Bio 97 Lectures Vocab Flashcards (QA Style)

QA-style flashcards drawn from the lecture notes, covering genetics, molecular biology, genome editing, cloning, bacterial genetics, and related ethics and terminology.

What is a complex trait?

A trait influenced by multiple genes and environmental factors; does not follow Mendelian inheritance (e.g., height).

What is a Mendelian trait?

A trait inherited according to simple Mendelian patterns, typically controlled by a single gene.

What is Broad-sense heritability (H2) and how is it calculated?

H2 = VG/VP; the proportion of phenotypic variance in a population due to genetic factors.

What does VP stand for and mean?

Phenotypic variance; the total observed variation in a trait within a population.

What does VG stand for and mean?

Genetic variance; the portion of VP attributable to genetic differences among individuals.

What does VE stand for and mean?

Environmental variance; the portion of VP attributable to environmental factors.

What does heritability mean in a population context?

Proportion of phenotypic variation in a population due to genetic variation, given the environment.

What are twin studies used for?

A research approach comparing identical (MZ) and fraternal (DZ) twins to estimate genetic contributions to traits.

What are monozygotic (MZ) twins?

Identical twins arising from a single fertilized egg; share nearly all genes.

What are dizygotic (DZ) twins?

Fraternal twins arising from two fertilized eggs; share about 50% of their genes.

What is regression toward the mean?

A statistical phenomenon where extreme observations tend to be followed by averages on subsequent measurements.

What is blending inheritance?

Outdated idea that offspring phenotypes are simply blends of parental traits; conflicts with genetic segregation.

What is polygenic inheritance?

A trait controlled by many genes, each contributing a small effect.

What is gene–environment interaction?

Genetic effects that depend on the environment; environment can modify gene expression.

What is genotype?

The genetic makeup of an individual, i.e., which alleles they carry.

What is phenotype?

The observable traits of an individual resulting from genetic and environmental factors.

What are allele frequencies p and q?

Proportions of the two alleles in a population; for two alleles, p + q = 1.

What is p in allele frequency?

Frequency of allele A in the population.

What is q in allele frequency?

Frequency of allele a in the population.

What is Hardy–Weinberg equilibrium?

Under random mating and no evolutionary forces, allele and genotype frequencies remain constant; genotype frequencies follow p^2, 2pq, q^2.

What is the p^2 frequency in Hardy–Weinberg terms?

Genotype frequency of AA under Hardy–Weinberg.

What is the 2pq frequency in Hardy–Weinberg terms?

Genotype frequency of Aa under Hardy–Weinberg.

What is the q^2 frequency in Hardy–Weinberg terms?

Genotype frequency of aa under Hardy–Weinberg.

What does random mating mean in Hardy–Weinberg context?

Assumption that mates are chosen independently of genotype; a key HW condition.

What is population stratification?

Population structure or subgroups causing departures from Hardy–Weinberg equilibrium.

What is inbreeding?

Mating among related individuals; increases homozygosity but does not change allele frequencies.

How is height used in HW discussions?

Height is an example of a complex trait used to illustrate polygenic and environmental influences.

What is heterozygote advantage?

Heterozygotes have higher fitness than either homozygote, balancing allele frequencies (not HW equilibrium).

What is genetic drift?

Random fluctuations in allele frequencies, stronger in small populations, reducing genetic diversity.

What is a genetic bottleneck?

Sharp reductions in population size that reduce genetic diversity and alter allele frequencies.

What is the founder effect?

A bottleneck where a new population is started by a small number of individuals.

What is gene flow (immigration) in population genetics?

Movement of individuals between populations that changes allele frequencies.

What are GWAS?

Genome-wide association studies; identify genetic variants associated with traits; explain only part of heritability and require large cohorts.

What are concerns with genetic databases and privacy?

Expansion of genotype databases raises consent, privacy, and potential misuse concerns.

What is GINA?

Genetic Information Nondiscrimination Act; US law prohibiting use of genetic information for health insurance decisions (not all insurances).

What are ethics considerations in genetic testing?

Consent, privacy, potential discrimination, and impact on relatives.

What is sickle cell trait's selective advantage?

Sickle-cell trait provides protection against malaria in heterozygotes (heterozygote advantage).

What is sickle cell disease genetics?

Recessive disorder (homozygous HbS); heterozygotes gain some malaria protection but have health issues.

What is frequency-dependent selection?

Fitness of an allele depends on its frequency in the population; can maintain diversity.

What is positive frequency-dependent selection?

Fitness increases as the allele becomes more common (e.g., warning coloration).

What does high heritability with rapid environmental changes imply?

Environmental factors can still substantially influence phenotypes despite high heritability.

What is the population genetics objective?

Determine Hardy–Weinberg equilibrium, compute allele frequencies, and predict changes under selection or other forces.

What is a nucleotide?

The basic building block of DNA (and RNA) consisting of a sugar, phosphate, and nitrogenous base.

What is DNA?

Deoxyribonucleic acid; the molecule that stores genetic information, usually a double helix.

What is DNA vs RNA difference?

DNA uses deoxyribose and thymine; RNA uses ribose and uracil; DNA is usually double-stranded, RNA usually single-stranded.

What is a phosphodiester bond?

Chemical linkage joining nucleotides in a DNA/RNA backbone between 5' phosphate and 3' hydroxyl.

What does antiparallel mean in DNA?

Two DNA strands run in opposite 5'→3' directions, enabling base pairing.

What are base pairs in DNA?

A pairs with T (two H-bonds); G pairs with C (three H-bonds).

What is 5' to 3' polymerization?

DNA/RNA synthesis proceeds by adding nucleotides to the 3' end; templates read 3'→5'.

What is a replication fork?

Y-shaped region where the double helix is unwound and replication occurs.

What is a replication bubble?

Unwound DNA region containing two replication forks that proceed bidirectionally.

What is helicase?

Enzyme that unwinds the DNA double helix to create the replication fork.

What is primase?

RNA polymerase that lays down RNA primers to initiate DNA synthesis.

What is DNA polymerase?

Enzyme that adds dNTPs to the growing DNA strand; works 5'→3' and has proofreading exonuclease activity.

What is proofreading exonuclease activity?

3'→5' enzymatic activity that corrects misincorporated nucleotides during replication.

What are Okazaki fragments?

Short DNA fragments synthesized on the lagging strand during replication.

What does DNA ligase do?

Seals nicks between Okazaki fragments to form a continuous strand.

What are telomeres?

Repeater DNA sequences at chromosome ends that protect genes during replication.

What is telomerase?

Reverse transcriptase that extends telomeres using an RNA template.

What is Sanger sequencing?

Chain-termination sequencing method using ddNTPs to produce fragments read by size/fluorescence.

What is ddNTP?

Dideoxynucleotide; a base analog lacking 3' OH that terminates DNA synthesis.

What is Illumina sequencing?

High-throughput sequencing by synthesis using reversible terminator nucleotides for massively parallel short reads.

What is sequencing by synthesis (general)?

DNA is copied one base at a time with detection after each incorporation.

What is a nucleosome core particle?

~146 bp of DNA wrapped around a histone octamer (H2A, H2B, H3, H4).

What is a histone octamer?

Core protein complex (two each of H2A, H2B, H3, H4) around which DNA is wrapped.

What is histone H1?

Non-core histone that helps stabilize higher-order chromatin structure.

What are histone modifications?

Chemical changes to histone tails (e.g., acetylation, methylation) that regulate chromatin and gene expression.

What is histone acetylation?

Addition of acetyl groups to lysines; generally promotes open chromatin and transcription.

What is histone methylation?

Addition of methyl groups to histone tails; can repress or activate transcription depending on context.

What is CpG methylation?

Methylation of cytosine in CpG dinucleotides; often associated with gene silencing.

What is euchromatin?

Relatively open chromatin associated with active transcription.

What is heterochromatin?

Tightly packed chromatin associated with gene silencing; includes facultative and constitutive forms.

What is a Barr body?

Inactivated X chromosome in female somatic cells; contributes to dosage compensation and mosaicism.

What is mosaicism?

Presence of two or more genetically distinct cell populations within an individual.

What is a replication origin?

Specific chromosomal location where DNA replication initiates.

What did the Meselson–Stahl experiment demonstrate?

DNA replication is semi-conservative; each new DNA molecule has one old and one new strand.

What is semi-conservative replication?

A replication model where each daughter DNA molecule contains one parental strand and one newly synthesized strand.

What is mitosis?

Cell division producing two genetically identical diploid daughter cells for growth and maintenance.

What is meiosis?

Cell division producing four genetically diverse haploid gametes; introduces genetic variation.

What is synapsis?

Pairing of homologous chromosomes during prophase I of meiosis to form bivalents.

What is the synaptonemal complex?

Protein structure that holds homologous chromosomes together during meiosis I.

What are chiasmata?

Points where crossing over occurs between homologous chromosomes during meiosis.

What is disjunction?

Separation of chromosomes or sister chromatids during anaphase of mitosis or meiosis.

What is nondisjunction?

Failure of homologous chromosomes or sister chromatids to separate, leading to aneuploidy.

What are monosomy and trisomy?

Monosomy: one copy of a chromosome; Trisomy: three copies of a chromosome.

What is Turner syndrome?

Sex chromosome aneuploidy 45,X; female, short stature, often sterile.

What is Klinefelter syndrome?

Sex chromosome aneuploidy 47,XXY; male, typically tall and sterile.

What is Down syndrome?

Autosomal trisomy 21; characteristic features and increased risk of health issues.

What is reciprocal translocation?

Exchange of segments between nonhomologous chromosomes; can affect gene regulation and meiosis.

What is inversion in meiosis?

Chromosome segment is reversed end to end; can affect gene order and recombination.

What is deletion?

Loss of a chromosome segment; can have severe phenotypic consequences.

What is duplication?

Gain of a chromosome segment; can provide material for evolution.

What is karyotype?

A visual display of an individual's chromosomes, typically arranged by size and banding.

What do p and q arms refer to?

p is the short arm and q is the long arm of a chromosome.

What is euploid?

Chromosome number that is an exact multiple of the haploid set.

What is aneuploid?

Chromosome number that is not a multiple of the haploid set.

What is diploid?

Two complete sets of chromosomes (2n) typical of somatic human cells.

What is haploid?

One complete set of chromosomes (n); typical of gametes.

What is a chromosome?

A DNA-containing structure with a centromere, packaged with proteins for organization and segregation.

What is a chromatid?

One of the two identical DNA molecules formed after DNA replication; held at the centromere.