Wednesday, November 30, 2011

Homework Due: None

Homework Assigned: UP p.99-110 due tomorrow, and EC-Lab #37 due thursday.

In Class:

We did a DNA model activity using a pack of tubes and connecters to create strands of DNA, replicate it, then put it through protein synthesis. The purpose of this activity was to learn more about translation. Here is a link to short clip on youtube, that explains translation.

http://www.youtube.com/watch?v=5bLEDd-PSTQ

NOTE: In the beginning of this clip it talks about Poly-A tails and methylated caps, you DO NOT need to know these, we did not cover these in class.

Next Scribe: Jex, you do not need to post until next tuesday

Wednesday 11/16/11 blog post

Today Ms. Andrews explained Pedigrees. First she checked in UP pages 63-72. Then we went over the answers. If you missed it, try to check the answers with a friend. There is a quiz on punnet squares on Friday.

Pedigrees

A pedigree is basically a chart to show gene dominance in a family through multiple generations. It shows the gender of the family members and if they have the recessive trait. They can be used to trace gene traits through many generations and to learn where a gene you might have comes from.

Pedigree key

A square indicates a male, and a circle a female. If they are shaded that means they have the recessive trait(EX: rr, tt). A horizontal line connecting 2 shapes indicates a marriage line. A line going down stemming off of a marriage line is a children line, indicating the children the couple had together.

This is a key showing other shapes and their meanings.

This is a pedigree showing a long family line of a certain recessive trait spanning 3 generations.

next scribe... Jackson

Today we worked on Punnet squares for Sex-linked traits, incomplete dominance and co- dominance.

Sex-linked traits are connected to the either the X or the Y sex chromosomes.

We will only be going over traits attached to the X chromosome

example

citruscollege.edu

the above shows how sex-linked traits are passed. Because the gene is recessive, males are more likely to have it because there is no dominant gene to mask the recessive. Therefore, males cannot be carriers

Incomplete dominance is a blending of genes, i.e. Red flower+White flower=pink flower

understandingdnaonline.blogspot.com

Co-dominance is both genes expressed, but remain seperate

i.e. Red fur + White fur = White fur with red patches

Next scribe: Jackson

On Thursday in class, we finished pages 6 and 7 in the notes packet and learned about Punnett squares.

Page 6 and 7 Notes: Test Crossing and Probability

• test crossing: the mating between an individual of unknown genotype and an individual of a homozygous recessive genotype
• test crossing is used to determine the unknown genotype

In Mendel's experiments: a purple flower with an unknown genotype 'B_' (unknown second allele) and a white flower with a homozygous recessive genotype 'bb' are bred. If the genotype of the purple flower is homozygous dominant or 'BB', all offspring will be purple. If the genotype of the purple flower is heterozygous dominant or 'Bb',

some of the offspring will be white.

http://www.monteweston.com/Biology/Coll10.html

• probability: what is the chance that the offspring will exhibit a particular genotype of phenotype?

• What is the chance that two parents will have two girls? There is a 50% chance that each baby is female because the father can give the child either an X (the child is female) or Y chromosome (the child is male). Multiply 50% (or 1/2) by 50% (1/2) to get 25%. There is a 25% that both children will be girls.

UP pg 55-57: Punnett Squares and 1-factor crosses

• Punnett Squares are used to find the different possibilities of phenotypes and genotypes in the offspring of two parents.

If two heterozygous dominant purple flower (Bb) are bred, the offspring possible phenotypes and genotypes include:

Phenotype: purple or white

Genotype: BB (homozygous dominant), Bb (heterozygous dominant) and bb (homozygous recessive)

The Punnett Square for this situation looks like this:

Phenotype: 75% of the offspring will be purple and 25% of the offspring will be white. The ratio of purple to white flowers is 3:1.

Genotype: 25% of the offspring have the genotype BB, 50% have Bb and 25% have bb. The ratio of BB to Bb to bb is 1

:2:1.

This is a 1 factor cross because the we are finding possibilities for just one gene.

http://wiki.answers.com/Q/What_is_a_Punnett_square

With certain genes, an offspring with a heterozygous genotype will exhibit a mixed phenotype. This is called a blending of genes. For example, one parent has curly hair and a homozygous dominant genotype HH. The other parent has straight has and a homozygous recessive genotype hh. The offspring will have the genotype Hh but in this case the dominant gene doesn't completely mask the recessive gene. Instead, the genes "blend" and the child has wavy hair.

http://www.geekinheels.com/2009/11/02/genetic-diagram.html

Homework: UP pg. 45-49 and 55-57 and work ahead if you are ready to.

next scribe: Kiran

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

http://kentsimmons.uwinnipeg.ca/cm1504/mendel.htm

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

Homework:

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

next scribe - Lydia