BIOLOGY- GENTICS TEST

Vocabulary

Understanding the following terms is crucial for fluency in genetics:

• ABO blood group system: A classification system for human blood based on the presence or absence of antigens A and B. There are four blood types: A, B, AB, and O.

• Allele: Different versions of a gene that exist at a specific locus on a chromosome; can be dominant or recessive.

• Autosomal genes/traits: Genes located on the autosomes (non-sex chromosomes) that contribute to various traits, inherited in a Mendelian fashion.

• Blood types (ABO system): Blood classification that influences compatibility for blood transfusions and is determined by alleles A, B, and O.

• Clumping - blood reactions: The agglutination or clumping of blood cells happens when incompatible blood types mix, resulting in dangerous immune responses.

• Codominance: A genetic scenario where both alleles in a heterozygous organism contribute equally to the phenotype, such as in AB blood type.

• Complete dominance vs. incomplete dominance: Complete dominance occurs when one allele completely masks the effects of another. Incomplete dominance involves blending traits, leading to a third phenotype.

• Dominant vs. recessive: Dominant alleles express their trait in a heterozygous pairing, while recessive alleles only display their trait if homozygous.

• Dihybrid cross: A genetic cross that examines two traits, used to demonstrate the law of independent assortment.

• Gamete: Sex cells (sperm and eggs) that carry alleles to offspring; produced through meiosis.

• Gene / mutation: A gene is a sequence of DNA that encodes for protein. A mutation is a change in the DNA sequence that can alter gene function.

• Genetics: The study of heredity and the variation of inherited characteristics.

• Generation (P, F1, F2, etc.): Refers to the different stages of offspring; the P generation is the parent generation, F1 is the first filial generation, and F2 is the second.

• Genotype vs. phenotype: Genotype refers to the genetic makeup (alleles), while phenotype is the observable trait resulting from the genotype.

• Heredity: The process by which traits and characteristics are passed from parents to offspring.

• Heterozygous vs homozygous: Heterozygous individuals carry two different alleles for a trait, while homozygous individuals carry two of the same alleles.

• Law of independent assortment: Mendel's principle stating that alleles for different traits are distributed to sex cells (& subsequently, offspring) independently of one another.

• Law of segregation: The principle stating that alleles segregate from each other during the formation of gametes.

• Mendelian vs. “non-Mendelian” genetics: Mendelian genetics follows predictable patterns of inheritance (e.g., dominant/recessive traits), while non-Mendelian genetics includes complex inheritance patterns such as polygenic inheritance and gene linkage.

• Multiple alleles: Situations where more than two alleles exist for a particular gene within a population, such as the ABO blood group.

• Pedigree: A diagram representing the lineage or descent of individuals, often used to track genetic disorders.

• Sex-linked (AKA X-linked) genes/traits: Traits associated with genes found on the X chromosome, often exhibiting unique inheritance patterns, particularly in males.

• Testcross: A method to determine an organism's genotype by breeding it with a homozygous recessive individual.

• Universal donor vs. universal recipient: Type O blood is known as the universal donor as it can be given to any blood type, while Type AB blood is considered the universal recipient because it can receive from all blood types.
  

Necessary Skills

·       Given a genotype, determine the possible gametes. (For example TtYy has the possible gametes TY, Ty, tY, and ty. TT would only have gametes with T in them.

·       Solve various Punnett square problems, including Mendelian crosses involving one or two traits. Also, be able to solve crosses involving incomplete dominance and codominance, blood types, and sex-linked traits.

·       Predict the genotype and phenotype ratios of possible offspring in the crosses described above.

·       Determine what blood types can be donated to what recipients, and why.

·       Determine the genotype of a phenotype using a testcross.

·       Be able to read and draw pedigrees. Predict genotypes and phenotypes of individuals in pedigrees.

Fundamental Questions

·       How are traits passed from one generation to the next, and what determines which trait will be expressed?

·       What is the relationship between a pair of homologous chromosomes and a pair of alleles for a given gene?

·       How did Mendel’s experiment disprove the blending hypothesis? How did it show that traits could skip a generation?