Chapter 14- Mendel and the Gene

14.1 Mendel’s Experimental System

Heredity is the inheritance or the transmission of traits from parents to offspring
A trait is any observable characteristic of an individual, ranging from outward appearance such as height to molecular characteristics such as the prima structure of a particular membrane protein.
A model organism is a species that is used for research because it is easy to work with and conclusions drawn from studying it may apply to many other species.
Whenever a trait appears commonly in two or more different forms, for example purple or white flowers, it is called a polymorphic trait.
Self-fertilization occurs when a flower's pollen falls on the female reproductive organ of that same flower.
Phenotype can be any observable characteristic, from molecular-level aits such as protein shape to the familiar aits of entire organisms at Mendel studied.
A pure line consists of individuals that produce offspring identical to the parents when they are crossed to another member of the same pure-line population or are self-fertilized.
Hybrids are offspring from matings between true breeding parents that differ in one or more traits.

14.2 Mendel’s Experiments with a Single Trait

The individuals used in the initial cross are the parental generation.
Their progeny ( offspring) are the F1 generation.
A mating between parents that each carry two different genetic determinants for the same trait-is called a monohybrid cross.
In genetics, the terms “dominant” and “recessive” identify only which phenotype is observed and which is masked in individuals carrying two different genetic determinants for a given trait.
Reciprocal cross is a set of matings where the mother’ s phenotype in the initial cross is the father’ s phenotype in a subsequent cross, and the father's phenotype in the initial cross is the mother’ s phenotype in a subsequent cross.
Particulate inheritance is that the hereditary determinants for traits do not blend together or become modified through use.
Different versions of the same gene are called alleles.
The combination of alleles found in an individual is the genotype.
Two copies of the same allele are said to be homozygous.
Two different alleles for the same gene are said to be heterozygous.

14.3 Mendel’s Experiments with Two Traits

These F1 individuals are called dihybrids, and a mating between dihybrids is a dihybrid cross.
The principle of independent assortment is that alleles of different genes are transmitted independently of one another.
In a traditional testcross, a parent with a dominant phenotype but unknown genotype is crossed with a parent that contributes only recessive alleles.

14.4 The Chromosome Theory of Inheritance

Common phenotypes are referred to as wild type
Mutation is a heritable change in a gene.
An individual with an unusual phenotype due to a mutation is referred to as a mutant.
A gene on the X chromosome is now described as an X-linked gene.
A gene on the Y chromosome is a Y-linked gene
The general term for genes being located on either sex chromosome is sex-linked genes.
The patterns of inheritance of these genes are said to show sex-linked inheritance.
If the gene is on the X chromosome, it is X-linked inheritance, if on the Y chromosome, it’ s Y-linked inheritance.
Genes on non-sex chromosomes are said to be autosomal, and their patterns of inheritance are called autosomal inheritance.

14.5 Extending Mendel’s Rules

Linkage is the tendency of alleles of particular genes to be inherited together.
Morgan referred to these individuals as recombinant because the alleles on their X chromosome were different (recombined) from the combinations present in their mother.
Morgan concluded that alleles on the same chromosome then stay together, but not always.
A genetic map is a diagram showing the relative positions (loci) of genes along a particular chromosome.
The existence of more than two common alleles of the same gene is multiple allelism.
In the traits Mendel studied, only the phenotype associated with the dominant allele appeared in heterozygotes. This form of dominance is called complete dominance.
A gene that influences many traits is said to be pleiotropic.
When two or more genes influence a single trait, it is called gene interaction.
Epistasis occurs when the expression of a phenotype associated with a particular genotype of one gene can be completely masked by a particular genotype of a different gene.
Environmental effects are anything that influences phenotypes other than the genotype, including temperature, sunlight, nutrient availability, competition, and even a mother’s hormone levels during development of an embryo.
Discrete traits are traits that are clearly different from each other
Continuously vaη ing traits that don’t fall into distinct categories are called quantitative traits.
Polygenic is where each of many different genes adds a small amount to the value of the trait.

14.6 Applying Mendel’s Rules to Human Inheritance

A mode of transmission describes a trait as autosomal or sex-linked and the type of dominance of the allele.
To learn the mode of transmission, scientists construct a pedigree, or family tree, of affected and unaffected individuals.
Heterozygous individuals who do not have an inherited disease but carry a recessive allele for it are called carriers of the disease.

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Chapter 14- Mendel and the Gene

14.1 Mendel’s Experimental System

Heredity is the inheritance or the transmission of traits from parents to offspring
A trait is any observable characteristic of an individual, ranging from outward appearance such as height to molecular characteristics such as the prima structure of a particular membrane protein.
A model organism is a species that is used for research because it is easy to work with and conclusions drawn from studying it may apply to many other species.
Whenever a trait appears commonly in two or more different forms, for example purple or white flowers, it is called a polymorphic trait.
Self-fertilization occurs when a flower's pollen falls on the female reproductive organ of that same flower.
Phenotype can be any observable characteristic, from molecular-level aits such as protein shape to the familiar aits of entire organisms at Mendel studied.
A pure line consists of individuals that produce offspring identical to the parents when they are crossed to another member of the same pure-line population or are self-fertilized.
Hybrids are offspring from matings between true breeding parents that differ in one or more traits.

14.2 Mendel’s Experiments with a Single Trait

The individuals used in the initial cross are the parental generation.
Their progeny ( offspring) are the F1 generation.
A mating between parents that each carry two different genetic determinants for the same trait-is called a monohybrid cross.
In genetics, the terms “dominant” and “recessive” identify only which phenotype is observed and which is masked in individuals carrying two different genetic determinants for a given trait.
Reciprocal cross is a set of matings where the mother’ s phenotype in the initial cross is the father’ s phenotype in a subsequent cross, and the father's phenotype in the initial cross is the mother’ s phenotype in a subsequent cross.
Particulate inheritance is that the hereditary determinants for traits do not blend together or become modified through use.
Different versions of the same gene are called alleles.
The combination of alleles found in an individual is the genotype.
Two copies of the same allele are said to be homozygous.
Two different alleles for the same gene are said to be heterozygous.

14.3 Mendel’s Experiments with Two Traits

These F1 individuals are called dihybrids, and a mating between dihybrids is a dihybrid cross.
The principle of independent assortment is that alleles of different genes are transmitted independently of one another.
In a traditional testcross, a parent with a dominant phenotype but unknown genotype is crossed with a parent that contributes only recessive alleles.

14.4 The Chromosome Theory of Inheritance

Common phenotypes are referred to as wild type
Mutation is a heritable change in a gene.
An individual with an unusual phenotype due to a mutation is referred to as a mutant.
A gene on the X chromosome is now described as an X-linked gene.
A gene on the Y chromosome is a Y-linked gene
The general term for genes being located on either sex chromosome is sex-linked genes.
The patterns of inheritance of these genes are said to show sex-linked inheritance.
If the gene is on the X chromosome, it is X-linked inheritance, if on the Y chromosome, it’ s Y-linked inheritance.
Genes on non-sex chromosomes are said to be autosomal, and their patterns of inheritance are called autosomal inheritance.

14.5 Extending Mendel’s Rules

Linkage is the tendency of alleles of particular genes to be inherited together.
Morgan referred to these individuals as recombinant because the alleles on their X chromosome were different (recombined) from the combinations present in their mother.
Morgan concluded that alleles on the same chromosome then stay together, but not always.
A genetic map is a diagram showing the relative positions (loci) of genes along a particular chromosome.
The existence of more than two common alleles of the same gene is multiple allelism.
In the traits Mendel studied, only the phenotype associated with the dominant allele appeared in heterozygotes. This form of dominance is called complete dominance.
A gene that influences many traits is said to be pleiotropic.
When two or more genes influence a single trait, it is called gene interaction.
Epistasis occurs when the expression of a phenotype associated with a particular genotype of one gene can be completely masked by a particular genotype of a different gene.
Environmental effects are anything that influences phenotypes other than the genotype, including temperature, sunlight, nutrient availability, competition, and even a mother’s hormone levels during development of an embryo.
Discrete traits are traits that are clearly different from each other
Continuously vaη ing traits that don’t fall into distinct categories are called quantitative traits.
Polygenic is where each of many different genes adds a small amount to the value of the trait.

14.6 Applying Mendel’s Rules to Human Inheritance

A mode of transmission describes a trait as autosomal or sex-linked and the type of dominance of the allele.
To learn the mode of transmission, scientists construct a pedigree, or family tree, of affected and unaffected individuals.
Heterozygous individuals who do not have an inherited disease but carry a recessive allele for it are called carriers of the disease.