TOPIC 2 - Central Dogma : DNA Relplication, Transcription, Translation Flashcards
What is the Central Dogma of Molecular Cell Biology?
Concept that Genetic Information FLOWS from DNA to RNA to Proteins.
DNA Replication
Process of producing 2 identical replicas from 1 original DNA molecule. This biological process occurs in all living organisms and is the basis for biological inheritance. DNA is made up of 2 strands and each strand of the original DNA molecule serves as a template for the production of the Complementary strand, a process referred to as semiconservative replication. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication.
RNA Transcription
Synthesis of an RNA molecule from a DNA template
mRNA Processing
Protein Processing ?
Protein Translation
Synthesis of Polypeptide chain from mRNA Template.
DNA Polymerase
Catalyzes DNA Synthesis.
What is the REACTION Catalyzed by DNA Polymerase?
ALL (known) of this type of Enzyme ADD a Deoxyribonucleoside 5’-Triphosphate to the 3’-Hydroxyl group of a growing DNA chain (the Primer strand; see Fig 6.1).
ALL known DNA Polymerases share 2 Fundamental Properties w/ Critical Implications for DNA Replication. What are these Properties?
(1st) . ALL Polymerases Synthesize DNA only in the 5’ to 3’ direction, ADDING a dNTP to the 3’-Hydroxyl group of the Growing chain.
(2nd) . DNA Polymerases can ADD a New Deoxyribonucleotide ONLY to a Pre-formed Primer Strand that is H-bonded to the Template.
Can DNA Polymerase initiate DNA synthesis de novo by catalyzing the Polymerization of Free dNTPs.
NOPE!
DNA Polymerase CANNOT initiate DNA Synthesis by Catalyzing the Polymerization of Free dNTPs.
∵ ???
Replication Fork
Region of DNA synthesis where Parental Strands separate & 2 new Daughter Strands Elongate.
Okazaki Fragments
Short DNA segment synthesized to Form the Lagging Strand of DNA.
DNA Ligase
Enzyme that SEALS Breaks in DNA strands.
Leading Strand
Strand of DNA synthesized CONTINUOUSLY in the direction of movement towards Replication Fork.
Lagging Strand
Strand of DNA synthesized OPPOSITE to the direction of the movement of Replication Fork by LIGATION of Okazaki Fragments.
Primase
RNA Polymerase used to Initiate DNA Synthesis
Exonuclease
Enzyme that Hydrolyzes DNA molecules in either the 5’ —> 3’ or 3’ —> 5’ direction,
RNase H
Enzyme that Degrades the RNA strand of RNA-DNA Hybrid molecules.
Helicases
Catalyze the UNWINDING of Parental DNA, COUPLED to the Hydrolysis of ATP, ahead of the Replication Fork
Single-Stranded Binding Proteins
SSBPs
Proteins that STABILIZES unwound DNA by Binding to Single-Stranded regions.
Topoisomeras
Catalyze the REVERSIBLE Breakage + Rejoining of DNA strands.
SUMMARIZE: The Fidelity of Replication
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Proofreading
One of Major Mechanisms responsible for Accuracy of DNA Replication (activity of DNA Polymerase).
SUMMARIZE: Origins & the Initiation of Replication
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Origins of Replication
Specific DNA sequence that serves as Binding site for Proteins that Initiate the Replication process.
Figure 6.3 - Replication Origins in Eukaryotic Chromosomes.
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Autonomously Replicating Sequences
ARSs
Origin of DNA Replication in Yeast
Origin of Replication Complex
ORC
Req’d for the Initiation of DNA Replication @ Eukaryotic origins.
SUMMARIZE: Telomeres + Telomerase: Maintaining the Ends of Chromosomes
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Telomeres
Repeat, Simple-sequence DNA that Maintains the Ends of Linear Chromosomes.
Telomerase
Is a REVERSE Transcriptase that Synthesizes Telomeric repeat sequences at the Ends of Chromosomes FROM its OWN —> RNA Template.
Reverse Transcriptase
DNA Polymerase that USES an RNA Template.
What is Reverse Transcription?
The Synthesis of DNA from an RNA Template
Semiconservative Replication
Process of DNA Replication in which 2 Parental Strands separate + serve as Templates for 2 new progeny strands.
Nucleosome
Basic Structural unit of Chromatin consisting of DNA wrapped around a Histone Core
