12-4 Mutations, blood types and pedigrees

1. Mutations Germ-cell Mutation– occurs in gametes, does not affect individual but can be passed on. Somatic Mutation– found in the body cells, does affect individual, cannot be passed on.

A. Deletion – loss of a piece of chromosome due to a breakage. 2. Chromosome Mutations A. Deletion – loss of a piece of chromosome due to a breakage. B. Inversion – a chromosome segment breaks off and then reattaches in reverse orientation to the same chromosome. C. Duplication – Chromosome breaks off and attaches some where different on it’s homologous chromosome.

D. Translocation a chromosome breaks off and then reattaches to a non-homologous chromosome. E. Non-disjunction – failure of a chromosome to separate during meiosis causing gametes to have more or less chromosome than normal. Frame shift – the reading frame shifts by a insertion or a deletion of a nucleotide.

Non – disjunction diseases 1. Down Syndrome – one added 21st chromosome, Trisomy 21. 2. Turners syndrome – Only one X chromosome. (X) 3. Klienfelters – Extra X (XXY) 4. Jacobs syndrome – Extra Y (XYY) 5. Triple X syndrome – (XXX) 6. Edwards – extra 18th, most die. 7. Patau – extra 13th, almost all babies die. 8. Cri – Du – Chat – Missing part of #5.

E. Gene Linkage – Genes that tend to be close together on a chromosome, tend to be inherited together when crossing over occurs. Point mutation- involves the sub., add., or subtracting of a nucleotide.

F. Substitution – one nucleotide in a codon is replaced by another, new codon. 1. Sickle Cell anemia – adenine replaces thymine in a codon causing RBC to be distorted causing blood not to flow smoothly.

G. Karyotype – Visual of all 23 pairs of chromosomes on an individual H. Pedigrees: a family record that shows how a trait is inherited over several generations. I. Carriers – have a copy of the trait on one chromosome, generally do not know or are affected but can pass it on to offspring.

Males: represented by squares. Females: represented by circles. H. Pedigree Key Males: represented by squares. Females: represented by circles. Carriers: represented by shading in one half the circle or square. Displays trait: represented by shading in whole circle or square.

More Disorders I. Multiple allele: controlled by three or more alleles of the same gene that codes for a single trait 1. ABO blood groups, IA, IB, I 2. A and B are co-dominant and dominant to the recessive allele, O blood. 3. O blood in the universal donor. 4. AB blood is the universal recipient.

a. Cannot distinguish between certain colors (usually red and green) J. X-linked traits: Genes found on the x- chromosome 1. Colorblindness a. Cannot distinguish between certain colors (usually red and green)

a. Occurs mostly in males b. Impairs blood to clot 2. Hemophilia a. Occurs mostly in males b. Impairs blood to clot 3. Muscular Dystrophy a. Weakens and progressively destroys muscle tissue. K. Sex influenced traits- Controlled by hormones in the body. Common is baldness. Testosterone.

L. Medical Examinations 1. Genetic screening: an examination of the parents genetic makeup a. Looks for proteins b. Make a karyotype 2. Amniocentesis: removing a portion of amniotic fluid to analyze fetal cells

3. Chorionic Villi Sampling: removing a portion of the Cervics to analyze the cells, which were made by fetal DNA 4. Blood Sampling: take a sample of blood from the baby within hours of birth to test for the presence or absence of certain proteins. 5. Ultra sound- a photograph of the unborn fetus.