CH 11 SG

• Describe Mendel's contribution to science and how he experimented with peas ^^

^ mendel studied and experimented with garden peas t o determine how gentics work

^ proposed that genetic determinants (genes) occur in pairs and are segregated in the gametes

^ he created the laws of dominance, segregation, independent assormtent and dominance

• Explain why Mendel chose peas to experiment ^^

^ he chose peas because they were easy to grow and manipulate and experiments could be done in short periods of time compare to other living things like humans (which are also more complicated) + he could control waht peas pollinated eachother

• Explain the following laws

  • Law of dominance

  • Law of segregation

    ^only one of the two gene copies present in an organism is distributed to each gamete that it makes

  • Law of independent assortment

    ^ states that alleles of two or more different genes get soßte into gametes independently of one another(separate genes don’t influence each other)

• Contrast genotype and phenotype ^^

^ genotypes are are the genetic makeup (ex. Rr)

^ Phenotypes are the physical appearance of an organism (ex. round seed)]

• Contrast homozygous and heterozygous ^^

^ homozygous is when an organism has two ideniticlal alleles for a trait

^ heterozygous os when an organism has two different alleles for a trait

• Explain how geneticists use the principles of probability to make Punnett squares. ^^

^ the principles of probability can be used to predict the outcome of genetic crossing

• Describe the other inheritance patterns and how they are different than Mendelian Genetics ^^

  • Codominance

    ^ two alleles of a gene produce both phenotypes in the heterozygous (a heterozygous allele shows both traits in its phenotype)

  • Incomplete dominance

    ^ a blend of each allele where neither is dominant (Rr (R=red r+white Rr=pink)

  • Multiple alleles

    ^a gene with more than two alleles (ex blood type)

  • Polygenic traits

  • ^ traits controlled by two of more genes (often used shows a wide variants of phenotypes ex. Skin color, eye color)

• Contrast the number of chromosomes in body cells (somatic) and in sex cells (gametes). ^^

^somatic cells are diploid cells (2n - contains 2 sets of chromosomes) + contains 46 chromosomes half from mother half from father)

^ gametes are haploid (n - contains 1 set of chromosomes) + contains 23 chromosomes

• Summarize the events of meiosis.

• Describe how genetic diversity is increased

  • ^ genetic diversity is increased by the mechanisms of crossing over, random assortment and fertilization

  • Explain Crossing over and when it occurs

    ^ crossing over is the genetic recombination (exchange of genetic info) between sister chromatids (homologous are separated)

  • Explain Independent assortment

    ^ states that alles of two or more different genes get sorted into gametes independently of one another (the alle a Gamer receive for one gene doesn’t affect/influence the Allele received for another gene)

  • Explain Fertilization

• Contrast meiosis and mitosis.

  • Mitosis

    • Has one division

    • Has outcome of two cells

    • Diploid cells

    • Duplicates body cells

    • Cells duplicated are identical

  • Meiosis

    • Has two divisions

    • Has outcome of four cells

    • haploid cells

    • Uses independent assortment (meta 1)

    • Uses bivalve to synapsids

    • Uses crossing over (pro 1)

    • Duplicates sex cells

    • Cells duplicated have genetic variation