mendal

Quick Facts

ALSO LISTED IN

Geneticists

ALSO KNOWN AS

father of modern genetics

NATIONALITY

Austrian    Famous Austrian Men

BORN ON

22 July 1822 AD

BIRTHDAY

22nd July    Famous 22nd July Birthdays

DIED AT AGE

62

SUN SIGN

Cancer    Cancer Men

BORN IN

Heinzendorf bei Odrau, Austrian Empire

DIED ON

06 January 1884 AD

PLACE OF DEATH

Brno (Brünn), Austria-Hungary

FATHER

Anton Mendel

MOTHER

Rosine (Schwirtlich) Mendel

SIBLINGS

Veronica Mendel, Theresia Mendel

EDUCATION

Palacký University Olomouc University of Vienna

Gregor Mendel, born as Johann Mendel, was an Austrian scientist and monk hailed as the “Father of modern genetics” for his pioneering research in the field of heredity. He was a monk in Augustinian Abbey of St Thomas in Brno where he worked as a teacher. He had a deep interest in botany which led him to conduct experiments on pea plants. Inspired by the work of a biologist named Franz Unger, he began his experiments in the monastery’s sprawling gardens. Over the course of his study he observed that there were seven characteristics in the pea plants, and two forms of each characteristic. These characteristics included seed shape and pod shape in addition to plant height and seed colour. Mendel observed that the seven characteristics he had recognized remained consistent over generations in purebred plants. For eight years, he carefully crossbred and grew thousands of pea plants, and patiently analyzed and compared the plants and seeds for difference in colour and size of the seeds, and variations in length of the plants. He took various precautions to prevent the accidental pollination of the flowers which could have altered the results of the experiments. His meticulous study and the resultant observations led to what is today known as Mendel’s Laws of Inheritance.

Childhood & Early Life

• Gregor Mendel was born as the middle child and only son of Anton and Rosine Mendel. He had two sisters and the family lived and worked on the farm they had owned for generations.
  
• As a child he worked in the garden and studied beekeeping which cultivated in him a deep love for biological sciences.
  
• He received his early schooling in his own small village but had to be sent to a nearby town for his secondary education. The decision to send away their only son was not an easy one for his parents, but they did it for sake of his future.
  
• Later on he went to the University of Olomouc where he studied philosophy and physics from 1840 to 1843.
  
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Career & Works

• In 1843, he began his training as a priest and joined the Augustinian Abbey of St Thomas in Brno as a monk. He took the name ‘Gregor’ on entering the religious field.
  
• The monastery sent him to the University of Vienna to study under Abbot C.F.Napp. There he studied physics and mathematics under Christian Doppler and botany from Franz Unger.
  
• He rejoined the monastery as a teacher in 1853 where he was motivated by his colleagues to conduct a study on plants.
  
• He began to conduct his practical study on plants in 1856.He studied edible pea plants and recognized seven distinct characteristics that remained consistent over generations in purebred varieties. These characteristics included: height of the plant, shape of the pod, shape of the seed, size and colour of the seeds, etc.
  
• He cross-pollinated the plants with contrasting characteristics in order to study the effects on the offspring. He also took due precaution to prevent accidental pollination by insects. He cultivated thousands of pea plants over the course of his experiments.
  
• He collected the seeds of the offspring and analyzed them for variations in colour, shape, and size. He also compared the plants for differences in height.
  
• Over a period of eight years he painstakingly examined the plants, pods and seeds and made observations that would form the basis for a deeper study of genetics.
  
• He presented the results of his experiments at the Natural History Society of Brno in 1865. His findings were published in a paper ‘Experiments on Plant Hybridization’ in 1866. But his research failed to create an impact at that time.
  
• In 1868, he was made abbot of the monastery where he had been teaching for the past many years. The increased responsibilities prevented him from conducting any further scientific experiments.
  
• Gregor Mendel’s works failed to gain much importance during his lifetime, but formed the foundation for what is today known as Mendel’s Laws of Inheritance.
  

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Major Works

• Mendel through his extensive experimentation and analysis founded the three laws or principles of inheritance: The law of segregation, the law of dominance, and the law of independent assortment.
  
• He developed the concepts of dominant and recessive genes that explain how genetic traits are passed along from generation to generation.
  
• His 1865 paper ‘Experiments on Plant Hybridization’ which was largely ignored during his lifetime is today regarded as the base of genetic experimentation.
  

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Personal Life & Legacy

• As a young man he had very close and loving relations with his parents. Being a monk, he never married and led a life of celibacy.
  
• He died at the age of 61 after suffering from kidney problems.
  
• His work on heredity which did not find much acceptance during his lifetime took on much greater significance after his death and he was posthumously hailed as the father of modern genetics.
  

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Trivia

• He founded the 'Austrian Meteorological Society' in 1865.
  
• He had also tried conducting experiments on honeybees but was not much successful.
  
• All the papers in his possession were burned after his death.

Read more at http://www.thefamouspeople.com/profiles/gregor-mendel-3786.php#IOH9OZ1q676r6ecx.99

syllabus

COURSE CODE: FCPBS PEDAGOGY OF BIOLOGICAL SCIENCE - PART I

OBJECTIVES:

At the end of the course the student-teachers will be able to

>       acquire the knowledge about the school content in Biological Science;

>       understand the aims and objectives of teaching Biological Science;

>       acquire various teaching skills and develop competence in structuring lesson plans;

>       understand the integration and organisation of Biological Science curriculum;

>       identify the various learning resources;

>       explore the methods of teaching Biological Science;

>       understand the issues in teaching and learning Biological Science;

>       understand the diversified needs of the students;

>       develop skill on classroom management; and

>       construct appropriate assessment tools for evaluation.

UNIT- I: SENSITISING THE SCHOOL CURRICULUM

Analysis of the Content course of Standard VI to VIII (Tamil, English, Mathematics, Science and Social science) Text Books prescribed by Government of Tamil Nadu and content course of standard IX - X ( for UG), XI - XII (for PG) Biology Text Books Prescribed by Government of Tamil Nadu.

UNIT - II: AIMS AND OBJECTIVES OF TEACHING BIOLOGICAL SCIENCE

Need and significance of teaching Biological Science -Aims: Practical, Social, Disciplinary and Cultural- Aims: General Instructional Objectives and Specific Instructional Objectives relating to the Cognitive, Affective and Psychomotor Domain based on Bloom's Taxonomy- Revised Bloom's Taxonomy.

UNIT-III: TEACHING SKILLS AND ORGANIZATION OF PRACTICE -TEACHING PROGRAMME

Micro teaching: Origin, Need, Phases, Definition, Characteristics, Process, Cycle, A Plan of action, Advantage of Micro teaching and its Uses-Skills : Explaining, Questioning , Blackboard usage, Reinforcement, Stimulus variation, Introduction - Unit Plan - Year Plan - Lesson Plan: Need and importance ,Characteristics of good Lesson Plan, Herbartian steps, Format of a typical Lesson plan - Motivation, Presentation, Application, Recapitulation and Assignment -Uses of Lesson plan - Organisation of Practice -Teaching Programme for B.Ed., Student-teachers. Role of the Supervisor; Role of the Principal and the Academic Staff in the Conduct of Practice-teaching Programme. General Teaching Competence Scale, Self-Appraisal Scale, Guidelines for Peer Observation and Framework of Evaluation

UNIT - IV:  INTEGRATION AND  ORGANIZATION  OF BIOLOGICAL

SCIENCECURRICULUM

Meaning of Curriculum, components of curriculum - Principles of curriculum construction -Organisation of curriculum - Process of curriculum organisation: Analysis of needs, Objectives, formulation of objectives, selection of content, selection of learning experience, organisation and integration of content and learning experience and evaluation techniques.

UNIT V: DEVELOPMENT OF TEACHING LEARNING MATERIALS

Edgar dale's cone of experience - Classification of teaching aids - Projected aids: OHP, slides, LCD projector, Epidiascope and Slide Projector - Non Projected Aids: Charts, Flash Cards, Printed Materials, Bulletin Board, Magnetic Board and Flannel Board. Need and importance of Audio Visual aids - Types of Audio Visual Aids - Radio, Television, Computer and Activity aids. Mobile Laboratories and Improvised Apparatus -

Science club, Science lab, Library, field trip, Field work and Science Exhibition: Need and importance, Organization, activities and its advantages.

UNIT-VI: STRATEGIES OF TEACHING BIOLOGICAL SCIENCE

Methods of Teaching: Analytic, Synthetic, Inductive, Deductive, Heuristic, Problem solving, Project and Laboratory - Activity Based Learning (ABL) -Active Learning Method (ALM), Lecture Method, Demonstration Method, Scientific Method - Symposia - workshop - Brain storming- panel discussion - seminar- team teaching - Assignment and Discussion. Techniques of Teaching Biological Science: Individualized Instruction, Programmed Instruction, Computer Assisted Instruction.

UNIT -VII: ISSUES IN TEACHING AND LEARNING

Gender issues - Individual differences, Language problem in learning - Nature of subjects, Examination and grading system - Teaching and Learning styles - Classroom behaviour of Teacher and Learner - Interest and Attitude of students towards learning -Difficulties in Learning Biological Science - Slow learners and gifted learners in Biological Science - Remedial and Enrichment programmes.

UNIT VIII: DIVERSIFIED NEEDS OF STUDENTS

Need for Learner Centred Approach; Historical Perspective; Attributes of learner Centred Classroom; Application of Learner Centred Approach; Integration of Learner Centred Approach with the Main Stream Education System - Non - Cognitive Abilities: Meaning and Nature - Interest: Meaning, Classification and sources - Attitude: Meaning and Importance - Value: Meaning, Importance and Source of Values. Organisation and management of a variety of co-curricular activities.

UNIT IX: CLASSROOM MANAGEMENT

Concept of class Room Management - Class Room Organisation - Components of Class Room Management - Class Room Learning atmosphere - Positive Classroom climate -

Factor supporting an Effective Learning atmosphere - Advantages of Positive Learning climate - Creative Ideal classroom atmospheres - Technical teaching skills - Prevention and Control of Students - Classroom Activities - Classroom Records and Rules.

UNIT-X: EVALUATION OF TEACHING - LEARNING

Concept of Evaluation, Objective Based Evaluation, Continuous and Comprehensive Evaluation (CCE): Summative and Formative Evaluations. Different types of tests: Standardised and Teacher made test - Achievement, Diagnostic, Prognostic- Criterion and Norm referenced evaluation - Construction of Achievement Test - Statistical Measures: Mean, Median, Mode, Range, Mean Deviation, Quartile deviation, Standard Deviation, Rank Order Correlation Coefficient Method and Karl Pearson's product moment method - Graphical representation of data: Bar diagram, Histogram, Pie Chart, Frequency Polygon, Frequency curve and Ogive curve.

SUGGESTED ACTIVITIES

1.      Visit to Zoological Park / Botanical garden/ Food industry/ Agro based industry.

2.      Write the life history and contributions of Carl Linnaeus/ Gregor John Mendel/ Louis Pasteur/ Ian Wilmut.

3.      Preparation of improvised Biological Science kit.

4.      Conducting and Organising Biological Science Quiz /Biological Science Club / Science fair.

5.      Organise an event on Earth day/ Environment day/ Water day/ World health day.

6.      Collection, preservation and display of museum specimen.

7.      Preparation of Herbarium ( 5 Families).

8.      Maintenance of aquarium, terrarium, vivarium, use of incubator and so on.

Carolus Linnaeus

Carolus Linnaeus is one of the giants of natural science. He devised the formal two-part naming system we use to classify all lifeforms.

A well-known example of his two-part system is the dinosaur Tyrannosaurus rex; another is our own species – Homo sapiens.

In fact, Linnaeus pushed the science of biology to new heights by describing and classifying our own human species in precisely the same way as he classified other lifeforms. Other people at that time demanded that humans must be regarded as a special case in biology, different from animals.

Early Life and Education

Carl Linnaeus was born on May 23, 1707 in the village of Råshult in southern Sweden. His father was Nils Ingemarsson Linnaeus, a church minister and amateur botanist; and his mother was Christina Brodersonia.

His father believed that the best thing he could offer his children was a solid education and, in addition to botany, taught Carl about religion and to speak Latin before the young boy could walk.

Carl paid close attention to his father’s activities. He soon picked up his father’s love of plants and botany; he began growing his own plants in his family’s generously sized garden and walking further afield, searching for new plants.

His father recognized that Carl had a good mind. To improve his education he brought in a private tutor when the boy was seven.

In comparison with lessons given by his father, and his days in the garden and countryside cultivating and searching for plants, Carl found the tutor’s work very dull.

carl Linnaeus started school at the age of 10. He was not a bad student, but he did not excel. He continued to work hard on his own private botanical studies.

By the end of his secondary schooling, his teachers had formed the opinion that he was not bright enough to go to university. His immense interest in and knowledge of botany were ignored – it was not a ‘proper subject.’ His teachers expected their students to be skilful in Greek, Hebrew, mathematics and theology, but Carl was not especially interested in these subjects.

Fortunately, one of his school teachers, Johan Rothman, who was also a medical doctor, recognized the boy’s talents and advised his father that Carl should aim for a career in medicine. Carl moved into the Rothman family home, where Rothman gave him formal lessons in anatomy and physiology as well as botany.

By the age of 21, Linnaeus was ready for university.

He enrolled at Lund University using the Latin form of his name, Carolus Linnaeus. This was common practice for students in Europe. For example, centuries earlier, when Mikolaj Kopernik enrolled at university in Poland, he took the Latin name Nicolaus Copernicus.

After just one year at Lund University, Linnaeus switched to Uppsala University, because Rothman told him the medicine and botany courses were better at Uppsala. This proved to be untrue, but actually worked out well for Linnaeus.

After studying at Uppsala for a year, Linnaeus wrote up some of his thoughts and observations on reproduction in plants. One of Uppsala’s medical professors, Olof Rudbeck, read what Linnaeus had written.

The courses at Uppsala were so bad that Rudbeck formed the view that the second year student Linnaeus knew more about botany than the lecturers! In 1730, aged just 23, Linnaeus became a botany lecturer at Uppsala University. He turned out to be a rather good lecturer, and his lectures were popular.

His mother, who had always been unhappy that her eldest son had not been good enough to study theology at university, now consoled herself that he had become a university lecturer – and at such a young age!

Carolus Linnaeus: The Science

Lapland, New Species, Classifying and Naming Plants

In the winter of 1730/31 Linnaeus continued working hard on botany in Uppsala. In particular, he had grown dissatisfied with the way plant species were classified. He began making notes about how he could improve this.

Carolus Linnaeus dressed as a native Sami in Lapland. The plant in his right hand is the Linnaea borealis, named in his honor. This was his favorite plant of all.

In 1732 he was awarded funding for an expedition to Lapland, in the far north of Sweden.

From May to October that year the 25 year-old botany lecturer traveled 1250 miles (2000 km) in Lapland, making observations of the native plants and birds. He also made geological notes.

On this journey he discovered about 100 new plants.

He wrote a book about Lapland’s plants called Flora Lapponica, describing his new discoveries. He also started using a two-part naming system – which would eventually become the Linnaean orbinomial system, used worldwide to name living things.

It also came to him that he could use his new system to name animals as well as plants.

The Netherlands and a Medical Doctorate

In 1735, aged 28, Linnaeus traveled to the University of Harderwijk in the Netherlands to get a doctoral level degree in medicine. Harderwijk was famous for awarding degrees very quickly. Linnaeus had already written a thesis in Uppsala about malaria and its causes, which he submitted to Harderwijk. Within two weeks he had diagnosed a patient, defended his thesis and become a doctor of medicine!

Systema Naturae

In the Netherlands Linnaeus met Johan Frederik Gronovius, a Dutch botanist. He showed Gronovius his recent writings on the classification and naming of plants. Linnaeus had replaced some very lengthy plant names with logical, much shorter, two-part names.

Gronovius saw that Linnaeus’s work could transform botany. He became very excited.

He wanted to get the book published as quickly as possible. He contacted his friend Isaac Lawson, a Scottish doctor, and together Gronovius and Lawson paid for Linnaeus’s work to be published. And so in 1737 the first edition ofSystema Naturae (System of Nature) came to the world.

Over the years, Linnaeus continued to develop his ideas and add new species so that Systema Naturae grew in a period of about 30 years from 12 outsize pages in its first edition to 2400 pages in its twelfth edition. This was the first serious attempt ever made to document all of our planet’s species. It was a huge effort: Linnaeus took the apparently chaotic natural world and organized it, making it easier for everyone to grasp it and understand it.

The classification of lifeforms is called taxonomy. Linnaeus classified living things by looking for similarities. For example he would look at the teeth of different mammals to decide if they were related. In modern times, DNA is used to classify lifeforms. In the case of fossils, where no DNA is present, scientists still use similarities between fossils – and between fossils and current lifeforms – to classify them.

After publishing Systema Naturae, Linnaeus also visited England and France, where he met other scientists, collected specimens, and discussed his work.

Linnaeus was not a modest man. He was well-aware of his achievements, and in later life, he wrote of himself:

“No one has been a greater botanist or zoologist. No one has written more books, more correctly, more methodically, from personal experience. No one has more completely changed a whole science and started a new epoch.”

CAROLUS LINNAEUS

 

Physician and President of the Royal Swedish Academy of Science

Linnaeus returned to Sweden in 1738, becoming a physician in the nation’s capital city, Stockholm. While in Stockholm, Linnaeus helped found the Royal Swedish Academy of Science and became its first president.

Professor of Botany

In 1741, aged 34, Linnaeus returned to Uppsala University and became a full professor of medicine, taking control of botany, natural history and the university’s botanical garden. He immediately undertook a one-month long visit to the Swedish island of Gotland with some of his new students, where together they discovered 100 new plant species.

In summertime, Linnaeus would take his botany students on walks around Uppsala to observe and record the plant and animal life they could find. This was almost a return to his early boyhood enthusiasm for plants, when he walked freely in the countryside around his village searching for plants.

When he had given his first lectures in Uppsala as a 23 year-old student, they had been popular. Now, as an older professor, his lectures were more popular than ever – and he held some of them in the botanical garden. His students were captivated by Linnaeus’s enormous enthusiasm for botany and nature.

In 1750, at the age of 43, Linnaeus was appointed as Uppsala University’s rector.

Species Plantarum – Transforming Biology

In 1753, Linnaeus published his natural science masterpiece in two volumes and 1200 pages: Species Plantarum (Plant Species). In this work, he listed all of the plant species that had been discovered at that time – almost 6000 – and classified them into about 1000 appropriate genera. This enabled him to use two-part names for all plants throughout Species Plantarum – the first time all plants had been named in this way.

Many of the plants in the two volumes had been discovered by Linnaeus’s own students. A select group of his best students (who became known as the Apostles) traveled the world spreading the word about Linnaeus’s two-part naming system, and describing new plant species, many of which they sent as specimens back to Linnaeus in Uppsala. The Apostles traveled to wild and remote places. Out of 17 Apostles, 7 died on expeditions.

In 1758, Linnaeus published the tenth edition of Systema Naturae in which he classified all of the animal kingdom into genera and gave all of the species two-part names.

Plant drawings from Systema Naturae. Linnaeus organized plants into 24 classes. This illustration shows his readers how to tell the difference between these classes.

During his career, Linnaeus named about 13,000 lifeforms and classified them into suitable categories such as mammals, birds, fish, primates, canines, etc.

Other Notable Contributions

• Linnaeus modified the Celsius temperature scale into the form that we use today. The scale had been invented by his compatriot, Anders Celsius, who had said 0 °C was the boiling point of water and 100 °C was water’s freezing point. Linnaeus realized that it would be more useful if these values were reversed and persuaded the rest of the scientific world to follow his example.

• Linnaeus was the first person to place humans in the primate family and to describe bats as mammals rather than birds. Linnaeus did not categorize humans alongside apes with any idea of an evolutionary link. He did it with the same reasoning he used to categorize all life, which was similarities he identified between species.

• Linnaeus was one of the founders of the science of ecology – describing the relationship between living organisms and their environments.

• Linnaeus’s idea of going on expeditions to study nature and gather specimens inspired Charles Darwin and Alfred Russel Wallace to go on the expeditions that led to their theories of evolution by natural selection.

• Linnaeus invented index cards. He did this in response to his ever growing lists of species which required a cataloging method that was easily expandable and easy to reorganize.

Linnaeus invented the index card system to record and store data.

The End

Carolus Linnaeus was knighted by the King of Sweden in 1761 and took the nobleman’s name of Carl von Linné.

He died at the age of 70, on 10 January, 1778, after suffering a stroke. He was survived by his wife Sara, and five children. Two of the couple’s other children died when they were very young.

Linnaeus died on his farm about 6 miles (10 km) from Uppsala. He had bought the farm 20 years before his death. The farm was called Hammarby. Linnaeus cultivated his own private gardens at Hammarby and had hoped to be buried there. In fact he was buried in Uppsala.

Today Hammarby is a museum which features exhibitions of Linnaeus’s work, his botanical collections, and a garden and a park where his love of the natural world has been preserved.

Gregor Mendel

Gregor Mendel is the father of genetics. He:

• Founded the science of genetics.

• Identified many of the rules of heredity. These rules determine how traits are passed through generations of living things.

• Saw that living things pass traits to the next generation by something which remains unchanged in successive generations of an organism – we now call this ‘something’ genes.

• Realized that traits could skip a generation – seemingly lost traits could appear again in another generation – he called these recessive traits.

• Identified recessive and dominant traits which pass from parents to offspring.

• Established, momentously, that traits pass from parents to their offspring in a mathematically predictable way.

Mendel’s work only made a big impact in 1900, 16 years after his death, and 34 years after he first published it.

Mendel’s Education and the Abbey of St. Thomas

Johann Mendel (he wasn’t called Gregor until later) was born July 20, 1822, in Heinzendorf bei Odrau. This small village was in the Austrian Empire, but is now in the Czech Republic.

Mendel’s parents were small farmers who made financial sacrifices to pay for his education.

He did well enough at high school to make it, aged 18, to the University of Olomouc in 1840. The university was about 40 miles (60 km) from his home village. He took courses in physics, mathematics and philosophy.

You want to keep doing science? You need to be a monk!

In 1843, aged 21, and in financial difficulty, one of his teachers, Professor Friedrich Franz, a physicist, advised Mendel to join the Abbey of St. Thomas in Brünn as a monk.

The Abbey actually had a good reputation for its teaching of sciences, and its director, Abbot Franz Cyril Napp, was particularly interested in heredity of traits in plants and animals on farms.

If he could join the Abbey, he could continue studying science, while ensuring he could get by financially. And so Mendel, who was more interested in science than religion, became a monk.

The move to Brünn carried him much farther away from his home village. On joining the Abbey, he took the name Gregor. From then on he ceased to be Johann Mendel and became Gregor Mendel.

Learning and Teaching Science

In 1846, aged 24, Mendel took fruit-growing classes given by Professor Franz Diebl at the Brünn Philosophical Institute. Diebl was an authority on plant breeding.

Mendel became a priest in 1847 and got his own parish in 1848. He did not enjoy working as a parish priest and got a job as a high school teacher in 1849.

In 1850, aged 28, he failed exams which would have qualified him as a high school teacher.

A year later, he went to the University of Vienna where he studied chemistry, biology and physics. The idea was that by strengthening his knowledge in these subjects, he could qualify as a high school teacher.

Two years later, after completing his studies, he returned to the monastery in 1854 and took a position as a physics teacher at a school at Brünn, where he taught for the next 16 years.

Research and Admin

In 1856, aged 34, he again failed to qualify formally as a high school teacher. This time, illness prevented him completing the exams.

In the same year, he began his major, groundbreaking study of heredity in plants.

In 1865, still interested in physical science, he founded the Austrian Meteorological Society. In fact, during his life, Mendel published more about meteorology than he did biology!

In 1866, he published his heredity work. Unfortunately, most people who read it did not recognize the intellectual gold that his paper contained.

In 1867, aged 45, he became Abbot of his monastery and devoted himself to its smooth running as its administrator.

At the monastery in Brünn in the early 1860s. Mendel is pictured back right, looking at part of a plant in his left hand. Abbot Franz Cyril Napp sits in the front row, wearing a large cross. Abbot Napp encouraged Mendel’s science and heredity studies.

Mendel and Genetics: Experiments with Peas: 1856 to 1863

During his time in Olomouc, Mendel had made friends with two university professors: Friedrich Franz, a physicist, and Johann Karl Nestler, an agricultural biologist, who was interested in heredity.

Nestler passed his interest in heredity to Mendel, who was intrigued by the subject.

Mendel’s monastery had a 5 acre (2 hectare) garden, and his two former professors encouraged Mendel to pursue his interest in heredity by using the garden for experiments.

Abbot Franz Cyril Napp and Professor Franz Diebl also encouraged him to follow this path.

Mendel was unhappy with how inheritance of traits was being explained

People had known for millennia about selective breeding. They knew that by breeding from those individuals that showed the most desirable traits, future generations were more likely to show these desirable traits.

• Guard dogs might be bred from parents that were loyal and friendly to their owners, but were suspicious or even aggressive with strangers.
• Cattle might be bred from cows that yielded most milk and bulls that yielded most meat.
• Wheat might be kept and sown the following year from those plants which had produced the most abundant crop.

The main theory of heredity in Mendel’s time was that offspring were a smooth blend of their two parents’ traits.

Mendel set himself the very ambitious task of discovering the laws of heredity.

To achieve this, he embarked on a mammoth sized, highly systematic, eight year study of edible peas, individually and carefully recording the traits shown by every plant in successive generations.

His work involved growing and recording the traits in about 30,000 plants.

One of the keys to his success was breeding from closely related pea varieties which would differ in only a small number of traits.

The seven traits of pea plants that Mendel chose to study: seed wrinkles; seed color; seed-coat color, which leads to flower color; pod shape; pod color; flower location; and plant height. Image by Mariana Ruiz.

Mendel’s Results for Flower Color

Mendel found the same results for all traits, but we’ll look at flower color as an example.

When Mendel bred purple-flowered peas (BB) with white-flowered peas (bb), every plant in the next generation had only purple flowers (Bb).

When these purple-flowered plants (Bb) were bred with one-another to create a second-generation of plants, some white flowered plants appeared again (bb).

Mendel realized that his purple-flowered plants still held instructions for making white flowers somewhere inside them.

He also found that the number of purple to white was predictable.

75 percent of the second-generation of plants had purple flowers, while 25 percent had white flowers. He called the purple trait dominant and the white traitrecessive.

A Punnett Square. Both of the starting plants have purple flowers but they contain the genes for purple (B) and white (b). The pollen from the male plant fertilizes the egg in the female flower. In this variety of plant, purple flowers are caused by a dominant gene (B). Dominance is indicated by a capital letter. White flowers are caused by recessive genes, indicated by the small letter (b). Both the male and female parent plants in the diagram above carry the dominant gene B for purple and the recessive gene b for white flowers. The ratio of purple flowers to white flowers in their offspring will be 3:1 as shown in this diagram. For a white flower to appear, the offspring must inherit the recessive gene from both parents. Purple appears with any other combination of genes inherited from the parent plants. Image by Madeleine Price Ball

Mendel’s Conclusions

Mendel’s most important conclusions were:

• The inheritance of each trait is determined by something (which we now call genes) passed from parent to offspring unchanged. In other words, genes from parents do not ‘blend’ in the offspring.
• For each trait, an organism inherits one gene from each parent.
• Although a trait may not appear in an individual, the gene that can cause the trait is still there, so the trait can appear again in a future generation.

Scientists who did research later found that Mendel’s results do not only apply to pea plants. Trait inheritance in most plants and animals, including humans, follows the patterns Mendel recorded.

In Mendel’s honor, these very common patterns of heredity are now calledMendelian Inheritance.

Fast Forward to 1900: The Sleeping Giant Awakes

In 1900, three scientists independently carrying out heredity research got exciting results.

However, when they searched the literature, they realized their results were not really new. Their results actually verified the forgotten results Mendel had published 34 years earlier.

Mendel’s results gave the scientists of 1900 greater confidence in their own results and the new science of genetics was truly born.

The scientists were Carl Correns, Hugo de Vries, and Erich von Tschermak.

“I thought that I had found something new. But then I convinced myself that the Abbot Gregor Mendel in Brünn, had, during the sixties, not only obtained the same result through extensive experiments with peas, which lasted for many years, as did de Vries and I, but had also given exactly the same explanation, as far as that was possible in 1866.”

CARL ERICH CORRENS, 1864 TO 1933

Geneticist and Botanist

 

Mendel’s Results Were “Too Good”

Mendel’s published work was rather vague about detailed experimental procedures, including dates.

Enter Ronald Fisher, a very eminent geneticist and statistician. It was Fisher who first used the term ‘null hypothesis’ in statistical testing.

In 1936, Fisher tried to reconstruct on paper the way Mendel carried out his experiments.

He also wanted to discover why Mendel’s work had been overlooked for so long until it was rediscovered in 1900.

He found that, although some people in a position to see the importance of Mendel’s work had actually read it, they did not realize its importance. Their minds were unreceptive to Mendel’s words and ideas. They may have believed he was repeating plant hybridization work others had already carried out.

Controversially, Fisher said that his statistical analysis of Mendel’s results showed too few random errors to have come from real experiments. Nearly all of Mendel’s data showed an unnatural bias.

Fischer wrote:

“Although no explanation can be expected to be satisfactory, it remains a possibility among others that Mendel was deceived by some assistant who knew too well what was expected. This possibility is supported by independent evidence that the data of most, if not all, of the experiments have been falsified so as to agree closely with Mendel’s expectations.”

RONALD FISHER, 1890 TO 1962

Statistician, Geneticist, Evolutionary Biologist

 

Fisher’s analysis said there was only a 1 in 2000 chance that Mendel’s results were the fully reported results of real experiments.

The controversy begun by Fisher continues to this day, with a steady stream of publications seeking to give reasons for Mendel’s results. One possibility is that results from ‘bad’ experiments were discarded to leave only the results of ‘good’ experiments. Another is that the results arose from an unconscious bias on the part of the experimenters.

The End

Gregor Mendel was unaware of the new science of genetics which he had founded, and unaware of any future controversies. He died of a kidney disease, aged 61, on January 6, 1884.