Genetics and Genomics Practice Flashcards

Vocabulary list including terminology from chapters 11, 12, 13, 16, 20, 21, and 22, covering topics from gene expression and mutation to population genetics and biotechnology.

Transcriptome

All RNA molecules being produced in a cell at a specific time.

Single-cell transcriptomics

Measures RNA in individual cells to reveal different cell types and gene-expression patterns.

Gene expression

Using information in DNA to make a functional RNA or protein product.

Proteome

All proteins produced by a cell, tissue, or organism at a given time.

Promoter

DNA region where RNA polymerase and transcription factors assemble to begin transcription.

Transcription factor

Protein that binds DNA and increases or decreases transcription of target genes.

Enhancer

DNA sequence that can increase transcription when activator proteins bind to it.

Epigenetic change

A heritable change in gene activity that does not alter the DNA base sequence.

Chromatin remodeling

Changing how tightly DNA is packaged so genes become more or less accessible.

Histone acetylation

Usually loosens chromatin and increases gene expression.

Histone deacetylation

Usually tightens chromatin and decreases gene expression.

DNA methylation

Addition of methyl groups to DNA; often silences transcription.

microRNA (miRNA)

Small noncoding RNA that binds an mRNA and blocks translation or promotes mRNA breakdown.

Microprotein

Very small protein that can regulate larger proteins or cellular pathways.

Exon

Gene segment retained in mature mRNA and usually translated.

Intron

Gene segment removed from pre-mRNA during RNA splicing.

Alternative splicing

Different combinations of exons are joined to make multiple proteins from one gene.

Noncoding RNA

RNA that is not translated into protein but can have regulatory or structural roles.

Repeated DNA sequences

DNA sequences present in many copies; they make up a large portion of the genome.

Viral DNA in the human genome

DNA left from ancient viral infections that became integrated into chromosomes.

Globin gene switching

Different hemoglobin genes turn on and off during development, changing the type of hemoglobin produced.

Mutation

A change in a DNA sequence.

Wild type

The common or reference version of a gene or trait.

Deleterious mutation

A harmful mutation that reduces, alters, or misdirects a gene product.

Loss-of-function mutation

Reduces or eliminates the activity of a gene product; often recessive.

Gain-of-function mutation

Creates increased, new, or harmful gene activity; often dominant.

Polymorphism

A DNA variant common enough to be found in at least about $1\%$ of a population.

Germline mutation

Mutation in a sperm, egg, or precursor cell that can be passed to offspring.

Somatic mutation

Mutation in a body cell that is passed to daughter cells but not usually to offspring.

Mosaicism

Presence of two or more genetically different cell populations in one person.

Gonadal mosaicism

A mutation is present in some egg- or sperm-producing cells but may not appear in a blood test.

Mutagen

An agent, such as radiation or a chemical, that increases the mutation rate.

Point mutation

A change involving a single DNA base.

Transition vs. transversion

Transition swaps purine-purine or pyrimidine-pyrimidine; transversion swaps purine-pyrimidine.

Missense mutation

A base substitution that changes one amino acid in a protein.

Nonsense mutation

A base substitution that creates a premature stop codon.

Nonsense-mediated decay

Cellular process that destroys mRNA containing a premature stop codon.

Splice-site mutation

Mutation that disrupts normal removal of introns or joining of exons.

Frameshift mutation

Insertion or deletion not in multiples of three that changes the reading frame.

Insertion vs. deletion

Insertion adds DNA bases; deletion removes DNA bases. Either can cause a frameshift if not in multiples of three.

Tandem duplication

A duplicated DNA segment positioned directly next to the original segment.

Pseudogene

DNA sequence similar to a functional gene but usually unable to make a functional protein.

Transposon

Mobile DNA sequence that can move and disrupt gene function or regulation.

Expanding repeat mutation

A repeated DNA sequence grows longer across generations and may damage cell function.

Copy-number variant (CNV)

DNA segment that varies in number of copies among individuals.

Short tandem repeat (STR)

Short repeated DNA sequence that varies among people and is useful in forensics.

Silent mutation

A base change that does not alter the encoded amino acid.

Conditional mutation

A mutation that affects the phenotype only under certain environmental conditions.

Three major DNA repair systems

Base excision repair, nucleotide excision repair, and mismatch repair.

Nucleotide excision repair

Removes a damaged stretch of DNA, such as UV-related pyrimidine dimers, and replaces it.

Base excision repair

Removes and replaces a small number of damaged bases, often after oxidative damage.

Mismatch repair

Corrects incorrectly paired bases or small loops left after DNA replication.

p53

Protein that can pause the cell cycle, promote DNA repair, or trigger apoptosis after severe damage.

Structural variant

A large DNA change involving deletion, duplication, inversion, or movement of a chromosome segment.

Cytogenetics

Study of chromosome structure, number, and abnormalities.

Heterochromatin vs. euchromatin

Heterochromatin is tightly packed and often less active; euchromatin is more open and often actively transcribed.

Telomere

Protective repeated DNA at a chromosome end.

Centromere

Constricted chromosome region where spindle attachment is organized during cell division.

Kinetochore

Protein structure assembled at the centromere that binds spindle fibers.

p arm and q arm

The p arm is the short chromosome arm; the q arm is the long arm.

Chromosome types by centromere position

Metacentric: near middle. Submetacentric: off-center. Acrocentric: near one end with a very short p arm.

Karyotype

Organized display of chromosomes used to detect large changes in number or structure.

FISH

Fluorescent probes bind specific DNA sequences to locate or count chromosome regions.

Euploid

Having the expected complete set of chromosomes.

Polyploidy

Having one or more extra complete sets of chromosomes.

Aneuploidy

Having an extra or missing individual chromosome.

Nondisjunction

Failure of chromosomes or chromatids to separate normally during cell division.

Trisomy

Presence of one extra copy of a chromosome.

Monosomy

Missing one copy of a chromosome.

Comparative genomic hybridization (CGH)

Compares DNA copy number to detect small deletions or duplications.

Robertsonian translocation

Fusion of long arms from two acrocentric chromosomes; short arms are usually lost.

Reciprocal translocation

Exchange of chromosome segments between two nonhomologous chromosomes.

Paracentric vs. pericentric inversion

Paracentric excludes the centromere; pericentric includes the centromere.

Isochromosome

Abnormal chromosome with two identical arms.

Ring chromosome

Chromosome whose ends fuse into a ring, often after terminal DNA is lost.

Uniparental disomy (UPD)

Both copies of a chromosome or chromosome region come from one parent.

Population genetics

Study of allele and genotype frequencies in populations and how they change.

Haplotype

Group of nearby DNA variants inherited together on the same chromosome.

Identical by descent

DNA segments inherited from the same ancestor.

Run of homozygosity

Long chromosome region where both copies carry the same variants, often reflecting shared ancestry.

Population substructure

Genetic differences among subgroups within a larger population.

Nonrandom mating

Some individuals are more likely than others to reproduce together.

Endogamy

Mating or marriage within a defined community.

Gene flow

Movement of alleles between populations through migration and reproduction.

Admixture

Mixing of genetic variants when members of different populations reproduce.

Cline

Gradual change in allele frequency across a geographic area.

Genetic drift

Random change in allele frequency, especially strong in small populations.

Founder effect

A new population begins with a small group whose allele frequencies differ from the original population.

Population bottleneck

A population shrinks sharply, reducing genetic diversity.

Natural selection

Traits affecting reproductive success change allele frequencies over generations.

Positive vs. negative selection

Positive selection increases advantageous alleles; negative selection removes harmful alleles.

Genetic load

Collection of deleterious recessive alleles present in a population.

Artificial selection

Human-controlled breeding for desired traits.

Balanced polymorphism

A disease allele remains in a population because heterozygotes have an advantage.

Eugenics

Attempts to control human reproduction to alter population genetics; historically unethical and harmful.

Cancer

Disease caused by genetic and epigenetic changes that disrupt normal control of cell growth.

Benign vs. malignant tumor

Benign tumors stay localized; malignant tumors invade nearby tissue and may spread.

Metastasis

Spread of cancer cells from the original site to distant parts of the body.

Carcinogen

Environmental agent that increases cancer risk by damaging cells or DNA.

Oncogene

Overactive or inappropriately expressed gene that promotes cancer; usually gain-of-function.