Podcast
Questions and Answers
What does a homozygous recessive genotype indicate?
What does a homozygous recessive genotype indicate?
Which of the following correctly symbolizes dominant and recessive alleles?
Which of the following correctly symbolizes dominant and recessive alleles?
In a Punnett square with parent genotypes Aa and Aa, what is the genotypic ratio of the offspring?
In a Punnett square with parent genotypes Aa and Aa, what is the genotypic ratio of the offspring?
What is the phenotypic ratio expected from a cross of genotypes Aa and Aa?
What is the phenotypic ratio expected from a cross of genotypes Aa and Aa?
Signup and view all the answers
How did Gregor Mendel demonstrate the concept of hidden alleles?
How did Gregor Mendel demonstrate the concept of hidden alleles?
Signup and view all the answers
What is the outcome when an individual has the genotype R1R2 concerning ABO blood types?
What is the outcome when an individual has the genotype R1R2 concerning ABO blood types?
Signup and view all the answers
Which of the following statements best describes co-dominance?
Which of the following statements best describes co-dominance?
Signup and view all the answers
What is the potential effect of having homozygous sickle cell alleles?
What is the potential effect of having homozygous sickle cell alleles?
Signup and view all the answers
What advantage does the sickle cell trait provide in certain environments?
What advantage does the sickle cell trait provide in certain environments?
Signup and view all the answers
In the context of pleiotropy, what does it mean for a single gene to affect multiple traits?
In the context of pleiotropy, what does it mean for a single gene to affect multiple traits?
Signup and view all the answers
What does the term 'hybrid' refer to in genetic terms?
What does the term 'hybrid' refer to in genetic terms?
Signup and view all the answers
Which generation follows the parental generation in Mendel's classification?
Which generation follows the parental generation in Mendel's classification?
Signup and view all the answers
Which of the following best defines 'phenotype'?
Which of the following best defines 'phenotype'?
Signup and view all the answers
What is meant by the term 'alleles'?
What is meant by the term 'alleles'?
Signup and view all the answers
Which of the following statements accurately describes 'homozygous'?
Which of the following statements accurately describes 'homozygous'?
Signup and view all the answers
What key concept did Gregor Mendel establish regarding inheritance?
What key concept did Gregor Mendel establish regarding inheritance?
Signup and view all the answers
What was one reason why Mendel chose pea plants for his experiments?
What was one reason why Mendel chose pea plants for his experiments?
Signup and view all the answers
What does the term 'heterozygous' indicate about an organism?
What does the term 'heterozygous' indicate about an organism?
Signup and view all the answers
What condition is characterized by a musty odor in breath, skin, or urine due to the accumulation of phenylalanine?
What condition is characterized by a musty odor in breath, skin, or urine due to the accumulation of phenylalanine?
Signup and view all the answers
Which of the following is a neurological problem associated with PKU?
Which of the following is a neurological problem associated with PKU?
Signup and view all the answers
How do regulatory genes function in genetic expression?
How do regulatory genes function in genetic expression?
Signup and view all the answers
What process involves two or more genes that are required to complete a single trait?
What process involves two or more genes that are required to complete a single trait?
Signup and view all the answers
What phenomenon does not apply to genes that are closely located on the same chromosome?
What phenomenon does not apply to genes that are closely located on the same chromosome?
Signup and view all the answers
What characteristics can result from the build-up of phenylalanine in PKU patients?
What characteristics can result from the build-up of phenylalanine in PKU patients?
Signup and view all the answers
Which genetic concept describes how genes that are far apart tend to be separated more often during crossing over?
Which genetic concept describes how genes that are far apart tend to be separated more often during crossing over?
Signup and view all the answers
Which of the following traits is a classic example of polygenic inheritance?
Which of the following traits is a classic example of polygenic inheritance?
Signup and view all the answers
Which type of genetic disorder is Tay-Sachs classified as?
Which type of genetic disorder is Tay-Sachs classified as?
Signup and view all the answers
What is the age of onset for infantile Tay-Sachs disease?
What is the age of onset for infantile Tay-Sachs disease?
Signup and view all the answers
What is the primary function of the enzyme encoded by the HEXA gene?
What is the primary function of the enzyme encoded by the HEXA gene?
Signup and view all the answers
How do dominant genetic disorders differ from recessive disorders?
How do dominant genetic disorders differ from recessive disorders?
Signup and view all the answers
Why are carriers of recessive disorders often unaware of their condition?
Why are carriers of recessive disorders often unaware of their condition?
Signup and view all the answers
What is a potential consequence of incest in genetic terms?
What is a potential consequence of incest in genetic terms?
Signup and view all the answers
Which chromosomes typically determine sex identity in humans?
Which chromosomes typically determine sex identity in humans?
Signup and view all the answers
What do sex-linked genes influence?
What do sex-linked genes influence?
Signup and view all the answers
What genetic inheritance pattern primarily determines the expression of recessive traits linked to the X chromosome in males?
What genetic inheritance pattern primarily determines the expression of recessive traits linked to the X chromosome in males?
Signup and view all the answers
Which of the following statements is true regarding X-linked disorders?
Which of the following statements is true regarding X-linked disorders?
Signup and view all the answers
What is the primary characteristic of a male with red-green color blindness?
What is the primary characteristic of a male with red-green color blindness?
Signup and view all the answers
What does hemophilia result from?
What does hemophilia result from?
Signup and view all the answers
Which sex chromosome carries genes specifically involved in creating male sex identity?
Which sex chromosome carries genes specifically involved in creating male sex identity?
Signup and view all the answers
Study Notes
Patterns of Inheritance - Chapter 10
- Early attempts to understand inheritance had deep roots, with figures like Hippocrates and Aristotle struggling with this fundamental aspect of life.
- By the 19th century, it was established that offspring inherit traits from both parents, contradicting the prior belief that all traits come from the father. The mechanisms were, however, initially flawed.
Gregor Mendel
- Considered the father of classical genetics.
- Worked with pea plants in the 1860s, choosing them due to their rapid reproduction and readily observable traits (many varieties).
- Pea plants were easy to manipulate genetically.
- Established that parents pass heritable factors to their offspring.
Terms Coined by Mendel
- Hybrid: Offspring of two different genetic varieties (e.g., a purple-flowered plant and a white-flowered plant).
- Cross (or hybridization): Process of mating two different organisms.
- P generation: Parental generation.
- F1 generation: Offspring of the P generation.
- F2 generation: Offspring of the F1 generation.
- Monohybrid Cross: Cross of organisms differing in only one trait. This cross is often represented in a Punnett Square to show the resultant offspring probabilities.
More Terms
- Genotype: The actual genetic makeup (genes) of an organism.
- Phenotype: The observable characteristics (e.g. hair color, eye color, height) of an organism that are expressed from the organism's genotype .
Alleles
- Most organisms within a species have the same genes, but these genes can have variations, called alleles.
- Alleles are different forms of a gene, and these differences can lead to different versions of a particular trait (e.g. different eye colors).
- Homozygote/Homozygous: Means an individual has two identical alleles for a particular gene.
- Heterozygote/Heterozygous: Means an individual has two different alleles for a particular gene.
Dominance Versus Recessive
- When two genes have differing alleles and one is visible (fully expressed) the other hidden, the visible is called dominant; the hidden is called recessive.
- Dominant alleles are often symbolized with uppercase letters, and recessive alleles are often symbolized with lowercase letters.
- Homozygous dominant: AA; Homozygous recessive: aa; Heterozygous: Aa
Mendel's Seven Pea Plant Traits
- Traits observed in Mendel's classic experiment using peas. These include seed shape, seed color, flower color, pod shape, pod color, flower position, and stem height. These traits were tracked through generations to observe patterns of inheritance.
Punnett Square
- A device used to predict genotypes of offspring from a cross between two individuals.
- Used to determine potential genotype ratios.
- Can determine potential phenotype ratios.
- The parents' genotypes are used to generate potential offspring genotypes and their associated probabilities.
Hidden Alleles
- Organisms can carry recessive alleles that are not expressed if a dominant allele is present.
- These recessive alleles can still be passed down to offspring.
Mendel's Principle/Law of Segregation
- Pairs of genes separate (segregate) during meiosis and gamete formation to produce the "Gamete Set."
- During fertilization, these gametes fuse to form a new organism that returns to the diploid number once fertilization occurs.
Test Cross
- A method to determine the genotype of an organism with a dominant phenotype.
- Crosses the organism of unknown genotype with a recessive phenotype individual.
Mendel's Principle of Independent Assortment
- Different pairs of alleles segregate independently of each other during gamete formation.
- Linked genes (genes on the same chromosome) will often be inherited together, contradicting this principle; hence, they're not independent.
Conclusions
- Mendel's experiments using Pea Plants supported independent assortment of alleles.
Variations of Mendel's Principles
- Relationship between genotype and phenotype is rarely simple; multiple alleles often contribute to a single trait (e.g., eye color)
- Multiple genes often contribute to a single trait. Complex traits are often influenced by multiple genes.
- Eye color is a product of at least three genetic traits.
Incomplete Dominance
- When one gene is not dominant over the other, both genes express themselves which results in a "blending" of traits.
Co-dominance
- Neither allele is completely dominant, so both traits are expressed.
- ABO blood types are an example of co-dominance. The blood type is determined by the presence or absence of the A, B, or O carbohydrate on the surface of red blood cells. Different combinations result in different blood types.
Sickle Cell Anemia
- A genetic disorder resulting from a point mutation in the gene that codes for hemoglobin.
- Sickle cell trait results in a change in the shape and function of the red blood cells; in severe cases, this can lead to reduced oxygen carrying ability.
Pleiotropy
- One gene causes multiple traits.
- A single gene mutation changes an enzyme (phenylalanine hydroxylase) that results in the conversion of phenylalanine to tyrosine. In some cases, this can lead to build-up of dangerous toxic levels, affecting traits in several body systems. Phenylketonuria or PKU is an example of pleiotropy.
Regulatory Genes and Pleiotropy
- Regulatory genes control other genes to regulate processes (metabolism, development).
- Humans, chimpanzees, and bonobos are similar genetically, but differences in regulatory genes lead to different developmental outcomes in the organisms.
Epistasis or Polygenic Inheritance
- Two or more genes needed to complete a trait.
- The combined action of multiple genes can affect the outcome of a particular trait (e.g. eye color).
- Humans produce several pigments that influence eye color.
- Some traits are the result of pigments in birds; different genes encode for different pigments.
Linked Genes
- Genes located close together on the same chromosome tend to be inherited together.
- Linked genes do not follow Mendel's principle of independent assortment.
Inherited Disorders Caused by a Single Gene
- Autosomal Disorders: on non-sex chromosomes.
- Range from harmless (albinism) to deadly (Tay-Sachs).
Tay-Sachs
- Caused by a mutation in the HEXA gene on chromosome 15.
- This mutation results in a fatty acid (ganglioside) build-up that is toxic to the nervous system.
- The severity differs depending upon the type (infantile, juvenile, adult).
A genetic pedigree representing Tay-Sachs
- A family tree that illustrates the inheritance pattern of Tay-Sachs in multiple generations.
- Shows how the disorder is typically passed from parents to offspring.
Disorders Can Be Recessive or Dominant
- Most genetic disorders are recessive. A recessive disorder only manifests if an individual is homozygous recessive.
- Dominant genetic disorders are expressed in both homozygous and heterozygous forms.
Carriers
- People who carry a recessive allele for a disorder are called carriers, but typically do not show symptoms.
- Genetic testing helps detect fatal abnormalities and assist in informed parental decision-making.
Incest
- Closely related people share more similar genes and are more likely to carry the same recessive alleles.
- This increases the likelihood of offspring inheriting recessive disorders, particularly those resulting from shared recessive alleles.
Sex Chromosomes
- A pair of chromosomes that determines sex in most species.
Sex Identity
- The XX pair of chromosomes typically determines the female sex, whereas the XY pair is typically associated with the male sex.
- Other species have different chromosomal systems.
Sex-Linked Genes
- Genes found on the sex chromosomes.
- Some genes on the X chromosome affect traits not related to sex.
Mammals
- Sex-linked genes are located on the X chromosome.
- Genes on the Y chromosome are primarily associated with sex determination.
- Other species may have sex-linked genes on different chromosomes.
X-Linked Gene Expression
- Males inherit an X chromosome from their mothers; therefore all X-linked genes from their mothers are expressed.
- Females inherit one X chromosome from each parent, which means alleles from both parents are involved.
Recessive X-Linked Disorders
- Recessive disorders on the X chromosome manifest more frequently in males, where a single recessive allele is sufficient for the disease to be expressed.
Red-Green Color Blindness
- In males, color blindness occurs when a recessive allele on the X chromosome causes problems distinguishing shades of red from shades of green.
- Vision testing can help detect the level of colorblindness.
Hemophilia
- A disorder that prevents blood clotting.
- Can result from several different genetic mutations, often located on the X chromosome.
- Individuals with hemophilia may require supplemental clotting agents.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the foundational concepts of inheritance as outlined in Chapter 10. This quiz delves into early theories, the pivotal contributions of Gregor Mendel, and the key terminology associated with genetics. Test your knowledge on how traits are passed from parents to offspring.
