Genetics & Heredity

Who was Gregor Mendel? Austrian monk who studied mathematics and science Between 1856-1863 Mendel made careful use of scientific methods, which resulted in the first recorded study of how traits pass from one generation to the next.

What is GENETICS? The study of how traits are inherited through the interactions of genes.

What is a GENE? The material that controls which traits are expressed in an organism Genes come in pairs and offspring inherit one copy of each gene from each parent

The passing of traits from parent to offspring Define HEREDITY The passing of traits from parent to offspring Define ALLELE The different forms of a trait that a gene may have. One form of a gene Define TRAIT Ways of looking, thinking, or being. Traits that are genetic are passed down through the genes from parents to offspring

Describe RECESSIVE A trait that is covered over, or dominated, by another form of that trait and seems to disappear Hidden when the other copy of the gene contains the dominant allele. A recessive allele shows up only when there is no dominant allele present Shown with a lower-case letter

Describe DOMINANT A trait that covers over, or dominates, another form of that trait Trait that always shows up, even when only one of the two alleles is in the dominant form Shown by a capital letter

What is HOMOZYGOUS? Both alleles [forms of the gene] are the same When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive

What is HETEROZYGOUS? When alleles occur in different forms When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous Since the dominant gene will be expressed, they are said to be heterozygous dominant

Define GENOTYPE An organism's genetic makeup

Outward physical appearance and behavior of an organism Define PHENOTYPE Outward physical appearance and behavior of an organism

What is a PUNNETT SQUARE? A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine. Letters stand for dominant and recessive alleles An uppercase letter stands for a dominant allele Lowercase letters stand for recessive alleles

Monohybrid Cross r r Rr Rr R R Rr Rr Trait: Seed Shape Mendelian Genetics 4/16/2017 Monohybrid Cross A breeding experiment that tracks the inheritance of one traits. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Round seeds x Wrinkled seeds RR x rr Genotype: Rr Phenotype: Round Genotypic Ratio: All alike Phenotypic Ratio: All alike r r Rr Rr R R Rr Rr

Dihybrid Cross RY Ry rY ry RRYY RRYy RrYY RrYy RRyy Rryy rrYY rrYy Mendelian Genetics 4/16/2017 Dihybrid Cross A breeding experiment that tracks the inheritance of two traits. RY Ry rY ry Round/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 1 9:3:3:1 phenotypic ratio RRYY RRYy RrYY RrYy RRyy Rryy rrYY rrYy rryy

Mendelian Genetics 4/16/2017 Generation “Gap” Parental P1 Generation = the parental generation in a breeding experiment. F1 generation = the first-generation offspring in a breeding experiment. (1st filial generation) From breeding individuals from the P1 generation F2 generation = the second-generation offspring in a breeding experiment. (2nd filial generation) From breeding individuals from the F1 generation

Describe Co-Dominance and Incomplete Dominance Incomplete Dominance when both alleles are present, neither is dominant, and the flower color is pink due to the blending of colors. Co-Dominance is when two alleles are expressed and one does not mask the other.

List the 3 Principles of Heredity Traits are controlled by alleles on chromosomes An allele’s effect is dominant or recessive When a pair of chromosomes separate during meiosis the different alleles for a trait move into separate sex cells

Mendelian Genetics 4/16/2017 Law of Segregation During the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other. Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.

Law of Independent Assortment Mendelian Genetics 4/16/2017 Law of Independent Assortment Alleles for different traits are distributed to sex cells (& offspring) independently of one another. This law can be illustrated using dihybrid crosses.

What is meant by MULTIPLE ALLELES? A trait that is controlled by more than two alleles is said to be controlled by multiple alleles Traits controlled by multiple alleles produce more than three phenotypes of that trait For Example: The alleles for blood types in humans are called A, B, and O The O allele is recessive to both the A and B alleles

What is POLYGENIC INHERITANCE? Occurs when a group of gene pairs acts together to produce a trait The effects of many alleles produces a wide variety of phenotypes

What is a Karyotype The characterization of the chromosomal complement of an individual or a species, including number, form, and size of the chromosomes.

What is a pedigree chart? Pedigree charts show a record of the family of an individual They can be used to study the transmission of a hereditary condition They are particularly useful when there are large families and a good family record over several generations.

Symbols used in pedigree charts A marriage with five children, two daughters and three sons. The eldest son is affected by the condition. Eldest child  Youngest child Normal male Affected male Normal female Affected female Marriage

Organizing the pedigree chart Generations are identified by Roman numerals I II III IV

DNA Fingerprinting DNA Fingerprinting is a procedure whereby the genetic information, called DNA, in a person's cells is analyzed and identified. The word fingerprinting is used because, just like a fingerprint, no two person's genetic code is exactly the same. It can be used to: Determine Family Relationship - DNA can help find out who a person's parents or siblings are. Prenatal paternity tests are available to mothers who need to identify the father of their unborn babies. Detect Inherited Diseases - Your genetic code can be tested to determine your likelihood of getting certain diseases. Prove Guilt or Innocence - DNA left at the scene of a crime can be matched with a sample from a suspect. Identify a Dead Body - The DNA from an unidentified body can be matched with a person in a government DNA database.

Sample Of A DNA Fingerprint