Biology
Inheritance and Variation flashcards
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- What is genotype at a locus?Mendelian Patterns
- The allele combination at that genetic position.
- What is phenotype?Mendelian Patterns
- An observable feature shaped by genes and context.
- What does heterozygous mean?Mendelian Patterns
- Having two different alleles at a locus.
- Does dominant mean more common?Mendelian Patterns
- No; dominance describes expression in a specified heterozygote.
- What is the law of segregation?Mendelian Patterns
- The two alleles at a diploid locus ordinarily separate into gametes.
- What allele does a typical gamete carry at one locus?Mendelian Patterns
- One of the two parental alleles.
- What are expected gametes from Aa?Mendelian Patterns
- A and a, usually modeled at equal probabilities.
- Does expected 1:1 mean every tiny sample is 1:1?Mendelian Patterns
- No; chance causes sample variation.
- What is independent assortment?Mendelian Patterns
- Independent inheritance of allele choices at effectively unlinked loci.
- What is genetic linkage?Mendelian Patterns
- Tendency of loci on the same chromosome to be inherited together.
- What gametes are expected from unlinked AaBb?Mendelian Patterns
- AB, Ab, aB, and ab at 1/4 each.
- How can linked alleles be separated?Mendelian Patterns
- Crossing over between their loci can recombine them.
- What does a Punnett square show?Probability and Punnett Models
- Modeled combinations of parental gametes and their probabilities.
- What is the Aa × Aa genotype ratio?Probability and Punnett Models
- 1 AA : 2 Aa : 1 aa under equal segregation.
- What is the Aa × Aa phenotype ratio with complete dominance?Probability and Punnett Models
- 3 dominant : 1 recessive as an expectation.
- Does a Punnett box represent a guaranteed child?Probability and Punnett Models
- No; it represents a possible outcome with a probability.
- When do we multiply probabilities?Probability and Punnett Models
- When independent specified events must both occur.
- When do we add probabilities?Probability and Punnett Models
- When mutually exclusive routes lead to a result.
- What is conditional probability?Probability and Punnett Models
- Probability after restricting attention to a stated subset of outcomes.
- What is P(aabb) for independent AaBb × AaBb?Probability and Punnett Models
- 1/16 under simple equal-segregation assumptions.
- When is 9:3:3:1 expected?Probability and Punnett Models
- A two-locus heterozygote cross with independent assortment and complete dominance.
- What is sampling variation?Probability and Punnett Models
- Chance differences between observed counts and expected proportions.
- What can linkage change?Probability and Punnett Models
- Expected frequencies of two-locus combinations.
- Does a close ratio prove a model?Probability and Punnett Models
- No; multiple models may fit limited data.
- What is incomplete dominance?Beyond Simple Dominance
- An intermediate heterozygote phenotype for a stated trait.
- What is codominance?Beyond Simple Dominance
- Both allele-associated effects are detectable in a heterozygote.
- Are alleles physically blended in either model?Beyond Simple Dominance
- No; intact alleles still segregate.
- What phenotype ratio may result from a heterozygote cross with three distinguishable genotypes?Beyond Simple Dominance
- 1:2:1 under equal-segregation assumptions.
- What are multiple alleles?Beyond Simple Dominance
- More than two variants of a locus in a population.
- What is a polygenic trait?Beyond Simple Dominance
- A feature influenced by variants at multiple loci.
- What is a multifactorial trait?Beyond Simple Dominance
- A feature influenced by genetic and environmental factors.
- What does heritability summarize?Beyond Simple Dominance
- A population-level fraction of observed variation under particular conditions.
- What is epistasis?Beyond Simple Dominance
- One locus modifying the phenotypic effect of another.
- What is a sex-linked gene?Beyond Simple Dominance
- A gene located on a sex chromosome in a given system.
- What is genetic linkage?Beyond Simple Dominance
- Nearby loci on one chromosome inherited together more often.
- What is organelle inheritance?Beyond Simple Dominance
- Transmission of genetic material from organelles such as mitochondria.
- What is a pedigree?Pedigrees and Evidence
- A diagram of relationships and traits across generations.
- What does shading usually mark?Pedigrees and Evidence
- An observed feature defined by the diagram key.
- Can an unshaded person carry a recessive allele?Pedigrees and Evidence
- Yes, a heterozygote may lack the recessive phenotype.
- Why is a pedigree not a genotype readout?Pedigrees and Evidence
- It primarily records relationships and observed traits.
- What pattern can unaffected carriers produce?Pedigrees and Evidence
- An offspring with an autosomal recessive phenotype.
- For Aa × Aa, what is P(Aa | unaffected) with full penetrance?Pedigrees and Evidence
- 2/3.
- What is full penetrance in a stated model?Pedigrees and Evidence
- Everyone with the specified genotype shows the modeled phenotype.
- Why is a 2/3 carrier probability conditional?Pedigrees and Evidence
- It applies after excluding the recessive phenotype outcome.
- What is a pedigree hypothesis?Pedigrees and Evidence
- A proposed inheritance model evaluated against family observations.
- Does a trait in every generation prove dominance?Pedigrees and Evidence
- No, several mechanisms or sampling patterns may fit.
- Can a sequence association alone establish cause?Pedigrees and Evidence
- No; other genetic and environmental factors need evaluation.
- What does model compatibility mean?Pedigrees and Evidence
- The observations do not contradict the model under its assumptions.
- What does independent assortment rearrange?Sources of Genetic Variation
- Whole homologous chromosome combinations.
- What does crossing over rearrange?Sources of Genetic Variation
- Segments and linked allele combinations.
- What does 2^n count in a simple model?Sources of Genetic Variation
- Whole-chromosome combinations for n independently assorting pairs.
- Do these processes create new bases from nothing?Sources of Genetic Variation
- No, they rearrange existing genetic material.
- What creates a new allele sequence?Sources of Genetic Variation
- A DNA mutation.
- What is a germline-transmitted change?Sources of Genetic Variation
- A variant in a lineage that contributes to gametes and can be inherited.
- What do repair systems do?Sources of Genetic Variation
- Reduce, but do not eliminate, DNA errors.
- Are needed mutations produced on demand?Sources of Genetic Variation
- No; selection does not direct their appearance.
- What is allele frequency?Sources of Genetic Variation
- A specified allele’s fraction among sampled gene copies at a locus.
- What is genotype frequency?Sources of Genetic Variation
- The fraction of sampled individuals with a stated genotype.
- What is genetic drift?Sources of Genetic Variation
- Chance change in allele frequencies across generations.
- Can frequency change alone identify a unique cause?Sources of Genetic Variation
- No; multiple population processes can contribute.