Scibeost 11/30/10

Homework:

Packet pages 30 and 31

Today in class we talked about Meiosis. Meiosis is the process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Meiosis looks like this

Today in c;ass we also talked about Genetics. we went over some word like:

Allele- which is a form of a gene represented by a single letter(ie: a, A)

Homozygous-a homozygous has to like genes for a given trait, AA, BB, zz, dd.

Phenotype-the result of a genotype in regards to it's function or appearance. What a thing looks like (its traits).

Genotype-Genes that give a phenotype.

We talked about Gregor Mendel. He was the founder of genetics and also created the Punnentt Square.(below)

12.2 The Structure of DNA

What is DNA? DNA is a nucleic acid made up of nucleotides joined into long strands or chains by a covalent bonds. Nucleic acids are long molecules found in cell nuclei. They are made up of smaller subunits or parts. These parts consist of three basic parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base. All the parts are linked together to form long chains.

Nitrogenous bases are bases that have nitrogen in them. DNA has four kinds of nitrogenous bases which include adenine, guanine, cytosine, and thymine. Each of these bases are held together by a hydrogen bond. In order for the bases to be with their partner in order to work called base pairing. Therefore, A (adenine) goes with T (thymine) and C (cytosine) goes with (guanine).

Erwin Chargaff had discovered that the percentages of A and T bases are almost equal in any sample of DNA which also works for G and C. DNA samples from organisms as different as bacteria and humans obeyed this rule, but no one knew why they did.

James Watson and Francis Crick tried to understand the structure of DNA. They tried to build many models of the possible DNA structure out of cardboard and wire. But nothing ever worked. Then, in 1953 Watson saw a copy of Franklin’s X-ray picture and suddenly figured out the missing piece. Later on, he ran to Crick to tell him that they had figured out the structure of DNA which was called the double-helix model. In a double-helix model two strands of DNA run in opposite directions and explains Chargaff’s rule of base pairing and how the two strands of DNA are held together.

13.1 Notes

The Role of DNA

• Cell separates the two strands od DNA and then uses base pairing to make a new complementary strand for each.

RNA: like DNA, is a nucleic acid that consists of a long chain of proteins.

• Genes contain coded DNA instructions that tell cells how to make proteins.

1. First step, copy base sequence of DNA into RNA.
2. Second step, RNA uses these instructions to direct the production of proteins.(determin characteristics of an organism.)

Comparing RNA and DNA

RNA                                                                      DNA
1. sugar is ribose                                                 1. sugar is deoxyribose
2. single stranded                                                2. double stranded
3. contains Uracil                                                 3. contains Thymine
4. leaves Nucleus and goes to Ribosomse         4. stays at Nucleus

• Because of differences enzymes can tell them apart

Functions of RNA

• Controlls the assembly of amino acids into proteins. Different types of RNA molecules specializes in different jobs.
• 1. Messenger RNA( mRNA): Carries instructions for proteins from the Nucleus to ribosomes in the cytoplasm.
• 2. Ribosomal RNA( rRNA): Forms an important part of both subunits of the ribosome.
• 3. Transfer RNA( tRNA): Carries amino acids to the ribosome and matches them to the coded mRNA message.

Transcription:
Segments of DNA serve as templates to produce complementary RNA molecules.

• In prokaryotes RNA synthesis and protein synthesis take place in cytoplasim.
• In eukaryotes RNA is poduced in Nucleus and then moves to cytpolasm to produce proteins

Transcription requires an enzyme RNA polymerase

• 1. Binds to DNA during transcription and separates DNA strands.
• 2. Uses strand of DNA as a template to produce a complementary strand of RNA

Promoters

RNA polymerase knows where to start and stop making a strand of RNA

• It binds to promoters, regions of DNA that have specific base sequence.
• Promoters signal in DNA molecule that show RNA polymerase exactly where to begin making RNA

RNA Editing

• RNA molecules need editing before they can be read.
• pre-mRNA molecules have bits cut out of them before they can go into action.

Introns: the portions that are cut out of the pre-mRNA also known as Exons( in eukaryotes) but the introns are taken out in the nucleus. The remaining pieces are then sliced back together to form the final mRNA.

• Introns and exons may play a role in evolution, making it possible for very small changes in DNA sequences to have dramatic effects on how genes affect cellular function.

             

13.2 Ribosomes and Protein Synthesis

The Genetic Code

Polypeptides are when amino acids join together to make long strands. 20 different amino acids are found in Polypeptides.

A,C,G, and U (adenine, cytosine, guanine, and uracil) the letters are called the genetic code. The genetic code is read three letters at a time, so that each "word" is three bases long and corresponds to a single amino acid. Each word is called a condon.

How to Read Codons

If you are trying to decode UGG

first go to the U the work your way to the next letter then after that the next letter.

If you match it up right you will get Tryptophan.

Start and Stop Codons

AUG (methionine) is a start codon which means that the strand starts there.

Then there is a stop codon which signals when the strand stops.

Translation

Once the polypeptide is complete it folds into its final shape.

The decoding of an mRNA message into a protein is called translation.

STEPS

1)mRNA attaches itself to a ribosome. tRNAs bring the right amino acids into the ribosomes. The ribosome then begins to attach the right amino acids onto the growing chain.

Each tRNA carries just one type of unpaired amino acid and it is called anticodon.

2)Form a peptide bond once the anticodon finds its match.

3)the polypeptide continues to grow until it reaches the stop codon.

Roles of tRNA and rRNA in Translation

tRNAs role is to decode mRNAs message so that the ribosome can find the right amino acid for the spot.

rRNAs role is to keep ribosomal proteins in place and to find the beginning of the mRNA message.

The Molecular Basis of Heredity

Basically that once polypeptide becomes a protein is when you start to get your skin color, pigment, hair color, eye color, and so on. Proteins are enzymes which produce a chemical reaction in which all of those happen.

Yes you may be thinking these notes are short, but thats because it was only about three pages.

LEGEND

Scribepost 11/15/2010

Scribepost 11/15/2010

Homework:

.13.1 and 13.2 notes due wednesday

.Tribute article due next monday

Today in class we started out with an open note quiz on 12.2 and 12.3 notes and in class notes we have been taking during class. After the quiz we went over it and were given the answers. Then Mr. Paek splatter DNA on Quinn's desk and he called it boogers.

The DNA came from a lab we were supposed to do last week but Mr. Peak forgot so we didn't get to see it happen.

Class Notes:

.DNA polymerase (unzips) the DNA strand to replicate the DNA

.Once the DNA is split a copy is added to form two new DNA strands

.DNA becomes RNA so that it can fit through the necleus membrane

DNA compared to RNA:

RNA DNA

1. Has ribose sugar 1.Has deoxyribose

2.Single stranded 2.Double stranded

3.Contains Vracil 3.Contains thymine

Types of DNA

.mRNA-Messenger RNA produced in nucleus then travels to cytoplasm

.rRNA-Makes up ribosome

.tRNA-Transfers RNA and carries amino acids

That is all for todays scribepost thank and come again. Also watch out for Mr. Paek he is flinging DNA all over the place.

12.3 DNA Replication

Key Terms:

Replication: This process occurs late in the interphase of the cell cycle, it ensures that each cell has the same complete set of DNA molecules.

DNA polymerase: It is an enzyme that joins individual nucleotides to produce a new strand of DNA.

Telomeres: DNA at the tips of chromosomes.

Histones: Proteins around which chromatin are tightly coiled.

Notes

Replication is when the DNA separates into two strands forming replication forks and then following base pairing they get complementary strands. (Such as A-T or C-G)

Enzymes: Replication is done by many enzymes the first separating the DNA molecule by breaking the hydrogen bonds between base pairs. When they separate each strand gives an outline for what complementary base it needs (A-T, C-G). The enzymes are named for their function since they are specific. The primary enzyme is DNA polymerase (see Key Terms). Another function enzymes perform is making sure that each new DNA strand is a copy of the original.

Telomeres: Telomerase replicates it, because it is difficult to replicate. Since it rapidly divides it helps genes not be damaged.

Prokaryotic DNA replication: Occurs during the S phase of the cell cycle. DNA is found in a single, circular, DNA molecule in the cytoplasm. Replication doesn't start until the regulatory proteins bind to a single spot on the chromatin. KEY: Replication in most prokaryotic cells starts from a single point and proceeds in two directions until the entire chromosome is copied.

Eukaryotic DNA Replication: Occurs during the S phase of the cell cycle. Their DNA is in the nucleus packaged into chromosomes. Eukaryotic chromosomes are bigger than prokaryotic cells. Key: In eukaryotic cells, replication may begin at dozens or even hundreds of places on the DNA molecule, proceeding in both directions until each chromosome is completely copied. Proteins check for damage or mismatched base pairs before the DNA is replicated, but sometimes they are replicated and base sequences may be changed and cause bad side effects. The two new DNA copies are separated at anaphase.

Period 8 November 10 Scribepost

We started the day with the following:


Announcements:
          Mr. Paek told us our homework, passed out our progress reports which had our test grades, passed out a new packet and calander for the month and told us about an assignement that is due November 23rd. The assignement is in the new packet "It's In Your DNA!" on page 3. He also showed us examples of papers that have been already completed. All in all the assingement is a paper about how you discovered the way DNA looks like(double helix). Ask Mr. Paek for more info. :)

Homework:
          Like I said before the homework is the assignement that is due on November 23 and the other homework is in the new packet "It's In Your DNA!" on page 7 and 8 that are due friday.

In Class:
          Mr.Paek made a power point and handed out another fill in the blank packet ( STS Biology Genetics I Student Notes) to the slide show so we can make notes on it.

This is how many notes we took so far:

Researchers involved in the Discovery of DNA

Watson and Crick won the Nobel Prize for discovering structure of DNA in 1953 however Rosalind Franklin helped with the discovery but she died an an anonymous person because Watson and Crick took all of the credit.

Model of DNA



                                                                         





DNA Structure: deoxyribonucleic acid.
1. Deoxyribose- 5 carbon sugar.
2. Phosphate group- PO4.
3. Nitrogen bases-connected together by H bonds.

Nucleotide: are the single units that make up nucleic acids

Double Helix- 2 strands connected together by a nitrogen bond.

Types of Bases: Purines and Pyrimidines.

Purines: Adenine (A), Guanine (G)

Pyrimidines: Thymine (T), Cytosine (C)

                                           -And thats all the notes we took.


         Our class also had a discussion about cloning: how it is illegal, what we know about it, any movies with cloning in it, and what our opinions are on it. We also discussed stem cell research. We debated on if it is okay to do so or just plain bad. Did you know that the embryo already has a heart beat by the time of 6 weeks? And at the end we had about three minutes to work on our homework: pages 7 and 8 in the new packet.


                                     Clones :) ( so cute )




                    Stem Cell Research

Thats all for today :)

ScribePost 10/29/10

Hello fellow classmates

Just to let you know, this scribepost is from last week so don't get it confused with this weeks.



We started class with a Disease For The Day!!!

It was Schistosomiasis. The agent for disease is a worm parasite.

Schistosomiasis causes over 1 million deaths per year in the world. The parasite lives in a snail. It is treated with antiparasitic drugs. A result of the disease is death and an enlarged stomach.

The Lab

The lab starts on pages 13 in the unit packet and ends on page 18. The lab was to swab any three places in the classroom any transfer that area by putting it on a petri dish with a kind of geletin that would keep the bacteria on the dish. Once we did that we were done with that part of the lab, because we had to put the bacteria cultures into an incubator which is sort of like an oven but it only goes up to a certain temperature that the bacteria thrives at. The next part of the lab was to swab another petri dish with broth culture of peppercorn bacteria, and then put a paper disk as the control in one quadrant, and three antibiotic disks in three seperate quadrants. And then Mr. Paek put the petri dish for each group into the incubator.

Homework: None!!!

It would be a good idea to read section 20.3 but you do not have to take notes on it.

11/1/10 Blog

Hellooo period 8 Bio-ers! Here is a recap on what happened today.

1) Mr. Paek talked about a new project: A post card to sent to your technology hating grandma Gurtrude about a new virus epidemic (you choose what one) and send a post card telling her how to prevent it. Look on UP page 2 for more information.

2)We finished the bacteria lab that we started last Friday by checking the petri dishes and seeing the growth of the bacteria that grew. According to some people, it smelled bad....but whatever. Then you finished the remaining questions about the lab.

3)Third and Finally, we watched a BILL NYE THE SCIENCE GUYY video about bacteria.

Annddddd thats about it!

REMEMBER: THE POST CARD IS DUE NEXT MONDAY!
HOMEWORK: 35.2 NOTES!

35.2 Defenses Against Infection Texter

The section of pages that you should have read were section 35.2, pages 1014 to 1019. The book talked about how your body protects yourself from infectious diseases.

The first barriers of defense your body has for protecting you from disease is your skin. Your skin is a thick barrier that keeps most of the diseases out of your body. But, microbes can still find ways into your body through your eyes, nose and mouth. Fortunately, they too have their own way of defending you. Your eyes protect you by using lysozyme, which is an enzyme that breaks down bacteria cell walls. The nose creates mucus that traps pathogens and your stomach acid kills most of the things that you swallow. If a pathogen doe enter your body the immune system uses its secondary line of defense that includes raising your body temperature (fever), inflammation response and interferons.

The inflammatory response is when infected areas becomes inflamed and painful because of histamines which cause increased blood flow to the infected area. When this occurs the amount of white blood cells in the area greatly increase because they are destroying the invading bacteria. Interferons are certain cells that interfere with virus growth by producing proteins that don’t allow the viruses to grow. A fever is your body’s way of slowing down or stopping the growth of pathogens. It is caused when the immune system releases certain chemicals that increase body temperature.

The immune system defenses distinguish your body’s own cells from harmful other cells. A healthy immune system recognizes its own cells and knows that they are not harmful. Your immune system also recognizes harmful cells. When a harmful cell invades your body your body attacks it and then remembers it so that if it ever attacks again your body will recognize it faster, this is known as immune response. Antigens are a foreign substance on a harmful cell that the immune system recognizes and tags to be destroyed. When it senses antigens it increases the amount of cells that kill the invaders. Antibodies tag antigens for destruction. Each antibody is made specifically for one type of cell only.

B-lymphocytes are cells that travel to the invasive cells and are created in red bone marrow. T lymphocytes are the cells that are made in the bone marrow but mature in the endocrine gland. They work together to locate and destroy invasive cells. The humoral immunity depends on the response activated when antibodies embedded on B cells hold onto antigens of invading cells. An antigen binds to an antibody and then waits for a T cell to stimulate the division of the B cells.

Plasma cells produce antibodies that are moved throughout the bloodstream. These antibodies float around and mark cells of pathogens. Healthy adults produce around 10 billion different types of antigen that allows the immune system to respond to virtually anything that enters the body. Memory B cells are the cells that remember the pathogen that the body fought off. After an infection is gone the plasma cells that destroyed it die. The memory B cells remember it and if it ever comes back it will know which plasma to make. In the long term it allows your body to build up immunity to it.

Cell mediated immunity guards the body against viruses, fungi, and single celled pathogens that take over and use the bodies own cells. It also protects the body from itself if any of its cells become cancerous. If a cell is infected with a pathogen the cell displays a little of the antigen on the outer surface and marks it to be destroyed.

This activates cytotoxic T cells, which hunt down the infected cells and kill them by puncturing their membranes or apoptosis. The memory T cells help the immune system detect if the same pathogen enters the body again. Suppressor T cells help the immune system stay in check once the infection is under control and also inhibit autoimmune deficiencies. Although cytotoxic T cells are useful to the body, they make organ transplants difficult because they recognize the organ as not itself and it tries to attack it. This is why organ transplant patients usually have to take medications the rest of their lives.

Now that you read this you should have a good idea about how the immune system works, and what it does. Thank you for reading. 8^th Period Mr. Paek’s BIO Rocks!!!!!!!