Genetics Concepts Flashcards

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Questions and Answers

What is the difference between blended and particulate inheritance?

Blended inheritance suggests that genetic factors average out when passed on, while particulate inheritance involves the transmission of genes according to Mendelian principles.

What is the major problem with the idea of blended inheritance?

It doesn't explain how traits can be passed on or how natural selection could operate.

Describe Mendel's scientific contributions and the four postulates behind his ideas.

Mendel bred pea plants, observed traits across generations, inferred gene operation, and discovered the mechanism for heredity. His four postulates include: 1) Hereditary factors are controlled by pairs of units (alleles); 2) Only one allele is expressed when two different alleles are present; 3) Each allele has an equal chance of being passed to offspring; 4) Alleles for different traits are passed independently.

What is the difference between discrete and continuous traits? Give an example of each.

Discrete traits have distinct categories (e.g., seed color), while continuous traits vary along a spectrum (e.g., height). Signup and view all the answers

What is the definition of allele?

Alleles are alternative versions of a gene that differ in their effects on phenotypic expression. Signup and view all the answers

What is the definition of homozygous?

Homozygous refers to having the same allele at both loci for a gene on homologous chromosomes. Signup and view all the answers

What is the definition of heterozygous?

Heterozygous means having two different alleles at the loci for a gene on homologous chromosomes. Signup and view all the answers

What is the definition of dominant?

Dominant refers to an allele that is expressed in a diploid organism when present on only one homologous chromosome. Signup and view all the answers

What is the definition of recessive?

Recessive refers to an allele that must be present in two copies to be expressed in a diploid organism. Signup and view all the answers

What is the definition of polygenic traits?

Polygenic traits are phenotypic traits that result from the combined action of multiple genes. Signup and view all the answers

What is the definition of pleiotropy?

Pleiotropy is the phenomenon where a single gene affects multiple phenotypic traits. Signup and view all the answers

Be able to calculate and explain the probabilities of traits based on a Punnett Square.

Use a Punnett Square to calculate the probabilities of inheriting traits based on allele combinations. Signup and view all the answers

What is the difference between genotype and phenotype?

Genotype is the genetic makeup of an individual, while phenotype is the observable or measurable feature. Signup and view all the answers

What is a balanced polymorphism? Why has the allele for sickle cell anemia persisted in African populations?

A balanced polymorphism is a stable state where natural selection prevents the fixation or loss of alleles. The allele for sickle cell anemia persists in African populations because it provides an advantage against malaria for carriers. Signup and view all the answers

Study Notes

Inheritance Concepts

Blended inheritance suggests parental traits average together in offspring; discredited by particulate inheritance which emphasizes gene transmission.
Major flaw in blended inheritance: it fails to explain trait transmission or the function of natural selection.

Mendelian Genetics

Gregor Mendel studied pea plants, establishing fundamental principles of heredity through observation and experimentation.

Mendel's Postulates

Particulate units: Heritable traits are controlled by discrete units (genes) that occur in pairs.
Dominant and recessive alleles: Inherit two different alleles, one is expressed. Dominant allele (T) is expressed over recessive allele (t).
Law of Segregation: Equal chance of passing each allele to offspring.
Independent assortment: Alleles for different traits are inherited independently.

Trait Classification

Discrete traits: Traits that have distinct categories, e.g., seed color or blood type. No intermediates exist.
Continuous traits: Traits that vary gradually, e.g., height or weight, not strictly Mendelian.

Genetic Terminology

Allele: Variant forms of a gene that affect the same trait's phenotypic expression.
Homozygous: Having identical alleles for a gene (e.g., TT or tt).
Heterozygous: Possessing two different alleles for a gene (e.g., Tt).

Dominance and Recessiveness

Dominant allele: Expressed if present on one homologous chromosome.
Recessive allele: Requires two copies (homozygous) for expression.

Complex Inheritance

Polygenic traits: Traits influenced by multiple genes, resulting in a wide phenotype range.
Pleiotropy: A single gene impacts multiple phenotypic traits.

Punnett Squares

A tool for calculating genetic probabilities and predicting offspring traits based on parental alleles.

Genotype vs. Phenotype

Genotype: Genetic makeup of an individual, may refer to entire complement or alleles at a specific locus.
Phenotype: Observable traits that can be anatomical, biochemical, or behavioral.

Balanced Polymorphism

Refers to stability in genetic traits within a population through natural selection, preventing allele fixation or loss.
Sickle cell anemia allele persists in Africa due to its protective effect against malaria when present in a single copy.

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Description

Explore the concepts of blended and particulate inheritance with these flashcards. This study material clarifies the differences and applications of each type of inheritance in genetics. Perfect for students looking to enhance their understanding of heredity principles.