Understanding Genetics: From Mendelian to Non-Mendelian Inheritance Saved

What is a phenotype?

The traits or characteristics of an organism, such as blood type, ear shape, and petal color.

What determines an organism's phenotype?

The genetic information passed from parents to offspring in the form of alleles.

How does protein synthesis relate to phenotype?

Genes are transcribed into RNA, which is translated into proteins that determine physical traits.

What is the genotype?

The genetic plan consisting of all the genetic information (DNA) in an organism, represented by the combination of alleles.

How do alleles influence traits in pea plants?

One gene determines the flower color; specific alleles code for traits like purple or white flowers.

What does it mean for a genotype to be homozygous?

It means the organism has two identical alleles for a trait, such as PP or pp.

What is a heterozygous genotype?

A genotype with two different alleles for a trait, such as Pp.

What is the dominant trait in pea plants regarding flower color?

The purple flower color is dominant, meaning it appears if at least one dominant allele is present.

What is a recessive trait?

A trait that is only observable in individuals who are homozygous for that allele.

How can two different genotypes lead to the same phenotype?

Both homozygous dominant (PP) and heterozygous (Pp) genotypes can result in the purple flower phenotype.

What is the significance of the letter 'P' in the context of pea plants?

It represents the alleles for the trait of purple flowers.

What happens when a pea plant has the genotype pp?

It will have white flowers, as it has two alleles that do not produce purple protein.

What role do environmental factors play in inheritance?

They can affect traits alongside genetic factors, complicating the inheritance patterns.

What is the relationship between alleles and protein production?

Alleles determine whether specific proteins are produced, influencing the organism's phenotype.

How are dominant alleles typically represented in genotypes?

Dominant alleles are shown by capital letters and are usually written first.

What does it mean for a trait to be dominant?

It means the trait is expressed in the phenotype whether the individual is homozygous or heterozygous.

What is an example of a trait that can be influenced by multiple alleles?

Flower color in pea plants, where different combinations of alleles can lead to various colors.

What is the importance of understanding genotype and phenotype in genetics?

It helps explain how traits are inherited and expressed in organisms.

What is the expected phenotype of a plant with the genotype Pp?

The expected phenotype is purple flowers due to the presence of the dominant allele.

Why is it important to use different letters for alleles?

To easily distinguish between the dominant and recessive alleles in a genotype.

What is the genetic basis for the color of flowers in pea plants?

The presence or absence of specific alleles that code for flower color determines the phenotype.

How does the inheritance of alleles from parents affect offspring?

Offspring inherit one allele from each parent, which influences their phenotype.

What is the relationship between mutations and observable traits?

Mutations can lead to observable characteristics, such as sickle cell trait or insect resistance.

What is a recessive trait and when is it observable?

A recessive trait is observable only in individuals who are homozygous for that allele, meaning it is expressed only when a dominant allele is not present.

What does it mean for an individual to be homozygous recessive?

An individual is homozygous recessive when they have two alleles for a trait that are both recessive, such as 'pp' for white flowers.

How are dominant and recessive alleles represented in genotypes?

Dominant alleles are represented with a capital letter, while recessive alleles are represented with a lowercase letter.

What is the difference between dominant and recessive phenotypes?

A dominant phenotype is expressed with one copy of the dominant allele, while a recessive phenotype requires two copies of the recessive allele.

What is the role of alleles in determining traits?

Alleles are different versions of a gene that can cause variations in protein production or expression, affecting traits.

What does it mean to be a carrier of a recessive allele?

An individual with one dominant and one recessive allele is a carrier; they possess the recessive allele but do not express the recessive phenotype.

Why can the terms dominant and recessive be misleading?

These terms do not imply that dominant alleles physically dominate recessive alleles; their effect depends on the proteins they code for and their interactions.

Who was Gregor Mendel and what was his contribution to genetics?

Gregor Mendel was a 19th-century monk whose work on hybridization in garden peas established the foundational principles of genetics.

What is Mendel's Law of Segregation?

Mendel's Law of Segregation states that individuals possess two alleles for each trait, and only one allele is passed to offspring from each parent.

What does it mean for an individual to be heterozygous?

An individual is heterozygous when they have two different alleles for a trait.

What happens to recessive alleles in heterozygous individuals?

In heterozygous individuals, the dominant allele is expressed, while the recessive allele's expression is hidden.

How did Mendel's experiments demonstrate independent assortment?

Mendel's experiments showed that traits were inherited independently, as he observed various combinations of traits in the offspring.

What were the seven pairs of contrasting traits Mendel analyzed in pea plants?

Mendel analyzed traits such as flower color (purple vs. white) and seed texture (round vs. wrinkled), among others.

What is the significance of Mendel's work in genetics?

Mendel's work allowed scientists to reliably predict the inheritance of traits, forming the basis for modern genetics.

What is the relationship between genotype and phenotype?

Genotype refers to the genetic makeup (alleles) of an individual, while phenotype refers to the observable traits expressed.

What is the expected outcome when true-breeding white and purple flowered plants are crossed?

The offspring will be purple flowered, demonstrating the dominance of the purple flower allele.

How do proteins affect phenotypes?

Proteins affect traits by influencing the expression and activity of genes, which can lead to variations in phenotypes.

What is the importance of understanding dominant and recessive traits in predicting genetic disorders?

Understanding these inheritance patterns helps predict the likelihood of offspring inheriting certain phenotypes, including genetic disorders.

What is the role of hybridization in Mendel's experiments?

Hybridization allowed Mendel to study the inheritance of traits by crossing different true-breeding plants to observe the resulting offspring.

How many alleles does an individual inherit for each trait?

An individual inherits two alleles for each trait, one from each parent.

What does it mean for traits to be inherited independently?

Independent inheritance means that the inheritance of one trait does not affect the inheritance of another trait.

What is the significance of Mendel's hybrid offspring results?

The results showed that traits do not blend but are inherited as distinct units, leading to the concept of dominant and recessive traits.

How can variations in protein expression lead to different phenotypes?

Variations in protein expression can affect when, where, and how much protein is produced, leading to observable differences in traits.

What is the Law of Independent Assortment?

It states that the inheritance of one pair of genes is independent of the inheritance of another pair, particularly for genes on different chromosomes.

What are non-Mendelian genetics?

Non-Mendelian genetics refer to inheritance patterns that do not follow Mendel's Law of Dominance, where traits may not be simply dominant or recessive.

What did Mendel's experiments reveal about inheritance?

Mendel's experiments provided the foundation for understanding basic genetics, but the full complexity of inheritance patterns was revealed later.

What is codominance?

Codominance occurs when two alleles are both expressed equally in a heterozygote, rather than one being dominant over the other.

Give an example of codominance in chickens.

Speckled chickens, resulting from a cross between black and white chickens, where both black and white feathers are expressed.

How does human blood type illustrate codominance?

In human blood types, A and B alleles are codominant, resulting in AB blood type where both A and B antigens are present.

What is incomplete dominance?

Incomplete dominance occurs when the traits of two alleles blend together, resulting in an intermediate phenotype.

Provide an example of incomplete dominance in flowers.

Crossing red snapdragons with white snapdragons produces pink flowers, which is an intermediate color.

What happens when two F1 hybrids showing incomplete dominance are crossed?

They produce offspring with red, pink, and white flowers.

What is the relationship between alleles in codominance?

Both alleles are expressed equally in the phenotype of the organism.

What is the relationship between alleles in incomplete dominance?

The traits blend together, resulting in a phenotype that is a mix of the two parental traits.

What did Mendel's Law of Dominance state?

One dominant allele masks the effect of a recessive allele in a heterozygote.

Why did scientists question Mendel's findings?

They observed inheritance patterns that did not match Mendel's predictions in test crosses.

How can traits be controlled beyond Mendel's predictions?

Traits can be controlled by multiple genes, multiple alleles, or exhibit relationships other than simple dominance.

What is a heterozygote?

An organism that has two different alleles for a particular gene.

What is an example of a trait that shows codominance in humans?

Human blood type AB, where both A and B alleles are expressed.

What is a characteristic of traits that exhibit incomplete dominance?

The resulting phenotype is a blend of the two parental traits.

What is the outcome of crossing a red flower with a white flower if the trait shows incomplete dominance?

The offspring will be pink flowers.

What does it mean for a trait to be controlled by more than one gene?

It means that multiple genes contribute to the expression of that trait, leading to more complex inheritance patterns.

How did Mendel's experiments simplify the understanding of genetics?

He focused on traits controlled by single genes with two alleles, establishing basic principles of inheritance.

What does the term 'phenotype' refer to?

The observable characteristics or traits of an organism.

What is the relationship between genotype and phenotype in incomplete dominance?

The genotype of an organism with incomplete dominance can be determined from its phenotype, as each genotype has a unique phenotype.

What does gene linkage conflict with in Mendelian genetics?

Gene linkage is in direct conflict with the Law of Independent Assortment.

What did Mendel's pea experiments demonstrate about traits?

Mendel's pea experiments demonstrated that traits located on different chromosomes are inherited separately.

How many genes can a single chromosome contain?

A single chromosome can have hundreds or thousands of genes; for example, Chromosome 1 has upwards of 2,000 different genes.

What is an example of gene linkage observed in fruit flies?

In fruit flies, brown bodies are more likely to be associated with normal wings, while black bodies are more likely to have itty-bitty wings.

What is epistasis in genetics?

Epistasis is a gene interaction where one gene masks or interferes with the expression of another gene.

What does the term 'epistasis' mean?

The term 'epistasis' is derived from Greek roots meaning 'standing upon', indicating that one gene's protein interferes with another's expression.

Provide an example of epistasis in mice pigmentation.

In mice, the agouti coat color (AA) is dominant to solid-colored fur (aa), but a recessive c allele at a separate gene locus prevents pigment production, resulting in an albino phenotype regardless of the A gene.

What is the role of gametes in sexual reproduction?

Gametes, such as sperm or eggs, pass genetic information from generation to generation and contain only half the genetic information of other body cells.

What is meiosis and its significance in genetics?

Meiosis is a type of cell division that produces gametes and is significant for reducing chromosome number and increasing genetic variation.

How many chromosomes do human gametes contain?

Human gametes contain 23 chromosomes, half the number found in body cells.

What is the diploid condition in cells?

The diploid condition refers to cells having matching pairs of chromosomes, one from the mother and one from the father.

How does meiosis contribute to genetic variation?

Meiosis is an important source of variation due to the random assortment and recombination of chromosomes.

What is the difference between body cells and gametes in terms of chromosome number?

Body cells have 46 chromosomes, while gametes have 23 chromosomes.

What is the significance of maternal and paternal chromosomes in inheritance?

Maternal and paternal chromosomes of each pair contain genes that affect the same traits.

What is the relationship between multiple genes and observable characteristics?

Observable characteristics are almost always under the influence of multiple genes acting in unison.

What is the role of complementary genes in phenotype expression?

Complementary genes need to be expressed simultaneously to affect a phenotype.

How do genes oppose each other in expression?

One gene may modify the expression of another gene, leading to antagonistic interactions.

What are unit factors according to Mendel?

Unit factors are what Mendel referred to as genes that control individual characteristics.

What is the significance of tracking chromosomes during meiosis?

Tracking chromosomes during meiosis helps understand patterns of inheritance.

What is the outcome of meiosis regarding genetic contribution from parents?

Meiosis forms cells that allow each parent to contribute equal amounts of genetic information to the offspring.

What does it mean for genes to function in complementary ways?

It means that two or more genes need to be expressed together to affect a phenotype.

What happens to the chromosome number during meiosis?

The chromosome number is reduced to half, resulting in gametes with 23 chromosomes.

What are gametes and how do they differ from somatic cells?

Gametes are haploid cells that contain one copy of each chromosome, while somatic cells are diploid and contain two copies of each chromosome.

What happens to chromosome numbers during meiosis?

Chromosome numbers are halved during meiosis, resulting in gametes that contain one chromosome from each pair.

What is the diploid number of chromosomes in a human zygote?

The diploid number of chromosomes in a human zygote is 46, or 23 matching pairs.

What would happen if chromosome numbers were not halved during meiosis?

If chromosome numbers were not halved, the number of chromosomes would double with each generation, leading to the death of the zygote.

Describe the process that occurs just before meiosis begins.

Each chromosome pair doubles to make two identical copies.

What occurs during the first meiotic cell division?

During the first meiotic cell division, the doubled chromosomes separate into two cells, each containing one doubled chromosome.

What is the result of the second meiotic cell division?

The second meiotic cell division results in a total of four haploid cells, each containing one chromosome from the original pair.

What is crossing-over in meiosis?

Crossing-over is a process where part of a chromosome from one parent swaps places with part of a chromosome from the other parent, resulting in new combinations of alleles.

What is the principle of segregation?

The principle of segregation states that alleles on the two chromosomes in a pair separate during meiosis, so each gamete receives only one allele for a given gene.

How does fertilization relate to allele combinations?

During fertilization, the random combination of alleles from the mother's egg and the father's sperm creates genetic diversity in the offspring.