Chapter 4: Mutation and Variation

Segregation

________ is the selection of one of the two copies of a locus when a gamete is made during meiosis.

Deletions

________ are when a segment of a chromosome is left out during replication.

Fusions

________ are structural changes in which two nonhomologous chromosomes are joined.

Tetraploidy

________ is when two unreduced gametes meet and fertilize each other, and the offspring is produced that has four copies of each chromosome.

Duplications

________ are a mutation in which a second copy of a gene is inserted into the genome.

Introns

________ are non- coding segments between the exons.

Single nucleotide polymorphism

________ is a specific DNA base in the genome that varies among individuals.

Chromosomes

__________ are long strings of DNA bases bound together with proteins.

Inversions

________ are structural mutations that occur when a chromosome breaks in two places and the middle segment is reinserted in the reverse orientation.

locus

A ________ is a basic unit of genetic inheritance.

Maternal effects

________ occur when the genotype or phenotype of the mother directly influences the phenotype of her offspring.

Horizontal gene transfer

________ is the movement of DNA between individuals without help from sexual reproduction.

Epistasis

________ is the situation in which the effect of an allele at one locus depends on the allele at a second locus.

Reciprocal translocation

________ is the exchange of chromosome segments between two nonhomologous chromosomes.

mRNA

________ is translated into a string of amino acids that make up a protein.

Genes

________ are segments of chromosomes that perform a function.

Genotypes

________ are gene characteristics.

Insertions

________ are when a segment of DNA is added to a chromosome, either from nearby on the same chromosome or elsewhere in the genome.

DNA

The genetic material of almost all organisms on Earth is _________

linkage disequilibrium

If some combination of alleles has a high fitness, selection will generate _________ between them.

Recombination

________ is the process that combines in a gamete a gene copy at one locus that was inherited from the mother with a gene copy at the second locus that was inherited from the father.

Alleles

_________ are one of several forms of the same gene, presumably differing by mutation of the DNA sequence.

Phenotypes

________ are observable characteristics.

deleterious

Because most mutations are ________, natural selection favors lower mutation rates, at least in organisms with sexual reproduction.

Gene families

________ are created when duplication is repeated several times.

Codons

________ represent the amino acids that make up the protein.

Hardy Weinberg equilibrium

________ tells us the relative proportions of genotypes in a population when segregation is the only factor that changes genotypes frequencies.

Transcription

________ is the process where the DNA is changed from a gene into pre- mRNA.

Exons

________ are segments of the gene that code for amino acids.

Fitness

________ is the number of offspring it leaves to the next generation.

Germ lines

________ produce gametes when the individual is sexually mature.

genetic code

The ________ is a set of rules that relates the codons to the amino acids they represent.

Cultural inheritance

________ is transmitted by behavior and learning.

100 million

The average chromosome in humans has more than ________ base pairs (bp)

Recombination rate

________ (r) is the probability that recombination occurs between a given pair of loci (genes)

Pleiotropy

________ occurs when a single mutation affects multiple traits.

Whole genome duplication

________ is when meiosis produces a gamete that carries the entire diploid genome, rather than a haploid with just one pair of chromosomes.

Structural mutations

________ affect more than one base pair; most happen as errors when chromosomes are replicated.

haplotypes

DNA sequence variants, which may differ at several or many sites, are usually called _________.

Transition mutations

________ happen between A and G, and C and T.

polymorphic

A locus is ________ if the DNA sequence at the given locus varies among the chromosomes carried by different individuals.

linkage equilibrium

Recombination moves the population toward a state where there is no statistical association between the alleles at the two loci, a situation called _________.

Gene families

________ are two or more loci with similar nucleotide sequences that have been derived from a common ancestral sequence.

Mutations

______ are errors in DNA sequences, made during replication, that account for genetic variation in all organisms.