Biology Learning Outcomes and Vocab

Chapters 11. 14-17

Compare and contrast the structure of RNA with that of DNA

DNA contains the sugar deoxyribose; RNA contains the sugar ribose. DNA has the base thymine; RNA has the base uracil. DNA is double-stranded; RNA is single-stranded

Describe the process of transcription and its role in gene expression

_______ is the first step of gene expression, where RNA polymerase copies a gene's DNA sequence into RNA, producing mRNA that carries instructions for protein synthesis

Summarize the modifications that occur during mRNA processing

The mRNA molecule must be processed by capping, the addition of a poly-A tail, and splicing in order for it to function properly in protein synthesis

Describe the process of translation and its role in gene expression

Translation is the second step of gene expression, whereby ribosomes use the sequence of codons in mRNA to produce a polypeptide with a particular sequence of amino acids

Summarize the operations of the lac operon in prokaryotes

The regulatory gene codes for a repressor, which bonds to the operator and prevents RNA polymerase from attaching to the promoter. Therefore, transcription of the lactose-metabolizing genes does not occur. When lactose is present, it binds to the repressor, changing its shape. The repressor becomes inactive and can no longer bind to the operator. Now, RNA polymerase binds to the promoter, and the lactose-metabolizing genes are expressed.

DNA (deoxyribonucleic acid)

Nucleic acid polymer produced from covalent bonding of nucleotide monomers that contain the sugar deoxyribose; the genetic material of nearly all organisms

RNA (ribonucleic acid)

Nucleic acid produced from covalent bonding of nucleotide monomers that contain the sugar ribose. Three major forms are messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).

Nucleotide

Monomer of DNA and RNA consisting of a 5-carbon sugar bonded to a nitrogenous base and a phosphate group.

Nitrogenous Bases

Organic, nitrogen-containing molecules that form the core of nucleotides; the building blocks of DNA and RNA

Adenine (A)

One of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA; pairs with thymine in DNA and uracil in RNA

Guanine (G)

One of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA; pairs with cytosine

Cytosine (C)

One of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA; pairs with guanine

Thymine (T)

One of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA; pairs with adenine

Uracil (U)

Pyrimidine base that replaces thymine in RNA; pairs with adenine

Complimentary Base Pairing

Hydrogen bonding between particular purines and pyrimidines in DNA

Messenger RNA (mRNA)

Type of RNA formed from a DNA template and bearing coded information for the amino acid sequence of a polypeptide

Transfer RNA (tRNA)

Type of RNA that transfers a particular amino acid to a ribosome during protein synthesis. At one end, it binds to the amino acid, and at the other end, it has an anticodon that binds to an mRNA codon

Ribosomal RNA (rRNA)

Type of RNA found in ribosomes that translates messenger RNAs to produce proteins

Gene Expression

The process of using the information within a gene to synthesize a protein

Transcription

Process whereby a DNA strand serves as a template for the formation of mRNA

Translation

Process whereby ribosomes use the sequence of codons in mRNA to produce a polypeptide with a particular sequence of amino acids

Ribosome

Structure consisting of rRNA and proteins in 2 subunits; site of protein synthesis in the cytoplasm

Codon

3-base sequence in mRNA that causes the addition of a particular amino acid onto a protein or the termination of translation

Anticodon

3-base sequence in a transfer RNA molecule base that pairs with a complementary codon in mRNA

RNA Polymerase

During transcription, an enzyme that joins nucleotides in a sequence complementary to that in a DNA template

Amino Acid

Organic molecule composed of an amino group and an acid group; covalently bonds to produce peptide molecules

Lac Operon

An operon required for the transport and metabolism of lactose; allows for the effective digestion of lactose when glucose is not available.

Promoter

A sequence of DNA that is involved in the regulation of gene expression. Located where the RNA polymerase binds prior to transcription.

Repressor

In an operon, a protein molecule that binds to an operator, preventing transcription of structural genes.

Operator

A DNA segment that acts as a regulatory switch, controlling whether nearby genes are transcribed by interacting with specific regulatory proteins

X-inactivation

Process in females that causes one of the two X chromosomes to condense into an inactive form called a Barr body. An example of epigenic inheritance.

Exon

Contains the protein-coding regions of a gene; in mRNA splicing, the introns are removed and the _____ join together, resulting in a mature mRNA molecule consisting of continuous _____.

Intron

Segments of DNA that do not code for protein

Summarize how 19th century scientists contributed to the study of evolutionary change

Charles Darwin developed the theory of natural selection; organisms with beneficial traits are more likely to survive and reproduce. Georges Cuvier studied fossils and established that extinction occurs; natural disasters change species populations. Jean-Baptiste de Lamarck suggested that more complex organisms are descendants of less complex organisms

Explain how Dawins study of fossils and biogeography contributed to the development of the theory of natural selection

Darwin’s fossil studies provided evidence of deep time and species change, while his biogeographic observations revealed patterns of distribution that could only be explained by common ancestry and adaptation. These combined to form the empirical foundation for his theory of evolution by natural selection.

Describe the steps in the theory of natural selection

(1) The members of a population have heritable variations. (2) The population produces more offspring than the resources of an environment can support. (3) The individuals that have favorable traits survive and reproduce to a greater extent than those that lack these traits. (4) Over time, the portion of a favorable trait increases the population, and the population becomes adapted to the environment.

Explain how the fossil record, biogeographical evidence, comparative anatomy, and biochemistry support evolutionary theory

The fossil record shows historical change, biogeography reveals patterns of distribution consistent with common ancestry, comparative anatomy highlights structural homologies and vestiges, and biochemistry confirms genetic relatedness

Who was George Cuvier?

_______ was a noted zoologist of the early 19th century and is considered to be the founder of the science of paleontology; believed in the fixity of species.

Who was Jean-Baptiste de Lamarck?

He was a biologist who hypothesized that evolution occurs and that adaptation to the environment is the cause of diversity; concluded that more complex organisms are descended from less complex organisms; and proposed the idea of inheritance of acquired characteristics.

Who was Charles Lyell?

Author of the book Principles of Geology; proposed the theory of uniformitarianism

Who was Charles Darwin?

Accepted the position of naturalist abroad the HMS Beagle; sensitive nature prevented him from studying medicine, and went to divinity school at Cambridge instead; proposed the theory of evolution; said that living organisms share characteristics because they have a common ancestry; concluded that organisms are related through common descent and that adaptations to various environments results in diversity

Fossil

Remains of a once-living organism that have been preserved in the Earth's crust.

Biogeography

Study of the geographic distribution of life-forms on Earth

Adaptation

A modification in an organism's structure, function, or behavior suitable to the environment.

Fitness

The reproductive success of an individual relative to other members of a population

Speciation

Formation of new species due to the evolutionary process of descent with modification.

Evolution

Inheritable changes in a population over time that make the population better adapted to their environment.

Natural Selection

Mechanism of evolution caused by environmental selection of organisms most fit to reproduce; results in adaptations to the environment.

Catastrophism

The theory that changes in the Earth's crust during geological history have resulted from sudden violent and unusual events; often contrasted with uniformitarianism

Gradualism

The hypothesis that evolution proceeds mainly by the accumulation of gradual changes.

Homologous Structure

In evolution, a structure that is similar in different types of organisms because these organisms are descended from a common ancestor.

Analogous Structure

Structure that has a similar function in separate lineages but differ in anatomy and ancestry.

Vestigial Structure

Anatomical feature that is fully developed in one group of organisms but reduced and nonfunctional in other, similar groups.

Describe the 3 types of natural selection - directional, stabilizing, and disruptive

Directional selection favors one extreme phenotype. Stabilizing selection favors the intermediate phenotype. Disruptive selection favors 2 or more extreme phenotypes over any intermediate phenotype

How do you use the Hardy-Weinberg principle to explain the process of microevolution?

Microevolution can be detected and measured by noting the amount of deviation from Hardy-Weinberg equilibrium that is exhibited by the genotype frequencies in a population

Describe how mutations, gene flow, nonrandom mating, genetic drift, and natural selection can cause changes in the frequency of an allele in a population

(1) Mutation: DNA sequence change - Introduces new alleles; small direct effect unless acted on by other forces. (2) Gene flow: Migration between populations - Adds/removes alleles; homogenizes populations. (3) Nonrandom mating: Inbreeding/assortative mating - Changes genotype frequencies; can expose alleles to selection. (4) Genetic Drift: Random sampling in small populations - Randomly increases/decreases allele frequencies; can fix or eliminate alleles. (5) Natural selection: Differential survival/reproduction - Increases beneficial alleles; decreases harmful ones.

Stabilizing Selection

Outcome of natural selection in which extreme phenotypes are eliminated and the intermediate (average) phenotype is conserved

Directional Selection

Outcome of natural selection in which an extreme phenotype at one end of a population distribution is favored over all other phenotypes, leading to one distinct form

Disruptive Selection

Outcome of natural selection in which both extreme phenotypes at the ends of a population distribution are favored over the average phenotype, leading to more than one distinct form

Sexual Selection

Adaptive changes in males and females of a species, often due to male competition and female selectivity, leading to increased fitness

Microevolution

Small, measurable evolutionary changes in a population from generation to generation; change in allele frequencies within a population over time

Gene Pool

The various alleles at all the gene loci in all individuals in a population

Hardy-Weinberg Equilibrium

The real world condition in which a population meets the assumptions of the Hardy-Weinberg principle; Indicates no evolution is occurring at the locus: allele frequencies remain stable across generations; rare in natural selection because the required conditions (no mutations, no gene flow, random mating, no genetic drift, and selection) are almost never fully met

Gene Flow

Movement of alleles among populations by migration of breeding individuals

Nonrandom Mating

Mating that does not occur on a purely random basis; examples are inbreeding and sexual reproduction

Genetic Drift

Mechanism of evolution due to random changes in the allele frequencies of a gene pool; more likely to occur in small populations or when only a few individuals of a large population reproduce

Emigration

The one-way movement of individuals or groups out of a specific population or habitat, resulting in a decrease in the population size of the area being left

Immigration

Refers to the unidirectional movement of individual organisms, populations, or even entire species into a new habitat, population, or ecosystem from an external source

Bottleneck Effect

Evolutionary event in which a significant percentage of a population is prevented from reproducing, therefore reducing variation. Population _______ increase the influence of genetic drift

Founder Effect

Mechanism of genetic drift that occurs when a new population is established by a small number of individuals, carrying only a small fraction of the original population's genetic variation. The alleles carried by these individuals often, by chance, do not occur in the same frequency as in the original population.

Define species and describe the limitations of the biological species concept.

Group of similarly constructed organisms capable of interbreeding and producing viable offspring - organisms that share a gene pool - the taxon at the lowest level of classification;The biological species concept cannot be applied to asexually reproducing organisms. In addition, reproductive isolation may not be complete, so some breeding between species may occur

Distinguish between prezygotic and postzygotic isolation mechanisms, and provide an example of each

Prezygotic isolating mechanisms do not allow zygotes to be formed. Examples are habitat, temporal, behavioral, mechanical, and gametic isolation. Postzygotic mechanisms allow zygotes to be formed, but the zygotes either die or develop offspring that are infertile or that produce infertile offspring. Examples are zygote mortality, hybrid sterility, and low F2 fitness

Summarize the cause of mass extinction in the history of life on Earth

Continental drift, loss of habitat, the crash of a meteorite into the Earth, and climate change have contributed to mass extinctions

List the hierarchical levels of Linnaean classification from the most inclusive to the least inclusive

Domain, supergroup, kingdom, phylum, class, order, family, genus, species

Macroevolution

Large-scale evolutionary change, such as the formation of new species

Species

Group of similarly constructed organisms capable of interbreeding and producing viable offspring; organisms that share a gene pool; the taxon at the lowest level of classification

Biological species concept

Definition of a species that states that members of a species interbreed and have a shared gene pool and that each species is reproductively isolated from other species

Prezygotic isolation mechanisms

Anatomical or behavioral difference between two species that prevents the possibility of mating; those that occur before the formation of a zygote

Postzygotic isolating mechanisms

Anatomical or physiological difference between two species that prevents successful reproduction after mating has taken place; those that occur after the formation of a zygote

Habitat isolation

When two species occupy different habitats, even with the same geographic range, they are less likely to meet and attempt to reproduce

Temporal Isolation

Two species can live in the same locale, but if they reproduce at different times of the year, they do not attempt to mate

Behavioral Isolation

Many animal species have courtship patterns that allow males and females to recognize one another

Mechanical Isolation

When animal genitalia or plant floral structures are incompatible, reproduction cannot occur

Gamete Isolation

Even if the gametes of two different species meet, they may not fuse to become a zygote

Zygote Mortality

The hybrid zygote may not be viable, so it dies

Hybrid Sterility

The hybrid zygote may develop into a sterile adult

F2 Fitness

Even if hybrids can reproduce, their offspring may be unable to reproduce

Domain

Largest of the categories, or taxa, used by taxonomists to group species; Archaea, Bacteria, and Eukarya are examples

Kingdom

One of the categories, or taxa, used by taxonomists to group species; the taxon above the phylum level

Phylum

One of the categories, or taxa, used by taxonomists to group species; the taxon above the class level

Class

One of the categories, or taxa, used by taxonomists to group species; the taxon above the order level

Order

One of the categories, or taxa, used by taxonomists to group species; the taxon above the family level

Family

One of the categories, or taxa, used by taxonomists to group species; the taxon above the genus level

Genus

One of the categories, or taxa, used by taxonomists to group species; contains those species that are most closely related through evolution

Describe the structure of a virus

Viruses are composed of an outer capsid of protein subunits and an inner core containing DNA or RNA

Describe the process of viral reproduction

Viruses reproduce in one of two ways: through the Lytic cycle (Attachment, penetration, biosynthesis, maturation, and release), or the lysogenic cycle (occurs before the lytic cycle; attachment, penetration, integration, biosynthesis, maturation, release)

Distinguish between bacteria and archaea

The plasma membrane of archaea have unusual lipids, so they can survive in extreme environments such as conditions of high heat. They have diverse types of cell walls, sometimes containing proteins or polysaccharides but not peptidoglycan. They also have unusual metabolic characteristics, such as the ability to generate methane or live in high-salt environments. Because of these characteristics, they do not compete with bacteria

Summarize the general characteristics of all protists

Protists are eukaryotes with a nucleus and a wide range of organelles. Many are single-celled. They are a diverse group that represents the common ancestors of different multicellular organisms.

Distinguish the main supergroups of protists, and provide an example of each

Archaeplastids have chloroplasts derived from endosymbiotic cyanobacteria; green algae are an example. The Chromalveolata consist of brown algae, which are photosynthetic but evolved differently than green and red algae, and protists, which have an internal series of cavities. The rhizarians have threadlike appendages and external shells; diatoms and foraminifera are examples. Excavata lack mitochondria and have distinct flagella and/or oral grooves; euglenids are an example. Amoebozoa move by means of pseudopods; slime molds are an example. Opisthokonts are chemoheterotrophs with flagellated cells; choanoflagellates are an example

Virus

An infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host