Week 1 Biology 1110 PDF

Biosphere and Taxonomy Evolution Viruses Lab: Dichotomous key  Biosphere and Taxonomy OBJECTIVES: 1. Describe some of the properties and processes associated with living organisms and explain why defining life is problematic 2. Define biosphere and describe the levels of organisatio...

Biosphere and Taxonomy Evolution Viruses Lab: Dichotomous key  Biosphere and Taxonomy OBJECTIVES: 1. Describe some of the properties and processes associated with living organisms and explain why defining life is problematic 2. Define biosphere and describe the levels of organisation within the biosphere. 3. Discuss the differences between prokaryotic and eukaryotic cells. Identify the major components of eukaryotic cells in a diagram and explain their function. 4. Name the major taxonomical categories used in classification and describe the binomial system of nomenclature 5. Describe the 3- domain system of classification 6. Interpret the evolutionary relationships represented in phylogenetic trees. 1. Describe some of the properties and processes associated with living organisms and explain why defining life is problematic  Biology is the study of living things, or organisms.  We are all familiar with and are able to recognise living things, yet defining life and distinguishing living from non-living is not a clear-cut matter.  Can you describe some characteristics of living things? Characteristics of living things  Complex and highly organised  Respond to fluctuations in the environment  Use energy  Reproduce  Populations of living things evolve  Growth and development 2. Define biosphere and describe the levels of organisation within the biosphere  The biosphere is all areas of the earth that contain life  Ecosystems contain all living and non living components of the environment in a particular with which life interacts (e.g rain forests)  A community refers to the different species that live in a particular ecosystem.  A population are all members of a single species that occupy a given area.  Organisms are the individuals of a population  Organisms can be made up of organs systems which have specialized functions. Levels of Organisation  These organ systems, are again, made up of structures with specialized functions called organs  Organs are made up of different types of tissues  Tissues are composed of cells, which are the fundamental units of life as they have all the characteristics of life.  Organelles are structures within cells that have specialized functions  Molecules are made up of atoms and when they join together they can form larger structures. Levels of Organisation 3. Discuss the differences between prokaryotic and eukaryotic cells. Identify the major components of eukaryotic cells in a diagram and their function. Schleiden and Schwann’s Cell Theory All organisms are made up of cells. The cell is the simplest collection of matter that can live.  Prokaryotes vs Eukaryotes No membrane around nuclei Membrane bound nuclei No membrane bound organelles Has membrane bound organelles (e.g. mitochondria, chloroplasts) Cells are small Cells are large Peptidoglycans in the cell wall (Bacteria) No peptidoglycans in cell wall Circular chromosomes Linear chromosomes No histones associated with the DNA Histones associated with the DNA Prokaryotic Cell E. coli Overview of an animal cell  ANIMAL CELLS Organelles are specific subcellular structures which perform specialised functions for the cell  The plasma (cell) membrane controls what goes into and out of the cell and separates the internal cell environment from that outside environment  Lysosomes contain enzymes and are responsible for the digestion of organic particles in the cell  Mitochondria produce adenosine triphosphate (ATP) by cellular respiration (animal cells). ATP is an energy rich molecule that drives metabolism in cells.  Ribosomes are involved in the production of proteins. They are non membranous organelles. The endomembrane system consists of endoplasmic reticulum and the Golgi apparatus.  Endoplasmic reticulum  Rough endoplasmic reticulum (RER) is associated with the transport of proteins from attached ribosomes. It provides protein containing vesicles to the Golgi.  Smooth endoplasmic reticulum (SER) has a function in detoxification and can produce a number of steroids in humans  Golgi processes and packages material for export or use within the cell. Various types of vesicles are produced with different destinations. The following are components of the cell nucleus  The nuclear envelope encloses the genetic material of the cells and controls what enters or leaves the nucleus. It is comprised of a double membrane with pores.  The nucleolus is are specialised regions of some chromosomes with multiple copies of genes for the synthesis of ribosomes and other types ribonucleic acids (RNA). It is considered to be a non membrane bound organelle  Chromatin is the name given to chromosomes that have associated proteins bound to them such as histones and histidine. It is generally seen as long threads during interphase. Overview of a plant cell Plants have all the organelles just discussed but have a few extra things  They have a rigid cell wall used to protect the plant cell  Many have a central vacuole that controls water content and waste excretion in some plants  Chloroplasts are present in plants and function to transduce energy from sunlight to produce ATP  Bacterial cell walls are composed of a carbohydrate polymer called peptidoglycan while plant cell walls are composed of cellulose  Chloroplasts are similar to mitochondria in a number of ways.  Both have DNA in them  Both have ribosomes  Both have an inner and outer membrane system  Both can produce ATP via chemiosmosis  Prokaryotic or eukaryotic? Why? Animal or plant cell? Why? 4. Name the major taxonomical categories used in classification and describe the binomial system of nomenclature Binomial Nomenclature  In the 18th century, Carolus Linnaeus published a system of taxonomy based on resemblances  Two key features of his system remain useful today: two-part names for species and hierarchical classification  The two-part scientific name of a species is called a binomial  The first part of the name is the genus  The second part, called the specific epithet, is unique for each species within the genus  The first letter of the genus is capitalised, and the entire species name is italicized  Both parts together name the species (not the specific epithet alone) Hierarchical Classification  Linnaeus introduced a system for grouping species in increasingly broad categories  The taxonomic groups from broad to narrow are domain, kingdom, phylum, class, order, family, genus, and species  Taxonomy is the ordered division and naming of organisms  A taxonomic unit at any level of hierarchy is called a taxon 5. Describe the 3- domain system of classification From Two Kingdoms to Three Domains  Early taxonomists classified all species as either plants or animals  Later, five kingdoms were recognized: Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia  More recently, the three-domain system has been adopted: Bacteria, Archaea, and Eukarya  The three-domain system is supported by data from many sequenced genomes  The three domains of life EUKARYA Land plants Dinoflagellates Green algae Forams Ciliates Diatoms Red algae Amoebas Cellular slime molds Euglena Trypanosomes Animals Leishmania Fungi Sulfolobus Green nonsulfur bacteria Thermophiles (Mitochondrion) Spirochetes Halophiles Chlamydia COMMON ANCESTOR Green OF ALL sulfur bacteria LIFE Methanobacterium BACTERIA Cyanobacteria ARCHAEA (Plastids, including chloroplasts) A Comparison of the Three Domains of Life 6. Interpret the evolutionary relationships represented in phylogenetic trees. Systematists depict evolutionary relationships in branching phylogenetic trees Phylogenies show evolutionary relationships  The discipline of systematics classifies organisms and determines their evolutionary relationships  Phylogeny is the evolutionary history of a species or group of related species  Systematists use fossil, molecular, and genetic data to infer evolutionary relationships  A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor.  Order Family Genus Species Panthera Felidae Panthera pardus Taxidea Carnivora Taxidea Mustelidae taxus Lutra Lutra lutra Canis latrans Canidae Canis Canis lupus The connection between classification and phylogeny  A phylogenetic tree represents a hypothesis about evolutionary relationships  Each branch point represents the divergence of two species  Sister taxa are groups that share an immediate common ancestor  A rooted tree includes a branch to represent the last common ancestor of all taxa in the tree  A polytomy is a branch from which more than two groups emerge  Branch point (node) Taxon A Taxon B Sister taxa Taxon C ANCESTRAL LINEAGE Taxon D Taxon E Taxon F Common ancestor of taxa A–F Polytomy How to read a phylogenetic tree What We Can and Cannot Learn from Phylogenetic Trees  Phylogenetic trees do show patterns of descent  Phylogenetic trees do not indicate when species evolved or how much genetic change occurred in a lineage  It shouldn’t be assumed that a taxon evolved from the taxon next to it  Phylogeny provides important information about similar characteristics in closely related species  Evolution OBJECTIVES: 1. Define evolution and distinguish between the process of evolution and a mechanism of evolution (eg. natural selection). 2. Describe at least three sources of scientific evidence supporting evolution. 1. Define evolution and distinguish between the process of evolution and a mechanism of evolution (eg. natural selection). Definition of evolution Evolution is the observation that changes occur in the genetic material of populations of organisms over time Genetic variation is the raw material of evolution. It can be defined as differences among individuals in the composition of their DNA or other DNA segments  Table 1. Some Sources of Genetic Variation Source of variation Description Existing variation Populations of all organisms have existing genetic variation in many traits. Meiosis/Fertilization In sexually-reproducing organisms, both the rearrangement of the genetic material during production of gametes (meiosis) and the genetic contributions from male and female parents (fertilization) contribute to the production of new genetic combinations. Mutations Changes occur in DNA and are passed to the next generation creating new genetic variation in populations. Mutations can occur spontaneously, or be caused by radiation or chemicals.  Some genetic vocabulary  Heredity: the biological process whereby genetic factors are transmitted from one generation to the next  Character: An observable, heritable feature such as hair colour or eye colour  Trait: a variant of a character, such as purple or white flowers  Gene: A hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism  Allele: One member of a pair or series of genes that occupy a specific position on a specific chromosome.  A population is a group of individuals living in the same geographical area and sharing a common gene pool.  The gene pool is the sum of all genetic information carried by the members of a population.  Principal Mechanisms of Evolution. Mechanism Key Features Gene flow Genetic changes may occur in populations as a consequence of migration of individuals among populations. Natural Differential survival or reproduction occurs within a Selection population such that certain genetic makeups are “selected” or favoured under the influence of environmental factors (eg. predators, competitors, weather, food supply). The genetic makeup of the population changes over time as organisms interact with their environment. Genetic Drift Genetic changes occur in populations due only to chance or random factors (eg. bottleneck effects, founder effects). Random factors may enhance or eliminate certain genetic makeups. Gene Flow  Gene flow consists of the movement of alleles among populations  Alleles can be transferred through the movement of fertile individuals or gametes (for example, pollen)  Gene flow tends to reduce differences between populations over time  Gene flow is more likely than mutation to alter allele frequencies directly Gene flow and human evolution Gene flow can increase the fitness of a population  Insecticides have been used to target mosquitoes that carry West Nile virus and malaria  Alleles have evolved in some populations that confer insecticide resistance to these mosquitoes  The flow of insecticide resistance alleles into a population can cause an increase in fitness Gene flow can decrease the fitness of a population  In bent grass, alleles for copper tolerance are beneficial in populations near copper mines, but harmful to populations in other soils  Windblown pollen moves these alleles between populations  The movement of unfavorable alleles into a population results in a decrease in fit between organism and environment Fig. 23-12 70 NON- MINE NON- MINE SOIL MINE 60 SOIL SOIL 50 Prevailing wind direction 40 30 20 10 0 20 0 20 0 20 40 60 80 100 120 140 160 Distance from mine edge (meters)  Genetic Drift  The smaller a sample, the greater the chance of deviation from a predicted result  Genetic drift describes how allele frequencies fluctuate unpredictably from one generation to the next  Genetic drift tends to reduce genetic variation through losses of alleles  The Founder Effect  The founder effect occurs when a few individuals become isolated from a larger population  Allele frequencies in the small founder population can be different from those in the larger parent population  The Bottleneck Effect  The bottleneck effect is a sudden reduction in population size due to a change in the environment  The resulting gene pool may no longer be reflective of the original population’s gene pool  If the population remains small, it may be further affected by genetic drift Fig. 23-9 Original Bottlenecking Surviving population event population  Understanding the bottleneck effect can increase understanding of how human activity affects other species Bottleneck effect and reduction of genetic variation Pre-bottleneck Post-bottleneck (Illinois, 1820) (Illinois, 1993) Range of greater prairie chicken (a) Number Percentage Location Population of alleles of eggs size per locus hatched Illinois 1930–1960s 1,000–25,000 5.2 93 1993