Tuesday, November 30, 2010

Transcription and Translation

Bridget 11/30/10

  • A chart for reading genetic codes.... know how to read this for the test
  • find first letter in center of circle
  • find second letter in the 2nd row
  • find third letter in 3rd row
  • 61 codes for amino acids- 3 of them, UAA, UAG, and UGA tell the ribosomes to stop making the polypeptide
  • AUG= Methionine but also provides signal to start a polypeptide chain
  • Most codes are shared by all organisms
DNA Replication
  • making exact copies of DNA in nucleus, occurs before cell division(mitosis/meiosis
    enzyme= DNA polymerase

  • molecule of DNA is copied into a complementary strand of mRNA
    enzyme=RNA polymerase

Steps of Transcription:

  1. Initiation- RNA polymerase attaches to the DNA promoter nucleotide sequence on DNA, RNA is made
  2. RNA elongation- RNA grows longer, peels away from DNA, DNA strands come back together
  3. Termination-RNA polymerase reaches the end of the gene (the terminator), polymerase molecule detaches from RNA molecule and the gene
Processing RNA:
  • Prokaryotes- the mRNA is already ready
  • Eukaryotes- need to proccess, add extra nucleotides
  • cap and tail-protect RNA from enzymes, help ribosomes recognize it as mRNA
  • introns- bad, noncoding regions
  • exons- good, cooding regions
  • RNA splicing- introns removed before RNA leaves nucleus
  • Now mRNA is ready!!!!
  • mRNA (Messenger RNA) translated into tRNA (Transfer RNA)
  • mRNA goes to ribosome
  • 2 subunits made of proteins and rRNA (ribosomal RNA)
  • small subunit- binding site for mRNA
  • large subunit- binding site for tRNA
  • tRNA-twists and folds, end of folded molecule=anticodon
  • anticodon recognizes codon on mRNA, then the other end of the tRNA is where an amino acid can attach
  • Bonds between (AA)s ((amino acids)) are peptide bonds
  • The polypeptide that is growing and forming is the protein!!

Steps of Translation:
  1. Initiation- mRNA binds to small ribosomal subunit, tRNA attached to amino acid binds to start codon, AUG on mRNA; large ribosomal subunit binds to small one, which creates a working ribosome
  2. Elongation- amino acids are added to the first amino acid, creating a polypeptide chain
  3. Termination- one of the stop codons tells the translation to stop. Polypeptide is freed ( many A.A), and ribosome splits into its subunits
RNA has:
  • Ribose sugar
  • 1 strand
  • U instead of T
  • smaller than DNA, can go inside/outside nucleus
  • 3 types: mRNA, tRNA, rRNA
Next scribe: Katie!! :)
  • UP 99-110 due 12/2
  • Pre-lab 37- cut out????
  • DNA/ Chicago Tribune Project Due next Tues.

Monday, November 29, 2010


Claire 11/29/10

AZT- has a shape similar to T nucleotide in DNA and binds to the viral enzyme instead of T. Therefor, it blocks spread of HIV virus

Griffith- found "Transforming Factor"-killed harmful bacteria with heat, mixed with living cells of nonharmful bacteria, nonharmful bacteria became harmful. "Transforming Factor" was inherited by originally unharmful bacteria(which changed)

Hershey and Chase- DNA of a virus that is injected into host cells reproduces new viruses.

Franklin (& Wilkins)- Found helical shape (spins around itself) of DNA with x-ray crystallography

Watson and Crick- model of DNA, base pairing(what bonds with what), double helix structure
Earn Nobel Prize with Wilkins in 1962--Franklin died and was not included because they didn't want to give to this award to a female

Double Helix

nucleotide=1 sugar, 1 phosphate, 1 base

nucletides change to DNA through d
ehydration synthesis

Nucleic acid-"polynucleotide"
4 Nucleotides(bases): A=Adenine C=Cytosine T=Thymine G=Guanine

G bonds with C
A bonds with T
form hydrogen bonds with each other

DNA has three rings across, A and G have 2 rings and C and T have one. A and G can't bond because there would then be 4 rings across

T and C=pyrimidines(single ring)
A and G=purines(double ring)

N bases protrude from sugar
sugar-phosphate backbone
sugar=5 carbon ring=deoxyribose(missing oxygen atom)

1 nucleotide= nitrogen base, sugar, phosphate
nucleotides joined by covalent bonds between sugar and phosphate

Chargaff- in DNA, amount of A=amount of T, amount of G=amount of C (proves base pairing)

Sequence of bases in DNA determines kind of gene on chromosome

DNA Replication

occurs in nuclues
Parent DNA untwists, strands separate
N bases attach to complementary base (A to T, G to C)
2 Daughter DNA molecules-rewinds and formed

Polymerases- enzymes that make covalent bonds between nucleotides of new DNA strand
very unlikely to be paired incorrectly
DNA Polymerase and other protiens can repair damaged DNA

DNA harmed by: UV rays, X-rays, viruses

Replication begins at origins(beginning)
goes in both directions-forming a bubble

bubbles can merge

genetic instructions are copied for the next generation

Beadle and Tatum- one gene produces one speacific enzyme/protien/polypeptide

Sections on DNA code for certain amino acids
20 amino acids total

triplet codes-codons(necessary)

G,T,C,A(4) * G,T,C,A (4)= 16 (not enough

G,T,C,A(4) * G,T,C,A (4)*G,T,C,A(4)=64 different triplets(more than enough)

Next Scribe:Bridget

Sunday, November 21, 2010

Scribe Post 11/19/10

In class on Friday, November 19th, we finished up the Genetics note packet, which is chapter 9 in our Biology textbooks.

- occurs when ONE gene influences MANY physical traits

polygenic inheritance - when MANY genes effect ONE physical trait
-explains how parent can have offspring with different eye/skin color that they have

Genetics Disorder Crosses:

disorders include Achondroplasia (Dwarfism), Alzheimer's disease (mental disorder), Huntington's disease (mental disorder/uncontrollable movements), and Hypercholesterolemia (too much cholesterol in blood/heart disease). Requires at least one dominant allele to get these diseases. (Aa)

Recessive disorders include Albinism (white skin/hair/eyes), Cystic fibrosis (excessive mucus in lungs/liver, more vulnerable to infections), Sickle-cell disease (sickled red blood cells, damaged tissues), and Tay-Sachs disease (messed up brain cells). Requires 2 recessive alleles to get these diseases. (aa)

Types of Fetal Testing:
amniocentesis -
extracting SAMPLE of baby's amniotic fluid, baby's cells, and karyotypes to check baby's status

chorionic villus sampling (CVS) - sample of fetal tissue cells from woman's placenta (fetus feeder/cleaner)

ultrasound imaging - uses sound waves to produce an image of the fetus (doesn't harm the baby)

fetoscopy - a tube with a scope is inserted into the uterus for a direct view

family history, blood tests, genetic counseling~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Potpourri (Pedigree Charts too) crosses

Chromosomal Theory of Inheritance -
genes are located on ch
romosomes; inheritance patterns are explained by the behavior of chromosomes during meiosis

Gene Linkage - alleles that are on the same chromosome travel together during meiosis and fertilization which means they're inherited together. They DO NOT follow Mendel's principle of independent assortment.

Y Chromosome - MANLINESS, 1/3 size of X chromosome, has 1/100 as many genes as X chromosome, not much crossing over, passes intact from father to son, can trace ancestry of males based on Y chromosome

Next Scribe: Claire

Thursday, November 18, 2010

Nov. 17, 2010

Scribe Post 11/17/10

Sally Y.

What did we do in class today?

• Went over UP pgs. 63~72

• Pedigree chart

• Homework: Lab #35, UP 92 A-F

• Possibility of a quiz tomorrow or Friday!

Pedigree Chart

What is a pedigree chart?

A pedigree chart is a chart that shows the phenotypes of an organism and its ancestors.

<---------- P1 Generation (Parents)

<---------- F1 Generation (Kids in birth order)

<---------- F2 Generation (Grandkids)

You can identify the phenotypes of each shape by looking at the key!

• every rectangle would be male and every circle would be female

• rectangle filled with only orange, we know that phenotype would be a colorblind male

• rectangle is filled entirely with yellow, it is a male with normal vision

• circle contains only yellow, it is a female with normal vision

• a circle with half orange and half yellow would have normal vision with a recessive gene

Note: If you are unsure of whether or not the gene is homozygous or recessive, leave the second allele blank. DO NOT ASSUME!

Next Scribe: James C

Tuesday, November 16, 2010

Scribe Post 11/16/10

Nov. 16, 2010.

Class contained:
Sex linked crosses
Blood type crosses
Incomplete dominance (blending phenotype ONLY)
Co-dominant (both traits show up)
Notes pages 8-9, and 12
Homework: Pages 63-72 and the extra credit and Lab 34

I. Sex linked Crosses
A. Genes are located only on sex chromosomes for sex-linked crosses
1. Mostly on the X chromosomes

This is how a sex-linked cross punnet square would look like:

There is no trait on the Y chromosome.

II. ABO Blood Groups

A. Types of blood
1. A= IAIA or IAi (DOMINANT)2. B=IBIB or IBi

Story time.

As Ms. Dillion says, If Sally had a baby, and she forgot who the father was, they could find the blood type of the baby, of Sally, and find the blood type of Sam, Joe, and Kevin.

Let's say Sally had 2 babies. One with blood type AB and one with O.
Sally's blood type is IBi
The father's blood type must be IAi. Congrats Kevin.

III. Incomplete Dominance
A. "Blends" together.
1. There is no dominant trait.
i. The "middle trait"

EX. If a red flower and a white flower cross, there will be pink flowers because there is no dominant color, they BLEND

IV. Co-Dominant
A. Both traits show up
1. They do not blend.
i. The traits are both dominant

If a black feathered chicken crosses with a white feathered chicken and both white and black are co-dominant, then their chickies will have black and white feathers, not gray because THEY DO NOT BLEND. THEY ARE BOTH DOMINANT COLORS.

SCRIBE: Sally.

Monday, November 15, 2010

Scribe Post 11/15/10


used to determine true-breeding variety of plant (A_ x aa  cross an unknown dominant phenotype with a homozygous recessive to determine if second allele is A OR a.)

2-Factor Crosses:

2 traits being passed on
- probabilities
2 coins flipped simultaneously.
Chance of tails/tails? 1/2 tails x 1/2 tails = 1/4.
- phenotypes
ratios, what you see
- genotypes
ratios, genes

*Within each trait, dominant allele before recessive.
*stay in the order of the traits that you are given
ex. SSyy
Lab #34:
Mendel's Lawsknow these!!
-law of dominance
-law of segregation
-law of independent assortment

Read carefully!!

Finish Lab #34, UP p.59-62

Make sure you understand Meiosis and Mitosis!!!

Next Scribe: CJ

Sunday, November 14, 2010

Scribe Post: 11/12/10


Today was a busy day in Bio 173!!
We started off with a spot of notes; Set 2, Mendels's Laws, Pgs. 2-5


-Parents pass on heritable factors to their offspring, which in turn, retain individuality generation after generation.
- Self vs. Cross Fertilization are different ways an organism may reproduce.

  • Self fertilization, occuring in flowers, consists of two gametes being formed within one organism. This type of reproduction does not need another organism to reproduce.
  • Cross fertilization, occuring in humans, consists of one gamete being formed in each individual and the other in another individual. This type of reproduction needs two individuals with diferent gametes.

- The first generation are call P for parent generation. The following generations that follow are F1, F2, F3 and so forth.

- Hybrids (Aa)- the offspring of two different true breeding varieties (AA+aa)

- Monohybrid Crosses- 1 trait being passed

- Allele- alternative forms of a gene

- Dominant vs. Recessive- AA (dominant) vs. aa (recessive)

- Genotype- Our genetic structure (non-visible); AA, Aa, aa

- Phenotype- What we can see; Physical traits (visible); tall, short, freckles..ect.

- Homozygous- same; AA or aa

- Heterozygous- Different; Aa

Mendel's 2 Principles

Mendel's principle of segregation:

- Pairs of alleles separate during gamete formation

Mendel's principle of independant assortment:

- each pair of alleles segregates independantly of the other pairs during gamete formation (meiosis)



Thursday, November 11, 2010

November 10


Human Genetics

Today we reviewed meiosis for the quiz on Friday.

We did UP pg. 41 which measured the classes' different genetic traits such as tongue rolling, cleft chin, and Widow's peak.

We were also introduced to different terms on UP pg. 43-44.

Homozygous- two like genes for a given trait
ex. AA and aa

Heterozygous- has two different gene forms for a given trait.
ex. Aa

Phenotype- What a thing looks like
ex. What is the phenotype of a white cat? white.

Genotype- Genes that give the phenotype
ex. D (geno)= Dimples (pheno)

Complete Dominant Traits:

Dominant Gene- the gene that shows up in the heterozygous condition.

Recessive Gene- a gene that will give a phenotype only when in the homozygous condition.

Incomplete Dominant Traits- Neither gene is "hidden", both are expressed
ex. RR=red Rr=pink rr=white

Pure Breeding- organisms with genes only in the homozygous condition
ex. AA aa

Hybrids: (Aa, Gg)

Monohybrid- 1 trait
ex. Aa

Dihybrid- 2 traits
ex. AaBb

Trihybrid- 3 traits
ex. AaBbRR

This is where Punnet squares come in.

For Monohybrids, it is a 2 x 2 cross

For Dihybrids, it is a 4 x 4 cross

For Trihybrids, it is an 8 x 8 cross

- EC UP pg. 39-40
- Read Ch. 9 pg 142-168

Next scribe: Aliza

Tuesday, November 9, 2010

Nov. 9

Today we finished the notes packet of Meiosis, did a demo of meiosis using
beads and magnets, and started the lab on UP 19-37.


Nondisjunction: The chromosomes fail

to separate at Anaphase I or II. Occurs

with autosomes or sex chromosomes.

Nondisfunction causes some syndromes like
Klinefelter syndrome for males and Turner
syndrome for females.

Those syndromes cause almost like a steroid effect. For the people effected by these syndromes, they may become sterile.
Klinefelter syndrome: males, XXY: have 47 chromosomes instead of 46
Turner syndrome: females, XO: have 45 chromosomes and only one X chromosome.
Breakage of a Chromosome:
Deletion: part of chromosome is lost or removed
Duplication: a region of the chromosome is repeated
Inversion: a segment of the chromosome repositions and reverses the order of the genes

Translocation: one part of a chromosome goes on another chromosome and that piece cannot be found

next scribe: Kristin

Monday, November 8, 2010


Yunsu Y.
Today we took notes on MEIOSIS.

Meiosis goes through reduction division, 2 part division. Reduction=reduce , Division= Separate sister chromatids. Meiosis occurs in the ovaries or testes. It starts with a diploid parent cell then goes into prophase 1, metaphase I, anapahse I, telophase I, prophase II, metaphase II, anaphase II, then telophase II. The cell goes through each step twice but it does not really go through interphase II. It "goes" through interphase II, but it is just a resting period, it does not go through the same steps like in interphase I because it does not need to synthesize more chromosomes. (No G1, S, or G2 just stays the same.) These phases are very similar to mitosis, but are slightly different and have different end products.

1. Metaphase I: the homologous pairs of chromosomes called tetrads, line up in the middle.
2. Telophase II: instead of having 2 daughters cells, like in mitosis, you end up with 4. They also are not genetically identical.

Through meiosis, egg and sperm (gametes) cells are produced, not like mitosis where many different kinds of cells can be produced. Remember because this is sexual reproduction there are variations among offsprings. This variations amoung offspring occurs because of independent assortment and random fertilization.

1. Independent Assortment: when the chromosomes line up, there is no specific way it is all by chance.
2. Random Fertilization: a random pairing of 1 egg to 1 sperm, many different combinations.

Crossing over: where genetic material gets exchanged, segments of homologous chromatids.
-Crossing over happens because the genetic material gets tangled and they cross, so when they divide the daughter cells are not all the same. This would occur in prophase I.
There are somatic cells and sex cells---
1. Somatic cells: out body cells which are diploid -46 chromosomes for humans.
2. Sex cells: Sperm and egg which are haploid -23 chromosomes for humans.
-The end products of meiosis are sex cells that are haploid cells (n) and the parent cells in the beginning are diploid cells (2n). The diploid is the total number of chromosomes, 2 sets. Haploid is half the number of chromosomes.
★It is important to remember that end products of meiosis are haploid. They have to be haploid so that when an egg meets a sperm it can create a full human equaling 46 chromosomes. (23+23=46)
-Each human has sex chromosomes, usually 2. Females have XX and males have XY, so since 2 are sex chromosomes there are 44 leftover chromosomes. These are called autosomes. (not sex)

These are karyotypes of female and males humans.
-On the left is the female and on the bottom is the male. You can tell by the difference of the last 2 sex chromosomes.
-You can see that the first somatic chromosome is the largest and the last somatic chromosome is the smallest.

We also watched a video on meiosis:
1. There are 4 egg cells and 4 sperms cells produced. All 4 of the sperm cells are viable but only 1 of the 4 eggs will be used and mature, the other 3 eggs are useless.
2. Centrioles move before the second division, making a right angle to the first location of the centriole at the first division.

Homework: UP. pgs 15-16B, Study Meiosis, Read Up pgs 13-14, Cut out pg 21 for tomorrows lab

Next scribe: Carey E