PRELIM LEC: DNA: STRUCTURE, REPLICATION, ENZYMES, RECOMBINATION, AND PLASMIDS

It is the process by which DNA makes a copy of itself during cell division

Dna replication

• Every double helix in the new generation of an organism consists of 1 complete "old" strand and 1 complete "new" strand wrapped around each other

• Key to maintaining the sequence of the nucleotides in DNA through new generations

Semi conservative

Who is the the person that Demonstrated the mechanism of semiconservative replication using the technique of equilibrium density centrifugation on a cesium gradient?

Matthew meselson and Franklin stahl

Binds to origin and separate strands

Helicase

Keep the strand apart

Binding

Makes a short stretch of RNA on the DNA template

Primare

Adds DNA nucleotides to the RNA primer

DNA polymerase

Proofreading activity checks and replaces incorrect bases

DNA polymerase

Continues strand synthesis continues in a what?

5 to 3

Discontinues synthesis produces _______ on the 5 to 3 template

Okazaki fragments

Enzyme removes RNA primers ______ reals sugar- phosphate backbone

Ligase

• it is a continuous process

• Circular, double stranded DNA

• Single origin of replication

• Large okazaki fragments

Prokaryotes

• This process occurs in the s-phase of cell cycle

• Linear, double stranded DNA with end

• Multiple origins of replication

• Small okazaki fragments

Eukaryotes

• 1st purified enzyme shown to catalyze DNA replication in prokaryotes

• Followed by dna polymerase II & III

DNA polymerase I

• Addition of labeled nucleotides

• It used to in vitro as a method to introduce labeled nucleotides into DNA molecules

Nick translation

Where to locate the pol A in the eukaryotic cell?

Nucleus

This function Most active, identified with chromosome replication

Pol A

Where to locate the pol B in the eukaryotic cells?

Nucleus

This function is Associated with DNA pair

Pol B

Where to locate the pol Y in the eukaryotic cell

Mitochondria

This function is to Replication of Mitochondrial DNA

Pol Y

Where to locate the Pol O in the eukaryotic cell

Bone marrow

What type of polymerase that this function associated with DNA repair and 3 to 5 exonuclease activity

Pol O

• Type of DNA polymerase that can synthesize polynucleotide chains without a template

• Used in the laboratory to generate 3'-end labeled DNA species

Terminal transferase

It is important a central role in modern biotechnology

Polymerase

What are most useful for biotechnology?

A AND B

What are those characteristics that useful of modern biotechnology

1. Processivity

2. Fidelity

3. Substrate

staying with the template longer to make longer products

Processivity

faithful copying of the template

Fidelity

affinity for altered nucleotides

Substrate specificity

It is the process by which cellular DNA is maintained.

DNA Metabolism

Named for the organism in the endonuclease from which they were isolated:

• Bacillus amyloliquefaciens H

• Haemophilus influenzae Rd

• Serratia marcescens Sb

Endonucleases can be divided into two categories:

• restriction enzymes

• Non restriction enzymes

are endonucleases that recognize and cleave specific DNA sequences.

Restriction enzymes

Are endonacleases not require specific recognition sequences and can cleave DNA at random locations.

Non-restriction enzymes

• A type of endonucleases Nuclease & methylase activity in a single enzyme

• example: ecok from e.coli

Type I Restriction Enzymes

• A type of endonucleases it Used most frequently in the laboratory

• Do not have inherent methylation activity

Type II Restriction Enzymes

• A type of endonucleases that Resemble Type enzymes in their ability to both methylate & restrict (cut) DNA

• Have multiple subunits, including helicase (unwinding) activity

Type III Restriction Enzymes

• Similar subunit structures & enzyme requirements

• Cut site: assymetrical

Type IV Restriction Enzymes

• Catalyzes the formation of a phosphodiester bond between adjacent 3'-hydroxyl & 5'-phosphoryl nucleotide ends

• Discovered in 5 different laboratories in 1967

DNA ligase

Series of enzymes that cut & re-close the DNA sugar-phosphate backbone

helicases

What are the 2 types of helicases

• Topoisomerase

• Gyrase

• a type of topoisomerase that specifically introduces negative supercoils into DNA.

• untangles DNA through double-strand breaks & separate linked rings of DNA

Gyrase

It is the mixture & assembly of new genetic combinations.

Recombination

The one that holds a new combination of DNA sequences is called

Recombinant molecules

Each generation of sexually reproducing organisms s is a new combination of the larentals genomes — generate genetic diversity

Mendel's law

• transfer for genetic information by physical association of cells

• It must be in physical contact with each other for successful transfer of the F+ phenotypes

Conjugation

It transfer of genetic information from 1 cell to another through a viral intermediate

Transduction

It transfer of genetic information among cells without physical association, such that a new phenotype is produced in the recipient cells

Transformation

These are small, usually circular dsDNAs, often carrying genetic information, that replicates independently or in synchrony with host cell replication

Plasmids

Classified the initial plasmids

• large plasmids

• Small plasmids

• It include f factor & some of the R plasmids

• It carry genes for their own transfer & propagation & self-transmissible

Large plasmids

• more numerous in the cell

• Do not carry genes directing their maintenance

Small plasmids

Class of plasmids carrying resistane to ______ what?

Bacteriocins