Heredity Test 4 Flashcards
What is a population?
an interbreeding group of the same species in a given geographical area
Gene Pool
collection of all alleles in a population
population genetics
the study of the genetics of a population and how alleles vary over time
gene flow
the movement of alleles between populations due to migration and mating.
Microevolution
refers to small genetic changes that alter allele frequencies within a population’s gene pool, occurring over short periods of time
macroevolution
speciation over longs periods of time, where accumulated microevolutionary changes result in populations that can no longer produce fertile offspring with each other, leading to new species
Hardy-Weinberg Equilibrium
- uses equations to calculate allele and genotype frequencies in a population
5 factors that can violate the Hardy-Weinberg Equilibrium
1.) Non-random mating
2.) Mutations
3.) Natural selection
4.) Genetic drift (especially in small populations)
5.) Gene Flow (immigration/emigration)
HW and DNA Profiling
- helps calculate the likelihood of specific genetic profiles appearing in a population
- provides a baseline for comparing observed frequencies to those expected under equilibrium
- aiding in forensic and population studies
STRs in DNA profiling
- short tandem repeats
- highly variable making them more effective for distinguishing between profiles
FBI CODIS Database and Probabilities
- CODIS uses STR profiles to match DNA samples
- probability matches are calculated using Hardy-Weinberg principles
- comparing observed STR allele frequencies with population-specific days to estimate the likelihood of a match
Membership in the same population and relatedness
-determine if individuals are a part of the same population
-analyze their genome sequences or allele frequencies
-related individuals often share regions of similarity called “identical by decent”
Runs of Homozygosity (ROH)
long stretches of homozygous DNA observed in offspring related individuals or populations with high levels of interbreeding. These stretches indicate reduced genetic diversity
Hardy-Weinberg disruption: Non-random mating
preference for certain traits or interbreeding increases homozygosity and disrupts equilibrium
Hardy-Weinberg disruption: Mutation
introduces new alleles, altering allele frequencies over time
Hardy-Weinberg disruption: Gene flow
migration introduces new alleles or changes their distribution across populations
Hardy-Weinberg disruption: Genetic drift
random changes, especially in small population, can lead to significant shifts in allele frequencies
Founder Effect
a small group establishes a new population, resulting in a limited gene pool
Population Bottleneck
A drastic reduction in population size reduces genetic variation
Hardy-Weinberg disruption: Natural selection
differential survival and reproduction based on phenotype can lead to an increase or decrease in certain alleles
Eugenics
- meaning “good in birth”, aimed to promote “desirable traits” while reducing “undesirable” ones
- historically led to forced sterilizations, genocidal events linked to perceived genetic “purity” ideals
- modern implications include ethical concerns in genetics
Sanger Sequencing
- developed in the 1970s
- used the basic principles of DNA replication but introduces modified nucleotides called dideoxynuucleotide triphosphates (ddTP)
- ddTTP lack the 3’ hydroxyl group, causing DNA replication to terminate whenever they are incorporated
-The resulting fragments of varying lengths are then analyzed to determine the DNA sequences
Map based (public) sequencing projects
- conducted by the international human genome sequencing project
- involves creating a detailed molecular marker map
- fragments of DNA are mapped to specific chromosomes to establish order before sequencing
Shotgun (private) sequencing projects
- conducted by Celera Genomics
- Fragments of the entire genome were sequenced randomly and then assembled using computation methods
- faster, less expensive – as it relied on robotics, supercomputers, and public data
Insights of the Human Genome Projects
- the human genome contains ~20,000 genes, fewer than expected
- only ~1.5% of the genome codes for proteins; the rest includes non-coding RNA, viral DNA, and repetitive sequences
- many non-coding sequences perform regulatory or other essential functions
Current human genome sequencing projects
current projects aim to:
- sequence genomes from diverse populations to improve health outcomes globally
- develop databases of genetic variants for personalized medicine and disease research
Next-Generation sequencing (NGS) and its advantages
- high throughput sequencing is faster and cheaper than Sanger sequencing
- Sanger sequencing ~$500 per megabase
- NGS can produce~$0.50 per megabase
- NGS process more data in a single run - sequencing the entire genome in under $1,000
Whole genome sequencing
- captures the entire genome, including non-coding region
Exome sequencing
- focuses on the ~%1.5 of the genome that codes for proteins
- makes it less expensive
- may potentially miss regulatory regions and non-coding variations
Impact of personalized medicine
- improve diagnostic precision
- tailor treatments to an individual’s genetic makeup, such as using pharmacogenomic for drug response predictions
- enhance preventative care by identifying genetic risks for disease
Ethical, legal, and social implications (ELSI) of personalized genome sequencing
- privacy: concerns about genetic data being misused or accessed without consent
- discrimination: risks of genetic information being used to discriminate in employment or insurance decisions, despite protections like the Genetic Information Nondiscrimination Act (GINA 2008)
- Interpretation accuracy: the risk of providing genetic results to individuals without ensuring they can be interpreted responsibly
- access inequalities: potential disparities in who can afford or access genomic technologies
Beery Twins
- fraternal twins initially misdiagnosed with CP but later identified with dopa-responsive dystonia (DRD)
- genome sequencing helped pinpoint the genetic mutations responsible for DRD
- leaded to appropriate treatment and improved health outcomes
Jill Viles
- Diagnosed with a rare genetic disorder (lipodystrophy) using genomic data
- her case highlights the power of genome sequencing to solve medical mysteries and guide tailored treatments
Privacy and Healthcare protections related to genome sequencing
- genetic information nondiscrimination act (GINA)
- prohibits health insurance companies from using genetic information to determine coverage or premiums
- prevents employers from using genetic data in hiring or employment decisions
- Limitation: does not cover life, disability, or long-term care insurance
- patient protection and Affordable Care Act
- prevents exclusion of coverage for pre-existing conditions
- regulates premium adjustments based on non-genetic factors like age or tobacco use
Genetics and Brain Development
- genetics significantly influence brain and neuron development
- guides processes such as synaptic formation, pruning, and plasticity
- variations in genetic expression or mutations can lead to differences in neurodevelopment, impacting behaviors and cognitive functions
Disorder
- refers to the condition where the body or behavior functions abnormally
- symptoms may vary qualitatively and are often harder to quantify (ex. depression)
- used in genetics and behavior to reflect the complex, multifactorial nature of many conditions
Disease
- typically implies a diagnosable condition caused by a specific pathogen or physiological malfunction
Necessity of sleep
- sleep is critical for brain plasticity, memory processing metabolic repair, and immune regulation
Circadian Rhythm
- regulated by the suprachiasmatic nucleus (SCN) and pineal gland
- controls sleep and wake cycles
Effects of sleep disorders
Disorders that affect sleep quality or quantity can disrupt health, cognition and mood
Narcolepsy
- condition marked by excessive daytime sleepiness, sleep paralysis, and in rare cases, cataplexy
- linked to a reduction in orexin-producing neurons, possibly due to autoimmune mechanisms
- genetic associations include variations in the HLA gene
Sleep Phase Disorders
- involve shifts in circadian rhythms, leading to sleep patterns misaligned with societal norms, such as advanced or delayed sleep patterns (waking up earlier than “normal” or later)
Depression
- Symptoms: persistent sadness, loss of interest, fatigue, and impaired concentration
- Types: Major Depressive Disorder (most common), Persistent Depressive Disorder, PMDD, SAD, etc.
- Treatments: SSRI (Selective Serotonin Reuptake Inhibitors) - increase serotonin availability, improving mood regulation
Bipolar Disorder
- Symptoms: alternating manic and depressive episodes
- Genetics: highly heritable but complex, involving interactions of hundred of genes
Addiction
- Mechanisms: Drugs mimic endogenous chemicals, binding to receptors and altering neurotransmitter release, such as dopamine. Prolonged use desensitizes receptors, causing withdrawal symptoms upon cessation
- genetic contribution: heritability estimates vary (~50% for nicotine addiction). Specific variants, such as SNP rs16969968 in the CHRNA5 gene, are linked to increased susceptibility
