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Hereditary (OAT) 2
| Question | Answer |
|---|---|
| What is a gene? | A basic unit or sequence of genetic material that encodes a trait |
| What is a locus? | A gene's location within a genome |
| What is an allele? | A variant form of a gene. Wild type = normal version; Mutant = altered DNA sequence affecting phenotype |
| What is a genotype vs. phenotype? | Genotype = the alleles an individual carries (e.g., Aa); Phenotype = the set of observable characteristics resulting from expression of the genotype |
| What is the difference between homozygous dominant, homozygous recessive, and heterozygous? | Homozygous dominant = two copies of the dominant allele (BB); Homozygous recessive = two copies of the recessive allele (bb); Heterozygous = one dominant and one recessive allele (Bb) |
| What is hemizygous? | Having only one copy of a gene instead of two (e.g., sex chromosomes of males are XY) |
| What are homologous chromosomes? | A pair of chromosomes (1 maternal, 1 paternal) that contain the same genes in the same locations |
| What is the Law of Segregation? | During Anaphase I, homologous chromosomes segregate, resulting in haploid gametes that contain only one allele per gene |
| What is the Law of Independent Assortment? | The lining up and separation of one pair of homologous chromosomes does not influence that of a different pair — allele pairs sort independently when gametes form |
| What is the Law of Dominance? | A dominant allele masks the effect of a recessive allele |
| What is a test cross? | A genetic cross between a homozygous recessive individual and an individual of unknown genotype to determine the latter's genotype for a given trait |
| What is a monohybrid vs. dihybrid cross? | Monohybrid = tests a single gene; Dihybrid = tests two different genes simultaneously |
| What are P1, F1, and F2 generations? | P1 = parental generation; F1 = first generation of offspring; F2 = second generation of offspring |
| What is epistasis? | One gene affects the phenotypic expression of an independently inherited gene (e.g., baldness: 1st gene controls whether one is bald, 2nd controls hair color) |
| What are multiple alleles? | More than two typical alleles exist for a gene (e.g., A, B, O alleles in the ABO blood type system) |
| What is polygenic inheritance? | Many genes interact to shape a single phenotype, often with continuous variation (e.g., height) |
| What is pleiotropy? | A single gene controls the expression of multiple phenotypic traits (e.g., a single gene controls a plant's height, color, and texture) |
| What is incomplete dominance? | There is a blending of alleles, producing a unique heterozygous phenotype (e.g., R red × W white = RW pink) |
| What is codominance? | Both alleles are completely expressed (e.g., R red × W white = RW red & white speckled) |
| What are sex-linked genes vs. sex-influenced genes? | Sex-linked = reside on a sex chromosome; Sex-influenced = can be affected by the sex of the individual carrying the trait (e.g., same baldness gene, but males go bald while females don't) |
| What is a linkage map? | Uses recombination frequency to show the relative positions of genes on a chromosome; closer genes are less likely to be separated by recombination |
| What are linked genes? | Genes that reside close together on a chromosome, making them less likely to be separated by recombination during meiosis and more likely to be inherited together |
| What is X-inactivation? | During embryonic development in female mammals, one of the two X chromosomes is inactivated, forming a highly condensed chromosome called a Barr body |
| What is penetrance vs. expressivity? | Penetrance = the proportion of individuals with a specific genotype that will express the corresponding phenotype; Expressivity = the variation of a phenotype for a specific genotype |
| What is aneuploidy? | An abnormal number (extra or missing) of chromosomes, often caused by nondisjunction (e.g., Trisomy 21 / Down syndrome = three copies of chromosome 21) |
| What is nondisjunction? | The failure of chromosomes or chromatids to separate during mitosis/meiosis; can result in gametes with too many or too few chromosomes |
| What is monosomy vs. trisomy? | Monosomy = missing one chromosome (2n−1 = 45); Trisomy = extra chromosome (2n+1 = 47) |
| What are the inheritance patterns of autosomal dominant disorders? | One copy of the mutated gene is enough to express the condition; cannot skip generations; affects males and females equally; two heterozygous affected parents can have unaffected offspring |
| What are the inheritance patterns of autosomal recessive disorders? | Two copies of the mutated gene must be present; can skip generations; affects males and females equally; two unaffected carrier parents can have affected offspring |
| What are the inheritance patterns of X-linked dominant disorders? | One copy of the mutation on the X chromosome causes the condition in both males and females; can skip generations; two unaffected parents can have affected offspring |
| What are the inheritance patterns of X-linked recessive disorders? | Two copies needed in females, one copy in males causes the condition; can skip generations; affects males more commonly than females; affected mothers always have affected sons; normal fathers never have affected daughters |
| What are Y-linked inheritance patterns? | Genes on the Y chromosome; affects only and all males |
| What is inbreeding? | Close genetic relatives mating and producing offspring; increases the chances of recessive conditions appearing |
| What are the four types of chromosomal aberrations? | 1) Inversion – segment rearranged in reverse orientation; 2) Deletion – segment is missing/deleted; 3) Translocation – segment moves to another chromosome (reciprocal or nonreciprocal); 4) Duplication – segment is repeated on the same chromosome |
| What is colchicine? | A drug that arrests mitosis by interfering with mitotic spindle formation; can prevent cell replication and has anticancer effects |
| What are proto-oncogenes and tumor suppressor genes? | Proto-oncogenes stimulate normal growth; if mutated they become oncogenes (cancer-causing genes). Tumor suppressor genes make proteins that help control cell growth; if mutated they may lead to cancer. |
Created by:
smurtab