Gene Expression, Engineering, + DNA Replication

Leading Strands

The leading strand is synthesized by adding nucleotides to the 3’ end of the growing strand and it is synthesized in short fragments that are stitched together.

Lagging Strands

The lagging strand is synthesized by adding nucleotides to the 5’ end and it is synthesized continuously.

The Replication Fork

DNA polymerase will add nucleotides continuously on the leading strand, and the 5’-3’ direction will be heading IN towards the fork. DNA polymerase will add new nucleotides in fragments on the lagging strand, and the direction, while still 5’-3’ will be heading OUT from the fork

Ligase…

seals the backbone (sugar-phosphate backbone),

Helicase…

unzips

DNA polymerase…

adds nucleotides

Primase…

lays down RNA primer

Plasmids

carry genes for replicating their DNA, transferring themselves from one host cell to another, and for a variety of phenotypes. They are small circular double stranded DNA molecules.

How reporter genes are used to select for transformed cells?

They select them by incorporating them into the DNA of the transforming cells. These genes produce proteins that can be easily detected, allowing researchers to identify which cells have successfully taken up the foreign DNA. This selection process helps isolate and study transformed cells.

Restriction enzymes

a protein isolated from bacteria that cleaves DNA sequences at sequence-specific sites, producing DNA fragments with a known sequence at each end. The use of restriction enzymes is critical to certain laboratory methods, including recombinant DNA technology and genetic engineering.

Sticky Ends

short, single-stranded sections of DNA that result from cutting DNA with a restriction enzyme. Sticky ends are called such because the single stranded DNA can easily be paired with a complementary sequence, allowing two pieces of DNA to stick together.

DNA ligaze

A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.G

Gene Expression

A gene is expressed when it is being transcribed and translated into a protein. If a gene is being expressed in a cell, the protein for that gene will be present.

the role of RNA polymerase in transcription

it binds to the promoter sequence in front of the gene and moves down the gene, creating mRNA aka does the process of transcription

RNA polymerase and transcription factors are…

proteins

All the cells in your body have the same DNA, but…

they have different transcription factors present that cause different genes to be transcribed and translated. 

Eukaryotic genes have…

introns + expns

Introns

non-coding regions that must be removed before translation.

Prokaryotic genes don’t have ...

introns

To get a eukaryotic gene expressed in bacteria, …

introns must be removed

We have introns so…

exons of 1 gene can be spliced together in different ways.

exons

a segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence.