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nucleic acids and protein synthesis


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what does each polypeptide chain contain
a combination of any or all of the 20 different amino acids.
what is ribosomal RNA
it makes up the major part of the ribosomes
what is a codon
a three letter code word that specifies a particular amino acid that is to be placed in the polypeptide chain.
what is an initiator codon
a codon that serves as a starter for the synthesis of a protein......AUG
what are the three stop codons and what do they do.
UAA, UAG, UGA......they signify the end of a polypeptide
How does a messenger RNA molecule acutally produce a polypeptide
by translation
describe the method of translation
1. the t- RNA carries amino acids to the ribosomes
2. the amino acids are joined together to form polypeptides
what is transfer RNA
a single strand of RNA that loops back on itself.
what is an anitcodon
the three transfer RNA nucleotides that match up with the exposed bases on the
describe the process of protein synthesis that takes place in the ribosomes.
1. two subunits of the ribosome bind to a molecule of messenger RNA.
2. the initiator codon AUG binds to the first anticodon of t-RNA.
3. the anticodon of another transfer RNA binds to the next messenger RNA codon.
4. the seccond transfer RNA carries the second amino acid that will be placed into the chain of the polypeptide.
5. a peptide bond forms between the two amino acids.
6. this chaing keeps growing until the ribosome reaches the stop codon on the messenger RNA.
Why does DNA replicate
so that the DNA remains in the safety of the nucleus, while the RNA goes to the protein building sites in the cytoplasm
what are the three main differences between DNA and RNA.
1. sugars: DNA-deoxyribose, RNA- ribose
2. strands:DNA-double, RNA-single
what is a peptide bond
the covalent bond that joins two amino acids together.
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what bases pair in RNA
true or false: the RNA molecule being synthesized is different form the molecule being copied
what is transcription
the process by which a molecule of dna is copied into a complementary strand of RNA.------ the process of transferring information from DNA to RNA.
why is it necessary for DNA to transfer its genetic information to RNA.
because DNA does not leave the nucleus- a messenger or carrier must bring the genetic information from the DNA In the nucleus out to the ribosomes in the cytoplasm
what does messenger rna do
it brings the genetic information from the DNA in the nucleus out to the ribosomes in the cytoplasm
describe polymerase
the polymerase works on the polymers RNA and DNA.
What happens during transcription
1. the RNA polymerase attaches to special places on the DNA molecule.
2. the double helix is seperated into two strands.
3.the polymerase synthesizes a messenger RNA strand.
4. the m-RNA strand is complementary to one of the DNA strands.
5. The base pairing mechanism ensures that the messenger RNA will be a complementary copy of the DNA strand that serves as its template
What kind of information is contained in DNA
four nitrogenous bases that contain information that directs protein synthesis.
what do proteins do within the cell
1.they control biochemical pathways within the cell the synthesis of lipids, carbos, and nucleotides,
3. responsible for cell structure and cell movement
What are proteins made of
by stringing amino acids together to form long chains called polypeptides.
what helped watson and crick figure out the structure of dna
they saw franklins x-ray pattern and realized that there was something important in that pattern
what was the shape of the dna strand
double helix that was similar to a spiral
describe the characteristics of the double helix
the nitrogenous bases are positioned exactly opposite each other. THis positioning allows weak hydrogen bonds to form between the bases A and T, C and G.
How did erwin chargaff's information help watson and crick
the # of A molecules was equal to the # of T molecules..... also C and G.
what is base pairing
the force that holds the two strands of the DNA double helix together
when was all the work on Dna acknowledged and who was awarded
in 1962- nobel prize for medicine or physicalogy was given to watson, crickl, and maurice wilkins-----franklin was dead at the time and not awarded
describe replication of a dna strand
1. enzymes unzip the two strands of the double helix.
2. enzymes insert the appropriate bases
3. produce covalent sugar phosphate links to extend the growing Dna chains.
4. enzymes proofread the bases
when does the unzipping of the double helix occur
when the hydrogen bonds between the base pairs are broken and the two strands of the molecule unwind.
what is RNA.
the nucleic acid that acts as a messenger between DNA and the ribosomes and carries out the process by which proteins are made from amino acids..
what are ribosomes
the organelles in which proteins are made.
what did martha chase and alfred hershey want to find
the kinds of viruses that infect bacteria.
what are bacteriophages
bacteria eaters
what are bacteriophages composed of
a DNA core and a protein coat.... they attach themselves to the surface of a bacterium and then inject a material into the bacterium
how do bacteriophages spread
1. the injected material begins to reproduce.
2. the bacterium bursts
3. infects other cells and each contains the genetic code.
How did chase and hershey find out if either the protein coat or the dna was the material that was injected in the bacterium
1.added radioactive sulfur-35 to one batch
2.added radioactive phosphorus-32 to the other.
3. sulfur-35 and phosphorus-32 are radioactive isotopes--used as tracers to follow the pathway of certain materials
4. protein was labeled with sulfur-35
5.Dna was labeled with phosphorus-32
6. they mixed the labeled viruses with the bacteria
7.all the radioactive phosphorus had entered the bacteria
8. dna contains the genetic information.
Dna is a polymer formed from units called nucleotides.....describe these nucleotides
a molecule made up of three basic parts--- 5-carbon sugar:deoxyribose, phosphate group, and a nitrogenous base.l
what are the four nitrogenous bases
adenine, guanine, cytosine, thymine
what bases are purines
adenine and guanine
what bases are pyrimidines
cytosine, thymine
describe the polymer chain
sugars and phosphate groups form the backbone,,,,,,nitrogenous bases stick out ffrom the chain.
What did mccarty, macleod, and avery want to discover
what molecules were responsible for transformation
What did Rosalind franklin do
1. purified a large amount of dna
2. stretched its fibers in a glass tube so the strands were parallel.
3.aimed a narrow x-ray and recorded the pattern on film.
4.the x-ray difracts the matter
5. the scattering produces a pattern that is important to the structure of many molecules
what did rosalind franklins patterns show
1.the fibers that make up dna are the strings on a rope
2.large groups of molecules in the fiber are spaced out at regular intervals along the lenth of the fiber
What were watson and crick trying to solve
the mystery of dna structure by building three dimensional models of the atomic groups in dna.
describe avery,mccarty and macleods experiments
1.made an extract from the heat killed bacteria.
2. they put enzymes that kills lipids, proteins, and carbos in the extract.
3.the transformation still occured
4.they repeated the experimentusing enzymes that would break down RNA.
5. the transformation still took place
6.used enzymes that would break down DNA.
7. the transformation didnt occur.
8. DNA was the transforming factor.
9.DNA carries the genetic code.
describe the genetic code
is the way in which cells store the program that they seem to pass from one generation of an organism to the next generation
What was Frederick Griffith studying
the way in which certain types of bacteria casue the diseasse pneumonia
describe Griffiths experiments of bacteria
1. he had two different strains-types- of pneumonia bacteria.
2. the disease causing strain was smooth.
3. the harmless bacteria strain was rough.
4. He injected mice with the smooth strain-the mice died.
5. he injected mice with the rought strain-the mice were fine.
6. he injected a heat killed smooth strain into the mice-the mice were fine.
7.he proved that the cause was not a chemical poison released by the disease causeing bacteria
describe griffiths experiment with transformation.
1.injected mice with a misture of the harmless strain and the heat killed strain-the mice developed pneumonia.
2. the heat killed strain passed its disease causeing ability to the live harmless strain.
3. he recovered bacteria from the animals that had developed pneumonia.
4. one strain of bacteria had been transformed into another
what is transformation
when one strain of bacteria has been transformed into another.
what did griffith hypothesize
when the harmless bacteria and the heat killed bacteria were mixed a factor was transferred from the heat killed to the live cells.

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