bio

Chapter 15:

1. What is feedback inhibition?

Feedback inhibition is when a product that the cell is making stops the production of said product.

2. What is an operon?

An operon consists of the promoter, operator, and genes that are involved on the DNA strand.

3. What is a genome?

A genome is the entire set of genetic information in an organism.

4. Why is it favorable to have functionally related genes on one transcription unit?

All of the genes are controlled, and only one operator is necessary to turn the strand on or off.

5. What is the role of the operator?

The operator is responsible for keeping the gene on or off for gene expression.

6. What is the role for the promoter?

The promoter is either available or unavailable for RNA polymerase to bind and activate gene expression. It is where this whole process begins.

7. Compare activity of the tryptophan operon in both the presence and absence of tryptophan.

The tryptophan operon will be turned off in the presence of tryptophan. If there is an absence of tryptophan, then the operon will turn on for gene expression.

8. Describe differences in the shape and activity of the repressor in both the presence and absence of tryptophan.

If there is a presence of tryptophan in the cell, then a signaling molecule can bind to the repressor to change shape, since the repressor is produced in an inactive state. Once that occurs, the repressor will change shape so that it can bind to the operator and prevent gene expression from taking place. If there is an absence of tryptophan, then the repressor will be removed so RNA polymerase can bind and activate gene expression.

9. Is this an anabolic or catabolic pathway? It is an anabolic pathway.

10. Inducible or Repressible? Repressible.

11. Compare the activity of the Lac Operon in both the presence and absence of lactose.

If there is lactose in the cell, then the operon will be turned off. If there is an absence of lactose in the cell, then the operon will turn on.

12. Is this an anabolic or catabolic pathway? This is a catabolic pathway.

13. Describe differences in the shape and activity of the repressor in both the presence and absence of lactose.

The repressor is naturally bound to the operator in this case. If there is an absence of lactose in the cell, then allolactose will bind to the repressor to remove it from the operator. After that, RNA polymerase will bind to the operator and activate gene expression.

14. What is allolactose?

Allolactose is the signalling molecule that binds to the repressor to remove itself from the operator?

15. In addition to having lactose present, what other conditions must be met for the positive (activator) gene regulation?

There must be low glucose, and high levels of cAMP.

16. What is the role of cAMP?

cAMP is a signaling molecule that attaches to CRP and enhances RNA polymerase activity.

17. What does cAMP accumulate?

cAMP accumulates in the cell when glucose levels are low.

18. What is CRP?

CRP is the cyclic AMP receptor protein.

19. How does it become activated?

It becomes activated when lactose levels outside the cell are high and glucose levels are low.

20. What is the enzyme that breaks down lactose?

Lactase is the enzyme that breaks down lactose.

21. Describe the role of chromatin modification (acetylation and methylation) in gene regulation.

Acetylation is the method in which DNA becomes unwound so gene expression can occur. Methylation is the method in which DNA becomes tightly compacted so gene expression cannot occur. DNA is tightly wound around histones, and the histones have tails that contain acetylation. The DNA is then unwound from the histones, and once that happens RNA polymerase can bind and activate gene expression since the DNA is accessible. Methylation allows the DNA to tightly wound around the histones, so gene expression cannot occur because the DNA becomes inaccessible.

22. Describe the regulation of transcription by transcription activators and enhancers.

Cell specific activation of genes, transcription is regulated by enhancers when activation of cell specific genes are activated Ex liver cells activate albumin by regulating enhancers DNA turning on available activators for albumin cells within the lens activating crystallin. All cells have the same genome. Turns on gene expression that the cell type requires.

23. Describe the role of RNA splicing in transcript modifications.

With RNA splicing, exons are expressed while introns are removed.

24. What are introns?

Introns are the sections of the mRNA that are removed from the strand and not expressed.

25. What are exons?

Exons are the sections of the mRNA that remain on the strand and are expressed.

26. Describe the role of ubiquitin in protein degradation.

Ubiquitin is a molecule that is attached to a protein that triggers its destruction.

Chapter 19:

27. What is meant by “descent with modification”?

Descent with modification refers to the way in which organisms use their environment for protection and adapt to their surroundings. It is the idea that species change over time, give rise to a new species, and share a common ancestor.

28. How have fossils contributed to Darwin’s ideas?

Fossils have provided evidence for Darwin’s theories, demonstrating that species evolve over time and that earth is in fact over billions of years old.

29. What are Strata?

Strata are the layers of sedimentary rock in which fossils are contained.

30. What do each layer represent?

According to Cuvier, each layer of strata represented a catastrophic event that wiped out a species.

31. What is Paleontology? Paleontology is the study of fossils.

32. How do strata and paleontology support evolution?

Strata and paleontology support evolution by not only providing evidence of species that have existed previously, but also proving that the earth is in fact billions of years old. Populations evolve across generations, so one can see how one species evolved to become an entirely different species. This would happen over the course of millions of years, disproving the idea that the earth is six thousand years old.

33. What did Lamarck believe?

Lamarck believed that species evolved over the use or disuse of certain body parts. He also believed that species would inherit acquired characteristics from their parents.

34. How did Darwin’s travels contribute to his perception of adaptation?

On his travels, Darwin collected many species and studied them. He noticed that these species were well adapted to their environment and possessed traits that would help them survive. On the Galapagos islands, Darwin noticed that different species of finches possessed a certain beak shape that allowed them to consume food that was available to them in that specific environment. He concluded that species adapted to their environment and developed traits that would help them survive and reproduce.

35. Describe this perception.

As a result of his findings, Darwin reasoned that species would adapt to their environment based on the conditions that they faced. They would gradually acquire characteristics that would allow them to survive and reproduce.

36. What 3 broad observations are explained in the Origin of Species?

Darwin observed that members of a population often vary in their inherited traits. He also observed that species tend to produce more offspring than the environment can support,

and as a result, many offspring fail to survive and reproduce. Finally, he observed that traits that increase suitability to a species’ environment will be passed on.

37. Compare and contrast natural selection and artificial selection.

Natural selection is the process by which the environment selects for which members of a population will survive and reproduce, depending on their traits and whether they are well suited for their environment. Artificial selection is the process by which humans breed certain members of species with favorable traits in order to produce offspring with these favorable traits.

38. Give an example of each (Understand the observations and inferences in natural selection).

A good example with natural selection would be finches with certain beak sizes to consume food that is available to them. If a finch has a beak shape that is designed for consuming insects in their environment, then those finches will be more likely to survive than finches who have a beak shape that is designed to consume say cactus plants in that same environment. A good example with artificial selection would be the breeding of the wild mustard plant to produce kale, brussel sprouts, cabbage, and broccoli.

39. Describe the two observations and inferences that Darwin made in his book On the Origin of Species.

Darwin observed that members of a population often vary in their inherited traits. He also observed that all species tend to reproduce more offspring than the environment can support, and many offspring fail to survive and reproduce as a result. Darwin inferred that individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals. Finally, Darwin inferred that unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits over generations.

40. What is Homology?

Homology is the similarity between species as a result of common ancestry, but the similar structures serve different purposes.

41. Give examples of homologous structures.

An example of homologous structures would include similar bone structures found within humans, cats, whales, and bats.

42. How do homologous structures support a common ancestor?

Homologous structures support a common ancestor by demonstrating these similar structures found within these different species. Humans, cats, whales, and bats all descended from a common ancestor and as a result, contain these similar bone structures.

43. How do they provide evidence of adaptation?

Homologous structures provide evidence of adaptation by proving that although these structures are similar, they serve different purposes. They serve different functions because these species had to adapt to their different environments. Because they adapted to their environments in different ways, these structures now carry out different functions.

44. What is convergent evolution?

Convergent evolution is when two species that are distantly related share common structures as a result of adapting to their similar environments.

45. What are analogous features?

Analogous features are similar features found between different species, used to carry out similar functions.

46. How do they differ from homologous features?

Analogous features differ from homologous features in the sense that they are not a result of common ancestry. Rather, they are a result of different species adapting to their environment in similar ways.

47. What are endemic species?

Endemic species are species that are only found in one particular area in the world and nowhere else.

48. What is meant by Biogeography?

Biogeography is the study of geographic distribution of species.

49. Pangaea?

Pangaea was once a large landmass containing every piece of land on planet earth, but separated over time.

50. How do these and the Fossil Record support evolution?

Biogeography would explain how different species adapt to their different environments, evolving over time. The fossil record documents evolution and provides evidence that species have changed over time. Extinction and the appearance of new species have also supported the theory.

Chapter 20:

51. What is Linnaeus accredited for?

Linnaeus is accredited for taxonomy, the classification of species. He classified them based on their physical appearance.

52. Describe and identify proper binomial nomenclature.

The binomial nomenclature is a two part naming system used to name species. The first part is the genus, and the second part is the species name.

53. What is a taxon?

A taxon is a taxonomic unit at any level of hierarchy classified on a phylogenetic tree.

54. Understand how to read a phylogenetic tree. What do each branch point represent?

On a phylogenetic tree, each branch point represents a new species diverging from a common ancestor.

55. What are sister taxa?

Sister taxa are two species that diverged from one common ancestor.

56. What are the 8 taxonomic groups from narrow to broad?

The 8 taxonomic groups from narrow to broad are species, genus, family, order, class, phylum, kingdom, and domain.

57. What are the three domains?

The three domains are Eukarya, Archaea, and Bacteria.

58. Compare each.

The eukarya domain includes plants, animals, fungi, and other multicellular organisms. The bacteria domain consists of all of the organisms in the kingdom of bacteria, while the archaea domain includes the rest of the prokaryotes and unicellular organisms.

59. On what is this new classification system based?

Before the domains archaea and bacteria were grouped together in the kingdom of monera, but biologists decided to separate them into two domains. This was based on rRNA sequencing.

60. Explain the role of convergent evolution in analogous structures, contrasting homologous structures.

Convergent evolution is the way in which distantly related groups evolve to adapt to their similar environments. These groups do not share a common ancestor, but because their

environments are similar, they have adapted in similar ways and share analogous structures. Groups who share homologous structures are a result of common ancestry.

61. What is horizontal gene transfer? Why is it important? Name three ways it can occur.

Horizontal gene transfer is the movement of genes from one genome to another. It can occur by exchange of DNA, viral infection, or fusion of organisms. It plays a role in the evolution of antibiotic resistance in bacteria and affects growth rates in populations, so its important to understand it.

Chapter 21:

62. What is microevolution?

Microevolution refers to changes in allele frequency in a population over time.

63. Describe the role of mutations and sexual reproduction in phenotypic and genetic variation.

Mutations and sexual reproduction can

64. What is a Population?

A population is a localized group of individuals capable of reproduction.

65. Gene Pool?

A gene pool consists of alleles for all loci in a population of individuals.

66. Calculate allele (p+q=1) and genotype frequencies of dominant, recessive and

heterozygous allele using Hardy Weinberg equilibrium p2 + 2pq + q2 = 1. (p+q=1) - allele frequency

p2 + 2pq + q2 = 1 - genotype frequency

67. Name and describe 5 assumptions of Hardy Weinberg Principles.

● No mutations

● No random mating

● No natural selection

● Extremely large population size

● No gene flow/migration

68. What is genetic drift?

Genetic drift is how alleles fluctuate unpredictably from one generation to the next. It is typically seen in larger populations. Loss of alleles can reduce genetic variation. When a small proportion of the original population leaves offspring, and the second generation changes.

69. What is gene flow?

Gene flow is the movement of alleles among populations. It can be the result of migration, and it can change genetic variation over time. It can increase or decrease fitness, depending on whether certain individuals are adapted to their environment.

70. How can it reduce genetic variation over time?

Gene flow can reduce genetic variation over time with natural selection, the founder effect, or bottlenecking.

71. What is adaptive evolution?

Adaptive evolution is when an increase in frequency of alleles improves fitness and enhances survival and reproduction.

72. Describe and compare directional, disruptive and stabilizing selection.

Directional selection is when natural selection favors individuals at one end of the phenotypic range. Disruptive selection favors individuals at both ends of the phenotypic range, and stabilizing selection favors individuals with moderate/average phenotypes, essentially in the middle.

73. What is sexual selection?

Sexual selection is natural selection for mating success, when individuals compete for potential mates within a population based on their traits.

74. Compare intersexual selection and intrasexual selection.

Intersexual selection is when members of one sex choose a mate of the other sex based on their traits, while intrasexual selection is when members of the same sex (usually male) compete with each other to find a mate.

75. What is heterozygote advantage?

Heterozygote advantage refers to the higher fitness level of a heterozygote compared to either homozygous.