Chapter 9 Biology-Dna

Front 1

Who WHo is Frederick Griffith?

Back 1

bacteriologist, injected mice with

Front 2

vaccine

Back 2

A substance that is prepared from killed or weakened microorganisms and is introduced into the body to protect the body against future inferctions by microrganisms.

Front 3

Explain the first strain.

Back 3

S strain. It is enclosed in a capsule made of polysachaarides, and is a virulent (disease causing) strain of bacteria. Because of the capsule, the body defense system cannot fight against the bacteria.

Front 4

Explain the second strain.

Back 4

It does not have the polysaccaride capsule and is therefore not virulent. It is rough.

Front 5

What did Griffith do to determine whether the capsule had anything to do with the mice deaths?

Back 5

injected the mice with dead S-bacteria and the mice remained healthy. he then injected heat-killed (no longer able to reproduced) weakened s-bacteria.

Front 6

what happened then?

Back 6

the mice lived-(heat killed S). thus griffith knew it was not the capsule on the S bacteria that killed the mice.

Front 7

next step in griffs experiment was......?

Back 7

he mixed harmless LIVE

Front 8

what was the next step in griffie's experiment?

Back 8

he mixed the harmless LIVE r bacteria with the harmless HEAT KILLED s-bacteria.

Front 9

what was the result of this fascinating step in griffs experiemnet?

Back 9

meese injected with this PREVIOUSLY HARMLESS (duh duh duh dum) mixture.....died. (yeah thats right)

Front 10

what cause did griffie attribute to these deaths of these meese?

Back 10

first he examined the blood of the DEAD miceiemoo and found that the live R BACTERIA had aquired the POLYSACCARIDE CAPSULES (capsules how couldyou? soap opera music...) somehow, the harmless r bacteria had changed and became virulent S BACTERIA!! MORE DRAMATIC MUSIC

Front 11

Griffie then discovers transformation. WHAT IS THAT?????? :-)

Back 11

it is a change in phenotype caused when bacterial cells (like R) take up foreign (thats S) genetic material.

Front 12

what did AVERY do??? (elegent experiments)

Back 12

avery (hes pretty cool) demonstrated that DNA is the material responsible for that griffith crap called transformation. EXPLAIN-DNA had the instructiones for the making of the capsules in the S strain

Front 13

What was known at this time?

Back 13

It was known that viruses,which are much asimpler than cells, arem ade of DNA surrounded by a protective protein coat. Bacteriphage, are viruses that infect bacteria, wheh phage does so, the phage are able to produce more viruses, which are releases when the bacterial cells rupture.

Front 14

What was not known at this time?

Back 14

IT wawas not known how the phage reporgrammed the baccterial cell to make vriuses. Was it the phage DNA, the protein, or both, that issued the instructions to bacteria during infection?

Front 15

Why did Hershey and Chase use t2 to determine an answer for the experiment?

Back 15

They knew that the only molecule in this phage that contained phosphurus was DNA. Liewise, the only phage molecules that contained sulfur were in the protein coat.

Front 16

What was the first step?

Back 16

1. THey first gre t2 with e coli bacteria in a medium that contained radiocative sulfur.(35s). THe protein coat of the virus would incrporate the 35s.
2.They grew a second patch of phage that contained phospurus(32p)The radioactive phosphurus would become part of the phages' DNA.

Front 17

What was the second step?

Back 17

The two different pahges were used to infect two seperate batches of e coli. BEcuae radioactive elements release particles that can be detected by machines, they can be traced. THis way, scientists can determine how bacterial cells are reprogrammed.

Front 18

Step 3.

Back 18

1. After a few minutes, the scientists tore open the 35s phages with the help of a blender, and then they did the same thing to the 32p. Then they used a centrifuge to seperate the bacteria and the phages. The bacterial sunk to bottom, viral floated at top.
2. When the layers of the 35s bateria were examined, they found that most of the 35s still part of the phage, meaning that the protein was not injected in the bacteria.
3. WHen 32p was examined, they found that the bacteria had most of the 32p, meaning that the DNA had been injected into the hosts. The new generation of phages that was produced by these bacteria also contained radioactive DNA.

Front 19

Conclusion

Back 19

The DNA of the viruses is injected into the bacterial cells while most of the proteins remain outsideThe injected DNA molecueles caused the bacterial cells to produce more viral DNA and proteins. THis meant, that the DNA, rahter than proteins, was hereditary material, at least in virusses.

Front 20

What has this shown?

Back 20

THat the DNA is the molecule that stores genetic info in living cells.

Front 21

Who determined the structure of DNA?

Back 21

Jmes Watson, Francis Crick,

Front 22

Why was this imporatnt?

Back 22

IT clarified how DNA can serve as teh genetic material.

Front 23

Step 3.

Back 23

1. After a few minutes, the scientists tore open the 35s phages with the help of a blender, and then they did the same thing to the 32p. Then they used a centrifuge to seperate the bacteria and the phages. The bacterial sunk to bottom, viral floated at top.
2. When the layers of the 35s bateria were examined, they found that most of the 35s still part of the phage, meaning that the protein was not injected in the bacteria.
3. WHen 32p was examined, they found that the bacteria had most of the 32p, meaning that the DNA had been injected into the hosts. The new generation of phages that was produced by these bacteria also contained radioactive DNA.

Front 24

Conclusion

Back 24

The DNA of the viruses is injected into the bacterial cells while most of the proteins remain outsideThe injected DNA molecueles caused the bacterial cells to produce more viral DNA and proteins. THis meant, that the DNA, rahter than proteins, was hereditary material, at least in virusses.

Front 25

What has this shown?

Back 25

THat the DNA is the molecule that stores genetic info in living cells.

Front 26

Who determined the structure of DNA?

Back 26

Jmes Watson, Francis Crick,

Front 27

Why was this imporatnt?

Back 27

IT clarified how DNA can serve as teh genetic material.

Front 28

Double Helix

Back 28

Two strands twistd around each other , like a winding staircase. Each strnd is made of linked nucleotides.

Front 29

Nucleotides

Back 29

the subunits that make up DNA. Made up of three parts.
1. Nitrogen containing base
2. 5 carbon sugar
3. phosphate group

Front 30

Deoxyribose

Back 30

the fivve carbon sugar

Front 31

What are the four types of nitrogen bases?

Back 31

Guanine/Adenine-classified as purines
Thyamine/Cytosine- classified as pyrimidians

Front 32

Pyrimidians/Purines

Back 32

Purines: 2 rings of carbon, and nitrogen atoms.
Pyrimidians:Made up of 1 ring of carbon and nitrogen atoms.

Front 33

Explain the phosphate groups visually.

Back 33

The sugar-phosphate backbonesare similar to the side rails of a ladderand the paired nitrogen are similar to the rungs of a ladder. THe nitrogen bases face each other. The double helix is held together by weak hydrogen bonds between the pairs of the bases.

Front 34

Who was Erwin Chargaff?

Back 34

A biochemist tha made an interesting observation abot DNA. THe amount of a=t and the amount of g=c. But amounts are varied between organisms.

Front 35

What was the signifigance of Chargaff's data?

Back 35

It became signifigant wen the began using xray defraction to study the structure of molecules. IN an xray dereaction, a beam of xrays is directed at an object, the xray bounces off teh object and is scattered on the film.

Front 36

WHo were Wilkins and Franklin?

Back 36

They developed high quality xray defraction photos of fibers in the DNA molecule. These photos suggested that the DNA molecule resembled a tightly coiled helix and was composed of 2 or 3 chains of nucleotides.

Front 37

Describe Watson's and Crick's DNA model.

Back 37

With tin and wire models of molecules, they built a model of DNA with the configuration of a double helixof two strands of nucleotides twisting around a central axis.

Front 38

State the theory of base pairing rules.

Back 38

a=t and g=c are on opposte strnads, and only allows these two pairs ebcuase of structure and size.

Front 39

HOw many bonds do they form?

Back 39

a=t, 2 hydrogen bonds.
g=c, 3 hydrogen bonds.

Front 40

complementary

Back 40

The sequence of bases on one strand are complementary(determines) to the sequence on the other side.

Front 41

What did scientsist predict about specific DNA structure?

Back 41

That eh complementary structure was used as a basis to make exact copies of the DNA each time the cell divided.

Front 42

When dos replication occur?

Back 42

S phase

Front 43

Step 1.

Back 43

1. BEofre it begins, the DNA helix begins to unwind.
2. THis is done by enzymes, called DNA helicases, ehich open the double helix by breaking the hydogen bonds.
3. Once the 2 strands are seperated, additional prteoins are attached to each strand, holding them apart and preventing them from twisting bsck.
3. Replication forks are the two areas on either end of the DNA, where the double helix seperates.

Front 44

Step 2.

Back 44

At replication fork, enzymes known as DNA polymerases move along each of the DNA strands, adding nucleotides to the exposed nitrogen bases, according to the base pairing rules. As the ploymerases move along, two new double helixes are formed.

Front 45

Step 3.

Back 45

ONce a DNA piolymerase has begun adding nucleotides to the growing double helix, the enzyme remains attached until all the DNA has been copied then is signaled to detach. This process produces two DNA molecuele, composed a new and original strand. Each DNA is exactly replicated.

Front 46

Describe Mutations.

Back 46

-wrong nucleotide asses to new strnad-prevented by the polymerases to have a proofreading role-add nucleotides to growing strand, only if the previous one is right.
*Also able to backtrack and remove incorrect and replace.

Front 47

Multiple Replication Forks INcrease the Speed of REplication

Back 47

~all the boxes caried in one trip, rather than one at a time.

Front 48

Step 1.

Back 48

1. BEofre it begins, the DNA helix begins to unwind.
2. THis is done by enzymes, called DNA helicases, ehich open the double helix by breaking the hydogen bonds.
3. Once the 2 strands are seperated, additional prteoins are attached to each strand, holding them apart and preventing them from twisting bsck.
3. Replication forks are the two areas on either end of the DNA, where the double helix seperates.

Front 49

Step 2.

Back 49

At replication fork, enzymes known as DNA polymerases move along each of the DNA strands, adding nucleotides to the exposed nitrogen bases, according to the base pairing rules. As the ploymerases move along, two new double helixes are formed.

Front 50

Step 3.

Back 50

ONce a DNA piolymerase has begun adding nucleotides to the growing double helix, the enzyme remains attached until all the DNA has been copied then is signaled to detach. This process produces two DNA molecuele, composed a new and original strand. Each DNA is exactly replicated.

Front 51

Describe Mutations.

Back 51

-wrong nucleotide asses to new strnad-prevented by the polymerases to have a proofreading role-add nucleotides to growing strand, only if the previous one is right.
*Also able to backtrack and remove incorrect and replace.

Front 52

Multiple Replication Forks INcrease the Speed of REplication

Back 52

~all the boxes caried in one trip, rather than one at a time.