Don’t let this happen to you!!

Changes in organism’s DNA MUTATIONS Changes in organism’s DNA

Reflection 3/22 - Name the location and end products of transcription and translation.

REFLECTION 3/23 – Describe the three results caused by mutations. 3/27 – Describe the 2 types of mutations

Are Mutations Helpful or Harmful? Mutations happen regularly Almost all mutations are harmless!!! Chemicals & UV radiation cause mutations Many mutations are repaired by enzymes 5

Are Mutations Helpful or Harmful? Some type of skin cancers and leukemia result from somatic mutations Some mutations may improve an organism’s survival (beneficial) 6

Types of Gene Mutations 1. Point Mutations – changes in one or a few nucleotides Substitution THE FAT CAT ATE THE RAT THE FAT HAT ATE THE RAT

Point Mutation Sickle Cell disease is the result of one nucleotide substitution Occurs in the hemoglobin gene 8

Gene Mutations 2. Frameshift Mutations – shifts the reading frame of the genetic message so that the protein may not be able to perform its function. EFFECTS THE PROTEIN MORE!!!! A. Insertion THE FAT CAT ATE THE RAT THE FAT HCA TAT ETH ERA T B. Deletion TEF ATC ATA TET GER AT H H

Amino Acid Sequence Changed 10

2. Mis-sense – Altered protein – VERY HARMFUL!! Results of Mutations Silent – No effect 2. Mis-sense – Altered protein – VERY HARMFUL!! 3. Nonsense – Premature stop codon

Significance of Mutations Most are neutral Eye color Birth marks Some are harmful Sickle Cell Anemia Down Syndrome Some are beneficial Sickle Cell Anemia to Malaria Immunity to HIV

What Causes Mutations? There are two ways in which DNA can become mutated: Mutations can be inherited. Parent to child Mutations can be acquired. Environmental damage Mistakes when DNA is copied

Mutagens Physical – cause physical damage to the DNA EX - x-rays Chemical – chemical becomes involved in the DNA structure EX – gas, smoke, nitrites Know as carcigens – CANCER CAUSING

Chromosome Mutations May Involve: Changing the structure of a chromosome The loss or gain of part of a chromosome 15

Chromosome Mutations Down Syndrome Chromosome 21 does not separate correctly. They have 47 chromosomes in stead of 46. Children with Down Syndrome develop slower, may have heart and stomach illnesses and vary greatly in their degree of inteligence.

Chromosome Mutations Cri-du-chat Deletion of material on 5th chromosome Characterized by the cat-like cry made by cri-du-chat babies Varied levels of metal handicaps

Sex Chromosome Abnormalities Klinefelter’s Syndrome XXY, XXYY, XXXY Male Sterility Small testicles Breast enlargement

Sex Chromosome Abnormalities XYY Syndrome Normal male traits Often tall and thin Associated with antisocial and behavioral problems

Sex Chromosome Mutations Turner’s Syndrome X Female sex organs don't mature at adolescence sterility short stature

Sex Chromosome Mutations XXX Trisomy X Female Little or no visible differences tall stature learning disabilities limited fertility

Male, Trisomy 21 (Down’s) 2n = 47 22 22

Female Down’s Syndrome 23 23

Klinefelter’s Syndrome 24 24