Chapter 10: DNA Part 1 Flashcards
What does DNA stand for?
Deoxyribonucleic Acid
What kind of bond are in DNA?
Covalent bond
What is DNA composed of?
Phosphate Group
Deoxyribose
Nitrogenous Base
What are the four bases in DNA?
Adenine
Guanine
Cytosine
Thymine
The number of bases are…
Equal
Bacterial Transformation
Bacteria can take up the plasmid, which causes the genetic code to be changed.
Plasmid
Circular DNA
Phage
Virus
How do viruses reproduce?
- Virus attach to the host cell, binding to receptor that allows access to the cell.
- Virus injects either DNA or RNA into the cell.
- Cell take genetic material from virus and begins following instructions. The cell then begins using its resources to reproduce the virus
- The cell lyses and releases new phages, allowing these viruses that were reproduce in the cell to infect others cells when it bursts.
What are nucleotides composed of?
Phosphate groups
Nitrogenous base
5-carbon sugar
Which nitrogenous bases pair with each other?
Thymine (T) and Adenine (A)
Cytosine (C)and Guanine (G)
Pyrimidines
Single Ring
Thymine (T) and Cytosine (C)
Purines
Double Ring
Adenine (A) and Guanine (G)
Adenine and Thymine create a
Double hydrogen bond
Guanine and cytosine create a
Triple hydrogen bond
Complimentary base pairing
Percentage of Adenine equals the percentage of thymine
And
Percentage of cytosine equals the percentage of guanine
DNA replication is
Semiconservative
DNA Replication
parental molecule unwinds and serve as templates. Then two identical daughter molecules of DNA are formed.
Where does replication begin?
Origin of replication
In origin of replication
DNA unwinds AND produces a “bubble”
Replication proceeds in both directions of the origin.
Origin of replication
The specific site of replication
Replication bubble
The open and unwounded area where DNA replication occurs
Replication Fork
End of a replication bubble. “Y” shaped region where new DNA strands of DNA are elongating.
Leading strand
CONTINUOUS complementary DNA strand elongating in the 5’ to 3’ direction.
Continuous adding of nucleotides as the replication form progresses.
Only one primer
Lagging strand
DNA strand elongating in the 3’ to 5’ direction by adding short segments (Okazaki fragments) adding of nucleotides AWAY FROM THE REPLICATION FORK.
More than one primer!
Antiparallel elongation
DNA strands are oriented in opposite directions of each other.
Affects replication.
DNA polymerase will only add nucleotides to the 3’ end of a growing strand.
A new DNA strand can elongate only in the 5’ to 3’ direction.
Helicase
Breaks hydrogen bonds and separates the DNA strands creating two template strands and a replication fork.
Topoisomerase
Removes helical twist (UNWINDS DNA) by cutting a DNA and releasing the cut.
Single Stranded Binding Proteins (SSBs)
Stabilize strands and prevent annealing (reconnection of DNA strands)
Primase
Makes RNA PRIMER
Helps DNA polymerase figure out where to start work.
Ligase
Joins the sugar-phosphate backbone of Okazaki Fragments to create single DNA strand.
DNA polymerase
Add nucleotides, makes covalent bonds.
Involved in repairing damaged DNA . (Proof reads DNA)
Replicates DNA to build new strands.
Step by step DNA replication
- Topoisomerase unwinds DNA
- Helicase breaks hydrogen bonds to create two template strands
- SSBs prevent annealing and stabilizes the strands
- Primase will create primer which will allow DNA polymerase to bind and start replication.
- DNA polymerase (III) binds to primers and add complementary bases. Lagging strand will stop once it reaches the old primer.
- DNA polymerase (I) arrives and removes old primer (RNA nucleotides) with the DNA version.
- Ligase joins the Okazaki fragments.
How do chromosomes form?
DNA is a readable form.
DNA wraps on histones and continuous to wrap wrap wrap into bundles.
Eventually forming into chromatin and then chromosomes.
Chromatin
Bundles of DNA and proteins (histones) are UNORGANIZED
Chromosomes
Bundles of DNA and proteins but ORGANIZED
