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Ch. 1: The Molecular Basis of Hereditary, Variation, and Evolution

Terms in this set (46)

Genetics affects many aspects of our lives. Identify three ways genetics affects your life or the life of a family member or friend. The effects can be regularly encountered or can be one time only or occasional.
1. Some of your food is available thanks to the advances in selection and genetic engineering.

2. Embryonic stem cell research has been a topic discussed by political candidates.

3. Your physical appearance and health are partially due to the genetic material provided by your parents.
How do you think the determination that DNA is the hereditary material affected the direction of biological research?
DNA structure provided profound insight into the mechanism of heredity, suggesting a simple, elegant mechanism for duplication (inheritance), change (mutation and evolution), and phenotype specification (coding).

The finding that DNA is universal facilitated rapid progress because study results from all organisms were now directly related.

This also fostered the development of recombinant DNA technologies in bacteria and bacteriophage, which led to the explosion of biological information that excites and confounds us today.
A commentator once described genetics as "the queen of the biological sciences." The statement was meant to imply that genetics is of overarching importance in the biological sciences. Do you agree with this statement? In what ways do you think the statement is accurate?
Genetics provides the principles and mechanisms for evolution and evolution is the foundation of our understanding of biology. Genetics and evolution are the fundamentals of biology
All life shares DNA as the hereditary material. From an evolutionary perspective, why do you think this is the case?
*Evolution states that all life descended from a common ancestor, which passed its genes and the mechanisms by which those genes were used to its descendants.

These mechanisms would include the structure of nucleotides, the structure of DNA, the enzymes that replicate and read DNA, the enzymes that translate mRNA into amino acid sequences, and many more. Any change to one of these components would be harmful, slowing or preventing reproduction, and would be removed by natural selection. Thus, once established as the genetic material, DNA would be maintained as the genetic material by natural selection and therefore would be expected to be found as the genetic material in all existing organism
Define the terms allele, chromosome, and gene and explain how they relate to one another. Develop an analogy between these terms and the process of using a street map to locate a new apartment to live in next year (i.e., consider which term is analogous to a street, which to a type of building, and which to an apartment floor plan).
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Define the terms genotype and phenotype, and relate them to one another.
Genotype refers to the genetic makeup of a cell or organism.

Phenotype refers to observable characteristics of the cell or organism, such as appearance, physiology, and behavior.

The genotype of an organism is part of what determines the phenotype of the organism; however, environment also plays a role in the organism's phenotype.

The genotype is heritable, and, therefore, its contribution to phenotype will be inherited. The aspects of phenotype that are due to environment are not heritable.
Define natural selection, and describe how natural selection operates as a mechanism of evolutionary change.
Natural selection is differential reproduction among individuals in a population due to differences in heritable phenotypes which are said to be adaptive. Individuals with the adaptive phenotype have a reproductive advantage; therefore they contribute a disproportionately high number of progeny to the next generation.
Describe the modern synthesis of evolution, and explain how it connects Darwinian evolution to molecular evolution.
The modern synthesis of evolution is the reconciliation of Darwin's evolutionary theory with the findings of modern genetics.

Darwin's theory proposed that all evolution was adaptive. Genetic studies on mutation and genetic recombination initially argued against the importance of natural selection as an agent for change because mutation and recombination were nonadaptive.

The modern synthesis stated that evolution is due to the combined action of adaptive and nonadaptive evolutionary forces. In particular, the modern synthesis explained how mutation and recombination could provide the raw material (new genotypes and phenotypes) on which natural selection acts
What are the four processes of evolution?
Natural Selection, Migration, Mutation, Genetic Drift
Natural Selection
the differential survival and reproduction of members of a population owing to possession of favored traits. Population members with the best-adapted morphological form are best able to survive and reproduce, and they leave more offspring than those possessing less-adaptive forms. Over time, the frequency of the best-adapted form and the alleles that produce it increase in the population.
Migration
the movement of individual organisms from one population to another. This migratory movement transfers alleles from one population to another, and if the allele frequencies between the populations are different and if the number of migrating individuals is large enough, migration can rapidly alter allele frequencies.
Mutation
the slow acquisition of inherited variation that increases the diversity of populations and serves as the "raw material" of evolutionary change. Mutation, occurring in many different ways in genomes, provides the genetic diversity that is essential for evolution.
Genetic Drift
the random change of allele frequencies due to chance in randomly mating populations. Genetic drift occurs in all populations, but it is most pronounced in very small populations, where statistically significant fluctuations in allele frequencies can occur from one generation to the next.
Transcription
Is the synthesis of RNA by RNA polymerase. The RNA is complementary to the strand of DNA that was used as the template for transcription.
Allele
Is a specific form of a gene or genetic locus.
Central Dogma of Biology
Originally stated that genetic information flows from DNA to RNA (by transcription) and from RNA to protein (by translation). A point of emphasis of this dogma was that information does not flow in the reverse direction and has been modified to account for reverse transcription
Translation
is the synthesis of a polypeptide using the information in an mRNA. Translation and protein synthesis are synonyms
DNA Replication
Is the process by which DNA is copied by DNA polymerase.
Gene
Is a segment of DNA that contains all the information necessary for its proper transcription, including the promoter, transcribed region, and termination signals
Chromosomes
Is a heritable molecule composed of DNA and protein that typically contains genes
Antiparallel
refers to the orientation of the two strands of
nucleic acid in a double-stranded nucleic acid (RNA or DNA). Each end of the double-stranded nucleic acid will contain the 5′ end of one strand and the 3′ end of the other.
Phenotype
refers to the observable characteristics of an organism, which include morphology, physiology, and molecular composition. The phenotype of an organism is a product of the interaction between its genotype and its environment.
Complementary Base Pair
refers to the two nucleotides on opposite, antiparallel strands of a double-stranded nucleic acid, which are hydrogen bonded to each other. One nucleotide contains a purine base that makes hydrogen bond to the pyrimidine base that is part of the other nucleotide.
Nucleic Acid Strand Polarity
refers to the orientation of the nucleotides along a single strand of nucleic acid. One end of the strand terminates at the 3′ hydroxyl group of a ribose (or deoxyribose) sugar, whereas the other strand terminates at the 5′ phosphate group on the sugar. These are commonly referred to as the 3′ and 5′ ends of the strand
Genotype
refers to the genetic makeup of an organism. The genotype can refer either to the organism's entire genetic makeup or to the genetic information at only one or a few loci.
Natural Selection (2)
is the process by which populations and species
evolve and diverge through differential rates of survival and reproduction of members that are due to their inherited differences
Mutation (2)
is the process that generates new genetic variety through change to existing alleles.
Modern Synthesis of Evolution
is the term applied to the reconciliation of modern genetic analysis with Darwin's theory of evolution by natural selection.
Compare and contrast the genome, the proteome, and the transcriptome of an organism.
a genome is the genetic material of an organism. It consists of DNA. The genome includes both the genes and the noncoding DNA, as well as mitochondrial DNA and chloroplast DNA

Proteome is the the complete set of proteins encoded in a genome

Transcriptome is the complete set of genes that undergo transcription in a given cell
With respect to transcription describe the relationship and sequence correspondence of the RNA transcript and the DNA template strand. Describe the relationship and sequence correspondence of the mRNA transcript to the DNA coding strand
The template DNA strand is complementary and antiparallel to the RNA transcript. The coding DNA strand is parallel and identical to the mRNA transcript, except that thymidine is located in the DNA strand where uridine is located in RNA.
If thymine makes up 21% of the DNA nucleotides in the genome of a plant species, what are the percentages of the other nucleotides in the genome?
21% of Adenine

29% of Cytosine
29% of Guanine

(Adenine + Thymine: Have equal or almost equal %)
(Cytosine + Guanine: Have equal or almost equal %)
What reactive chemical groups are found at the 5' and 3' carbons of nucleotides? What is the name of the bond formed when nucleotides are joined in a single strand? Is this bond covalent or noncovalent?
The 5′ end is a phosphate group. The 3′ end is a hydroxyl group.

A phosphodiester bond is a covalent bond that joins nucleotides in a strand of nucleic acid.
Identify two differences in chemical composition that distinguish
DNA from RNA.
In RNA complementary base pairing A pairs with U whereas in DNA it pairs with T.

RNA nucleotides contain the sugar ribose in place of deoxyribose in DNA nucleotides.
What is the central dogma of biology? Identify and describe the molecular processes that accomplish the flow of genetic information described in the central dogma.
The central dogma is a description of the flow of genetic information.

The flow is unidirectional, from DNA to RNA to protein. The process by which information flows from DNA to RNA is called transcription. Transcription is the synthesis of RNA by RNA polymerase.

The RNA is complementary to the strand of DNA that was used as the template for transcription. The flow of information from RNA to protein is called translation. Translation is the synthesis of a polypeptide using the information in an mRNA.
The following segment of DNA is the template strand transcribed into mRNA:

5'-...GACATGGAA...-3'

a. What is the sequence of mRNA created from this sequence?

b. What is the amino acid sequence produced by translation?
The mRNA sequence is 5′-UUCCAUGUC-3′.

The amino acid sequence is Phe-His-Val.
Examine Figure 1.17 and answer the following questions.

a. How many clades are shown in the figure?

b. What characteristic is shared by all clades in the figure?

c. What characteristics are shared by the mammalian clade and the primate clade? What characteristic distinguishes the primates from other members of the mammalian clade?
a. 6

b. They all have a backbone (They are all vertebrates)

c. The characteristics that are shared by primates and mammals are (1) backbone, (2) four legs, and (3) fur and milk.

The characteristic that distinguishes primates from other mammals is opposable thumbs.
Shorter fragments of DNA (those with fewer base pairs) have a higher electrophoretic mobility then larger fragments. Thinking about electrophoresis gels as creating a matrix through which fragments must migrate, briefly explain why the size of a DNA fragment affects its electrophoretic mobility.
The gel matrix acts as a sieve that retards larger (longer) molecules more than smaller (shorter) ones, therefore, larger (longer) D N A molecules progress more slowly through the gel than smaller (shorter) D N A molecules.
When is DNA or RNA single and double strand
Double Strand: Equal % of base pairs

Single Strand: Unequal % of base pairs
What is meant by the term homology? How is that
different from the meaning of homoplasmy?
Homology is the presence of the trait or sequence in a common ancestor.

Homoplasmy is when in some apparent cases of synaptomorphy, the similarities are not a result of sharing a close common ancestor. Instead, convergent evolution has led unrelated organisms to display similar-looking traits
If one is constructing a phylogeny of reptiles using DNA sequence data, which taxon (birds, mammals, amphibians, or fish) might be suitable to use as an outgroup
Mammals
Archibald Garrod's Contribution to the Development of Genetics or Genetic Analysis
identified the first human hereditary condition, an autosomal recessive disorder called alkaptonuria, by examining several generations of British families with the condition.
Rosalind Franklin's Contribution to the Development of Genetics or Genetic Analysis
Led to the identification of the double-helical structure of DNA.

Franklin's most famous X-ray diffraction photograph, Photo 51, clearly showed (to the welltrained eye) that DNA is a duplex, consisting of two strands twisted around one another in a double helix
Robert Hooke's Contribution to the Development of Genetics or Genetic Analysis
In 1665, Robert Hooke first described cells he observed in thin sections of cork. First to visualize a microorganism.
William Bateson's Contribution to the Development of Genetics or Genetic Analysis
produced the first documented example of a human hereditary disorder, continued to study alkaptonuria for decades, eventually devising the designation "inborn error of metabolism," a phrase still used today to describe many recessive genetic conditions
Rudolph Virchow's Contribution to the Development of Genetics or Genetic Analysis
expanded and extended the ideas of the cell theory in 1855, declaring that "every cell stems from another
cell."

Virchow's contribution was important for giving the cell theory an evolutionary basis.
Edmund B. Wilson's Contribution to the Development of Genetics or Genetic Analysis
proposal of Edmund Beecher Wilson in 1895 that DNA, known at the time as "nuclein," was the hereditary molecule and a component of chromosomes
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