Genetics

Front 1

Mendelian Genetics

Back 1

-based on the work of Gregor Mendel
-worked with pea plants and determined that "traits" are passed on from the parental generation to the offspring

Front 2

Pollination

Back 2

-when pollen in transferred from anther to the stigma (sexual reproduction)
-self-pollination=within the same flower and offspring will look like parent
-cross-pollination: between two different flowers of same species (through wind, water, insects) offspring look different

Front 3

Mendel's Conclusion

Back 3

1)There are 2 forms (alleles) for every trait. Each is controlled by a factor (gene). These factors are pass on from parents to offspring. One allele from each parent
2) 3:1 ratio can be explained if the forms are arranged in pairs. Trait shown is dominant trait not shown is recessive (law of dominance)
3) Law of Segregation: the pairs must separate and only one of the pair gets passed on to the offspring. Parental genes separate during meiosis. Alleles recombine during fertilization.

Front 4

Independent Assortment

Back 4

-random separation of homologous chromosomes during meiosis I
-it is totally random as to where the chromosomes line up during metaphase I
-alleles are passed to offspring independently of each other
-new combinations of alleles not seen in parents

Front 5

Test Cross

Back 5

-the cross of an organism with an unknown dominant genotype with an organism that is homozygous recessive for that trait
-used to determine genotype of Mendel's F1 generation
-reliability increases with the number of offspring produced
-if offspring show recessive trait, unknown genotype is heterozygous
-if all offspring is dominant, unknown genotype is homozygous

Front 6

Non-Mendelian Genetics

Back 6

-do not follow the law of dominance
-in the traits considered previously, an organism heterozygous for a trait has been indistinguishable from a homozygous individual
-this is because a dominant allele prevents the expression of a recessive allele
-thus mendel's peas were either tall or short. Of a pea plant had one tall allele and one short allele it is just as tall as the homozygous dominant

Front 7

Incomplete Dominance

Back 7

-Japanese 4 O'clock plants, the gene controlling flower color has alleles that are neither dominant or recessive
-two red alleles=red flowers (RR)
-two white alleles=white flowers (WW)
-one white one red=pink flowers (RW)

Front 8

Recognizing Incomplete Dominance

Back 8

1)Notice that the offspring is showing a third phenotype. The offspring are different from the parents. Heterozygous individual has a phenotype different from that of homozygous
2) Trait in the offspring is a blend or mix of parental traits

Front 9

Codominance

Back 9

-the recessive and dominant traits appear together in the phenotype of heterozygous organisms
ex: red x blue= red & blue spots
-a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both parental traits are shown together
-cattle can be red (CrCr), white (CwCw) or roan (CrCw= red and white)

Front 10

Multiple Alleles

Back 10

-genes with more than two different alleles
-Ex. 1 person has 1+ 2 of a gene, someone else has 2+5
-in humans genes for blood type are multiple alleles, person only gets 2, located on chromosome 9, 2 copies in all human body cells

Front 11

Male Structures in Flower

Back 11

-Anther: produces pollen, pollen grain contains sperm cells
-Filament: supports anther
-stamen

Front 12

Female Structures in Flowers

Back 12

-Stigma: sticky to allow pollen to stick
-Style: long tube that attaches the stigma to the ovary
-Pollen Tube: forms to carry sperm cells to ovary
-Ovary: fertilization occurs her and will become "fruit"