Molecular Basis for
This presentation is the property of its rightful owner.
Sponsored Links
1 / 13

Molecular Basis for Relationship between Genotype and Phenotype PowerPoint PPT Presentation


  • 70 Views
  • Uploaded on
  • Presentation posted in: General

Molecular Basis for Relationship between Genotype and Phenotype. genotype. DNA. DNA sequence. transcription. replication. RNA. translation. amino acid sequence. protein. function. phenotype. organism. Overview of DNA Synthesis.

Download Presentation

Molecular Basis for Relationship between Genotype and Phenotype

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Molecular basis for relationship between genotype and phenotype

Molecular Basis for

Relationship between Genotype and Phenotype

genotype

DNA

DNA sequence

transcription

replication

RNA

translation

amino acid

sequence

protein

function

phenotype

organism


Molecular basis for relationship between genotype and phenotype

Overview of DNA Synthesis

DNA polymerases synthesize new strands in 5’ to 3’ direction.

Primase makes RNA primer.

Lagging strand DNA consists of Okazaki fragments.

In E. coli, pol I fills in gaps in the lagging strand and removes RNA primer.

Fragments are joined by DNA ligase.


Molecular basis for relationship between genotype and phenotype

DNA Replication at Growing Fork

DNA polymerases add nucleotides in 5’ to 3’ direction.

Because of antiparallel nature, synthesis of DNA is continuous for one strand and discontinuous for the other strand.


Molecular basis for relationship between genotype and phenotype

DNA Replication:

Synthesis of Lagging Strand

Several components and steps are involved in the discontinuous synthesis of the lagging strand.

Note that DNA polymerases move in 3’ to 5’ direction on the template DNA sequence.


Molecular basis for relationship between genotype and phenotype

DNA Replication:

Synthesis of Lagging Strand

DNA extended from primers are called Okazakifragments.

In E. coli, pol I removes RNA primers and fills in the gaps left in lagging strands.

DNA ligase joins these pieces.


Molecular basis for relationship between genotype and phenotype

Replisome and Accessory Proteins

Looping of template DNA for the lagging strand allows the two new strands to be synthesized by one dimer.

pol III holoenzyme is a complex of many different proteins.

Refer to Figure 7-20 from Introduction to Genetic Analysis, Griffiths etal., 2012.


Molecular basis for relationship between genotype and phenotype

Priming DNA Synthesis

DNA polymerases can extend (but cannot start) a chain.

Primase enzyme makes short RNA primer sequence complementary to template DNA.

DNA polymerase extends RNA primer with DNA.

Primosome is a set of proteins that are involved in the synthesis of RNA primers.

Refer to Figure 7-20 from Introduction to Genetic Analysis, Griffiths etal., 2012.


Molecular basis for relationship between genotype and phenotype

Supercoiling results from separation of template strands during DNA replication.


Molecular basis for relationship between genotype and phenotype

Helicases and Topoisomerases

Helicase enzymes disrupt hydrogen bonding between complementary bases.

Single-stranded binding protein stabilizes unwound DNA.

Unwound condition increases twisting and coiling, which can be relaxed by topoisomerases (such as DNA gyrase).

Topoisomerases can either create or relax supercoiling.

They can also induce or remove knots.


Molecular basis for relationship between genotype and phenotype

Chromatin assembly factor I (CAF-I) and histones are delivered to the replication fork.

CAF-I and histones bind to proliferating cell nuclear antigen (PCNA), the eukaryotic version of clamp protein.

Nucleosome assembly follows thereafter.

Refer to Figure 7-23 from Introduction to Genetic Analysis, Griffiths etal., 2012.


Molecular basis for relationship between genotype and phenotype

Overview of DNA Synthesis

DNA polymerases synthesize new strands in 5’ to 3’ direction.

Primase makes RNA primer.

Lagging strand DNA consists of Okazaki fragments.

In E. coli, pol I fills in gaps in the lagging strand and removes RNA primer.

Fragments are joined by DNA ligase.


Molecular basis for relationship between genotype and phenotype

Initiation at Origin of Replication

Prokaryotes:

Fixed origin

DnaA proteins

DnaB (helicase)

Eukaryotes:

Multiple origins

ORC protein complex

Cdc6 and Cdt1

MCM complex (helicase)


  • Login