Untitled Quiz

Key Concepts in Genetics, Heredity, and DNA

• Introduction to genetics: Covers history, overview, and applications.
• Mendelian genetics: Describes inheritance patterns discovered by Gregor Mendel.
• Linkage and recombination: Explains how genes located on the same chromosome are inherited together, while also discussing the process of recombination.
• Identification of DNA as the hereditary material: Discusses the experiments of Griffith and Avery, Macleod & McCarthy proving DNA is the genetic material
• Quantitative genetics: Investigates how multiple genes influence traits.
• DNA, structure, and function: Details the double helix structure.
• DNA – mutation, recombination and repair: Covers methods of DNA repair and mutation types.
• The central dogma: Explains how genetic information is passed from DNA to RNA to protein.

A Whistle-Stop Tour of 150 Years of Genetics - History

• 1860s: Mendel published research on inheritance of unit factors. Cytologists described chromosomes and their behavior during mitosis and meiosis.
• 1900s: Mendel's work was rediscovered. Chromosomes were recognized as unit factors. The term "gene" replaced unit factors.
• 1905: William Bateson coined the term "Genetics" to describe the study of inheritance.
• 1940s: DNA was confirmed to be the genetic material, not protein.
• 1950s: Watson and Crick described the double-helical structure of DNA. This marked the beginning of the molecular biology era.
• 1960s: The triplet code and the pathway of information flow: “DNA makes RNA makes protein” was discovered.

Key Discoveries & Developments in Genetics

• 1970s: Restriction enzymes were discovered, making recombinant DNA technology possible. Expression of human growth hormone in E. coli was demonstrated.
• 1980s: Recombinant DNA technology became commercialized. Methods were developed to make transgenic plants and animals.
• 1990s: Genome sequencing of humans, plants, fruit flies, nematodes, and other organisms advanced significantly.
• 2000s: First complete human genome sequence published in 2003. Cost was approximately $3 billion. Technology for expression profiling was advanced. RNA interference and genome editing tools (e.g., CRISPR) emerged. Cost of whole genome sequencing fell dramatically to less than $1,000 in 2019.

Genetics & Disease

• Mendelian Disorders: Diseases caused by a mutation in a single gene. There are over 3,000 known Mendelian disorders. Examples include Achondroplasia, Cystic Fibrosis, and Huntington's Disease.
• Autosomal Dominant Disorders: Features, on average 50% of children are affected with the disease. Examples include Achondroplasia
• Autosomal Recessive Disorders: Features, on average 25% of children are affected with the disease. Examples include Retinitis Pigmentosa, in 1/1800 births in Ireland
• X-linked Disorders: Features, affects males more often. Examples include Haemophilia.

Genomics & Heredity

• Genomics: Large-scale analysis of the genome. Includes the study of sets of genes in a given species, and the study of whole sets of proteins.
• Human Genome Sequencing Project: Identified the sequence of the human genome (3 billion base pairs) in 2003, costing $2-3 billion. This cost has substantially decreased over the years.
• Cost-per-Genome Trend: A descending graph illustrating the declining cost of sequencing, demonstrating technological advancements.
• Pharmacogenomics: Research into how genes affect the response to drugs, allowing physicians to prescribe drugs based on patient's genetic profile.
• Examples of related diseases: Familial combined hyperlipidaemia Familial hypercholsterolaemia Dominant otosclerosis Adult polycystic kidney disease

The Cell Cycle & Mitosis/Meiosis

• Cell Division: Mitosis for somatic (non-reproductive) cells & Meiosis for gametes. The cell cycle (including interphase) is the series of events in the life of a typical eukaryotic cell that involves growth and reproduction.
• Mitosis: Cell duplication to yield two identical daughter cells.
• Meiosis: Cell division that produces four distinct daughter cells. Involved in gamete formation to enable sexual reproduction, ensuring that offspring receive half of their genetic material from each parent. Meiosis also involves crossing over.

DNA Structure & Function

• DNA molecule: Composed of two long chains in a double helix.
• Structure of DNA: Each chain is composed of nucleotides (adenine, thymine, guanine, and cytosine); connected by phosphates & sugars.
• DNA Structure: The double-helix structure of DNA is crucial for information storage & genetic material transmittance between generations.

RNA & Transcription

• Transcription: Using DNA as a template, synthesizes RNA.
• Different types of RNA: Messenger RNA (mRNA), Ribosomal RNA (rRNA), Transfer RNA (tRNA), and other non-coding RNAs.
• Central Dogma: DNA → RNA → Protein describes the flow of genetic information.
• Regulation of Gene Expression: Controlling the process of gene expression by controlling transcription, regulating how much of a gene is expressed (or when) and which cells within the body or organism the gene is expressed in.

Additional Points

• Human Karyotype: A visual display of an organism's chromosomes used to identify abnormalities, including whether an individual is male / female.
• Genetic Maps: Graphical representations showing the relative positions of genes along chromosomes, usually created by tracking recombination rates (frequency of crossing-over).
• Gene Therapy: Using a method, in principle, to insert a normal copy of a mutated gene into a particular cell type, to correct or replace the faulty protein.
• Genetic Diseases: Mutations, caused by variations in DNA, could cause disease, e.g., haemophilia, cystic fibrosis, Huntington's disease, X-linked ichthyosis, fragile X syndrome, duchenne muscular dystrophy, sickle cell disorder, and the examples highlighted in charts throughout the material