Genetic Research and Model Organisms Quiz

Unit 1: Overview of the cell and cell research

• Biology is the study of the composition, development, functioning, links, and distribution of living things.
• A cell is the fundamental unit of living beings, which can reproduce independently.
• Cell biology is a discipline that specializes in the analysis of cells, focusing on their structure, function, components, interactions, and properties.
• Cell biology draws on information related to genetics, biochemistry, and immunology.
• Molecular biology aims to study the processes that develop in living beings from a molecular point of view.
• Molecular biology focuses on the interactions of different systems within a cell, particularly nucleic acids (DNA and RNA), protein synthesis, metabolism, and how these interactions are regulated.
• Cell theory was formulated in 1839 by Matthias Schleiden and Theodor Schwann, with Rudolf Virchow's contribution, asserting that all living organisms are composed of one or more cells, that the cell is the basic unit of structure and organization in organisms, and that cells arise from pre-existing cells.
• Heredity information (DNA) is passed on from cell to cell.
• There are two main types of cells: prokaryotic and eukaryotic

1.1 Origin and evolution of cells

• The cell is the basic structural, functional, and biological unit of all known organisms.
• It is the minimum unit of an organism capable of acting autonomously.
• Robert Hooke (1635-1703) observed cells in cork (Micrographia, 1665).
• Antoni van Leeuwenhoek (1632-1723) observed bacteria, protozoa, and blood cells.

1.2 Cells as experimental models

• Unicellular models include Escherichia coli and Yeast
• Multicellular models include Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, and Mus musculus.

1.3 Cell biology instruments

• Optical microscopy
• Electron microscopy
• Super-Resolution Microscopy

Prokaryotes and Eukaryotes

• Prokaryotic cells lack a nucleus, their genomes are less complex and do not contain cytoplasmic organelles or cytoskeletons.
• Eukaryotic cells have a nucleus and more complex structures.
• Prokaryotes are smaller than eukaryotes.
• Eukaryotes are larger than prokaryotes.
• Table of characteristics of Prokaryotic and Eukaryotic Cells
  • Nucleus: absent in prokaryotes, present in eukaryotes.
  • Diameter: approximately 1-10 μm in prokaryotes, 10-100 μm in eukaryotes
  • Cytoplasmic organelles: absent in prokaryotes, present in eukaryotes
  • DNA content (base pairs): 1 x 10^0 to 5 x 10^6 in prokaryotes, 1.5 x 10^7 to 5 x 10^9 in eukaryotes
  • Chromosomes: single circular in prokaryotes, multiple linear in eukaryotes.

The first cell

• Life emerged at least 3.8 billion years ago, roughly 750 million years after the Earth originated.

Spontaneous formation of organic molecules

• Stanley Miller (1930-2007) conducted experiments in 1953 that demonstrated the spontaneous formation of organic molecules under plausible prebiotic conditions, including amino acids.

RNA self-replication

• The complementary pairs between nucleotides (Adenine with Uracil and Guanine with Cytosine) allow an RNA strand to serve as a template for the synthesis of a new strand with the complementary sequence.
• RNA is capable of catalyzing its own replication.

Central Dogma of Molecular Biology

• DNA → RNA → Protein.

Genetic code

• The genetic code determines how the sequence of nucleotides in DNA is translated into a sequence of amino acids in proteins.

Coating the self-replicating RNA with a phospholipid membrane

• The first cell is believed to have arisen from the coating of self-replicating RNA and its associated molecules by a membrane composed of phospholipids.

Evolution of metabolism

• Glycolysis is the anaerobic breakdown of glucose into lactic acid.
• Photosynthesis uses the energy from the sun to drive the synthesis of glucose from CO2 and H₂O, releasing O₂ as a product.
• Oxidative metabolism breaks down glucose into CO2 and H2O, releasing more energy than glycolysis.

Development of multicellular organisms

• Multicellular organisms have evolved from single-celled eukaryotes
• Different types of cells exhibit specialization and division of labor that contribute to organismal complexity

Animal cell types

• Animal cells are considerably more diverse than plant cells.
• Different types of animal tissues encompass epithelial, connective, blood, nervous, and muscle tissues.

Epithelial cells

• Epithelial cells form sheets throughout the body and delineate the internal organs.

Connective tissues

• Connective tissue includes bone, cartilage and adipose tissue. They are made up of different cell types including (osteoblasts, chondrocytes and adipocytes), respectively).

Blood

• The blood contains different types of cells (red blood cells or erythrocytes, granulocytes, monocytes and macrophages, lymphocytes) that function in different aspects encompassing oxygen transport, inflammatory reactions and immune responses.

Nervous tissue

• Nervous tissue (neurons) are highly specialized for transmitting signals throughout the body. Sensory cells (e.g. those in the eyes and ears) are specialized at receiving signals from the environment.

Muscle cells

• Muscle cells are responsible for the production of force and movement.
• There are different types: smooth, skeletal, and cardiac muscle.

Model organisms

• Species used in research as models for other living beings.
• All cells descended from a common ancestor, whose fundamental properties have been conserved throughout evolution.
• Knowledge derived from studying one organism contributes to the study of others, including humans.
• Different types of cells and organisms are used as experimental models to study various aspects of molecular and cellular biology.

E. coli

• A rod-shaped bacterium that usually inhabits the intestines of humans and other vertebrates.
• Its genetic information is contained on a circular double-stranded DNA molecule
• Its small genome size is an advantage for genetic studies.

Yeast

• Yeasts are the simplest eukaryotes
• They divide every 2 h and can easily grow into colonies from a single cell.
• They are crucial models for genetic manipulations, particularly concerning DNA replication, transcription, RNA processing, and protein assembly, as well as regulation of cell division.

Saccharomyces cerevisiae and Schizosaccharomyces pombe

• They can be divided by budding and fission
• Between 2001 and 2013, four Nobel Prizes were awarded for discoveries in yeast research.

S. cerevisiae

• Currently, the best known eukaryotic genome

Methods of asexual reproduction: fission and budding

• Details the methods of reproduction
• Fission & Budding

Humanized yeast

• The possibility of humanizing yeast by introducing human genes or replacing yeast genes with human orthologs makes yeast models useful for studying human functions.

Nobel Prize 2001 in Physiology or Medicine

• Awarded jointly to Leland H. Hartwell, Tim Hunt, and Sir Paul M. Nurse for their discoveries of key regulators of the cell cycle.

Nobel Prize 2013 in Physiology or Medicine

• Awarded for discoveries of machinery that regulates vesicle traffic, a major transport system in cells.

Caenorhabditis elegans

• Nematodes (roundworms) have been found to be excellent biological models for research due to their characteristics such as being relatively small (around 1 mm in length), easy to manipulate in the laboratory, having a short life cycle, and being essentially transparent.

Drosophila melanogaster

• This fruit fly can be found practically anywhere on the planet and is a model organism for the study of many biological and genetic processes. It undergoes a complete metamorphosis.

Arabidopsis thaliana

• Model organism for plant molecular biology.
• Widely used
• Easy to culture in labs
• Many of its genes match human genes

Danio rerio (Zebrafish)

• Small, active fish.
• Natural habitat in central Asia
• Elongated, 3-5 cm in length, 1 cm wide.

Mus musculus (Mouse)

• Model organism par excellence that encompasses a wide spectrum of biological processes and diseases.
• Widely used in lab.
• Short gestation period (~20 days)

Cell cultures

• Technique of isolating and maintaining cells in lab conditions
• Use of cells from normal/tumorous organs or tissues
• Essential growth medium factors: salts, glucose, amino acids, vitamins, and polypeptides growth factors.

Viruses

• Viruses require a host and are essential to grow viruses in a lab
• Viruses serve as easy model systems for investigating cell biology

Optical Microscopy

• Techniques, like light field microscopy, phase contrast, DIC, fluorescence, confocal, and multiphoton
• Applications for imaging various cell structures

Electron Microscopy

• Techniques like Transmission and Scanning
• Advantages in resolution, allowing analysis at a much higher magnification level
• Preparation of the samples for electron microscopy

Flow cytometry

• Technique used for analyzing the number, and complexity of cells in a suspension
• Using fluorescent labeling with instruments like cytometers
• Assessing cells by size and complexity

Subcellular separation

• Methods to separate subcellular components are necessary for in-depth study of chemical composition and function
• Methods like osmotic shock, centrifugation, and enzymatic methods
• Centrifugation methods such as differential and density gradient

Cell cultures

• Isolation, and maintenance of cells
• Use of cells from normal/tumor organs/tissues
• Cultured Cells Advantages: better control of experimental conditions
• Use of single cell growth to obtain a clone

Immortal cells (HeLa cells)

• Origination
• Indefinite reproduction
• Importance and usage in life sciences research

Human organoids

• Model systems that are based on human 3D cells
• Applications and ease of establishment and manipulation

Test your knowledge on significant advancements in genetic research, specifically focusing on mice and their role in scientific studies. This quiz covers various aspects, including gene counterparts, model organisms, and their applications in research. Dive deep into cellular biology and understand the implications of these studies.