Organization of the Human Genome
This organelle contains a small circular genome that is inherited only from your mother.
What is mitochondrial DNA?
Explanation: mtDNA is maternally inherited and is ~ 16,500 bp long.
SNP stands for this type of genetic variant.
What is a Single Nucleotide Polymorphism?
Explanation: An SNP is a difference of one nucleotide between DNA sequences.
A heterozygous individual expressing a dominant trait has this inheritance pattern.
What is autosomal dominant inheritance?
Explanation: One copy of the allele is enough to produce the phenotype.
This evolutionary force is the ultimate source of all new genetic variation.
What is mutation?
Explanation: New allele begins as a mutation.
Humans are approximately this genetically similar to one another at the DNA sequence level.
What is 99.9%?
Explanation: On average, only about 0.1% of DNA differs between two people.
These parts of a gene remain in mature mRNA after splicing.
What are exons?
Explanation: Exons are retained and translated into protein, while introns are removed.
An abnormal number of chromosomes, such as Trisomy 21, is known as this.
What is aneuploidy?
Explanation: Aneuploidy occurs when chromosomes are gained or lost during meiosis.
Color blindness is a classic example of this type of inheritance.
What is X-linked recessive inheritance?
Explanation: Because males have only one X chromosome, recessive alleles are expressed more often in males.
Random changes in allele frequencies due solely to chance are known as this.
What is genetic drift?
Explanation: Drift is strongest in small populations where random sampling effects are larger.
Modern humans originated on this continent before dispersing to the rest of the world.
What is Africa?
Explanation: Genetic diversity patterns strongly support an African origin of modern humans.
Before a protein is made, introns are removed from RNA through this process.
What is splicing?
Explanation: During RNA processing, introns are cut out and exons are joined together to form mature mRNA.
These short repeated DNA sequences mutate rapidly through replication slippage and are commonly used in forensic analysis.
What are STRs (Short Tandem Repeats)?
Explanation: STRs gain or lose repeat units frequently, creating highly variable genetic markers.
If two heterozygous carriers of an autosomal recessive trait have a child, the probability that the child expresses the trait is this.
What is 25%?
Explanation: A Punnett square predicts a 1 in 4 chance of inheriting two recessive alleles.
Movement of alleles between populations through interbreeding is called this.
What is gene flow?
Explanation: Gene flow makes populations genetically more similar over time.
Genetic diversity decreases with increasing geographic distance from Africa due largely to repeated occurrences of this process.
What is the serial founder effect?
Explanation: Each migration event carried only a subset of the genetic diversity from the previous population.
Although humans have about 3 billion base pairs, only about this percentage directly codes for proteins.
What is 1%?
Explanation: The vast majority of the human genome is non-coding DNA.
Two SNPs observed together more often than expected by chance are said to be in this condition.
What is linkage disequilibrium?
Explanation: Linkage disequilibrium occurs when alleles are non-randomly associated on chromosomes.
Human height is an example of this type of trait involving many genes and environmental influences.
What is a complex (polygenic) trait?
Explanation: Hundreds of genetic variants and environmental factors contribute to height.
A small group founding a new population and carrying only a subset of the original genetic variation illustrates this effect.
What is the founder effect?
Explanation: Founder effects are a special type of genetic bottleneck caused by migration of a small population.
The statistic FST measures this characteristic between populations.
What is genetic differentiation between populations?
Explanation: Higher FST values indicate larger allele frequency differences between populations.
A mutation introduces a premature stop codon into a gene, eventually resulting in a nonfunctional copy that is no longer expressed. This type of genomic element is called a ____.
What is a pseudogene?
Explanation: Pseudogenes are former genes that lost function through mutations such as stop codons or frameshifts.
This evolutionary process is primarily responsible for breaking down linkage equilibrium over time.
What is recombination?
Explanation: Recombination shuffles chromosome segments and separates linked alleles.
Researchers compare concordance rates between monozygotic and dizygotic twins to estimate this property of a trait.
What is heritability?
Explanation: Heritability measures how much variation in a trait is due to genetic differences.
Sickle-cell anemia persists in some populations because heterozygotes have higher fitness than either homozygote. This is an example of what type of selection?
What is balancing selection?
Explanation: Balancing selection maintains multiple alleles because heterozygotes have an advantage.
Despite visible differences such as skin color, approximately what percentage of total human genetic variation is found within populations rather than between populations?
What is 85%?
Explanation: Most human genetic diversity exists within populations, not between them.