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Mendel’s model system

Mendel’s seminal work was accomplished using the garden pea, Pisum sativum , to study inheritance. This species naturally self-fertilizes, such that pollen encounters ova within individual flowers. The flower petals remain sealed tightly until after pollination, preventing pollination from 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.

Mendelian crosses

Mendel performed hybridizations , which involve mating two true-breeding individuals that have different traits. In the pea, which is naturally self-pollinating, this is done by manually transferring pollen from the anther of a mature pea plant of one variety to the stigma of a separate mature pea plant of the second variety. In plants, pollen carries the male gametes (sperm) to the stigma, a sticky organ that traps pollen and allows the sperm to move down the pistil to the female gametes (ova) below. To prevent the pea plant that was receiving pollen from self-fertilizing and confounding his results, Mendel painstakingly removed all of the anthers from the plant’s flowers before they had a chance to mature.

Plants used in first-generation crosses were called P 0    , or parental generation one, plants ( [link] ). Mendel collected the seeds belonging to the P 0 plants that resulted from each cross and grew them the following season. These offspring were called the F 1    , or the first filial ( filial = offspring, daughter or son), generation. Once Mendel examined the characteristics in the F 1 generation of plants, he allowed them to self-fertilize naturally. He then collected and grew the seeds from the F 1 plants to produce the F 2    , or second filial, generation. Mendel’s experiments extended beyond the F 2 generation to the F 3 and F 4 generations, and so on, but it was the ratio of characteristics in the P 0 −F 1 −F 2 generations that were the most intriguing and became the basis for Mendel’s postulates.

The diagram shows a cross between pea plants that are true-breeding for purple flower color and plants true-breeding for white flower color. This cross-fertilization of the P generation resulted in an F_{1} generation with all violet flowers. Self-fertilization of the F_{1} generation resulted in an F_{2} generation that consisted of 705 plants with violet flowers, and 224 plants with white flowers.
In one of his experiments on inheritance patterns, Mendel crossed plants that were true-breeding for violet flower color with plants true-breeding for white flower color (the P generation). The resulting hybrids in the F 1 generation all had violet flowers. In the F 2 generation, approximately three quarters of the plants had violet flowers, and one quarter had white flowers.

Garden pea characteristics revealed the basics of heredity

In his 1865 publication, Mendel reported the results of his crosses involving seven different characteristics, each with two contrasting traits. A trait    is defined as a variation in the physical appearance of a heritable characteristic. The characteristics included plant height, seed texture, seed color, flower color, pea pod size, pea pod color, and flower position. For the characteristic of flower color, for example, the two contrasting traits were white versus violet. To fully examine each characteristic, Mendel generated large numbers of F 1 and F 2 plants, reporting results from 19,959 F 2 plants alone. His findings were consistent.

Questions & Answers

what does the letters DNA stand for?
Princess Reply
desoxyribonucleic acid
MissMeriiit
It simply means 'decoy ribonucleic acid'
Mustapha
sorry ... deoxyribonucleic acid...
Mustapha
what are some functions of the DNA
Seth Reply
What is biodiversity
Chati Reply
the diversity of plants and animals life in a particula habitat
Harry
Biodiversity is the variety of organisms in their common groups
Osei
what is glycolisis
David Reply
glycolisis is the breakdown of glucose
Yazi
the answer is incomplete the breakdown of glucose to what
David
what is biodiversity?
Hope Reply
What is biodiversity
Chati
what is taxonomy
Patience Reply
Taxonomy is a branch of biology that deals with the description, identification, nomenclature, and classification of organisms
Farco
what is nomenclature
John
nomenclature is the scientific naming of organisms
Bigenis
state the structural differences between the termites
Massa
what causes the DNA results of an offspring
venius Reply
how are proteins digested?
Trox Reply
how are proteins digested
Kaka
guys what is locomotion?
Misheal Reply
what is anatomy
Mohamed Reply
no idea
Benard
Anatomy is the branch of science that deals with the study of internal and external structures of an organism
Bigenis
Anatomy is the branch of science that deals with the study of the internal structure of an organism
Nana
what is locomotion?
Misheal
no idea
John
Locomotion may simply mean the movement of an organism from one point to another without permanent displacement of the organidm it'self
Bigenis
simply, its the ability to move
MissMeriiit
Thanks guys
Misheal
I have gotten it
Dickens
locomotion as an art student is the ability to move from on place to another
John
muscles that are concerned with locomotion
John
Anatomy deals with the study of internal structures of an organism
Osei
The ability of cells or organisms to move and propel itself from place to place. supplement. locomotion in biology pertains to the various movements of organisms (single-celled or multicellular organisms) to propel themselves from one place to another.
garnhial
Anatomy is the branch of biology concerned with structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structure organization of living things - human anatomy is one of the essential basic sciences that are applied in medicine
garnhial
what is multicellular organisms
Massa
multicellular organisms these are living things which have more than one cell
John
what are the theory if cells
Julius Reply
What's the function of epiglottis
Ugo Reply
What Is The Other Name For Intestinal Juice?
Justin Reply
what is the largestest planet of the universe
rick Reply
what are the types of cell
Bernard Reply
prokaryotic and eukaryotic
Yazi
prokaryotic cell and eukaryotic cell
Grace

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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