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What is the study of inherited variation?
What is the study of inherited variation?
What is a sequence of DNA that instructs a cell to produce a particular protein?
What is a sequence of DNA that instructs a cell to produce a particular protein?
What is an alternate form of a gene that occurs at a given locus in a chromosome?
What is an alternate form of a gene that occurs at a given locus in a chromosome?
What is the term for having two identical alleles of a gene?
What is the term for having two identical alleles of a gene?
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What is the term for the expression of a gene in traits or symptoms?
What is the term for the expression of a gene in traits or symptoms?
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Who is called the Father of Genetics?
Who is called the Father of Genetics?
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What is the term for a cell containing two sets of chromosomes?
What is the term for a cell containing two sets of chromosomes?
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What is the term for a sex cell, such as a sperm or ovum?
What is the term for a sex cell, such as a sperm or ovum?
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What is the number of X chromosomes present in females?
What is the number of X chromosomes present in females?
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Which of the following conditions is an example of X-Linked recessive inheritance?
Which of the following conditions is an example of X-Linked recessive inheritance?
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When a mother is a carrier of an X-Linked recessive mutation, what is the chance that a son will be affected?
When a mother is a carrier of an X-Linked recessive mutation, what is the chance that a son will be affected?
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What is the pattern of inheritance of a condition caused by a mutation on the X chromosome?
What is the pattern of inheritance of a condition caused by a mutation on the X chromosome?
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What is the chance that a daughter will be a carrier when the mother is a carrier of an X-Linked recessive mutation?
What is the chance that a daughter will be a carrier when the mother is a carrier of an X-Linked recessive mutation?
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When a father is affected by a condition due to an X-Linked recessive mutation, what happens to his sons?
When a father is affected by a condition due to an X-Linked recessive mutation, what happens to his sons?
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Which of the following chromosomes is responsible for X-Linked diseases?
Which of the following chromosomes is responsible for X-Linked diseases?
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Why are daughters of a carrier mother only carriers of an X-Linked recessive mutation?
Why are daughters of a carrier mother only carriers of an X-Linked recessive mutation?
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What is the purpose of crossing over during prophase 1 of meiosis?
What is the purpose of crossing over during prophase 1 of meiosis?
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Which enzyme is responsible for breaking homologous chromosomes during crossing over?
Which enzyme is responsible for breaking homologous chromosomes during crossing over?
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During which stage of meiosis does crossing over occur?
During which stage of meiosis does crossing over occur?
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What is the term for a chromosome that determines sex?
What is the term for a chromosome that determines sex?
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What is the result of fertilization with a sperm containing a Y chromosome?
What is the result of fertilization with a sperm containing a Y chromosome?
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How many chromosomes does a human cell have?
How many chromosomes does a human cell have?
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What is the term for a trait determined by a gene located on the X chromosome?
What is the term for a trait determined by a gene located on the X chromosome?
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What is the main difference between the X and Y chromosomes?
What is the main difference between the X and Y chromosomes?
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What was the ratio of Tall to dwarf offspring observed by Mendel in the F2 generation?
What was the ratio of Tall to dwarf offspring observed by Mendel in the F2 generation?
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What is the term for the distribution of alleles of a gene into separate gametes during meiosis?
What is the term for the distribution of alleles of a gene into separate gametes during meiosis?
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What is the genotype of an organism that is homozygous recessive?
What is the genotype of an organism that is homozygous recessive?
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What is the term for the random arrangement of homologous chromosome pairs during metaphase 1 of meiosis?
What is the term for the random arrangement of homologous chromosome pairs during metaphase 1 of meiosis?
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What type of cross involves organisms that differ in two traits?
What type of cross involves organisms that differ in two traits?
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What is the ratio of the four possible combinations of seed characteristics in the F2 generation of a Dihybrid Cross?
What is the ratio of the four possible combinations of seed characteristics in the F2 generation of a Dihybrid Cross?
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What is the term for the offspring from homozygous parents differing in three pairs of genes?
What is the term for the offspring from homozygous parents differing in three pairs of genes?
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What is the genotype of an organism that is heterozygous?
What is the genotype of an organism that is heterozygous?
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Why are X-linked recessive diseases more common in males than in females?
Why are X-linked recessive diseases more common in males than in females?
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What happens when an affected male passes on the X chromosome to his sons?
What happens when an affected male passes on the X chromosome to his sons?
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What is the probability of a daughter being affected by an X-linked dominant gene if the mother is affected?
What is the probability of a daughter being affected by an X-linked dominant gene if the mother is affected?
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What is the characteristic of X-linked dominant inheritance in males?
What is the characteristic of X-linked dominant inheritance in males?
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What is the condition that follows a pattern of X-linked dominant inheritance?
What is the condition that follows a pattern of X-linked dominant inheritance?
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What is the cause of colour blindness?
What is the cause of colour blindness?
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What is the test used to diagnose red-green colour deficiencies?
What is the test used to diagnose red-green colour deficiencies?
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What is the ratio of colour blindness in men and women?
What is the ratio of colour blindness in men and women?
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Study Notes
Molecular Genetics
- Definition of Genetics: The study of inherited variation.
- Definition of Gene: A sequence of DNA that instructs a cell to produce a particular protein.
- Definition of Allele: An alternate form of a gene that occurs at a given locus on a chromosome.
- Definition of Homozygous: Having two identical alleles of a gene (e.g. TT or tt).
- Definition of Heterozygous: Having two different alleles of a gene (e.g. Tt).
- Definition of Genotype: The alleles combination in an individual that cause particular traits or disorders.
- Definition of Phenotype: The expression of a gene in traits or symptoms.
- Definition of Dominant: A gene variant expressed when present in even one copy (e.g. TT, Tt).
- Definition of Recessive: An allele whose expression is masked by another allele (e.g. tt).
- Definition of Diploid: A cell containing two sets of chromosomes.
- Definition of Haploid: A cell containing one set of chromosomes.
- Definition of Gamete: A sex cell (sperm or ovum).
Mendelian Genetics
- Gregor Mendel is considered the Father of Genetics (1822-1884).
- Mendel's Experiments:
- First Experiment: Crossed tall and dwarf plants, resulting in F1 offspring that were all tall (Tt).
- Second Experiment: Crossed plants with different traits, resulting in an F2 generation with a 9:3:3:1 ratio.
- Laws of Inheritance:
- Law of Segregation: The distribution of alleles of a gene into separate gametes during meiosis.
- Law of Independent Assortment: The random arrangement of homologous chromosome pairs during metaphase 1 of meiosis.
Crossing Over
- Definition: An event during prophase 1 of meiosis when homologous chromosomes exchange parts, mixing up maternal and paternal gene combinations.
- Features of Crossing Over:
- Probability of crossing over increases with increasing distance between two loci on the chromosome.
- Involves breakage of each of two homologous chromosomes by endonuclease enzymes, followed by exchange of parts and reunion by ligase enzymes.
- Occurs during prophase 1 of meiosis in the post-replication tetrad stage.
Sex Determination and X-Linked Inheritance
- Definition of Sex Chromosome: A chromosome containing genes that specify sex (X and Y chromosomes).
- Definition of Autosome: A chromosome that does not have a gene that determines sex.
- XX-XY Mechanism of Sex Determination:
- XX zygote develops into a female, and XY zygote develops into a male.
- X-Linked Inheritance:
- Refers to a trait determined by a gene located on the X chromosome.
- X-Linked diseases are inherited through one of the sex chromosomes (X or Y chromosomes).
- Examples of X-Linked recessive diseases include Hemophilia and Colorblindness.
X-Linked Inheritance Patterns
- When the mother is a carrier of an X-Linked recessive mutation:
- Sons have a 50% chance of being affected, and daughters have a 50% chance of being carriers.
- When the father is affected by an X-Linked recessive mutation:
- None of his sons will be affected, and all of his daughters will be carriers.
- X-Linked dominant inheritance:
- Examples include incontinentia pigmenti.
- Much more severe effects in males.
Sex-Linked Recessive Traits in Humans
- Colorblindness:
- Inherited and more common in men (1 in 20), affecting fewer women (1 in 200).
- The gene for red-green colorblindness lies on the X-chromosome.
- Follows a pattern of X-Linked recessive inheritance.
- Diagnosis: Uses a test with colored spots to diagnose red-green color deficiencies.
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Description
This quiz covers the basics of Mendelian genetics, including transmission genetics, crossing over in meiosis, and X-linked inheritance. Test your knowledge of how traits are passed down from generation to generation.
