Posted on

Enzymes Involved in DNA Replication of Prokaryotes

Enzymes Involved in DNA Replication of Prokaryotes

DNA Replication in prokaryotes is one of the most important topics. To understand the whole basic mechanism of replication; there is this one thing I always felt while studying that would have been great if I find a list of all the enzymes involved in the process in order. So I tried and made my list which really helped me, especially during exam for quick revision. In this post I am sharing the list of enzymes involved in DNA replication of prokaryotes.

Sr. No. Enzyme Involved Key Role
1. Dna A Recognizes and binds to Ori C
2. Dna C Loads Dna B
3. Dna B (Helicase) Breaks the H-bonds between two DNA strands
4. SSB Protein (Single Stranded DNA Binding Protein) Prevents ssDNA from re-forming a double helix
5. Topoisomerase II (Gyrase) Removes topological stress
6. Dna G (Primase) Synthesizes primers
7. DNA Pol. III Synthesizes new strands of DNA in 5’à3’ direction
8. DNA Pol. I Removes primers (has exonuclease activity)

Fills the gap created (has polymerase activity)
9. DNA Ligase Seals the gap by formation of phosphodiester bond
10. Topoisomerase IV Separates DNA catenanes

I hope this post helps 🙂

To understand more in details about the DNA replication process in prokaryotes, watch a video on this topic here.

Posted on

Genotype and Phenotype – What is the Difference?

Genotype and Phenotype – What is the Difference?

To understand this topic we must know what are genes and alleles. We have already discussed these in one of the previous blog.

In brief genes are stretches or small sequences of DNA that codes for a particular trait. Alleles are different variants of the same gene which means they might have little difference in their sequence.

Such as we have hair color gene but all of us don’t have same hair color and that is because we carry different allele of the hair color gene.

Genotype:  In simple words it is what ‘we have’.

The complete genetic makeup of an individual or set of all the alleles that an individual possesses is called the genotype.  Set of genes or alleles in our DNA are responsible for a particular trait.

Let’s say for example eye color gene is coded by B and b where B is dominant; codes for brown color and b is recessive; codes for blue color. Since we are diploid we can have three different possible genotypes and that is homozygous dominant; BB or heterozygous; Bb or homozygous recessive; bb.

Genes are what are passed from one generation to another generation and that is why genotype is inherited.

So as we saw in above example we can have three possible genotypes and they would express something isn’t it? That expression or outcome of genotype is called phenotype.

Phenotype: In simple words it is what ‘we see’.

The physical appearance or expression of a particular trait or genotype is called phenotype. Most of the time it is the visible or observable expression of the genes. But phenotype also includes the biochemical properties because that also is a result of expression of particular genes.

Let’s take the eye color example again. Homozygous dominant BB genotype gives brown color phenotype. Heterozygous Bb gives brown color phenotype and homozygous recessive bb gives blue color phenotype.

Therefore, Genotype Determines the Phenotype.

If we put it in Punnett square as given below, it is easy to understand. We can have 3 different genotypes but they would express 2 different phenotypes.

I hope this post helps J

To understand more in detail, watch a video on this topic here.