Genetics

Test Cross • Test Cross- to distinguish genotypes of organisms that are phenotypically identical; shows how the genotype of a dominant phenotype can be determined • Back Cross- refers to any cross between an offspring and one of its parents • Mendel came to three important conclusions from these experimental results: • that an individual inherits one such unit from each parent for each trait • That a trait may not show up in an individual but can still be passed on to the next generation. • That the inheritance of each trait is determined by “units” that are passed on to descendants unchanged • principle of segregation- for any particular trait, the pair of alleles of each parent separate and only one allele passes from each parent on to an offspring (segregation occurs during meiosis and allele chosen is by chance) • Principle of Independent Assortment- the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible. (Traits are unlinked; if you have black hair doesn’t mean u have black eyes) • Important Properties: Numerous traits to be studied, self fertilizing, minimal accidental pollination, self fertilized plants are fully fertile for further crosses • Monohybrid Cross- crosses two characteristics for a certain trait • Mendel only studied one characteristic at a time • True Breeding- always produces offsprings that are identical to itself; Mendel spent two year establishing true-breeding • During meiosis and gamete formation, pairs of genes separate from each other • Gametes- sex cells; Traits don’t blend or mix! • Mendel concluded that each parent makes an equal contribution to the offspring • F1 plants carry genes for both smooth and wrinkled peas; 5474 smooth; 1850 wrinkled • Alleles- An allele is one of two or more alternate forms of a gene. If an individual is homozygous (YY or GG) for a trait, it has inherited the same allele from both parents. (A or a= alleles) • Hybrid- offspring of a cross that has inherited non-identical alleles for the trait • Reginald Crundall Punnett- developed Punnet Square which depicts the probability of the number and variety of outcomes of a particular cross (invented after Mendel time) • Results of Monohybrid Cross: • The F1 offspring showed only one of the 2 parental traits and the trait not shown in the F1 offspring reappeared in about 25% of the F2 offsprings • Zygote- when the sperm and egg come they form a zygote cell • Genes- units of information about heritable traits; Filial- derivative; offspring • Each gene has a specific location on a chromosome known as the locus • Genotype frequency: many ratios; Phenotype: 2 • Dihybrid- 2 characteristics crossed at once • Probability has no memory; 1/2x1/2x1/2= 1/8 • Prior to Mendel, Nucleic Acids were first isolated from the nuclei of pus cells; DNA was identified as genetic material and DNA structure was proposed by Watson and Crick

Here is a link to some of the [|genetics powerpoint presentations]

Some questions and answers from the Jeopardy! PowerPoint:

Mendel used this to transfer pollen from the anther to the stigma of flowers- paint brush. Mendel did research on this ... the transmition of characteristics from parent to offspring- inheritence. Took courses in this subject at the University of Vienna that later helped him with his genetic studies- math aor statiscis.
 * Gregor Mendel**- Number of possible combinations in an F1 dihybrid cross- 4.

Heterozygous genotypes are also called- hybrid. 2 forms of a gene- alleles. Genotype refurred to as being pure- homozygous.
 * Vocabulary**- 2 forms that a gene or allele may take- dominant or recessive.

Mendel was able to cross 2 hybrids by doing this- cross pollinate. Flower part that produces pollen- stamen. Recessice seed shape in Mendel's peas- wrinkeled. Pure parent pea plants are obtained by doing this- self- pollinate.
 * Pisum Sativum**- Actual observed ratio that Mendel got from an F1 monohybrid cross- 3:1.

Another name for an F2 monohybrid cross- test cross. Percentage of tall pea plants resulting from an F1 monohybrid cross- 75%. Used to solve genetic crosses- punnett square.
 * Genetic Crosses**- Genotypic ratio for an F2 generation monohybrid cross- 1:1.

Separation of factors or alleles during the formation of gametes- law of segragation. Trait that appeared in the F1 generation was controlled by this factor or allele- dominance.
 * Mendel's Laws**- dihybrid crosses showed that alleles arent connected when being distributed to gametse- principle of independent assortment.

Gives hybrids an apperance in between the phenotypes of hte two parents- incomplete dominance. States that recessice trait alleles have no effect on phenotype when paired with a dominant trait allele- law of dominance. Used to represent allesles of factors that mask others- capital letter.
 * Dominance**- Type of dominace shown in Mendel's pea plant crosses- complete dominance.

Mendel observed that inheritance is fundamentally a [|discrete] process with specific traits that are inherited in an independent manner. These basic units of inheritance is now known as "[|genes]". In the [|cells] of organisms, genes exist physically in the structure of the molecule [|DNA] and the information genes contain is used to create and control the components of cells. Although genetics plays a large role in determining the appearance and behavior of organisms, it is the interaction of genetics with the environment an organism experiences that determines the ultimate outcome. For example, while genes play a role in determining a person's [|height], the [|nutrition] and [|health] that person experiences in childhood also have a large effect.
 * Genetics** is the [|science] of [|heredity] and [|variation] in living [|organisms].Knowledge that desired characteristics were inherited has been implicitly used since [|prehistoric] times for improving crop plants and animals through [|selective breeding]. However, the modern science of genetics, which seeks to understand the mechanisms of inheritance, only began with the work of [|Gregor Mendel] in the mid-1800s.[|[4]]


 * Genetics** is the science of heredity and variation in in living organisms. [|Modern genetics began with the work of gregory mendel. �30�Mendel saw that inheritance is fundamentally a small process with specific traits that are inherited in an independant manner. These basic units of inheritance is now known as genes. In the cells] of organisms, genes exist physically in the structure of the molecule dna and the information genes contain is used to create and control the components of cells.

Gregor Mendel was known as the father of modern genetics" for his study of the inheritance of traits in pea plants. Mendel showed that the inheritance of traits follows particular laws, which were later named after him. The significance of Mendel's work was not recognised until the turn of the 20th century. Its rediscovery prompted the foundation of genetics. ( Wikipedia)

Incomplete Dominance- When the alleles of the offspring are heterozygous (Rr, Zz, etc.) then the trait is a medium (in between) of the two parent Traits

Mendel's principle of segregation-Traits have 2 Units (genes) each on is contributed by one parent

1.**Test Cross- to distinguish genotypes of organisms that are phenotypically identical; shows how the genotype of a dominant phenotype can be determined
 * IMPORTANT VOCABULARY:
 * 2.**Back Cross- refers to any cross between an offspring and one of its parents
 * 3.**Principle of Independent Assortment- the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible.
 * 4.** Monohybrid Cross- crosses two characteristics for a certain trait
 * 5.**True Breeding- always produces offspring that are identical to itself; Mendel spent two year establishing true-breeding
 * 6.** Gametes- sex cells
 * 7.** Alleles- An allele is one of two or more alternate forms of a gene
 * 8.**Hybrid- offspring of a cross that has inherited non-identical alleles for the trait
 * 9.**Zygote- when the sperm and egg come they form a zygote cell
 * 10.**Genes- units of information about heritable traits
 * 11.**Filial- derivative; offspring
 * 12.**Dihybrid- 2 characteristics crossed at once
 * 13.**Incomplete Dominance- When the alleles of the offspring are heterozygous (Rr, Zz, etc.) then the trait is a medium (in between) of the two parent Traits
 * 14.**Principle of segregation-Traits have 2 Units (genes) each on is contributed by one parent

1.** Point Mutation: Changing of a single base pair in the DNA.
 * __Types of Mutations__
 * 2.** Insertion: Base pairs are added to the gene.
 * 3.** Deletion: Base pairs are removed from the gene.
 * 4.** Frameshift Mutation: An insertion or deletion in a protein coding region. It is not in multiples of three.
 * 5.** Nonsense Mutation: Makes a new stop codon. This is caused by a insertion, deletion or a point mutation.