9th Honors Bio Genetics Quizlet Notes

What is genetics?

The branch of biology that studies how traits are inherited from parents to offspring, focusing on mechanisms of inheritance and variation.

What is genetic variation?

The differences in genetic makeup among individuals in a population, crucial for evolution and biodiversity.

What is meiosis?

A specialized type of cell division that produces gametes, each containing half the number of chromosomes of the original diploid cell.

Why is meiosis important?

It ensures genetic diversity through crossing over and independent assortment, and prevents chromosome number doubling across generations.

What is a gene?

A segment of DNA that codes for a protein or RNA molecule, influencing specific traits.

What occurs during Prophase I of meiosis?

Chromosomes condense, homologous chromosomes pair up, and crossing over occurs, exchanging genetic material.

What did Mendel's Law of Segregation state?

Each individual has two alleles for each gene, which segregate during meiosis so that each gamete receives only one allele.

What is a silent mutation?

A permanent change in a DNA sequence that does not alter the protein due to redundancy in the genetic code.

What is complete dominance?

When one allele masks the effect of another, resulting in the dominant phenotype.

What is the function of Punnett Squares?

To predict the likelihood of offspring inheriting specific traits based on parental alleles.

What happens during independent assortment in meiosis?

Homologous chromosomes align randomly, leading to diverse genetic combinations in gametes.

What are X-linked traits?

Those located on the X chromosome, where males are more likely to express recessive traits due to having only one X chromosome.

What are the effects of missense mutations?

A change in the protein due to a different amino acid being incorporated, potentially affecting protein function.

What is the phenotypic ratio of a monohybrid cross Aa x Aa?

3 dominant : 1 recessive.

What is genetic counseling?

Principles of genetics are used to help individuals understand and manage genetic conditions, including risks and inheritance patterns.

What is nondisjunction?

An error in meiosis where chromosomes do not separate properly, often leading to abnormal chromosome numbers in gametes.

What are the phases of meiosis?

Meiosis I, which includes Prophase I, Metaphase I, Anaphase I, and Telophase I; and Meiosis II, which includes Prophase II, Metaphase II, Anaphase II, and Telophase II.

What are Mendel's three laws of inheritance?

1) Law of Segregation - alleles segregate during gamete formation; 2) Law of Independent Assortment - genes for different traits segregate independently; 3) Law of Dominance - one allele can mask the expression of another.

What is incomplete dominance?

A genetic phenomenon where the dominant allele does not completely mask the effects of the recessive allele, resulting in a phenotype that is a blend of both traits.

What is codominance?

A genetic phenomenon where both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that is neither dominant nor recessive. ex. AB blood type in humans.

What is Tay-Sachs disease?

A genetic disorder caused by a deficiency of the HEXA enzyme, leading to the accumulation of GM2 gangliosides in the nerve cells, resulting in severe neurological damage and early death.

What is Sickle Cell Anemia?

A genetic disorder caused by a missense mutation in the hemoglobin gene, leading to abnormal hemoglobin that distorts red blood cells into a sickle shape.

What are the symptoms of Sickle Cell Anemia?

Episodes of pain (crises), anemia, swelling in hands and feet, increased infections, and delayed growth.

How is Sickle Cell Anemia inherited?

An autosomal recessive pattern, meaning a child must inherit two copies of the sickle cell gene, one from each parent, to develop the disease.

What is Phenylketonuria (PKU)?

A genetic disorder caused by a mutation in the PAH gene, leading to the inability to metabolize phenylalanine, an amino acid.

What are the consequences of untreated PKU?

Intellectual disability, developmental delays, seizures, and other serious health issues due to toxic buildup of phenylalanine.

How is PKU screened and managed?

Through a blood test, and management includes a strict low-phenylalanine diet to prevent complications.

What type of mutation causes Sickle Cell Anemia?

A missense mutation where adenine is replaced by thymine in the gene coding for beta-globin in hemoglobin.

What are the symptoms of Tay-Sachs disease?

Progressive neurological deterioration, loss of motor skills, increased startle response, vision and hearing loss, seizures, and paralysis.

How is Tay-Sachs disease screened?

Using a blood test that measures the level of the HEXA enzyme. A significantly low level indicates a risk for the disorder.

What type of mutation causes Tay-Sachs disease?

A frameshift mutation or small insertion/deletion in the HEXA gene, resulting in the absence of the HEXA enzyme.

How is Tay-Sachs disease inherited

An autosomal recessive pattern, meaning a child must inherit two copies of the mutated gene, one from each parent, to develop the disease.