use only genes specific for function EX. Red blood cells use only genes that make it carry oxygen Other examples of proteins made include Enzymes, insulin, cell membrane, hair, muscles **THEREFORE, NOT ALL DNA IS EXPRESSED (MADE INTO PROTEIN) IN EVERY CELL!**

3 III. Mutations: A change in the genetic material which effects the genetic information and traits Not all mutations are bad, some are beneficial Ultimate source of genetic variation (depends on environment) MUTATIONS MUST OCCUR IN SEX CELLS IN ORDER FOR THEM TO BE PASSED ON TO NEXT GENERATION! Mutations occur during replication (meiosis / mitosis) and protein synthesis

4 Mutagenic Agents that cause mutations: 1. Radiation x- rays, UV, radioactive substances 2. Chemicals formaldehyde, benzene, asbestos fibers, nicotine

5 A. Gene Mutations A random change in DNA sequence **Review** What does DNA ultimately code for? Proteins!!! Is construction of protein based on original DNA strand? Yes! (b/c it is what codes for mrna) What would happen to the protein if DNA sequence was changed? Wrong protein made Wrong shape of protein This would make protein unusable

6 Types of Gene Mutations A. POINT MUTATION: o o affects 1 single nucelotide (base) Types: Substitution, Insertion, and Deletion Substitution Insertion Deletion

7 Frameshift Mutations One or more bases are either inserted or deleted When this occurs it moves the whole reading frame for the ribosome over changing each codon after the mutation Wrong AMINO ACID is coded for = wrong PROTEIN is made OR Translation will abruptly STOP

8 Disorders from Gene Mutations 1) Sickle cell anemia Sickle shaped cells get caught in capillaries (can t transport oxygen sufficiently) Normal red blood cells (left) Sickle cells (right) 2) Cystic Fibrosis- affects recessive allele on chromosome #7 mutating the CFTR gene effecting the lungs causing mucus build-up

9 Chromosomal Mutations Chromosomal mutations involves changing the number or structure of a chromosome which would affect many genes. There are four types: A. Deletion a piece of a chromosome is completely lost B. Duplication a piece of a chromosome is repeated C. Inversion a piece of a chromosome swaps with another piece on the same chromosome, changing order D. Translocation a piece of one chromosome breaks off and attaches to a different non-homologous chromosome

10 Chromosomal Mutation Related Disorders 1. Down Syndrome Due to failure of homologous chromosomes to separate during meiosis called NONDISJUNCTION An extra chromosome on # Klinefelter Syndrome XXY abnormal sexual development and infertility

11 III. Environmental Expression The adaptive value of a gene mutation is dependent upon the nature of the mutation and the type of environment with which the organism interacts The environment interacts with genes in the development and expression of inherited traits Some genes are turned on under certain environmental conditions this is referred to as gene expression

12 Effect of Cold on Himalayan Hare Fur Color The application of an ice pack to a region of shaved hair results in black hair growing back instead of the original white color. EX. Himalayan Rabbit: Fur changes color due to TEMPERATURE change WARM = White fur (no pigment produced) COLD = Black fur Why does this make sense? Because a black color absorbs the heat, helping little bunny rabbit to stay warm

13 IV. The Human Genome How do we know that traits and diseases are genetically related? THE HUMAN GENOME PROJECT What is it? Project to identify the location of 30,000 genes Why do it? To identify the locations of genetic diseases and possibly control and/or eliminate them How far along are we? The map was completed in 2004 The Human Genome Project Article Review