Term
| What was the purpose of the hershey-chase experiment? |
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Definition
| To study whether genes were made of protein or DNA |
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Term
| What did hershey and chase study? |
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Definition
| studied how a virus called T2 infects the bacterium Escherichia coli |
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Term
| T2 infection of E. coli begins when? |
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Definition
| The virus attaches to the cell and injects its genes into the cell |
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Term
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Definition
| the protein coat of the original parent virus |
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Term
| Hershey and Chase grew the virus in the presence of one of two radioactive isotopes, what were they? |
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Definition
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Term
Hershey and Chase hypothesized
If genes consist of DNA: then |
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Definition
| radioactive DNA would be found inside the cells while radioactive proteins would be found only in the ghosts outside the cells |
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Term
| If genes consist of proteins in the hershey chase experiment what would be the result? |
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Definition
| Then only radioactive protein found inside the cells no radioactive DNA found inside the cells |
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Term
| What theory did the hershey chase experiment confirm? |
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Definition
| This result supports the proposal that DNA, not protein, is the genetic material |
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Term
| What is are the two major components of The primary structure of DNA ? |
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Definition
A backbone made up of the sugar and phosphate groups of deoxyribonucleotides
A series of nitrogen-containing bases that project from the backbone |
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Term
| What is DNAs directionality? |
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Definition
| The molecule thus has a 3prime end and a 5prime end |
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Term
| What is antiparallel fashion? |
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Definition
| Two DNA strands line up in the opposite direction to each other |
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Term
| Who proposed antiparallel fashion? |
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Definition
|
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Term
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Definition
| antiparallel strands twist |
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Term
| The secondary structure of DNA is stabilized by what? |
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Definition
| complementary base pairing |
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Term
| Meselson and Stahl designed an experiment to? |
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Definition
| to provide more information on the mechanism of DNA replication |
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Term
| What did the meselson and stahl's experiment explained what? |
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Definition
| how the hereditary material is duplicated |
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Term
Meselson and Stahl
Showed that each parental DNA strand is copied in its entirety but they did not do what? |
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Definition
| Did not illustrate a mechanism for this process |
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Term
| DNA polymerase is the enzyme that does what? |
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Definition
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Term
| The discovery of DNA polymerase cleared the way for understanding what? |
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Definition
| DNA replication reactions |
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Term
| A critical characteristic of DNA polymerases is what? |
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Definition
| They can work only in one direction |
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Term
| DNA polymerases can add what? |
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Definition
| deoxyribonucleotides to only the 3′ end of a growing DNA chain |
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Term
| DNA synthesis always proceeds in the what direction? |
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Definition
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Term
| Why is DNA polymerization is exergonic? |
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Definition
| because the monomers that act as substrates in the reaction |
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Term
deoxyribonucleoside triphosphates (dNTPs)
Have high potential energy because? |
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Definition
| their three closely packed phosphate groups |
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Term
| A replication bubble forms in a chromosome that? |
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Definition
Is actively being replicated
Grows as DNA replication proceeds
Because synthesis is bidirectional |
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Term
| What is origin of replication In bacterial chromosomes? |
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Definition
Where the replication process
Begins at a single location |
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Term
| How many origins of replication do eukaryotes have? |
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Definition
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Term
| What is a replication fork ? |
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Definition
| is the Y-shaped region where the DNA is split into two separate strands for copying |
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Term
| Enzyme helicase catalyzes what? |
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Definition
| Enzyme helicase catalyzes the breaking of hydrogen bonds between the two DNA strands to separate them |
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Term
| Why do Single-strand DNA-binding proteins (SSBPs) attach to the separated strands? |
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Definition
| to prevent them from closing |
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Term
| Enzyme topoisomerase does what? |
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Definition
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Term
| DNA polymerase requires what? |
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Definition
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Term
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Definition
| A type of RNA polymerase that Synthesizes a short RNA segment that serves as a primer |
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Term
| The lagging strand is synthesized discontinuously because? |
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Definition
| It occurs because DNA synthesis must proceed in the 5 prime to 3 prime |
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Term
| Synthesis of the lagging strand starts when ? |
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Definition
| Primase synthesizes a short stretch of RNA that acts as a primer then DNA polymerase III then adds bases to the 3prime end of the primer |
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Term
| DNA polymerase moves away from the replication fork Helicase continues to open what? |
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Definition
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Term
| What is the discontinuous replication hypothesis? |
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Definition
Once primase synthesizes an RNA primer on the lagging strand,
DNA polymerase might synthesize short fragments of DNA along the lagging strand. These fragments would later be linked together to form a continuous whole strand |
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Term
| The discontinuous replication hypothesis was tested by who? |
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Definition
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Term
| What are Okazaki fragments? |
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Definition
| The lagging strand is synthesized as short discontinuous fragments |
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Term
| What removes the RNA primer at the beginning of each Okazaki fragment? |
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Definition
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Term
| What joins Okazaki fragments to form a continuous DNA strand? |
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Definition
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Term
| The lagging strand is also called the? |
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Definition
|
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Term
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Definition
| The enzymes responsible for DNA synthesis around the replication fork joined into one large, multi-enzyme machine |
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Term
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Definition
Region at the end of a linear chromosome that
Does not contain genes
Consists of short, repeating stretches of bases |
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Term
| DNA polymerase is highly selective in matching? |
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Definition
| complementary bases correctly |
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Term
| DNA polymerase inserts the incorrect base only about once every ? |
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Definition
| every 100,000 bases added |
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Term
| What happens to defective bases ? |
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Definition
| Repair enzymes remove and repair them. |
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Term
| What does it mean when it is said that DNA polymerase can proofread its work? |
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Definition
It checks the match between paired bases
It can correct mismatched bases when they do occur |
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Term
| What if dna polymerase finds a mismatch? |
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Definition
| It pauses and removes the mismatched base that was just added |
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Term
DNA polymerase III can do this because
Its e (epsilon) subunit acts as an? |
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Definition
exonuclease
It removes deoxyribonucleotides from DNA |
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Term
| What if If DNA polymerase leaves a mismatched pair behind in the newly synthesized strand? |
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Definition
| A battery of enzymes springs into action to correct the problem in spite of its proofreading ability |
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Term
| Mismatch repair occurs when ? |
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Definition
| mismatched bases are corrected after DNA synthesis is complete |
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Term
| What do Mismatch repair enzymes do? |
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Definition
Recognize the mismatched pair
Remove a section of the newly synthesized strand that contains the incorrect base
Fill in the correct bases |
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Term
| What system recognizes types of damage to DNA? |
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Definition
| The nucleotide excision repair system |
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Term
| The presence of a DNA strand complementary to the damaged strand provides a template for? |
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Definition
| resynthesis of the defective sequences |
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Term
| What is Xeroderma pigmentosum (XP)? |
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Definition
A rare autosomal recessive disease in humans
Characterized by the development of skin lesions |
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Term
| What if mutations in the genes involved in the cell cycle go unrepaired ? |
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Definition
The cell may begin to grow in an uncontrolled manner
This growth can result in the formation of a tumor |
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