Biology8.3-8.5Quiz Flashcards
All facts needed for the 8.3-8.5 quiz; based on Mr. Swavely's powerpoint.
What base does Guanine pair with?
Cytosine
What base does Adenine pair with?
Thymine
How many hydrogen bonds join Adenine and Thymine?
2 hydrogen bonds
How many hydrogen bonds join Guanine and Cytosine?
3 hydrogen bonds
How do the strands in DNA run?
Antiparallel
Where does the carbon numbering of DNA begin?
The carbon to the right of the oxygen
Through what process is DNA synthesized?
Semi-conservative replication
What are the three steps of semi-conservative replication?
Binding of enzymes to existing DNA; unwinding of the Double helix; synthesis of new matching strand for each existing strand
What are all the enzymes is DNA synthesis called?
The replisome
Where do enzymes bind during DNA synthesis?
Replication origins on the major groove
Topoisomerase
Straightens DNA so enzymes can function during replication
Helicase
Unwinds the double helix using ATP
DNA polymerases
Add nucleotides to the new DNA strand
DNA (RNA) primase
Gets DNA ready for the new nucleotides by adding short RNA segments on the lagging strand
DNA ligase
Bonds together deoxyribose and phosphate between Okazaki fragments with a phosphodiester bond
SSBP
Holds parent DNA strands apart during replication
Okazaki fragments
Short sections of new DNA added to the lagging strand by DNA polymerase alpha
RNA primer
Short section of RNA added by DNA primase
Leading strand
Daughter strand of DNA synthesized continuously by DNA polymerase delta
Lagging strand
Daughter strand of DNA synthesized discontinuously by DNA polymerase alpha
Hydrogen bonds
Very weak bonds formed between complimentary strands of DNA
phosphodiester bonds
covalent bonds formed between the phosphate group and the deoxyribose group (forms sugar phosphate backbone)
What happens to the leading strand?
DNA polymerase continously adds nuleotides
Why is the lagging strand made in segments?
DNA polymerase can only add nucleotides in a 3 prime to 5 prime direction, which means it would have to move opposite the movement of the replisome on the lagging strand.
In which direction can DNA polymerase work?
3 prime to 5 prime along the old strand
What joins the segments of DNA created on the lagging strand?
DNA ligase
What are the fragments of DNA formed on the lagging strand called?
Okazaki fragments
About how many base pairs are there in human DNA?
3 billion
1 mutation occurs in about every ___ base pairs.
10,000
This would lead to about 300,000
About how many mutations are left once the S phase is complete?
30
mutation
a change in the sequence of DNA
What can cause mutations?
mutagenic chemicals and radiation
What removes many of the mutations before the S phase is complete?
DNA polymerase checks its work, and if not, the excision repair sequence fixes the mistake.
What is the advantage of DNA polymerase checking its own work?
more efficient
Why do most human cells need to correctly read DNA?
not to divide, but to complete everyday functions
How are DNA replication errors detected in the excision repair sequence?
by the mismatch of the hydrogen bonds
What recognizes the mismatch of the hydrogen bonds?
the enzyme nuclease
What does nuclease do once an error is detected?
attach to the DNA, break the phosphodiester bond, and removes the erroronous section
What enzyme fixes the errors removed by nuclease?
DNA polymerase
What enzyme reforms the phosphodiester bond in the excision repair sequence?
DNA ligase
Why is the excision repair sequence necessary?
without a way of repairing errors, lethal mutations would accumulate quickly
Which nucleotides are purines?
Adenine and Guanine
What are purines?
nucleotides with 2 rings
Which nucleotides are pyrimidines?
Thymine and Cytosine
What are pyrimidines?
nucleotides with 1 ring
What are the two types of nucleotides?
purines and pyrimidines
Adenine bonds with…
Thymine
Guanine bonds with…
Cytosine
Thymine bonds with…
Adenine
Cytosine bonds with…
Guanine
How many bonds connect Adenine and Thymine?
2 hydrogen bonds
How many bonds connect Guanine and Cytosine?
3 hydrogen bonds
How can one tell which end of a nucleotide is the 5 prime end?
The 5 prime end has the oxygen molecule and the fifth carbon.
How can one tell which end of a nucleotide is the 3 prime end?
The 3 prime end is opposite the oxygen molecule and the phosphate group of each nucleotide.
Deoxyribose is a ___ carbon sugar.
5
