Heredity Mendelian Genetics Single Trait Cross Monohybrid Ppurple
Heredity
Mendelian Genetics Single Trait Cross. Monohybrid P=purple allele P=white allele
Phenotype Alleles Alternate versions Physical traits-green, tall, of a gene. wrinkled… Dominant Recessive Genotype Genetic makeup Homozygous Dominant-PP Homozygous Recessive-pp Heterozygous-Pp LAW OF SEGREGATION: Allele pairs segregate during gamete formation (meiosis)
TWO TRAIT CROSSDihybrid Cross Tall & Purple TTPP P 1 Generation Short & white ttpp T = tall t = short P = purple p = white
LAW OF INDEPENDENT ASSORTMENT Each allele pair segregates independently of other allele pairs during gamete formation
TEST CROSS • Cross an unknown genotype with a known genotype. Black Lab-unknown genotype; BB or Bb? Brown lab-known genotype; bb If Black lab is BB, then all offspring would be black If Black lab is Bb, the we would expect both black (Bb) and brown (bb) offspring
LAWS OF PROBABILITY RULE OF MULTIPLICATION: Probability that independent events will occur simultaneously is the product of their individual probabilities
Example #1: You have 2 coins, what is the probability that you will flip two heads? Coin 1 = 1 in 2 chance heads = 1/2 Coin 2 = 1 in 2 chance heads = 1/ 2 x 1/2 = 1/4 Answer = 1 in 4 chance
Example #2: What is the probability that offspring of an F 1 generation cross will be homozygous recessive? (Pp x Pp pp) Mom = 1 in 2 chance for p = 1/ 2 Dad = 1 in 2 chance for p = 1/ 2 x 1/2 = 1/4 Answer = 1 in 4 chance
RULE OF ADDITION: The probability of an event that can occur in two or more independent ways is the sum of the separate probabilities of the different
Example #1: You have 2 coins. What is the probability that you will flip a heads and a tails? Answer: Possibility #1 Possibility #2 Coin 1 = 1/ 2 Heads Coin 1 = 1/ 2 Tails Coin 2 = 1/2 Heads Coin 2 = 1/2 Tails ------------------1/ 2 x 1/2 = 1/4 + 1/ 2 x 1/2 = 1/4
Example #2: What is the probability that two heterozygous parents will produce heterozygous offspring? (Pp x Pp Pp) Possibility #1 Mom = 1/ 2 P Dad= 1/ 2 p ---------- Possibility #1 Mom = 1/ 2 p Dad= 1/ 2 P ---------- 1/ 2 x 1/2 = 1/4 + Answer: 1/2 1/ 2 x 1/2 = 1/4
Example #3: What is the probability that two parents heterozygous for both height and flower color will produce tall offspring with purple flowers? Probability of Tt Answer Mom = 1/ 2 T Dad = 1/ 2 t 1/ 2 Tt ------------1/ 2 x 1/2 = 1/4 + 1/ 2 x 1/2 = 1/4 Probability of Pp = 1/ 2 Answer = 1/2 (Tt) x 1/ 2 (Pp) = 1/4 chance
CODOMINANCE: Both alleles expressed Example: Roan cattle (spotted, red & white) Blood typing: A, B, AB, O
ABO BLOOD GROUPS
Blood Transfusions Rule: Match the antigen of the donor with the antibodies of the recipient. Blood Type Can Donate To Can Receive From A A, AB A, O B B, AB B, O AB AB AB, A, B, O O O, A, B, AB O
Mendelian Genetics in Humans P EDIGREES
Karyotypes Normal
Karyotype Down Syndrome-trisomy 21
Karyotype Klinefelters
Karyotype Turners Syndrome
Sex Linkage Or X-linkage Males: XY Females: XX Sry Gene: • • • Sex determination region On Y chromosome Triggers events that lead to testicular formation
Sex-linked Disorders EX. Colorblindness X N = normal vision colorblind X NX n x X NY X n = • • • Colorblind son the Xn came from mom • Affected males get Xn from mom • Affected females get one Xn from Mom and 1 from Dad • More males affected than females Females XX 1 of X inactive (forms Barr body) Inactivation happens during embryonic development Inactivation random • Females mosaics of 2 cell types u Parental X inactive u Maternal X inactive
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