Genetics: Key Concepts, Pedigrees, and Inheritance Patterns

What is the difference between phenotype and genotype?

Phenotype is the observable physical characteristics, while genotype is the genetic makeup (alleles) of an organism.

What are dominant and recessive alleles?

Dominant alleles are expressed in the phenotype even if only one copy is present, while recessive alleles are only expressed when two copies are present.

What is the difference between homozygous and heterozygous genotypes?

Homozygous genotypes have two identical alleles (either dominant or recessive), while heterozygous genotypes have two different alleles.

What is the purpose of a pedigree in genetics?

A pedigree is used to track the inheritance patterns of traits and to predict genotypes and phenotypes of individuals.

How do autosomal traits differ from X-linked traits?

Autosomal traits are inherited through non-sex chromosomes, while X-linked traits are inherited through the X chromosome, affecting males and females differently.

What is incomplete dominance?

Incomplete dominance is when the phenotype of heterozygotes is a blend of the phenotypes of both homozygotes.

What is a quantitative trait?

A quantitative trait is one that is influenced by multiple genes and shows a continuous range of phenotypes.

How does the inheritance of linked genes differ from unlinked genes?

Linked genes are inherited together due to their proximity on the same chromosome, while unlinked genes assort independently.

What is the process of meiosis?

Meiosis is the process that produces haploid gametes from diploid cells, ensuring genetic diversity through segregation and independent assortment.

What is the Law of Dominance?

The Law of Dominance states that some alleles are dominant and will be expressed in the phenotype, while recessive alleles will only be expressed if two copies are present.

What is the Law of Independent Assortment?

The Law of Independent Assortment states that alleles for different genes are inherited independently of each other.

What is the Law of Segregation?

The Law of Segregation states that alleles for a gene separate during gamete formation, so offspring inherit one allele from each parent.

How can you use a Punnett square?

A Punnett square is used to predict the genotypic and phenotypic ratios of offspring from a genetic cross.

What is Type I Diabetes?

Type I Diabetes is an inherited autoimmune disorder where the immune system attacks insulin-producing beta cells in the pancreas.

What happens to blood sugar levels in Type I Diabetes?

Blood sugar levels rise because glucose cannot be taken up by cells due to lack of insulin.

What is the significance of Gregor Mendel's experiments?

Mendel's experiments with pea plants laid the foundation for the modern understanding of genetics and inheritance patterns.

What is a trait in genetics?

A trait is a variation in a physical characteristic that can be inherited.

What does it mean for a genotype to be homozygous dominant?

A homozygous dominant genotype has two copies of the dominant allele (e.g., PP).

What does it mean for a genotype to be homozygous recessive?

A homozygous recessive genotype has two copies of the recessive allele (e.g., pp).

What is the F1 generation in Mendel's experiments?

The F1 generation is the first filial generation produced by crossing two different parental (P) generation plants.

What is the F2 generation in Mendel's experiments?

The F2 generation is produced by allowing the F1 hybrids to self-fertilize.

What does the Law of Independent Assortment state?

Two traits are inherited independently and do not influence one another.

What are autosomes?

Chromosomes that contain genes regulating general functions such as metabolism and growth (chromosomes #1-22 in humans).

What are sex chromosomes?

Chromosomes that contain genes involved in sex determination and sexual reproduction, as well as functions not related to sex.

How is human sex determined?

By the presence of XX (female) or XY (male) sex chromosomes.

What is a pedigree?

A diagram that shows the phenotypes of individuals in a family, used to trace the inheritance of alleles.

How are males and females represented in a pedigree?

Males are represented as squares (□) and females as circles (Ο).

What indicates a mating in a pedigree?

Horizontal lines between shapes indicate mating.

What does a filled shape in a pedigree represent?

Individuals expressing a trait, often a genetic disorder.

What characterizes autosomal dominant disorders?

The disorder is seen in every generation, and males and females are equally affected.

What characterizes autosomal recessive disorders?

The disorder 'skips' generations and males and females are equally affected.

What are sex-linked traits?

Traits for genes located on the X or Y chromosome.

How do males inherit sex-linked traits?

Males only pass on their Y chromosome to sons and their X chromosome to daughters.

What is an X-linked recessive disorder?

A disorder where all daughters of an affected male inherit his disease allele, but none of his sons do.

What is an example of an X-linked trait?

Color blindness is an X-linked recessive trait.

What are quantitative traits?

Traits with a wide variety of phenotypic possibilities existing along a continuum, such as human skin color.

What are linked genes?

Genes located on the same chromosome that are typically inherited together.

What is crossing over?

The process where homologous chromosomes exchange information, which can separate linked genes.

What is the significance of the genes OCA2 and HERC2?

They are linked genes that influence hair and eye color, located on Chromosome #15.

What should you do to prepare for the exam?

Review class notes, use the eTextbook and other resources, complete homework, and reflect on learning.