Kapitel 9 Flashcards
Family of mobile genetic elements that comprises about 10% of the human genome; this short - repetitive sequence is no longer mobile on its own - but requires enzymes encoded by other elements to transpose.
Alu sequence
The preservation of gene order and location in the genomes of different species.
conserved synteny
Large segment of DNA - 1000 nucleotide pairs or greater - that has been duplicated or lost in an individual genome (compared to the “reference” genome sequence).
copy-number variation (CNV)
Differences in sequence that accumulate over time in DNA segments derived from a common ancestral sequence.
divergence
Mechanism for the evolution of new genes; in the process - coding sequences from different genes are brought together to generate a protein with a novel combination of domains.
exon shuffling
A process by which new genes can form; involves the accidental generation of an additional copy of a stretch of DNA containing one or more genes - followed by an accumulation of mutations that over time can alter the function of either the original or its copy.
gene duplication and divergence
A set of related genes that has arisen through a process of gene duplication and divergence.
gene family
Cell type in a diploid organism that carries only one set of chromosomes and is specialized for sexual reproduction. A sperm or an egg; also called gamete.
germ cell
The lineage of reproductive cells that contributes to the formation of a new generation of organisms - as distinct from somatic cells - which form the body and leave no descendants in the next generation.
germ line
see homologous.
homologous gene
Process by which DNA is passed from the genome of one organism to that of another - even to an individual from another species. This contrasts with “vertical” gene transfer - which refers to the transfer of genetic information from parent to progeny.
horizontal gene transfer
Type of retrotransposon that constitutes 15% of the human genome; also called LINE-1.
L1 element
Short segment of DNA that can move - sometimes through an RNA intermediate - from one location in a genome to another; an important source of genetic variation in most genomes. Also called a transposon.
mobile genetic element
Long sequence of nucleotides that contains no stop codon; used to identify potential protein-coding sequences in DNA.
open reading frame (ORF)
Diagram or “family tree” showing the evolutionary history of a group of organisms or proteins.
phylogenetic tree
Change in a single nucleotide pair in a DNA sequence.
point mutation
Preservation of a specific nucleotide sequence driven by the elimination of individuals carrying mutations that interfere with its functions.
purifying selection
Type of mobile genetic element that moves by being first transcribed into an RNA copy that is reconverted to DNA by reverse transcriptase and inserted elsewhere in the chromosomes.
retrotransposon
RNA-containing virus that replicates in a cell by first making a double-stranded DNA intermediate that becomes integrated into the cell’s chromosome.
retrovirus
Enzyme that makes a double-stranded DNA copy from a single-stranded RNA template molecule. Present in retroviruses and as part of the transposition machinery of retrotransposons.
reverse transcriptase
Form of genetic variation in which one portion of the population differs from another in terms of which nucleotide is found at a particular position in the genome.
single-nucleotide polymorphism (SNP)
Any cell that forms part of the body of a plant or animal that is not a germ cell or germ-line precursor.
somatic cell
General name for short segments of DNA that can move from one location to another in the genome. Also known as mobile genetic elements.
transposon
Particle consisting of nucleic acid (RNA or DNA) enclosed in a protein coat and capable of replicating within a host cell and spreading from cell to cell. Often the cause of disease.
virus
Technique by which a mutation can be made at a particular site in DNA.
site-directed mutagenesis
