BIOLOGY Mutation A Causes of Mutations Failure to

BIOLOGY Mutation

A) Causes of Mutations • Failure to accurately replicate DNA • Inaccurate repairs of naturally breaking down DNA, aging • External Influences – – – Mutagens Carcinogens UV Light Nuclear Radiation (expected 3 errors per replication, over time leads to evolution)

B) Gene Alterations • Point Mutations or Substitutions – Changes of a single nucleotides in the DNA • Point Mis-sense Mutations – Change that alters 1 amino acid in a gene product Protein – UUU UUG • Point Nonsense Mutations – Change that turns a normal codon into a stop codon, shortens the length of the protein, no longer usefull – UAC UAA

Frameshift Mutations • Frame shift Mutation – Change in the Genetic code, (insertion/ deletion of nucleotide) that changes the 3 letter reading from of the DNA – UCA AGA ACA UCG AAC A – Causes major changes in final Protein shape/structure

Insertion or Deletion • Insertion/ Deletion Mutations – Placing into or removal of larger pieces of DNA, maybe the size of a codon, into the DNA sequence – Usually less drastic effect – UUG AGA CGC UUG AGA CCC CGC – Or – UUG AGA CCC CGC UUG AGA CGC

Duplication • Duplication – Unintentional repetition of a codon in the DNA sequence – Less drastic effect, only small change in protein – UGG UCA AGA

ALL TOGETHER NOW Type of Mutation Normal Proteins Structure Missense THQ BIG OLD HOG SAW ONE MAD DOG Nonsense THE BIG OLD Frameshift THE BIG QOL DHO GSA WON EMA DDO Deletion THE BIG OLD SAW ONE MAD DOG Duplication THE BIG OLD HOG SAW ONE MAD DOG Insertion THE BIG OLD HOG SAW ONE WET MAD DOG THE BIG OLD HOG SAW ONE MAD DOG

C) Chromosome Mutations • A mutation that involves long segments of DNA- entire genes Chromosome Map Short Arm Centromere Long Arm

Chromosome Number • Every organism has a specific number of chromosomes, they come in two sets, one maternal and one paternal ( Organisms with both sets are said to be 2 n- diploid) – n ( haploid) means one set of chromosomes – Humans have 23 pairs of Chromosomes • 22 Autosomal pairs • 1 pair of sex chromsomes – ( X, X)- Girl – (X, Y)- Boy Organism Chromosome # Human 46 Fruit Fly 8 Cat 38 Dog 78 Badger 32 Chicken 78 Chimp 48 Cow 60 Algae 148

Types of Chromosomal Mutations • Original • Deletion • Duplication • Inversion Chrom. # 1 • Translocation Chrom. #2

D) Gender/ Chromosome # Abnormalities • Trisomies – When there are 3 copies to a chromosome – Trisomy 18 – Edwards Syndrome • 1/3000 births, malfunctions of most of the major organs – Trisomy 13 - Patau’s Syndrome • 1/5000 births. Lots of defects- polydactyl, cleft lip etc – Trisomy 21 - Down Syndrome • • 1/900 births, influenced by mother’s age AGE 25 1/ 1562 births AGE 35 1/ 214 births AGE 45 1/19 births

Gender Abnormalities • • • Kleinfelter’s Syndrome Affects only males 1/1000 males (XXY) Chracteristics – – – Infertile Enlarged breast Small penis Long and lanky Little body hair CENSORED

• Turner’s Syndrome • Monosomy in sex chromosomes- the only viable(survivable) monosomy • ( X, O) • 1/ 2500 girls • Characterists – – – Short Low hairline Webbed neck No period Infertile Heart trouble

• Cri –du- Chat • “Cry of the Cat” • -Missing part of Chromosome # 5 • 1/ ~ 20, 000 births – More common in females • Characteristics – Low birth weight – Mental/ Speech/ Motor Delays – Unusual facial features – Constipation?

• • Triple X Syndrome 1/1000 Girls 10/ day born in US No abnormal features Learning/ Motor Delays Weak muscle tone Emotional Issues

• Testicular Feminization Syndrome • Y Chromosome does not work, body is unreceptive to male hormones • Look Identical to a mature woman • Have what is called a blank vaginal canal, no uterus, ovaries retained called undescended testis

E) Testing for Chromosomal Abnomalities • There are two ways to test for chromosomal abnormalities during pregnancy-before birth • Amniocentesis (AFT) • Chorionic Villus Sampling (CVS)

AFT • Amniotic Fluid Test • Used to diagnose errors in chromosome number and fetal infections • Can be performed at 1416 wks • Amniotic fluid contains cells from fetus DNA obtained from those cells • Risks – Potential Infection from needle – Leaky puncture wound – 1970 -1/200 risk of miscarriage ( 0. 5%) – 2006 - 1/1600 risk of miscarriage (0. 06%)

• CVS Sampling of Placental Tissue – The placenta supplies the fetus with maternal nutrients, and allows fetal waste to be disposed of via the maternal kidneys – ( Comes from the Greek word for Cake, also Afterbirth) • Can be done 4 wks earlier in pregnancy • Used when the chances of genetic defects is high • Risks – Risk of Miscarriage 1/100 ( 0. 01%) – Risk of infection as well

Karyotypes • Used to identify chromosomal abnormalities and analyze evolutionary relationships • Each set of autosomal chromosomes are present in sets of 2 - called homologous chromosomes • Homologous Chromsomes- same/ similar genetic information in the same spot on chromosomes of similar size

Normal Karyotypes

Abnormal Karyotypes