Podcast
Questions and Answers
In genetics, what distinguishes alleles from genes?
In genetics, what distinguishes alleles from genes?
- Alleles are the genetic makeup and genes are the physical expression of genetic traits.
- Genes are the physical expression of genetic traits, while alleles are the genetic makeup.
- Genes contain the information for a particular genetic trait, while alleles are slightly different versions of that gene. (correct)
- Alleles are basic units that affect genetic traits, while genes are slightly different versions of a trait.
If a plant has a genotype of 'Aa' for a particular trait, and 'A' is dominant, how would you describe the plant?
If a plant has a genotype of 'Aa' for a particular trait, and 'A' is dominant, how would you describe the plant?
- Homozygous dominant, displaying the 'A' trait.
- Homozygous recessive, displaying the 'a' trait
- Heterozygous, displaying a blend of 'A' and 'a' traits.
- Heterozygous, displaying the 'A' trait. (correct)
If a certain trait is X-linked recessive, which statement is most accurate?
If a certain trait is X-linked recessive, which statement is most accurate?
- Males and females are equally likely to express the trait.
- Females are more likely to express the trait.
- Males are more likely to express the trait. (correct)
- The trait will only be expressed in homozygous individuals, regardless of sex.
Which of Mendel's principles explains that the two alleles for a trait separate during gamete formation?
Which of Mendel's principles explains that the two alleles for a trait separate during gamete formation?
How does the Law of Independent Assortment relate to the inheritance of different traits?
How does the Law of Independent Assortment relate to the inheritance of different traits?
In genetic terms, what does the term homozygous mean?
In genetic terms, what does the term homozygous mean?
Which of the following best describes the relationship between genotype and phenotype?
Which of the following best describes the relationship between genotype and phenotype?
What is the significance of the 'P generation' in Mendel's genetic crosses?
What is the significance of the 'P generation' in Mendel's genetic crosses?
How does a dominant allele affect the phenotype when paired with a recessive allele in a heterozygous individual?
How does a dominant allele affect the phenotype when paired with a recessive allele in a heterozygous individual?
Which of the following is the most accurate definition of 'invariant trait'?
Which of the following is the most accurate definition of 'invariant trait'?
Flashcards
Genetic Trait
Genetic Trait
Any inherited characteristic of an organism.
Invariant Traits
Invariant Traits
Traits that are the same in all individuals of a species.
Variable Traits
Variable Traits
Traits that vary among individuals.
Gene
Gene
Basic unit of information that affects genetic traits.
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Alleles
Alleles
Slightly different versions of a gene.
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Genotype
Genotype
The genetic makeup of an individual (not visible).
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Phenotype
Phenotype
The physical expression of a genetic trait (what you see).
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Dominant Allele
Dominant Allele
An allele that prevents another allele from affecting the phenotype.
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Recessive Allele
Recessive Allele
An allele that has no effect on the phenotype when paired with a dominant allele. Requires two copies to show.
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Homozygous
Homozygous
Having two identical alleles for a gene.
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Heterozygous
Heterozygous
Having two different alleles for a gene.
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Genetic Traits
- Genetic traits are inherited characteristics of an organism.
- Invariant traits are the same in all individuals of a species.
- Examples include having two eyes, two legs, and two arms.
- Variable traits differ among individuals.
- Examples include curly hair and eye color changes.
Genes and Alleles
- A gene is the basic unit of information that affects genetic traits.
- Genes contain the information or code for a particular genetic trait.
- Alleles are slightly different versions of a given gene.
- Genotype refers to the genetic makeup of an individual for a given trait and cannot be seen.
- Phenotype is the physical expression of a trait's genetic makeup and can be seen.
Dominant vs. Recessive Alleles
- A dominant allele prevents a second allele from affecting the phenotype when the two alleles are together.
- If a child gets one dominant gene from either parent, they will show that trait.
- A recessive allele has no effect on the phenotype when paired with a dominant allele.
- A child needs two copies of the recessive gene, one from each parent, to show that trait.
Homozygous vs. Heterozygous
- Homozygous refers to a genotype consisting of two copies of the same allele.
- Homo=same.
- Example: BB or bb
- Heterozygous individuals have two different versions of a gene, one inherited from each parent.
- Hetero=Different.
- Example: Bb
- The individual will show the phenotype of the dominant allele.
X-Linked (Sex-Linked)
- The gene is found on the X chromosome.
- Males, having only one X chromosome, are more likely to show these traits, even if the gene is recessive.
Gregor Mendel's Principles of Genetics
- Law of Segregation: During gamete formation (sperm and egg cells), the two alleles for a given trait separate (segregate) so that each gamete carries only one allele for each gene.
- The two alleles of a gene are separated during meiosis 1 and end up in different gametes.
- Law of Dominance: When two different alleles for a trait are present in an organism, the dominant allele is expressed, while the recessive allele is masked.
- Law of Independent Assortment: Genes for different traits are inherited independently of each other, provided they are located on different chromosomes or are far apart on the same chromosome.
- Chromosome Theory of Inheritance: Genes are located on chromosomes, and the inheritance of traits is determined by the movement of chromosomes during meiosis.
- Codominance: When the effects of two alleles are equally visible in the phenotype.
- Pleiotropy: When a single gene influences a number of genetic traits.
- Polytrophy:
Mendel's Genetic Crosses
- Genetic crosses were performed as controlled mating experiments to examine how a particular trait is inherited.
- P generation: Parental offspring.
- F1 Generation: First generation of offspring.
- F2 Generation: Results of crossing the F1 generation.
- Crossing the P1 generation results in the F1 generation, and crossing the F1 generation results in the F2 generation.
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