(4.1) ADDITIONAL INHERITANCE PATTERNS & PEDIGREE ANALYSIS

Conditions caused by multiple small changes affecting gene expression levels and interactions, rather than a single large change.

Inheriting a risk for cancer, not a guaranteed development of cancer.

Traits influenced by many genes, each contributing slightly to the overall phenotype.

A series of chemical reactions in a cell catalysed by enzymes, where the product of one step is the substrate for the next.

A cellular process that regulates cell growth, a specific example of a metabolic pathway.

Slight increases or decreases in the activity of components in a metabolic pathway, which, if repeated in many steps, can lead to significant outcomes.

The enlargement of an organ or tissue caused by an increase in the number of cells.

A pattern of inheritance where the presence of one copy of a dominant allele (gene variant) is enough to cause a trait to be expressed.

Small changes in multiple factors can have more significant effects than the sum of the individual changes.

A pattern of inheritance where two copies of a recessive allele are needed for the trait to be expressed.

Cancer arises from a build-up of multiple (often small) genetic mutations in cells (somatic)

Genes located close together on the same chromosome are more likely to be inherited together.

The study of traits passed down through generations based on a systematic representation (family tree).

A disease caused by a combination of genetic predisposition, lifestyle, and environmental factors.

Inheritance pattern where genes are located on sex chromosomes (typically X in humans).

A sex-linked recessive genetic disorder that impairs blood clotting making individuals prone to prolonged bleeding.

The external conditions and influences that affect an organism or system, including lifestyle and internal cellular environment.

Different parts of an organism, even if in the same organism, can have different biochemical environments due to specialized barriers or tissues.

An individual who carries a recessive allele but does not exhibit the trait.

A person having two different alleles for a particular gene, one dominant and one recessive.

Look at every generation for affected individuals, see if affected couplings have unaffected offspring, and note differences between males and females for possible sex-linked inheritance.

Traits that result from an interplay of multiple genes and environmental components.

A trait controlled by a single gene; a simplistic concept that doesn't apply to humans.

A trait showing variation at a single locus, but with unexpected results in inheritance patterns.

A trait influenced by multiple genes and environmental factors (showing a range of phenotypes).

Predictable patterns of inheritance based on the presence/absence of dominant and recessive alleles.

Human traits are complex and influenced by multiple genes and environmental factors, not just a single gene.

A type of inheritance where the heterozygote displays an intermediate phenotype, a blend of the two alleles.

A type of inheritance where both alleles in a heterozygote are fully expressed, resulting in both traits being visible.

In contrast to simple Mendelian inheritance, quantitative traits are influenced by multiple genes, leading to a range of phenotypes.

The number of genes involved to influence a trait.

An example of co-dominance where multiple alleles are present (A, B, O) for distinct outcomes.

The difference between inheritance patterns controlled by single genes compared to the interactions of multiple genes, resulting in complex traits.

The level of expression of a trait determined by genes, similar to the different shades of color.

The probability that a specific genotype will manifest as the corresponding phenotype.

A genetic interaction where one gene affects or masks the expression of another gene, resulting in deviations from expected phenotypic ratios.

The observable physical or biochemical characteristics of an organism, resulting from the interaction between genotype and environment.

The genetic makeup of an organism, representing the combination of alleles for a particular trait.

A cross between two individuals identically heterozygous for two different traits.

A pattern of inheritance in which one allele completely masks the expression of another allele.

The expected phenotypic ratio in a dihybrid cross with complete dominance.

A deviation from the 9:3:3:1 ratio, where one or both traits are dependent on the presence of another.

A deviation from the 9:3:3:1 ratio, indicative of one gene masking another.

A trait whose variation is determined by a single locus (gene), resulting in distinct categories.

A trait influenced by multiple genes and possibly environmental factors, producing a range of phenotypes.

Heterozygous genotype results in an intermediate phenotype, a blend of the two homozygous phenotypes.

Both alleles in the heterozygous genotype are fully expressed, resulting in both traits being visible.

Probability that a specific genotype will manifest as the corresponding phenotype.

The degree to which a genotype is expressed as a phenotype.

A gene interaction where one gene masks the expression of another.

A family tree showing the inheritance of a trait or disease over multiple generations.

A family member related by blood to you in the first degree of kinship, such as parents, siblings, or children.

A family member related to you through one degree of kinship (your cousins, aunts & uncles).

Relationship by descent from a common ancestor.

The existence of more than two alleles for a single gene in a population.

A pattern where affected traits are present in every generation of a family tree. About half the offspring of an affected individual are also affected, and the trait appears equally in both sexes.

A progressive nerve disorder causing physical and mental disability, often beginning in middle age; a dominant genetic disorder.

A genetic disorder caused by a single gene; they are rare and severe.

Factors that favor one trait over another, can eliminate traits or alter their frequency in a population.

Someone who carries a trait causing a disease but doesn't show the disease symptoms.

Relationship by descent from a common ancestor.

Heterozygote phenotype is intermediate between the two homozygotes.

Protein levels significantly affect cellular function. Many recessive genes code for enzymes in biochemical pathways.

Reduction of gene product (by half in heterozygote) may be significant, especially for structural proteins.

Heterozygotes may produce enough gene product to show dominant phenotype and still carry recessive version.

Genes expressed to different degrees in different individuals (e.g., severity of a disease).

Phenotype predicted by genotype isn't always expressed (e.g., a gene mutation might not cause any effect).

Gene interaction modifying the 9:3:3:1 dihybrid ratio (F2 generation).

Homozygous recessive mutations in two genes produce the same phenotype.

A dominant allele of one gene masks the phenotype of a different gene.

Homozygosity for a recessive allele masks expression of a different gene.

The ability of multiple phenotypes to be encoded by one genotype, in response to environmental cues.

Studying traits through generations in a family/relatives to determine inheritance patterns, medical history.

Close relatives with shared genetics (parents, siblings, children).

Relatives one step removed (grandparents, aunts/uncles, nieces/nephews).

Even more distant relatives (cousins, great-grandparents).