Chapter Eleven: Nucleic Acid Structure, DNA Replication, and Chromosome Structure Flashcards
Genetic Material needs to: (4)
- Contain info to build and run an entire organism
- Be copied accurately
- Be transmitted from parent to offspring
- Account for known variation between species
Most scientists believed Genetic Material would be _____________ since they are known to be much more variable than Nucleic Acid
Proteins
Who set the stage for showing what the Genetic Material would be?
Griffith
Griffith worked with two strains of the bacteria Streptococcus Pneumoniae. What two strains?
S and R strain
What strain of Streptococcus Pneumoniae is virulent and kills mice by a pneumonia infection?
S strain
What strain of Streptococcus Pneumoniae is not virulent and a mouse’s immune system would kill it?
R strain
Griffith first injected mice with the ______ strain and saw that the mice died
S
After the death of the mouse when the S strain was injected, live ______ bacteria was found which established the virulence of the S strain
S
Griffith injected the mice with the _____ Strain and saw that mice did not die. This established the non-virulence of the R strain
R
Griffith killed the virulent S strain and injected the dead S strain. Since the bacteria was killed, did the mice die?
The mice did not die
Griffith mixed the live R strain (which did not kill mice) with the heat-killed S strain (which did not kill mice) and he injected that. Live S strain was recovered, did the mice die?
The mice died
Something from the S strain was transferred to the live R strain, transforming it to the live ____ Strain
S
Whatever agent had transformed the R strain to the S strain must be the…
Genetic Material
Who took the live R Streptococcus Pneumoniae bacteria and mixed it with heat killed S strain like Griffith but they firstly treated it with enzymes to destroy a class of organic molecules
Oswald Avery
If the _______ in the heat-killed S strain were proteins, they should have been destroyed and not able to transform the live R strain into the S strain
Genes
Genes could not be…
Proteins
Genes must consist of __________ ________ since when they are destroyed, so is the ability to transform the R strain to the lethal S strain
Nucleic Acids
Who demonstrated for the first time that genes were Nucleic Acids?
Oswald Avery
Who did the second demonstration of the nature of genes?
Hershey and Chase
What type of isotopes did Hershey and Chase use in viruses?
Radioactive
Of all the organic molecules, only ______________ have Sulfur, so if they grow viruses in radioactive 35S, only Proteins will be “marked”
Proteins
Only ____________ ________ have Phosphorus so viruses grown in radioactive 32P will only mark Nucleic Acids
Nucleic Acids
Watson and Crick made the what kind of helix model?
Double
What are the three parts of Nucleic Acids?
- Pentose Sugar
- Nitrogenous Bases
- Phosphate Group
Ribose Pentose Sugar is found in….
RNA
Deoxyribose Pentose Sugar is found in….
DNA
DNA backbone is composed of alternating what two things?
Sugar and Phosphates
What are the Four Nitrogenous Bases in DNA?
A
C
G
T
What are the four Nitrogenous Bases in RNA?
A
C
G
U
What two Nitrogenous Bases are Purines?
A
G
What three Nitrogenous Bases are Pyrimidines?
C
U
T
What kind of structure does DNA have in which two strands run in opposite directions?
Antiparallel Structure
How many strands are in RNA?
One
How many strands are in DNA?
Two
What are the three possible models of DNA replication?
- Conservative
- Semi conservative
- Dispersive
What type of DNA replication model?
Two old strands come back together after Replication. The entire old strand conserved in one of the two new strands
Conservative
What type of DNA replication model?
One new and one old strand form new molecule. Half of the old strand is conserved in the new strand
Semi conservative
What type of DNA Replication model?
A patch-work of new and old forms the new molecule. Old strand dispersed in new strands
Dispersive
Who were the first two to demonstrate Semiconservative DNA Replication using density gradient centrifugation?
Meselson and Stahl
DNA Replication occurs when the two strands open out, new ______________ line up opposite the old complementary bases, and DNA Polymerase catalyzes their addition to the new strand
Nucleotides
Most cells have multiple _________________ (human cells have at least 15)
Polymerases
Only one or two polymerases replicate chromosomes, the rest are involved in DNA…
repairs
What initiates replication by denaturing DNA using the energy from ATP?
Helicase
___________________ travels in front of Helicase, relieving the supercoiling caused by Helicase
Topoisomerase
Single Strand Binding Proteins coat __________ -___________ DNA to keep it from renaturing
Single-Stranded
Pairing between _______________ _________ line up Nucleoside Triphosphates opposite bases in old strand, which is the template for the new strand
Complementary Bases
___________ ______________ ______ splits off last 2 high-energy phosphates, polymerizing the Nucleotide into the new DNA strand
DNA Polymerase III
What are the two limitations of DNA Polymerase III?
It can’t start strands and it can’t add new Nucleotides to the 5’ end of growing DNA chains
How does Primase overcome the first limitation of DNA polymerase (can’t start strands)?
Primase replicates the first 12-20 nucleotides with RNA on which DNA Polymerase can then build
What type of strand?
Follows template in the 3’ to 5’ direction, so new strand is built continuously (5’ to 3’) after a Primer Strand is produced
Leading Strand
The second limitation of DNA Polymerase is overcome by building the Lagging Strand in a discontinuous fashion using…
Okazaki Fragments
What type of strand?
Follows template in the 5’ to 3’ direction so new strand must be build in the (3’ to 5’), direction but DNA Polymerase can only synthesize in the 5’ to 3’ direction
Lagging Strand
The lagging strand is build discontinously in fragments (Okazaki fragments) each built in the _____________ direction but overall 3’ to 5’ direction
5’ to 3’
After the first Okazaki Fragment is built, another primer then another fragment is built. Each fragment is built in the 5’ to 3’ direction, but are laid down in…
3’ to 5’ direction
Each Okazaki Fragments is laid down either __________________ or __________________
individually or discontinuously
What connects together Okazaki Fragments by closing last gap between fragments?
DNA Ligase
What follows the replication fork, replacing the primer strand, correcting errors when found?
DNA Polymerase I
The ends of Eukaryotic Chromosomes are termed…
Telomeres
Telomeres have special repeated sequences that prevent the ends of ________________ from attaching to one another
Chromosomes
The replication of telomeres has problems since the replication of the _____________ _________ does not start at the very end of the Chromosome
Lagging Strand
Telomeres may ____________ over many rounds of Replication
shorten
Shortened Telomeres has been implicated in…
aging
Some cells, including cancers, have the enzyme Telomerase which ____________ Telomeres
lengthens
Telomerase attaches to the _____ end of a DNA strand
3’
An internal _______ template is used to line up DNA nucleotides and extend the 3’ end of the Chromosome
RNA
After the 3’ end is lengthened, it can be long enough for DNA Polymerase to attach and produce another…
Okazaki Fragment
Okazaki fragment extends the bottom strand in a 5’ to 3’ direction which makes the whole chromosome…
longer
Ends of telomeres can loop back upon itself forming a circle preventing ends of chromosomes from….
attaching to one another
Researchers found Telomers can produce two proteins aka…
Dipeptides
Dipeptides are elevated in people with certain cancers and diseases resulting from…
telomeric defects
Eukaryotic Chromosomes consist of both…
DNA and Proteins
Many proteins within Eukaryotic Chromosomes are ______________ which form Nucleosomes, around which the DNA is wrapped in a groove
Histones
Two copies each of four Histones compose…
Nucleosomes
Nucleosomes contain many positively charged _____________ to attract and bind DNA
peptides
A fifth Histones H1 binds linker DNA which occurs between the DNA segments wrapped around…
Nucleosomes
DNA wrapped around Nucleosomes resembles…
beads on a string
Adjacent Nucleosomes are organized into a thicker fiber, ______ nm in diameter
30
The 30nm fiber of each chromosome is attached to a filamentous network of proteins termed the…
Nuclear Matrix
The Matrix consists of protein fibers which line the inner ____________ _____________ (Nuclear Lamina) and other fibers stretching throughout the Nucleus
Nuclear Membrane
Other proteins connect regions of DNA to the Nuclear Matrix, bending DNA into _________ ________ ___________ containing 25,000-200,000 nbp
Radial Loop Domains
DNA, and the Chromosomes they make up, are this anchored to specific regions in the…
Nucleus
Chromosomes are not free to move within the Nucleus, but are restricted to specific regions by binding to the…
Nuclear Matrix
During cell division, _______________ condense into thicker, shorter structures by a series of loops and bends, so they can be moved without tangling and breaking the long DNA fibers
Chromosomes