General Biology Exam 1 Flashcards
Science
- a way of knowing
- the endeavor to understand the natural world
- a way of viewing the world that focuses on objective information, put together to build understanding
Prehistoric Times (7,000-8,000 B.C.)
archeological evidence indicates domestication of animals and cultivation of plants
Observation of Cause and Effect
marked the beginning of scientific thought
Ancient Greeks (300-500 B.C.)
natural laws ‘philosophical principles’ that the universe obeyed; made systematic observations and formed generalizations, but provided No experimental verification
Roger Bacon (1214-1294)
credited as being the first to champion the scientific method, including accurate observations, experimental verification, the controlled experiment, and generalizations based on repeated experimental evidence
Observation
observation of objects or events in the physical universe
Question
ask a question or identify a problem to be solved based on observation
Hypothesis
making a prediction, that provides a possible answer to the question or a potential solution to the problem,; the hypothesis or prediction must be falsifiable
Experiment
design an experiment to test the hypothesis, the experiment should include appropriate controls and variables should be carefully selected and monitored
Replication
repeat the experiments as often as necessary to determine whether results will be consistent
Documentation
report objectively on the results and the conclusions drawn from them
Deductive Reasoning
applies general principles to predict specific results
Inductive Reasoning
constructs general principles based on specific observations
Limitations of Science/Scientific Knowledge
- in practice, science is a combination of subjective judgements and objective tests. It is a mixture of intuition and logic
- the insistence on testability limits the range of applications of science
- science cannot make value or moral judgements, however, it can provide information which may help in the formulation of such judgements
Hypothesis
a prediction supported by experimental data, and perhaps even supported by data collected from several different investigators (least degree of certainty)
Principle
a way of explaining a major phenomenon of nature, one that has been synthesized from a large body of information (greater degree of certainity)
Theory
a generally accepted scientific principle, an hypothesis that has been repeatedly and extensively tested, but never rejected. A scientific theory has the greatest degree of certainty, with the exception of a law
Law
most widely accepted, tested, and validated scientific principle
Biology
- the study of living things, the study of life
Abiotic
non-living
Biotic
living
Cellular Organization
all living things are made up of one or more cells– complex, organized assemblages of molecules enclosed within a membrane
Heredity
all organisms possess a form of genetic material that determines their morphological, physiological, and behavioral characteristics, and allows for adaptation and evolution over time
Sensitivity
all organisms have the ability to respond to stimuli- external and internal
Reproduction
all living things reproduce, passing on traits from one generation to the next
Growth
increase in size through the assimilation of energy (metabolism)
Development
multicellular organism undergo systematic gene-directed changes (differentiation) as they grow and mature
Regulation
mechanisms that coordinate internal processes (intake and processing of food, elimination of wastes, gas exchange, water intake and output–osmoregulation
Homeostasis
all living things maintain relatively constant internal conditions, different from their external environment
Biosphere
The sphere of life that surrounds the earth. Comprised of many ecosystems, including the major terrestrial ecosystems and the major aquatic ecosystems
Ecosystem
a community of organisms and the abiotic components of the environment in which they live
Community
all of the populations of organisms living in a particular place
Population
a group of individuals of the same species that live in the same area
Organism
an independent individual that expresses life’s characteristics
Organ System
several organs that work together to carry out a particular function within an organism
Organ
a functional unit, made up of several tissue types, that performs a specialized function
Tissue
groups of cells, similar in structure and function
Cell
the fundamental unit of structure and function in all living things
Organelles
structures that perform specialized functions within a cell. They are not capable of carrying out their functions independent from the cell
Molecules
clusters of atoms held together by chemical bonds
Atoms
the smallest units of matter that have distinct chemical properties
Pre-Darwinian Worldview
- young earth
- fixity of species
- diversity of species
- blending inheritance
- inheritance of acquired characteristics
Young Earth
age of the earth measured in thousands of years
Fixity of species
species did not change over time
Diversity of species
adaptations to different environments were designed by the creator
Blending Inheritance
the variation within members of the same species and the generation of new species resulted from interbreeding, and a blending of traits of each of the parents
Inheritance of acquired characteristics (John Baptiste Lamarck, 1809)
the variation among living organisms resulted from altered physical traits acquired in response to environmental challenges; these acquired physical traits could be passed on to the offspring
Post-Darwinian Worldview
- Old-earth
- Species change over time
- Adaptations
Old-Earth
age of the earth measured in billions of years
Species change over time
the operation of natural laws produce change over time and all living things are descended from organisms that lived before them
Adaptations
morphological, physiological, and behavioral modifications provide species with new ways to survive, to obtain and use energy, and to reproduce in new and changing environments. These adaptations result from genetic modifications that allow certain organisms within a given population to better cope with the challenges of their environment
Darwin’s Observations
Voyage of the H.M.S. Beagle (1831-1836)
Biogeography
the types and distribution of organisms that lived in similar environments on different continents were not the same
Variation
among individuals within a population and among populations of organisms that lived on islands– showed some resemblance to organisms on the mainland but also had noticeable differences necessary for survival in their new habitats
Five Basic Assumptions
- Vast spans of time have been available for change
- Many more individuals are born in each generation than will survive and reproduce
- There is variation among individuals in a population; they are not identical in all their characteristics
- Individuals with certain characteristics have a better chance of surviving and reproducing than individuals with other charactersitcs
- Some of the characteristics resulting in differential survival and reproduction are heritable
Processes of Natural Selection
- Variation
- Struggle for Survival
- Survival of the fittest
Variation
there must be variation among individuals in a population, and although some of the variation may be due to environmental influences, most of the variation has a genetic basis
Struggle for Survival
the environment poses problems for all species. Environmental factors that create a struggle for survival among individuals in a population include, but are not limited to, climatic changes, availability of resources, competition for resources, ability to find suitable mates, predators, and natural disasters
Survival of the fittest
individual characteristics influence the probability of survival. The environment acts as a sieve - those individuals within a given population that have the best survival characteristics will be most likely to reproduce, and their offspring will tend to possess their characteristics
Evidence for natural selection
- artificial selection
- direct observations
- industrial melanism
- resistance to antibiotics and insecticides
Artificial Selection
domestication of animals, hybridization plants, and experimental selection
Direct Observation
Darwin’s Finches
Industrial Melanism
pocket mouse and peppered moths
Resistance to antibiotics and insecticides
pesticides
Age of the earth
estimated to be 4.5-5 billion years old
- speed of geological processes
- fossil record- stratification
- radioactive decay - dating
Fossil Record
most direct evidence that evolution has occurred
- progression of life forms from simple to more complex - stratification
- flora and fauna have changed markedly over time, but they still resemble in some ways their apparent ancestral forms
- although the record is fragmentary due to the conditions necessary to produce fossils, many transitional forms, intermediate links between groups of organisms, have been discovered
Evidence in Support of Evolutionary Theory
- age of the earth
- fossil record
- biogeography and convergent evolution
- anatomical evidence for evolution
- development/comparative embryology
- vestigial organs
- Mechanism of heredity
Biogeography and Convergent Evolution
- types and distribution of plants, animals and all living organisms across continents, islands, and other geographic formations
Convergence
the evolution of similar forms in different lineages when exposed to the same selective pressures
Anatomical Evidence for Evolution
Homologous structures and analogous structures
Homologous Structures
indicate common ancestry/evolutionary origin; structures may be different in appearance and function, but they have the same structural elements
Analogous Structures
indicate different evolutionary history/lack common ancestry; structures may be similar in appearance and have a similar function, but they have very different structural elements and developmental patterns
Development/comparative embryology
common ancestry is apparent when comparing organisms during the early stages of their development, even though the adult organisms may look very different “ontogeny recapitulates phylogeny”
Vestigial Organs
organs that are fully developed in some groups of organisms and much reduced or dysfunctional in other groups of related organisms
Mechanism of Heredity
transmission, molecular, and population genetics
Major Criticism of Darwin’s hypothesis
lack of understanding of the genetic basis for adaptation
Genetic basis of inheritance
Mendal’s laws of inheritance
Molecular biology/genetics
DNA sequences, protein structure, gene expression
Population Genetics
properties of genes in populations
Challenges to Evolutionary Theory
- it is taught as a fact, but is just a theory
- lack of fossil intermediates
- violates the second law of thermodynamics
- natural selection does not imply evolution
- structural and functional complexity of DNA and proteins
- the intelligent design argument
- the irreducible complexity argument
Special Creation
life created by a supernatural force or divine being; the oldest and most widely accepted idea; ‘scientific creationism’
Extraterrestrial Origin (panspermia)
life carried to earth from another planet
Spontaneous Origin
life may have evolved from inanimate matter as selective forces lead to more complex associations of molecules culminating in the evolution of the first cells
4.5-5 billion years ago
the earth formed as a hot mass of molten rock
4.3 billion years ago
formation of the first rocks and oceans; as the earth cooled it crusted over and much of the water vapor present in its atmosphere condensed into liquid water, which accumulated on the surface in chemically rich oceans
Primordial soup (first oceans)
dilute, hot, smelly soup of ammonia, formaldehyde, formic acid, cyanide, methane, hydrogen sulfide, and organic hydrocarbons
Reducing Atmosphere (first atmosphere)
carbon dioxide, nitrogen, hydrogen gases and water vapor; oxygen which accounts for approximately 21% of our present atmosphere was most likely not present in the early atmosphere; a reducing atmosphere would have favored the formation of carbon rich molecules with very little energy compared with our current oxidizing atmosphere
Energy Sources
intense radiation from the sun with no ozone layer to filter out harmful UV rays; volcanic eruptions, severe storms and lightening, and very high temps when life first appeared
Chemical Evolution
molecules that are the building blocks of living organisms form spontaneously under conditions designed to simulate those of the primitive earth
Protobionts
membrane enclosed structures that concentrated more complex organic molecules, such as lipids, proteins, carbohydrates, and nucleic acids; internal compartment separate from the external environment
The Earliest Cells
represented by small, unicellular microfossils that lacked external appendages, and had little evidence of internal structure; resemble prokaryotes or bacteria; according to the fossil record prokaryotes were the only organisms that existed for almost 2 billion years
2.5-2.8 billion years ago
evidence of carbohydrates in rock formations and the appearance of the first micofossils; all living bacteria are members of either the archaebacterial or eubacteria
Archaebacteria
bacteria that live in oxygen-free environments
Halophiles
salt loving; live in high salt environments
Thermophiles
heat loving, live in very hot environments
Eubacteria
represent most bacteria living today; include all pathogenic bacteria photosynthetic autotrophs
2.0 billion years ago
photosynthetic bacteria, resembling modern day cyanobacteria, appeared in the fossil record; significant event in the evolution of life on earth
1.5 billion years ago
appearance of the first eukaryotic cells in the fossil record; large cells which appear to contain small membrane bound structures; they included elaborate shapes, surface projections, and the appearance of branched filaments
Endosymbiotic Theory
some of the membrane bound organelles, including the energy producing organelles, mitochondria and chloroplasts, found in eukaryotic cells may have originated from free-living bacteria that entered into endosymbiotic relationships with larger prokaryotic cells, evidence in support of this theory includes size, double membrane structure, location of enzymes involved in cellular respiration and photosynthesis, presence and structure of DNA, presence and structure of ribosomes, living examples
Meiosis and Sexual Reproduction
lead to an explosion of diversity among eukaryotes due to the introduction of high levels of genetic variation
Multicellularity
presumably began with early eukaryotes living in association with one another; cells began to take on specialized functions; perhaps the most significant innovation in the history of life; oldest multicellular fossils appeared about 600 million years ago
Invasion of Land
about 450 million years ago by plants followed by animals
The three domains of life
archae and bacteria and eukarya
The six kingdoms of life
archaebacterial, eubacteria, Protista, fungi, plantae, Animalia
Robert Hooke (1665)
discovered the first cells
Antonie Van Leeuwenhoek (late 1600’s)
observed first living cells - animalcules
Schleiden (1838)
botanist; all plants are composed of cells
Schwann (1839)
zoologist; all animals are composed of cells
Prokaryote Cells
small, simple cells that lack interior organization (no nucleus, no cytoskeleton, no membrane bound organelles, and no endomembrane system
Bacteria
all have a cell wall, a plasma cell membrane, cytosol, DNA and Ribosomes. Some have a gelatinous capsule, pili, and flagella
Capsule
outer protective covering found on some bacteria
Cell Wall
most bacterial are encased by a strong cell wall composed of peptidoglycan
Gram Positive Bacteria
single, thick peptidoglycan layer
Gram Negative Bacteria
thin peptidoglycan layer; thick outer lipopolysaccharide layer
Archaebacteria
cell walls do not contain peptidoglycan
Pili
- hair-like projections from the surface of some bacteria
- attachment to substrate
- exchange of genetic information
Flagella
-mechanism of motility in some bacteria; anchored in cell wall; rotary mechanism is unique to prokaryotes
Plasma (cell) membrane
phospholipid bilayer with globular proteins interspersed; highly invaginated (folded) and contains enzymes associated with metabolic processes
Nucleoid Region
contains a small, single, circular, double-stranded DNA molecule that is not complexed with proteins
Ribosomes
made up of rRNA and protein; sites of protein synthesis; smaller and less complex than eukaryotes
Eukaryotic Cells
- larger cells with more complex internal organization, including a nucleus, membrane bound organelles, a cytoskeleton, and an extensive endomembrane system
- protists, fungi, plants, and animals
Cell Wall
present in some eukaryotic cells, including plants, fungi and some protists; the primary component is usually a complex carbonhydrate; provides protection and structural support for the cell
Plant Cells
primary component cellulose; strong multilayered cell walls
Fungal Cells
primary component chitin
Animal Cells
cell walls absent; allows for cell movement
Plasma (cell) Membrane
- the thin membrane surrounding the cytoplasm of a cell
- functions as a selectively permeable barrier permitting specific substances to move in and out of the cell and allowing the cell to exchange information with its environment
- composed of a phospholipid bilayer and integral membrane proteins
Phospholipid Bilayer
serves as a permeability barrier and as a matrix for proteins
Transmembrane Proteins
active and passive transport and the transmission of information into the cell
Cell Surface Markers
glycoproteins and glycolipids involved in cell identity, recognition, and cell to cell communication
Cytoplasm (cytosol)
the gelatinous fluid enclosed within the plasma membrane; contains sugars, amino acids and proteins important for the maintenance of cell growth and reproduction
Ribosomes
rRNA - protein complexes in the cytoplasm; sites of protein synthesis
- components are synthesized in the nucleolus and move through nuclear pores to the cytoplasm
- in the cytoplasm they may be free or bound to membranes of the endoplasmic reticulum
- eukaryotic ribosomes are larger and more complex than prokaryotic ribosomes
Nucleus
contains the hereditary material in a eukaryotic cell; serves as the information or control center of the cell; directs and coordinates all cellular functions
Nuclear Envelope
a double membrane enclosing the nucleoplasm and the chromosomes
- the outer membrane is continuous with the endoplasmic reticulum
Nuclear Pores
small openings in the nuclear envelope where the outer and inner membranes pinch together that serve as molecular channels for proteins moving into the nucleus and RNA and RNA-protein complexes formed in the nucleus moving to the cytoplasm
Chromatin
complex of DNA and proteins of which eukaryotic chromosomes are comprised: chromatin is highly uncoiled and diffuse in non-dividing cells
Heterochromatin
more tightly coiled chromatin; portions of the DNA molecules where gene expression is NOT occurring
Euchromatin
more loosely coiled chromatin; portion of the DNA molecules where gene expression is occurring
Chromosomes
highly condensed form of chromatin only observed during cell division in eukaryotic cells; eukaryotic cells have multiple, linear chromosomes, each of which is composed of a single DNA molecule and associated histone proteins
Nucleolus
a spherical area within the nucleus where rRNA is being synthesized
Cytoskeleton
a network of protein fibers that supports cell shape and anchors organelles in fixed locations; there are three principal types of cytoskeletal fibers
Actin Filaments
long, thin filaments of the globular protein actin
- made of two strands of the fibrous protein actin twisted together
- usually occur in bundles and are often anchored to other cytoplasmic proteins
- ubiquitous, although concentrated below the plasma membrane
- responsible for cellular movements, such as contraction, formation of cellular extensions, crawling, and “pinching” of the cytoplasm during cell division
Intermediate Filaments
tough, durable, heterogeneous filaments
- comprised of intertwined protein tetramers
- heterogeneous group
- impart mechanical strength to the cell
Microtubules
hollow tubes of the globular protein tubulin
- formed by a ring of 13 tubulin protofilaments arrayed side by side around a central core
- often form near the nucleus and radiate out toward the periphery
- constant state of flux
- facilitate cellular movement and movement of materials within the cytoplasm of the cell
Mitochondria
organelles that carry out oxidative metabolism (ATP production)
- found in all types of eukaryotic cells
- elongated, double-membrane bound organelles about the size of bacteria
- smooth outer membrane
- intermembrane space
- highly folded inner membrane contains proteins that carry out oxidative metabolism
- matrix contains mitochondrial DNA and ribosomes
Chloroplasts
organelles that carry out photosynthesis
- found only in plant and algal cells
- larger and more complex than mitochondria; also have a double-membrane system
- smooth outer membrane
- intermembrane space
- highly folded inner membrane
- stroma contains chloroplast DNA and ribosomes
Leukoplasts
chloroplasts in plant cells deprived of light; in root cells they can be converted into starch storage units called amyloplasts
Centrioles
barrel shaped assemblies of microtublules
- found only in animal cells and some protists
- usually occur in pairs and at right angles to one another in a perinuclear position
- some are believed to contain their own DNA
- help in the assembly of microtubulues
Endomembrane System
an extensive system of highly folded membranes that divides the interior of eukaryotic cells into compartments and channels associated with the synthesis, packaging, modification, degradation, and distribution of proteins and other macromolecules within the cell; includes the endoplasmic reticulum, the Golgi apparatus, vesicles, and vacuoles
Endoplasmic Reticulum
an extensive network of highly folded membranes
- divides the interior of eukaryotic cells into compartments and channels
- involved in biosynthetic activities, and transport of macromolecules within the cell
- exists in two form, smooth and rough
Smooth Endoplasmic Reticulum
not associated with ribosomes; organizes the synthesis of lipids and other biosynthetic activities
Rough Endoplasmic Reticulum
bound ribosomes; associated with protein synthesis and the assembly of glycoproteins
Golgi bodies
smooth, concave stacks of membranes located in perinuclear positions
- functions to collect, modify, and package, and distribute molecules synthesized in the ER
- especially abundant in glandular cells
- receive transport vesicles that contain proteins from the ER
- the proteins are modified and packaged into secretory vesicles within the Golgi apparatus
- the secretory vesicles then migrate to other areas of the cell or to the cell surface where their contents are released
Lysosomes
membrane bounded vesicles formed from the Golgi apparatus
- contain hydrolytic enzymes (digestive)
- digest phagocytized food particles
- breakdown and recycle old or damaged cellular components
Micobodies
membrane-bounded vesicles that form from the fusion of preexisting vesicles
- contain specific enzymes to help organize cellular metabolism
Peroxisomes
animal cells; contain detoxifying enzymes to breakdown hydrogen peroxide, a toxic byproduct of oxidative metabolism
Glyoxysomes
plant cells; contain enzymes that convert fats into carbonhydrates
Vacuoles
large, membrane-bounded structures found mostly in plant cells
- storage of water, proteins, sugars, pigment molecules, secondary metabolites, and waste materials
Eukaryotic Cell Movement
all eukaryotic cell movement, including locomotion, changes in cell shape, and intracellular transport, is tied to the movement of actin filaments, microtubulues, or both
Microvilli
small, surface projections with actin cores that can extend and retract; increase cell surface area to facilitate absorption and other exchange processes
Pseudopodia
cytoplasmic extensions used as a form of cell locomotion; associated with cytoplasmic streaming and contracting actin filaments
Flagella
long cellular projections associated with cell locomotion
- eukaryotic flagella have a core of microtubules consisting two unpaired central microtubules surrounded by a circle of nine paired microtubules
- eukaryotic flagella move in a whiplike or undulating fashion
Cilia
short cellular projections often organized n rows
- more numerous than flagella, but have the same internal structure
- means of cell locomotion in some unicellular protists
- in multicellular organisms they are often involved in the movement of fluids or function in association with certain sensory structures
Theory of Endosymbiosis
- some eukaryotic organelles may have evolved from free-living bacteria that entered into symbiotic relationships with prokaryotic cells that were precursors to the first eukaryotic cells
- mitochondria and chloroplasts are believed to be descendants of these endosmybiotic prokaryotes
Evidence in support of the Theory of Endosymbiosis
- size about the same as most bacteria
- double-membrane structure, outer smooth; inner highly folded/contains enzymes for oxidative metabolism and photosynthesis respectively
- contain their own DNA; similar in structures and function to prokaryotic DNA
- contain their own ribosomes; similar in size and structure to prokaryotic ribosomes
- divide prior to cell division by binary fission
- living cells without mitochondria, but with free living bacteria that carry out the functions of oxidative metabolism
