Heredity Key Words Chromosome DNA strand containing genetic

Heredity

Key Words Chromosome: DNA strand containing genetic info; contains thousands of genes Gene: the factors that control traits – found in DNA as a specific sequence along the chromosome

Mendelian Genetics A trait that is controlled by a single gene is said to be a Mendelain trait Each parent contributes ones of two possible alleles for a trait Some allels are dominant and some are recessive

Genetics: the study of how traits are passed from one generation to the next Trait: a characteristic Allele: different forms of a gene that account for variations in inherited traits Every trait expressed is determined by 2 alleles (1 gene from each parent) Alleles can be dominant or recessive.

Dominant allele – the allele whose physical effect is always expressed in both homozygous and heterozygous conditions Ex. Allele “T” for height-tall TT or Tt = Tall Recessive allele – the allele whose physical effect that is only expressed when homozygous Ex. Allele “t” for height-short tt = Short

Homozygous – 2 identical alleles for a trait (ie TT or tt) Heterozygous – 2 different alleles for a trait (Tt) (individuals called hybrids)

Phenotype: the physical characteristic/appearance of a trait (as a result of the genetic makeup) in an organism Ex. Tall, short Genotype: the genetic makeup of a trait in an individual, represented by capital and lower case letters for the alleles Ex. TT, Tt, tt

Which of the following represents the homozygous recessive genotype? a) TT b) Tt c) tt

Which of the following represents the homozygous dominant genotype? a) TT b) Tt c) tt

Pea Plant Examples: plant height, color of flower, seed shape, coat, pod color, shape, flower position

Which of the following genotype(s) would result in the dominant phenotype? a) Tt, tt b) tt c) TT, Tt d) TT

Which genotype gives the recessive phenotype? a) TT b) Tt c) tt

Punnett Square -shows the possible combinations of alleles from the gametes being passed from the parents to the offspring -shows the probability of a trait type being passed to an offspring

P 1 and P 2 represent the original parents F 1 is used to show the offspring of the original parents

Look at the following punnet square. What is the phenotype of the offspring? a) 2: 2 b) 1: 2: 1 c) 3: 1

Look at the following punnet square. What is the genotype of the offspring? a) 2: 2 b) 1: 2: 1 c) 3: 1

STEPS TO SUCCESS! Make a Key. Determine genotypes of Parents (P 1) Determine gametes for each parent (meiosis) Make offspring (F 1). *Combine the gametes using a Punnett’s square*. 5) Determine genotypes and phenotypes of offspring. 1) 2) 3) 4)

Zebroid A zorse is the result of crossbreeding a horse and a zebra. A zonkey is the result of crossbreeding a donkey with a zebra. The Zony is the result of crossbreeding a pony to a zebra. All these three are called zebroids – defined as a cross between a zebra and any other equid. Zebroids are preferred over zebra for practical uses such as riding because of its body shape. However it is more inclined to be temperamental and can prove to be difficult to handle. A Zorse A Zony A Zonkey

Camel + llama = Cama

Grolar, Pizzly A grolar/pizzly hybrid is the product of a grizzly bear and a polar bear. Although the two bears are genetically similar, they tend to avoid each other in the wild. During 16 April 2006, a hybrid bear was shot dead by Jim Martell, a hunter from the United States, in Canada. It was the first time a hybrid was found in the wild where previous records of grolars or pizzlies have only been found in zoos. A grolar, pizzly displayed at the Rothschild Museum, Tring, copyright Sarah Hartwell

Wolphin A wolphin is a rare hybrid formed from a cross between a bottlenose dolphin and a false killer whale. There are currently only two in captivity at the Sea Life Park in Hawaii. A wolphin’s size, colour and shape are intermediate between the parent species. The first captive wolphin was Kekaimalu, which shows mixed heritage even in its teeth: bottlenose dolphins have 88, false killer whales have 44 and Kekaimalu has 66! Kekaimalu, The Wolphin

Example 1 1. Brown eyes are dominant over blue eyes. If a parent with both dominant genes for brown eyes and a parent with blue eyes produce offspring. What are the chances that the offspring has brown eyes? blue eyes?

Example 2 Brown eyes are dominant over blue eyes. If a parent with brown eyes has the genotype (Bb) and a parent with blue eyes produce offspring. What are the chances that the offspring has brown eyes? Blue eyes?

Example 3 In guinea pigs curly hair (C) is dominant over straight hair (c). If two guinea pigs that have curly hair and are straight hair carriers mate what is the chance they have a straight haired offspring?

Example 4 In cattle, the hornless condition (H) is dominant and the horned condition (h) is recessive. A bull is crossed with a cow. Of the four offspring, one (1) is horned and three (3) are hornless. Determine the genotype of the bull and the cow.