D1.1 DNA replication Notes

DNA Replication

The biological process by which a cell copies its DNA to ensure that each daughter cell receives an identical set of genetic instructions during cell division.

Helicase

An enzyme that unwinds the DNA double helix by breaking hydrogen bonds between complementary base pairs.

DNA Polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides to a growing chain, using the original strand as a template.

Semi-Conservative Replication

DNA replication method in which each new DNA molecule consists of one original strand and one newly synthesized strand.

Complementary Base Pairing

The specific pairing of bases (A with T, C with G) in DNA that ensures the accuracy of DNA replication.

Leading Strand

The DNA strand that is synthesized continuously in the same direction as the replication fork.

Lagging Strand

The DNA strand that is synthesized discontinuously in short segments (Okazaki fragments) in the opposite direction of the replication fork.

Okazaki Fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

DNA Primase

An enzyme that synthesizes a short RNA primer to provide a starting point for DNA polymerase during DNA replication.

DNA Ligase

An enzyme that joins Okazaki fragments by forming covalent bonds between adjacent DNA nucleotides.

PCR (Polymerase Chain Reaction)

A technique used to amplify DNA, creating millions of copies of a specific DNA sequence in just a few hours.

Gel Electrophoresis

A laboratory technique used to separate and analyze molecules such as DNA based on their size and charge.

DNA Profiling

A technique used to identify individuals based on unique patterns in their DNA, crucial for forensic science.

Taq Polymerase

A heat-resistant enzyme used in PCR to synthesize new DNA strands.

Thermal Cycler

A machine that precisely controls temperature changes during the PCR process.

Template DNA

The DNA to be copied in a PCR process.

Nucleotides (dNTPs)

The building blocks of DNA used in DNA synthesis during replication and PCR.

Primers in PCR

Short DNA sequences that bind to the template, marking the starting point for replication.

Replication Fork

The Y-shaped region where the DNA double helix is unwound and replicated.

Proofreading Function

The ability of DNA polymerases to detect and correct mismatched bases during replication.

Exonuclease Activity

The function of DNA polymerases that allows them to remove incorrect nucleotides during proofreading.

Hydrogen Bonds

Weak bonds between the bases of DNA that are broken during DNA replication.

Phosphodiester Bonds

Covalent bonds that link nucleotides in the sugar-phosphate backbone of DNA.

Short Tandem Repeats (STRs)

Regions of DNA that contain short sequences that repeat, used in DNA profiling to distinguish individuals.

Mismatch Repair

A process to correct mismatched bases that DNA polymerase does not catch during replication.

Anti-Parallel Structure of DNA

The orientation of the two strands of DNA that run in opposite directions, crucial for replication.

Error Rate of DNA Replication

Typically about 1 in 10 billion bases after proofreading.

Biological Significance of DNA Replication

DNA replication is vital for reproduction, growth, and tissue replacement.

DNA replication accuracy

The high fidelity of DNA replication ensures genetic stability and prevents mutations.

Replication Bubble

The region where DNA unwinds and replication occurs simultaneously on both strands.

Topoisomerase

An enzyme that relieves strain ahead of the replication fork by cutting and rejoining the DNA strands.

Single-Stranded Binding Proteins (SSBs)

Proteins that coat single-stranded DNA to prevent it from re-annealing or forming secondary structures.

DNA Repair Mechanisms

Processes that correct errors in DNA replication and maintain genomic integrity.

Genetic Continuity

The preservation of genetic information across generations facilitated by DNA replication.

Enzyme Coordination

The precise interaction of various enzymes during DNA replication to ensure accuracy and efficiency.

Adenine (A)

A nitrogenous base that pairs with thymine (T) in DNA.

Thymine (T)

A nitrogenous base that pairs with adenine (A) in DNA.

Cytosine (C)

A nitrogenous base that pairs with guanine (G) in DNA.

Guanine (G)

A nitrogenous base that pairs with cytosine (C) in DNA.

Sugar-Phosphate Backbone

The structural framework of DNA, composed of sugar and phosphate groups.

Replication Accuracy

The precision with which DNA replication occurs, minimizing errors to maintain genetic fidelity.

Replication Timing

The specific timing of DNA replication during the cell cycle.

Biotechnology Applications

Utilization of DNA replication techniques for medical and forensic advancements.

Forensic Analysis

Using DNA profiling to link suspects to crimes or identify remains.

Evolutionary Studies

Using DNA analysis to understand evolutionary relationships among species.

Environmental Applications

Using DNA techniques to monitor biodiversity and environmental health.

Agarose Gel

A substance used to create a gel matrix for gel electrophoresis.

Base Pairing Rules

The rules that determine which bases pair in DNA (A with T; C with G).

Function of DNA Ligase

To seal gaps and join Okazaki fragments on the lagging strand during DNA replication.

Role of RNA primers

To provide a starting point for DNA synthesis in DNA replication.

DNA Repair Types

Various mechanisms to fix errors in DNA, including base excision and nucleotide excision repair.

PCR Cycle Steps

The three main steps: denaturation, annealing, and extension in the PCR process.

Application of PCR in Medicine

PCR is used for early detection of diseases and genetic disorders.

Investigative Techniques

Methods that utilize PCR and gel electrophoresis for criminal investigations.