Term
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Definition
| Conclusions: chemical component of a pneumonia-causing bacterium could transform a harmless variety of the bacterium, and all of it's decendants into the harmless form |
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Term
| how many types of building blocks does DNA have? |
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Definition
| 4 types: Adenine, Thymine, Cytosine, Guanine... known as nucleotides |
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Term
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Definition
| Conclusions: showed that DNA is the genetic material of a virus called T2, which infects the bacterium, E Coli. |
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Term
| What are bacterial viruses called? |
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Definition
| Bacteriophages (phages, for short) |
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Term
| Where is the DNA in a phage? |
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Definition
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Term
| Why did Hershey and Chase use Sulfur and Phosphorus? |
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Definition
protein contains sulfur and DNA does not. Therefore as new phages were made, the sulfur atoms woudl only be incorporated into their protiens.
Used Phosphorous because nearly all of the phage's phosphorus is located in the DNA |
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Term
| Online Hershey and Chase's experiment |
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Definition
1) alloed the two batches of T@ to infect separate samples of nonradioactive bactiera
2)after the onset of infection, agitated the cultures in a blender to shake loose any parts of the phages that remains outside the bacterial cells.
3)spun the mixtures in a centrifuge. Cells were deposited as a pellet at the bottom of the centrifuge tubes, but phages and part of phages, being lighter, remained in the liquid
4)measured the radioactivity in the pellet and in the liquid |
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Term
| what did Hershey and Chase find? |
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Definition
1) when the bacteria had been infected with T2 phages ontaining labeled protein, the radioactivity ended up mainly in the liquid, which contained phages, but not bacteria... this suggested that the phage protein did not enter the cells
2)when the bacteria had been infected with phages whose DNA was tagged, then most of the radioactivity was in the pellet, made up of bacteria...when the bacterial cells lysed open and released new phages, they contained radioactive phosphorous in their DNA, but no radioactive sulfur in their proteins |
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Term
| what caused the T2 cells to produce additional phage DNA and proteins (new complete phages) |
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Definition
| the injected DNA molecules |
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Term
| what convinced Hersey and Chase that DNA, rather than protien, is the genetic material of phage T2? |
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Definition
| radioactively labeled pahge DNA, but not labeled protein, entered the host cell during infection and directed the synthesis of new viruses. |
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Term
| how are the atoms in DNA bonded? |
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Definition
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Term
| What essentially is DNA and RNA? |
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Definition
| DNA and RNA are nucleic acids... consising of long chains (polymers) of chemical subunits (monomers) called nucleotides |
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Term
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Definition
| building block of a nucleic acid; made of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group. |
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Term
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Definition
1)A polymer consisting of many nucleotide monomers
2)serves as a blueprint for proteins and cellular activities
3) two types: DNA and RNA. |
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Term
| what are the different types of nucleotides that make up DNA? |
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Definition
A: Adenine
T: Thymine
G: Guanine
C: Cytosine
G:
C: |
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Term
| What are the three components of a nucleotide? |
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Definition
1) nitrogenous base
2) a sugar
3) phosphate group
joined together by covalent bonds between the sugar of one nucleotide and the phosphate of the next |
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Term
| What is the sugar-phosphate backbone? |
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Definition
| the result of the covalent bonds between the sugar of one nucleotide and the phosphate of the next.... A repeating pattern of sugar-phosphate-sugar-phosphate.... nitrogenous bases are appendages along this backbone. |
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Term
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Definition
| has a phosphorous atom in the center; source of acid in the nucleic acid |
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Term
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Definition
| has 5 carbon atoms; 4 in its ring and 1 extending above the ring. the ring also includes and oxygen atom. sugar is called deoxyribose because compared to the sugar, ribose, it is missing an oxygen atom. |
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Term
| where does the nucleic part come from in the name of DNA? |
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Definition
| DNA's loaction in the nuclei of eukaryotic cells |
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Term
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Definition
| has a ring of nitrogen and carbon atoms w/ various functional groups attached; in contrast to the acidic phosphate group, nitrogenous bases are basic. |
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Term
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Definition
| Thymine and Cytosine; single-ringed structures |
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Term
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Definition
| Adenine and GUanine; larger double-ringed structures |
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Term
| Differences between RNA and DNA structurally |
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Definition
1) sugar is ribose in RNA and deozyribose in DNA
2) ribose has an -OH group attached to the C atom in its lower right corner.
3) instead of Thymine, RNA has a nitrogenous base called Uracil (U) |
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Term
| Similarities between DNA and RNA |
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Definition
| both are polymers of nucleotides... nucleotides consist of a sugar + a nitrogenous base + a phosphorous group |
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Term
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Definition
| invented the X-Ray crystallographic machine |
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Term
| what the the diameter of the DNA delix? |
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Definition
| a uniform 2 nm w/ nitrogenous bases stacked about 1/3 of a nanometer apart. |
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Term
| Why must the purines always be paired with the pyrimidines? |
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Definition
| because the the larger, double-ringed purines paired together would bulge, making the diameter of the DNA not uniform |
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Term
| Each base has chemical side groups that can best form hydrogen bonds with one appropraite partner. what are these partners? |
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Definition
1) Adenine and Thymine
2) Guanine and Cytosine |
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Term
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Definition
1) removed DNA from the Smooth ER and inserted it into the rough ER
2)smooth's genetic material "took over" the rough's, causing the rough coat to grow a "jelly-like" coat and become active
3) conclusive evidence indicated DNA was the genetic material |
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Term
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Definition
| discovered the amount of adenine in the DNA was equal to the amount of Thymine. the amount of guanine was equal to the amount of cytosine |
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Term
| How is the sugar-phosphate backbone oriented? |
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Definition
| in opposite directions of each other |
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Term
| is there any restriction on the sequence of nucleotides along the strand of DNA? |
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Definition
| No. the sequences of bases can vary in countless ways |
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Term
| Basic outline of the Replication of DNA |
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Definition
1) First the Two strands of parental DNA separate, and each becomes a template for the assembly of a complementary stands from a supply of free nucleotides.
2) Nucleotides line up one at a time along the template strand in accordance with the base-pairing rules
3) Enzymes then link the nucleotides to form new DNA strands |
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Term
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Definition
1) specific sites on the double heliz where proteins that start he process attach to the DNA and seperate the strands.
2) replication occurs in both directions called replication bubbles. |
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Term
| What is the sugar and phosphate of the sugar phosphate backbone attached to? |
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Definition
1) the sugar's 3' carbon atom is attached to an -OH group at one end
2) at the other end, the sugars 5' carbon has a phosphate group. |
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Term
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Definition
| enzymes that link DNA nucleotides to a prowing daughter strand |
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Term
| In what way can a DNA daughter strand grow? |
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Definition
| It can only grow in the 5' to 3' direction |
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Term
| How are daughter strands synthesized? |
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Definition
1) one of the daughter strands must be made in one continuous piece by DNA working TOWARD the forking point of the parental DNA
2) the other daughter strand must be made by polymerase working OUTWARD from the forking point |
|
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Term
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Definition
| it ties the pieces of the synthesized daughter strands together to make a single DNA strand. |
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Term
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Definition
| quickly removes nucleotides that have base-paired incorrectly during replication. |
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Term
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Definition
| daugher strand that is synthesized continously; 5' to 3' |
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Term
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Definition
| daughter strand that is synthesized in pieces; 3' to 5' |
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Term
| What does DNa replication ensure? |
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Definition
| that all the somatic cells in a multicellular organism carry the same genetic informatio. It is also the means by which genetic instructions are copied for the next generation of the organism. |
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Term
| What is the chain of command in DNA's production of proteins? |
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Definition
1) from DNA in the nucleus
2) to the RNA
3) to protein synthesis in the cytoplasm |
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Term
| Two main stages of the process of protein synthesis |
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Definition
1) transcription: the transfer of genetic information from DNa into an RNA molecule
2) translation: the transfer of the information in the RNA into a protein |
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Term
| one gene-one enzyme hypothesis |
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Definition
| the function of a gene is to dictate the production of a specific enzyme |
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Term
| what is the result of transcription? |
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Definition
|
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Term
| why are the nucleotide bases on the RNA molecule complementary to those on the DNA strand? |
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Definition
| because RNA was synthesized using the DNA as a template |
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Term
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Definition
| th conversation of the nucleic acids into polypeptides. the sequence of nucleotides of the RNA molecule dictates the sequence of amino acids of the polypeptide |
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Term
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Definition
| 3 bases on DNA that are next to each other that code for an amino acid |
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Term
| What is the flow of information from gene to protien based on? |
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Definition
| the triplet code. the genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of three-bases called codons |
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Term
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Definition
| instruct the ribosome to end the polypeptide |
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Term
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Definition
1) only one of the DNA strands serves as a template for the newly forming molecule.
2) the nucleotides that make up the new RNA molecule take their placs one at a time along the DNA template strand by forming hydrogen bonds with the nucleotide bases there |
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Term
| What links RNA nucleotides? |
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Definition
| the transcription enzyme, RNA polymerase |
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Term
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Definition
| a signal in a nucleotide sequence that tells them to starts transcribing. it is located in the DNA next to the beginning of the gene. it is also the specific binding place of RNA polymerase |
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Term
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Definition
| 1st phase of transcription; the attachment of RNA polymerase tot he promoter and the start of RNA synthesis. the promoter dictates which of the two DNA strands is to be transcribed. |
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Term
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Definition
| 2nd phase of transcription; RNA synthesis continues, and the RNA strand peels away from its DAN template, allowing the two separated DNA strands to come back together in the region already transcribed. |
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Term
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Definition
| 3rd phase of transcription; RNA polymerase reaches a special sequence of bases int eh DNA template called a terminator, this sequence signals the end of the gene and at that point, the polymerase molecule detached from the RNA molecule and the gene |
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Term
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Definition
| the type of RNA that encodes amino acid sequences by conveying genetic information from DNA to the translation machinery of the cell. |
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Term
| Where the is message that is translated into polypeptides? |
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Definition
|
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Term
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Definition
1) the addition of extra nucelotides to the ends of the RNA transcript.. this includes a small cap (G nucleotide) at one end, and a long tail (a chain of A's) at the other end
2) made necesary in eukaryotes by noncoding stretches of nucleotides that interrupt the nucleotides that actually code for amino acids |
|
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Term
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Definition
| internal noncoding regions |
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Term
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Definition
| coding regions and parts of the gene that is expressed. |
|
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Term
| how is the mRNA produced with a continuous coding sequence? |
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Definition
| before the RNA leaves the nucleus, the introns are removed adn the exons are joined to produce an mRNA molecule with a continuous coding sequence. |
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Term
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Definition
| in order to covert the codons of nucleic acid to the amino acids of proteins, tRNA needs to interpret the message |
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Term
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Definition
tRNA must match amino acids to the appropriate codons to form the new polypeptide. in order to do this, tRNA molecules must
1) pick up the appropriate amino acids
2) recognize the appropriate codons in the mRNA |
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Term
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Definition
| a special triplet of bases, complimentary to a codon triplet on mRNA. During translation, the anticodon on tRNA recognizes a particular codon on mRNA by using base-pairing rules. |
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Term
| What does the structure of tRNA have to do with it's function? |
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Definition
the anticodon and the attachment site
1) gives tRNA its ability to match a particular codon with its correct amino acid |
|
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Term
| what ensures that the approptiate amino acid attached to a tRNA? |
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Definition
| an enzyme. there is at leas tone enzyme for each amino acid. each enzyme specifically binds one type of amino acid to the appropriate tRNA molecule, using a molecule of ATP as energy to drive the reaction. this resulting amino acid-tRNA comples can then furnish its amino acid to a growing polypeptide chain. |
|
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Term
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Definition
| organelles in the cytoplasm that coordinate the functioning of the mRNA and tRNA and actualy make the polypeptides |
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Term
| tRNA codons and mRNA anticodons fit together on ribosomes |
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Definition
| each ribosome has a binding site for mRNA on it small subunit, it large subunit has a binding site for tRNA |
|
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Term
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Definition
1) P site: holds the tRNA carrying the growing polypeptide chain
2) Asite: holds a tRNA carrying the next amino acid to be added to the chain. |
|
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Term
| how does the ribosome, then, actually make the polypeptide |
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Definition
1) anticodon on each tRNA base-pairs with a codon on mRNA
2) subunits of the ribosome act like a vise, holding the tRNA and the mRNA molecule close together
3) ribosome can then connect the amino acid from the A site tRna to the growing polypeptide |
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Term
| translation can be divided into the same 3 phases as transcription |
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Definition
1) initiation
2) elongation
3) termination |
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Term
| initionation in translation |
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Definition
1) an mRNA molecule binds to a small ribosomal subunit. a special inititor tRNA binds to the specific codon, called the start codon, where translation if to begin on the mRNA molecule. the initiator tRNA carries the amino acid MET and its anticodon, UAC, binds to the start codon, AUG
2) large ribosomal subunit binds to the small one, creating a functional ribosome. the initiator tRNA fits into the P site on the ribosome |
|
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Term
| once initiation is complete, amino acids are added one by one to the first amino acid, each addition occurs in a 3-step elongation process |
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Definition
|
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Term
| the 3 step elongation process |
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Definition
1) codon regognition: the anticodon of an incoming tRNA molecule, carrying its amino acid, pairs with the mRNA coson in the A site of the ribosome
2) peptide bond formation: the polypeptide separates from the tRNA to which it was cound and attaches by a peptide bond to the amino acid accired by the tRNA in the A site. The ribosome catalyzes formation of the bond. Thus, one more amino acid is added to the chain
3) Translocation: the P site tRNA now leaves the ribosom, and the ribosome moves the tRNA in the A site, with its attached polypeptide, to the P sit. the codon and the anticodon remain bonded, and the mRNA and tRNA move as a unit. this movement brings into the A site the next mRNA codon to the translocated, and the process can start again with step one |
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Term
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Definition
1) elgonation continues until the stop codon reaches the ribosomes A site
2) stop codons: UAA, UAG, and UGA so not code for amino acid but instead tell translation to stop.
3) the completed polypeptide is freed from the last tRNA and from the ribosome, which then splits into its subunits. |
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