Exam 5: Variation Among Individuals

Genes can be duplicated when a processed messenger RNA,from which introns have been spliced out,is reverse-transcribed to form a double-stranded DNA segment that is reintegrated into the main chromosome.What is the name for this process that may form nonfunctional pseudogenes?

What DNA modifications characterize epigenetic marks?

An organism that develops different phenotypes in different environments is said to exhibit what trait?

In experiments with Caenorhabditis elegans,deleterious mutations accumulate at a slow but steady rate when the populations are grown in as benign an environment as possible,with optimal temperature and humidity,minimal crowding of individuals,abundant food,and no predators or parasites.From what important evolutionary force do these conditions insulate C.elegans?

Genes that are duplicated within a genome and later diverge in function,such as the RNASE1 and RNASE1B genes in douc langur monkeys,are described as ________.

Organisms that exhibit different phenotypes in different environments are said to exhibit phenotypic plasticity.Using the tobacco hornworm,Manduca sexta,studied by Suzuki and Nijhout,describe the experiments done to illustrate the dependence of color on temperature.Be sure to explain the importance of using reaction norms in this type of study.

Daphnia pulex grows protective armor upon sensing chemicals produced by the predatory phantom midge by the process of ________.

What is the term given to the average frequency of heterozygotes at all loci of an individual? This value can also be expressed as the fraction of genes that are heterozygous in the genotype of an average individual.

Frequencies of inversions and/or allele frequencies often vary regularly when examined over a geographic area changing in either latitude or climate.This type of regular change is called a ________.

In the mutation accumulation experiments of Dee Denvers and colleagues (2004)with Caenorhabditis elegans,deleterious mutations were observed to accumulate at a slow but steady rate when the populations were grown in a benign environment,with optimal temperature and humidity,minimal crowding of individuals,abundant food,and no predators or parasites.Control lines grown under normal conditions did not accumulate mutations at the same rate.After 240 generations,experimental lines that had accumulated substantial mutations were removed from the benign environment and these lines were propagated.Explain the results once the recovery lines were established,and how this experiment demonstrates the significance of natural selection in the evolutionary process.

Many studies on genetic variation in humans have been done with the perception of taste.The chemical phenylthiocarbamide (PTC)has been used extensively in these studies.Although many individuals cannot taste PTC,many individuals find the taste of PTC to be ________.

The haploid human genome contains approximately 3.2 billion base pairs.How many mutations,on average,does each individual inherit from each of the gametes that united to form the zygotes from which he or she grew?

The genetic code,which specifies the three-letter codons that specify particular amino acids,is said to be redundant because ________.

According to the studies of Eyre-Walker and Keightley (2007),there appear to be four types of mutations observed in most organisms.Which of the following is NOT a type of mutation that is observed?

Organisms with more than two chromosome sets are said to be ________.

In DNA,the substitution of a purine for a purine or a pyrimidine for a pyrimidine is called a(n)________.

What does one call a mutation that occurs in a DNA sequence that changes the amino acid specified by that sequence?

What is the term used to describe the smallest possible mutation in a DNA strand,which involves only one base?

What does one call a mutation that occurs in a DNA sequence,but leaves the resulting amino acid sequence unchanged?

Unequal crossing over often results in the formation of duplicate copies of existing genes.At what phase of meiosis can unequal crossing over occur,and why does this happen?