DNA Replication Process

Process by which a cell makes an exact copy of its DNA before cell division
Semi-conservative: each new DNA molecule contains one old strand (template) and one new strand
Steps:
1. Initiation: unwinding of DNA, binding of replication fork
2. Unwinding: helicase unwinds DNA, topoisomerase relieves tension
3. Binding: primase adds RNA primers to template strands
4. Elongation: DNA polymerase adds nucleotides to primers
5. Proofreading: DNA polymerase checks for errors
6. Ligation: DNA ligase seals gaps between nucleotides

Process by which information in DNA is used to synthesize a functional product
Central Dogma: DNA → RNA → Protein
Transcription:
- Initiation: RNA polymerase binds to promoter region
- Elongation: RNA polymerase adds nucleotides to mRNA
- Termination: transcription stops, mRNA is released
Translation:
- Initiation: ribosome binds to mRNA
- Elongation: amino acids are added to polypeptide chain
- Termination: protein synthesis stops, polypeptide is released

Process by which a polypeptide chain is synthesized from a mRNA template
Translation machinery:
- Ribosomes: read mRNA, assemble amino acids
- tRNA (transfer RNA): brings amino acids to ribosomes
- Aminoacyl-tRNA synthetases: link amino acids to tRNA
Steps:
1. Initiation: ribosome binds to mRNA, initiator tRNA
2. Elongation: amino acids are added to polypeptide chain
3. Termination: protein synthesis stops, polypeptide is released
Post-translational modifications: proteins may undergo folding, modification, targeting

Study of evolutionary processes at the molecular level
Key concepts:
- Neutral theory: most mutations are neutral, not affecting fitness
- Molecular clock: rate of molecular change is constant over time
- Phylogenetic analysis: reconstructing evolutionary relationships
Types of molecular evolution:
- Orthologs: genes with same function, different species
- Paralogs: genes with same origin, different function
- Xenologs: genes introduced from another species

Study of structure, function, and evolution of genomes
Key concepts:
- Genome: complete set of genetic information
- Proteome: complete set of proteins encoded by a genome
- Systems biology: study of biological systems as a whole
High-throughput sequencing technologies:
- Sanger sequencing: dideoxy chain termination method
- Next-generation sequencing (NGS): parallel sequencing of millions of fragments
Applications:
- Personalized medicine: tailoring treatment to individual genomes
- Synthetic biology: designing new biological systems

DNA replication occurs before cell division to create an exact copy of the cell's DNA
The process is semi-conservative, resulting in two new DNA molecules, each containing one old strand (template) and one new strand
Initiation involves unwinding of DNA and binding of replication fork
Helicase unwinds DNA, and topoisomerase relieves tension during unwinding
Primase adds RNA primers to template strands during binding
DNA polymerase adds nucleotides to primers during elongation
DNA polymerase checks for errors during proofreading
DNA ligase seals gaps between nucleotides during ligation

Gene expression is the process of synthesizing a functional product from DNA information
The Central Dogma outlines the flow of information: DNA → RNA → Protein
Transcription is initiated when RNA polymerase binds to the promoter region
RNA polymerase adds nucleotides to mRNA during elongation
Transcription stops, and mRNA is released during termination
Translation is initiated when a ribosome binds to mRNA
Amino acids are added to the polypeptide chain during elongation
Protein synthesis stops, and the polypeptide is released during termination

Protein synthesis is the process of synthesizing a polypeptide chain from a mRNA template
Ribosomes read mRNA and assemble amino acids during translation
tRNA brings amino acids to ribosomes during translation
Aminoacyl-tRNA synthetases link amino acids to tRNA
Initiation involves the binding of ribosome to mRNA and initiator tRNA
Amino acids are added to the polypeptide chain during elongation
Protein synthesis stops, and the polypeptide is released during termination
Post-translational modifications include folding, modification, and targeting

Molecular evolution is the study of evolutionary processes at the molecular level
The neutral theory states that most mutations are neutral and do not affect fitness
The molecular clock concept suggests that the rate of molecular change is constant over time
Phylogenetic analysis involves reconstructing evolutionary relationships
Orthologs are genes with the same function in different species
Paralogs are genes with the same origin but different functions
Xenologs are genes introduced from another species

Genomics is the study of the structure, function, and evolution of genomes
A genome is the complete set of genetic information in an organism
A proteome is the complete set of proteins encoded by a genome
Systems biology involves the study of biological systems as a whole
Sanger sequencing uses the dideoxy chain termination method
Next-generation sequencing (NGS) involves parallel sequencing of millions of fragments
Personalized medicine involves tailoring treatment to individual genomes
Synthetic biology involves designing new biological systems