Genetic Research and Model Organisms Quiz

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Questions and Answers

What significant advancement in genetic research involving mice occurred in the 1980s?

The identification of human gene counterparts in mice

The development of female mouse models

The construction of the first transgenic mice (correct)

The discovery of the mouse genome sequence

Why are male mice predominantly used in research on the effects of sex hormones?

They reach puberty faster than females

They are easier to handle in laboratory settings

They do not produce sex hormones

They allow for clearer experimental results (correct)

What percentage of mouse genes have a human counterpart?

97%

99% (correct)

75%

90%

Which model organism is primarily used to study fundamental molecular processes?

E. coli Signup and view all the answers

What has been emphasized in recent research regarding the use of mice in experimental studies?

The necessity of incorporating both sexes in studies Signup and view all the answers

Which organism is primarily studied for aging and cell death mechanisms?

C. elegans Signup and view all the answers

Which genetically modified mouse model is known for having certain genes deactivated?

Knock-out mice Signup and view all the answers

Which model organism is notably used in agricultural studies for pest resistance?

A. thaliana Signup and view all the answers

What is the primary function of epithelial cells?

Barrier and protection Signup and view all the answers

Which of the following cell types are NOT part of connective tissue?

Epithelial cells Signup and view all the answers

Which statement best describes Volvox algae?

It has two types of cells: germ cells and somatic cells. Signup and view all the answers

What is believed to have happened 1000-2000 million years ago?

The evolution of multicellular organisms from single-celled eukaryotes occurred. Signup and view all the answers

How do animal cells compare to plant cells in terms of diversity?

Animal cells are considerably more diverse than plant cells. Signup and view all the answers

Which type of cell is NOT typically found in connective tissue?

Epithelial cells Signup and view all the answers

What is a key feature of paramecium compared to chlamydomonas?

Paramecium has specialized movement through cilia. Signup and view all the answers

What is unique about the gene count of paramecium compared to human cells?

Paramecium has almost twice as many genes as human cells. Signup and view all the answers

What notable characteristic of C.elegans makes it suitable for genetic studies?

Its unique breeding system that allows isolation of hermaphrodites. Signup and view all the answers

Which of the following techniques was first described in C.elegans?

RNA interference. Signup and view all the answers

What percentage of Arabidopsis thaliana genes are similar to human genes?

30% Signup and view all the answers

Which of the following organisms is best known for its association with fruit?

Drosophila melanogaster. Signup and view all the answers

What is the average size range of adult zebrafish (Danio rerio)?

3-5 cm long Signup and view all the answers

What is a key application of Arabidopsis thaliana in agriculture?

Development of pest-resistant species Signup and view all the answers

What is the main advantage of C.elegans' transparency during experiments?

It allows in vivo monitoring of biological processes. Signup and view all the answers

What is the life cycle stage that follows the larval stages of Drosophila melanogaster?

Pupal stage. Signup and view all the answers

What enables the observation of all phases during zebrafish embryonic development?

Their transparent bodies Signup and view all the answers

Which Nobel prize-winning research area involved C.elegans?

Apoptosis. Signup and view all the answers

How long does it take for the embryonic development of zebrafish organs and tissues to occur?

24 hours Signup and view all the answers

What is a significant outcome of the studies conducted with Drosophila melanogaster?

Understanding of metamorphosis. Signup and view all the answers

Who proposed the use of zebrafish to study complex biological processes?

George Streinsinger Signup and view all the answers

Which of the following is NOT a known characteristic of C.elegans?

It has a long life cycle. Signup and view all the answers

What type of diet do zebrafish (Danio rerio) primarily have?

Omnivorous Signup and view all the answers

What is the estimated generation time for zebrafish?

3-4 months Signup and view all the answers

What is the primary component of paraffin used in optical microscopy?

Long-chain hydrocarbons Signup and view all the answers

What is the typical thickness range for histological sections prepared with a microtome for optical microscopy?

3 to 5 mm Signup and view all the answers

Which method doesn't require dehydration during the preparation of samples?

Cryostat sectioning Signup and view all the answers

Which of these dyes has a preference for basic substances found in cellular components?

Quick green Signup and view all the answers

What is the function of staining in optical microscopy?

To enhance the visibility of cell organelles Signup and view all the answers

What is the minimum thickness for sections made from freeze-fixed samples in a cryostat?

6 mm Signup and view all the answers

What type of microscopy requires using resins for the solidification of samples?

Transmission Electron Microscopy (TEM) Signup and view all the answers

Which staining agent is considered basic and favors acidic substances such as DNA?

Hematoxylin Signup and view all the answers

What is the primary advantage of using GFP in visualizing proteins within living cells?

It provides real-time observation without fixation or staining. Signup and view all the answers

What does the method of FRAP assess in living cells?

The rate of protein movement within the cell. Signup and view all the answers

How does FRET detect protein interactions?

Through the absorption and emission of light at different wavelengths by two probes. Signup and view all the answers

What is the function of the pinhole in confocal microscopy?

To allow only in-focus fluorescence signals to be detected. Signup and view all the answers

Which of the following correctly describes the process used in confocal microscopy to create 3D images?

Scanning several optical planes and stacking them using deconvolution software. Signup and view all the answers

What type of light is used to excite the first GFP variant in the FRET process?

A specific wavelength that matches the first variant's absorption spectra. Signup and view all the answers

What is the role of fluorescence recovery in the FRAP technique?

To measure the rate at which unbleached molecules replace bleached ones. Signup and view all the answers

Which method allows for higher detail images by focusing on a single plane within a sample?

Confocal microscopy. Signup and view all the answers

Study Notes

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