Which of the following is the best defenition for a cell that has been transformed?

a.) any cell that can protect from influenza

b.) sny cell that is able to cause death in a mouse

c.) any cell hat picks up any biological molecule from outside the cell

d.) any cell that gain a new property or function via transfer of genetic material

D. Any cell that gains a new property or function via transfer of genetic material

Which of the following expirimental setups most directly show that DNA is genetic material?

a.) Protein-digesting enzymes did not affect trasforming activity.

b.) DNA-digesting enzymes destroyed all trasnforming activity.

c.) Extracting lipids did not reduce transforming activity.

d.) Rna-digesting enzymes did not affect transforming activity

b.) DNA-digesting enzymes destroyed all trasnforming activity.

If bactrophage carrying 32p and 35s are alloud to infect a bacterium we would expect it find within these cells...

More 32P

What type of bond is a phosphodiester bond?

Covalent

Which of the following identifies a correct pairing of nucleotides with the accurate number of hydrogen bongs?

a.) G-T; 2

b.) A-T; 3

c.) T-C; 2

d.) G-C;3

d.) G-C;3

Which of the following is a necessary componet for DNA replication?

a.)A Template

b.) Nucleotides

c.)Polymerase

d.) All of the above

d.) All of the above

Semiconservative Replication

Which of the following statements about proaryotic replication is correct?

a.) Replication initiates from a unique origin and proceeds unidirectly in the replicon terminus.

b.) Replication initiates fom  unique origin and proceeds bidirectionally to the replicon terminus.

c.) Replication initiates from multiple origins and proceeds unidirectionally to the replicon terminus.

d.) Replication initiates from multiple origins bidirectionly to the replicon terminus.

b.) Replication initiates fom  unique origin and proceeds bidirectionally to the replicon terminus.

A DNA topoisomerase functions to:

Prevent supercoiling of DNA

Lagging Strand Synthesis:

Is discontinuous and requires multiple primers

Wat are genes made of?

Genes are made of DNA (Deoxyribonucleic Acid)

A-Adenine G-Guanine C-cytosine T-thymine

What differences between DNA and proteins initially made scientists think proteins made up genetic material?

Dna consists of 4 Chemcally similar nucleotides, in contrast protein contains 20 amino acids that are much more chemically diverse

What type of bacteria was tested in Grififith's expiriement? What is the S form? What is the R form? How are they different?

Streplococcus Pneumoniae. The S form is the normal virulent form that causes nuemonia, an the rform is the mutant non-virulent form that does not.

What does it mean to say that cells have been transformed? 

The transfer of genetic material that permanately alters the cell

Avery, Macleod, and mcary followed up these expiriements to determine what the substance was that was responsible for transformation. In what ways did the properties of the subsance resemble DNA?

1. The elemental composition agreed closely with that of DNA

2.)When spun a high speeds in an ultracertrifuge, it mgrated to the same density level as DNA.

3.) Exractig lipids and proteins did not reduce transformation activity.

4.) Protein digesting enzyes did not affect transforming activity, nor did RNA-Digesting Proteins.

5.) DNA digesting enzymes destoyed all tranforming activity.

Do DNA Molecules have phosphaste or Sulfer? Do Protein molecles have phosphate or sulfer?

Nucleotides contain phosphorus, Proteins contain sulfur.

Where does the term "Nucleic Acid" come from?

Miesher extracted DNA from the nucleus from the cell and its was slightly acidic

Distinguish between purine and a pyrimidine:

Purine (A- or G-) a two ringed structure. Pyrimidine (T-, or C-)  singlringed strucure.

**** What type of bond is a phosphodiester bond? Between wht molecules does it form? Where is it located in the double helix?

5' Phosphate. 3' Hydroxl

What is at the 5" end of the DNA molecule. What is at the 3" end? Why are the groups named this way?

The phosphate group is attached to the 5' Carbon atom of the sugar and the baseis attached to the 1' Carbon atom. A free hydroxal group is attached to the 3'Carbon atom. The 5' Phosphate and 3' hydroxal groups allo DNA + RNA to form long chains of nucleotides by the prcess of dehydration syntesis.

How did the x-ray difraction studies hep to discern the stucture of DNA?

In x-ray diffraction a molecule is bombarded with a stream of x-rays. When analyzed mathematically the diffraction pattern can yeild information about the 3-demensional shape of the molecule

Define the bold terms in the sentence: DNA forms a double helix where complimentry nucleotide form base pairs across anti parallel strands.

Double Helix: 2 chains of nucleotides that are intertwined

Complimentary: A=T, G=C

Base Pairs: A=T, G=C

Anti parallel: Means opposite polarity

Compare and contrast the models of conservative, Semiconservative, and dispersive replication. What are the products of each? How can you tell them apart?

The conservative model both parental strans would stay intact and the new DNA copies would consist of all new copies 

Semiconserative Models one parental duplex remains intact in daughter strands.

Despersive models copies of DNA would contian mixtures

What 3 Things are required for replication to occur?

Requires a template, nucleotides and polymerase enzymes. Something to copy, something to do the copying, and the building blocks to make the new copy.

What common features do all examined DNA polymerase have in common?

All have 5' to 3' exonuleus activity

All require a primer

They all add new bases to the 3' end

*** What is the origin of replication? What proteins bind there? What is the DNA sequence at that origin? Why is the sequence important for its function at an origin?

replication initites at a specific site binds an initiator protein Sequence that can be opened easliy

How many polymerases does Ecoli hae involved in replication ? What are their names?What additional activity do these enzymes have besides their ability to polymerise?  What is this activity useful to the cell?

Polymerase I

Acts on lagging strand to remove primers and replace them with DNA

Polymerase II

No role in replication but in repair proces

Polymerase III

Main replication enzyme it is responsible for bulk of DNA synthesis

Helicase

Enzymes that use energy from ATP to unwind the DNA template 

Single Strand Binding Proteins (SSB)

Used to coat unstable single strand

Topoisomerase

Enzymes that alter topological states

Why does the unwinding of DNA require energy?Are the resulting DNA molecules stable or unstable? 

The energy makes unwinding more efficent,Single strand DNA are unstble because the process exposed hydrophobic bases to water

What is torsional strain? Why does it come about?

Strain cause by unwinding

Why does the antiparallel nature of DNA strands lead to discontinuous replication

Because polymerase can only synthesize DNA in one direction and the 2 DNA strands run in opposite directions, polymerase on the 2 strands must be synthesizing in opposite directions

Leading Strand

The strand that runs continuous

Lagging Strand

The strand that is discontinuous

Okazaki Fragments

DNA fragments on the lagging strand

How is clamp activity related to processivity?

Both hold polymerase in place

Where does termination occur? After replication termination what is the state of the DNA molecules? How is this structure resoled?

What two factors make eukaryotic replication more complex? 

The initiation phase requires more factors to assemble both helicase and primase complexes onto the template than load with sliding clamp

What new enzymes, different than those in prokaryotic replication, are needed to deal with these complexeties? 

DNA polymerase and DNA polymerase delta

Why do eukaryotic cells use multiple origins of replication and multiple replicons?

Because they have multiple chromosomes that are each larger than ecoli. 

How does eukaryotic primase differ from prokaryotic?

It is complex of both an RNA and DNA polymerase

What are the two main polymerase in eukaryotic replication?

Polymerase Epsilon and Delta

What specialized structure exists at the end of eukaryotic chromosomes due to their linear nature? Why must the exist/ what role do they play?

The very structure of a linear chromosome causes cell problems in replicating the ends. The directionality of polymerase combined with their requirement for a primer, create this problem

How does the telomarse enzyme over come this problem?

Telomeres structure protects the ends of chromosomes from nucleuses and maintain the intergrety of the linear chromosome.

What would happen to a chromosome that lacked telomarse?

A gradual shortening of t he ends of the chromosomes occur in the absence of telomarse

Watson and Crick Model (1953)

DNA structure was a "Double Helix" and bases faced towards each other

Franklin X-Ray Diffraction (1952)

DNA was a helix and had a diameter of 2nm

Hershey and Chase - Viruses grown in isotopes (1952)

DNA was the hereditary material viruses use to infect cells

Griffith -- Transformation (1928)

Hereditary material could be passed from one bacteria to another

Meselon-Stahl Replication (1958)

DNA is replicated via semi-conservative replication

Avery -- Transformation (1944)

DNA was the hereditary material transforming cells

Data from the Meselson-Stahl expiriement was not consistent with th conservative model of replication because in this model: 

After one round of replication, two densities should have been observed.

The two stands of DNA double helix are antiparallel, which means _____.

One strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction.

What is it meant by semi-conservative repilacation? Compare that with the term semi-discontinuous?

In semi-conservative replication one strand of the parental duplex remains intact in daughter strands; a new complimentary strand is built for each parental strand consisting of new molecules. Semi-discontinuous means that the new strand (*lagging strand) must be made in peices.

DNA Polymerases add nucleotides to the ____ growing leading strand, and to the _____ of the growing lagging strand (okazaki fragments).

3' end; 3' end

Why id DNA replication necessary?

The replication of cells requires that the new cell have a copy of the genetic material

In bacterial replication there are ___ origins of replication and ___ replisomes.

1 ; 2

In a eukaryotic chromosome there are ____ origins of replication, and ____ replisomes

Multiple; Multiple

What limitation of DNA polymerases that requires the replication so be Semi-Discontinuous?

Polymerase can only move in a 5' to 3' direction

What is t he limitation of DNA polymerases that results in the requirement for RNA primers?

DNA replicates in sections called "okazaki fragments". Primers take place between DNA fragments until it is replaced with DNA material. DNA cannot begin to add nucleotides with out primers (which is attached with primase) (replaced with poly I)

Distingguish between DNA polymerase I and DNA  polymerase III in prokaryotic DNA replication.

DNA polymerase III is responsible for bulk of DNA replication. DNA polymerase I acts on the lagging strand to remove primers and replace with DNA. It also has a 5-3 exonucleus activity. 

I: Removes/Replaces the primer

III: Assembling complimentary strands

Compare the enzymes helicase and DNA gryase. What do each of them o in the process of DNA replication?

Enzymes hat use energy from ATP to unwind the DNA template are called helicases. Topoisomerase enzymes act to relieve the torsional strain caused by unwinding and prevet super coiling from happening. Knicks DNA molecules so it relaxes, then repairs it

Thinking of the role of DNA ligase, what would happen to DNA replication in a cell where this enyme does not function?

Okazaki fragments would not be joined together into complete strands.

Which types of cells have active telomerase? Why do certain cells have telomerase and others do not?

Telomerase are found in eukatyotic cells -- it extends the ends of chromosmes.

Prokaryotic cells have a circular chromosome, therefore they have no ends so the enzyme is not needed.

Telomerase-- ends of linear chromosomes