Wednesday, November 9, 2011

Wednesday, November 9

-Today we started class by taking the Meiosis quiz.

-After the meiosis quiz we worked on UP pg. 41 & 42.
  1. First find out if you have that gene, then look on the back of the page (page 42) and figure out what letter corresponds with that trait.
  2. If you do have the gene write the capital letter, then an underscore. EX- for tongue rolling if you can roll your tongue write R_ because you could have RR or Rr, but you wouldn't know which combination you have unless you looked back a few generations and traced the gene.
  3. If you can't roll your tongue you would write rr because tongue rolling is a dominant gene and if you are unable to roll your tongue you have the recessive gene.
  • The capitol letter is the dominant gene, and the lowercase letter is the recessive gene. If you have at least one dominant gene then you will get the dominant trait, so to have a recessive gene you must have both genes be recessive, or lowercase.

-After we talked about UP pg. 41 & 42, we went over notes(pg 1-4) in the new packet that we got during class.

  • Gregor Mendel was the 1st to analyze the patterns of inheritance scientifically
  • He studied this while working with peas in a garden
  • He realized that some of the pea plants had different characteristics such as flower color, stem length, flower position, and pod color
  • By taking some of the pollen from the purple flowered peas and replacing it with pollen from the white flowered peas he discovered

-all of the first generation peas had purple flowers, and in the second generation one out of four of the pea plants had white flowers.

-the stem length, pod color, seed shape, seed color and other traits were randomly picked

Mandel's Two Principles:

  1. Mandel's principle of segregation: Pairs of alleles separate during gamete formation. (fuse again at fertilization)
  2. Mandel's principle of independent assortment: each pair of alleles segregates independently of the other pairs during gamete formation.

-key points to know about genetics:

  • genes are inherited (passed on) from parents
  • genes retain individuality generation after generation
  • self vs. cross fertilization- self means only one organism is need, cross requires two organisms to reproduce
  • hybrids are offspring of two different true breeding varieties (purebreds), EX. AA or aa
  • Monohybrid crosses are one trait
  • alleles are alternative forms of genes EX. A=purple flowers, and a=white flowers
  • dominant vs. recessive, dominant genes mask recessive genes, so an Aa would look the same as someone who has AA
  • Genotypes are the letters for the trait- AA, Aa, aa
  • Phenotypes are the traits you can see (physical traits)
  • Homozygous is the same- AA or aa vs. Heterozygous which is different- Aa

If you are confused, read UP pages 43 and 44


  • Read ch. 9 Genetics, pg. 142-168
  • Read over UP pg. 43 and 44
next scribe - Lydia


  1. This one was really helpful--it went right to the point for Mendel's two principles. I like how a picture of Gregor Mendel is included, but it also would have been helpful if an example of a Punnett square was included, just for a little extra review. Good job though!

  2. This was a good "overview" post- it summarized the class well. Agreeing with what Emma mentioned, giving a short outline (+picture) of the Punnett squares would've been a good idea as well. Great job overall!