Biology: Chromosomes and Mechanism of Inheritance

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Questions and Answers

What type of allele is capable of expressing its trait even in the presence of an alternative allele?

Dominant allele

What is the term for the external appearance of an organism that can be easily seen for any trait?

Phenotype

What is the term for the genetic constitution of an organism that decides the trait?

Genotype

What type of cross considers only one heritable trait?

Monohybrid cross Signup and view all the answers

What is the term for an individual or a population that is homozygous for one or more traits?

Pure line Signup and view all the answers

What type of allele is not expressed in the presence of an alternative allele?

Recessive allele Signup and view all the answers

What is the term for the ratio of phenotypes produced in the F2 and subsequent generations?

Phenotypic ratio Signup and view all the answers

What is the term for the ratio of genotypes produced in the F2 and subsequent generations?

Genotypic ratio Signup and view all the answers

What is the fundamental concept of heredity or inheritance?

The transmission of genetic information from generation to generation. Signup and view all the answers

Who is credited with giving the explanation for heredity and proposing the principles of heredity?

Gregor Mendel Signup and view all the answers

What did Carl Correns discover independently and verify through his experiments on other model organisms?

The principles of heredity Signup and view all the answers

What term did Mendel use to describe the unit of heredity responsible for the inheritance and expression of a genetic character?

Factors Signup and view all the answers

What was one of the reasons for Mendel's success in his experiments?

Well-chosen contrasting characters which were recognizable and each controlled by a single factor. Signup and view all the answers

What is the difference between a character and a trait in genetic terminology?

A character is a specific feature an organism possesses, while a trait is an inherited character with its variant form. Signup and view all the answers

What is the term used to describe the two or more alternative forms of a given gene?

Alleles or Allelomorphs Signup and view all the answers

What is the specific segment of DNA responsible for the inheritance and expression of a genetic character?

A gene Signup and view all the answers

Study Notes

Heredity and Inheritance

Heredity is the transmission of genetic information from one generation to the next.
Gregor Mendel is known as the father of genetics for his work on heredity using hybridization techniques.

Gregor Mendel's Contributions

Mendel postulated principles of heredity and introduced the term "factors" which are now known as genes.
He carefully planned experiments, used a large sample, made meticulous recordings, and chose well-defined contrasting characters.

Seven Pairs of Contrasting Characters

Mendel studied seven pairs of contrasting characters in pea plants, including:
- Seed shape: round vs. wrinkled
- Seed color: yellow vs. green
- Pod shape: inflated vs. constricted
- Pod color: green vs. yellow
- Flower color: purple vs. white
- Flower location: axial vs. terminal
- Plant height: tall vs. dwarf/short

Genetic Terminology

Character: a specific feature that an organism possesses.
Trait: an inherited character with its variant form that can easily be seen (e.g. tall or dwarf).
Factor: a unit of heredity responsible for the inheritance and expression of a genetic character (now known as a gene).
Gene: a specific segment of DNA responsible for the inheritance and expression of a character.
Alleles or Allelomorphs: two or more alternative forms of a given gene (factor) located on identical loci on homologous chromosomes.
Dominant: an allele that is expressed even in the presence of an alternative allele.
Recessive: an allele that is not expressed in the presence of an alternative allele.

Genotype and Phenotype

Phenotype: the external appearance of an organism that can be easily seen for any trait (e.g. tallness or dwarfness).
Genotype: the genetic constitution of an organism that decides the trait (e.g. TT, Tt, or tt).
Homozygous (pure): having identical alleles for a particular trait, producing only one type of gamete (e.g. TT or tt).
Heterozygous (hybrid): having pairs of contrasting alleles for a particular trait, producing two types of gametes (e.g. Tt).
Pure line: an individual or population that is homozygous for one or more traits.
Monohybrid: a cross considering only one heritable trait (e.g. cross of pure tall and pure dwarf plants).
Dihybrid: a cross considering two heritable traits.
F1 generation: the first generation formed by mating of pure parents having contrasting characters (e.g. progeny of TT x tt).
F2 generation: the second generation formed by self-pollination of F1 individuals.

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Description

Learn about the transmission of genetic information, Gregor Mendel's principles of heredity, and the contributions of Carl Correns in verifying Mendel's work.