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By the end of this section, you will be able to:
  • Explain the scientific reasons for the success of Mendel’s experimental work
  • Describe the expected outcomes of monohybrid crosses involving dominant and recessive alleles
Image is a sketch of Johann Gregor Mendel.
Johann Gregor Mendel set the framework for the study of genetics.

Johann Gregor Mendel (1822–1884) ( [link] ) was a lifelong learner, teacher, scientist, and man of faith. As a young adult, he joined the Augustinian Abbey of St. Thomas in Brno in what is now the Czech Republic. Supported by the monastery, he taught physics, botany, and natural science courses at the secondary and university levels. In 1856, he began a decade-long research pursuit involving inheritance patterns in honeybees and plants, ultimately settling on pea plants as his primary model system    (a system with convenient characteristics that is used to study a specific biological phenomenon to gain understanding to be applied to other systems). In 1865, Mendel presented the results of his experiments with nearly 30,000 pea plants to the local natural history society. He demonstrated that traits are transmitted faithfully from parents to offspring in specific patterns. In 1866, he published his work, Experiments in Plant Hybridization, Johann Gregor Mendel, “Versuche über Pflanzenhybriden.” Verhandlungen des naturforschenden Vereines in Brünn , Bd. IV für das Jahr, 1865 Abhandlungen (1866):3–47. [for English translation, see http://www.mendelweb.org/Mendel.plain.html] in the proceedings of the Natural History Society of Brünn.

Mendel’s work went virtually unnoticed by the scientific community, which incorrectly believed that the process of inheritance involved a blending of parental traits that produced an intermediate physical appearance in offspring. This hypothetical process appeared to be correct because of what we know now as continuous variation. Continuous variation is the range of small differences we see among individuals in a characteristic like human height. It does appear that offspring are a “blend” of their parents’ traits when we look at characteristics that exhibit continuous variation. Mendel worked instead with traits that show discontinuous variation    . Discontinuous variation is the variation seen among individuals when each individual shows one of two—or a very few—easily distinguishable traits, such as violet or white flowers. Mendel’s choice of these kinds of traits allowed him to see experimentally that the traits were not blended in the offspring as would have been expected at the time, but that they were inherited as distinct traits. In 1868, Mendel became abbot of the monastery and exchanged his scientific pursuits for his pastoral duties. He was not recognized for his extraordinary scientific contributions during his lifetime; in fact, it was not until 1900 that his work was rediscovered, reproduced, and revitalized by scientists on the brink of discovering the chromosomal basis of heredity.

Mendel’s crosses

Mendel’s seminal work was accomplished using the garden pea, Pisum sativum , to study inheritance. This species naturally self-fertilizes, meaning that pollen encounters ova within the same flower. The flower petals remain sealed tightly until pollination is completed to prevent the pollination of other plants. The result is highly inbred, or “true-breeding,” pea plants. These are plants that always produce offspring that look like the parent. By experimenting with true-breeding pea plants, Mendel avoided the appearance of unexpected traits in offspring that might occur if the plants were not true breeding. The garden pea also grows to maturity within one season, meaning that several generations could be evaluated over a relatively short time. Finally, large quantities of garden peas could be cultivated simultaneously, allowing Mendel to conclude that his results did not come about simply by chance.

Questions & Answers

what Is taxonom
Don Reply
Taxonom is the the laws and principles guiding the classification of living things either plant 🌿 or animal
Samuel
protein synthesis began with what?
Kesselly Reply
What structures does a plant cell have that an animal cell does not hav
Martin Reply
A plant cell has a cell wall, a large central vacuole, and chloroplasts, which an animal cell does not have.
AI-Robot
what is the function of the cytoskeleton?
Martin
truly. Al-robot
Mark
why is it advantageous for the cell membrane to be fluid in nature?
Martin Reply
The fluid nature of the cell membrane allows for flexibility and dynamic changes in its structure. This allows for the movement of molecules and ions in and out of the cell, as well as the ability to respond to external stimuli. The fluidity of the membrane also allows for the formation of specialized structures such as receptor proteins, which are important for cell-cell communication.
AI-Robot
What is used as a visual marker for successful gene transfer into transgenic animals?
rhonda Reply
Parts of the body involved in homeostasis
Favour Reply
liver
Kirk
A collection of similar-typed cells working together to perform a specific function is called what?
Rachel Reply
tissue
Van
which structure consists of a phospholipid bilayers and it is known as the mosaic model?
Jamar Reply
cell membrane
Abanoub
what is diffusion
Patricia Reply
a passive process of transport
Jamar
Random movement of gas molecule from region of high concentration to a low concentration.
praise
10 difference between male and female reproductive system
Ina Reply
if a phase is omitted ,what will happen to the cell
Ewemoje Reply
discribe advantages and disadvantages of asexual and sexual reproduction
basi Reply
Compared to separate sexes and assuming self-fertilizing is not possible, what might be one advantage and one disadvantage to hermaphroditism?
Gift Reply
is nature of their environment among
basi
cool 😎
Precious
why are the laws of thermodynamics considered laws of nature and not scientific theories
Yolonda Reply
archea were given their own separate domain because they are?
Yolonda
which of the following is a basic component of all of the others?
Yolonda
which of the following organization levels is the least inclusive
Yolonda
which cell feature is absent in bacterial cells
Yolonda
which metric movies the base unit of measurement by one thousandth (0.001)?
Yolonda
What is biology?
Blessing Reply
List the branches of biology
Blessing
List the branches of biology
Blessing
List the branches of biology
Blessing
List the branches of biology
Blessing
Ecology,Anatomy,genetics,biophysics,biochemistry,microbiology and biotechnology.
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Source:  OpenStax, Concepts of biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11487/1.9
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