Midterm 2 Flashcards
What is biological evolution
Evolution is the change that occurs in the characteristics of organisms in a population over time
Theory of evolution
All modern organisms are related to each other and arose from a common ancestor
Theory of common descent
Modern organisms can be arranged on a “tree” of relationships based on similarities in morphology, development, and genes
modern biological classification system
classifies organisms based on physical similarities between them. supports theory of common descent
How do homologies in characteristics support theory of evolution?
- similarities in the underlying structures of organisms and vestigial structures (i.e. appendix) are difficult to explain except through theory of common descent
- modern data on similarities of DNA sequences match hypothesized evolutionary relationship suggested by anatomical similarities
how do details of embryonic development support theory of evolution
similarities in embryonic development and structures among diverse organisms are best explained as a result of common ancestry
what is biogeography, how does it support the theory of evolution?
the study of the geographical distribution of organisms.
-species that appear related physically are often close to each other geographically
How does fossil record provide direct evidence of evolutionary changes in species over time?
Fossilized remains of extinct species in many groups demonstrate progression of forms from ancient types to more modern types.
Why is theory of evolution considered the best explanation for the origin of humans and other organisms?
- evidence supports hypothesis that organisms have changed over time and are related to each other
- shared characteristics of all of life, universality of DNA and relationship between DNA and proteins support common ancestry theory.
Observations that led to inference of natural selection
- individuals in a population very, and some of this variation can be passed on to offspring
- Not all individuals born in a population survive to adulthood and not all adults produce maximum number of offspring possible
- Survival and reproduction is not random. Adaptations increase an individuals fitness.
fitness
the organisms chance of survival or reproduction
how does natural selection cause evolutionary change?
increased fitness of individuals with particular adaptations cases the adaptation to become more prevalent in a population over generations
examples natural selection leads to evolution of population
- artificial selection (humans deliberately control organisms fitness) causes evolution of different breeds of animals and plants
- populations exposed to environmental changes, in lab and nature, have been shown to evolve traits that give them better fitness
how does natural selection work on allele frequency in a population?
- modern definition of evolution is genetic change in population of organisms
- alleles that code for adaptations become more common in a population over generations as a result of natural selection
why doesn’t natural selection create “perfectly adapted” organisms
natural selection can only act on variants currently available in the population. natural selection makes organism better adapted not perfectly adapted as a result of trade-offs, natural selection does not push in direction of a predetermine “goal”
3 patterns of selection
selection can cause traits in a population to change in a particular direction. However, in some environments it may cause certain traits to resist change and in other environments cause multiple variants to evolve.
why is combination drug therapy an effective tool to combat drug resistance?
- disease causing organisms can evolve resistance to antibiotics because they consist of multiple variants that have differential survival when exposed to various drugs; evolve drug resistance through natural selection
- mutant organism that is resistant to several different antibiotics is relatively unlikely so combination therapy can reduce risk of antibiotic resistance evolving
- as a result of trade-offs, varieties of disease causing organisms that are multiple drug resistant are less likely to survive and reproduce under normal conditions than are non resistant varieties. resistant organisms are therefore less transmissible than nonresistant varieties.
define biological species
a group of individuals that can interbreed and produce fertile offspring. Biological species are reproductively isolated from each other, thus separating the gene pool of species.
Reproductive isolation
maintained by prefertilization factors such as differences in mating behavior or timing or post fertilization factors such as hybrid inviability or sterility
describe 3 steps of speciation
- populations of a species become separated from each other
- populations diverge from each other and reproductive isolation between populations evolves
explain how “race” in biological species can be defined using genealogical species concept
biological races are populations of a single species that have diverged from each other but have not become reproductively isolated.
list evidence that modern humans are young species that arose in Africa
- morphology of human ancestors in fossil record provides evidence modern species is app. 200000 years old
- genetic evidence indicates modern humans have limited genetic diversity a characteristic of young species and that the oldest populations (containing most genetic diversity) are found in Africa
How is Hardy-Weinberg theory used in studies of population genetics.
- Provides a rule for calculating allele frequency from genotype frequency
- if the assumptions of Hardy-Weinberg (no natural selection, no migration, and random mating of individuals within a population) are violated, allele frequency will not match expectations
evidence human races are not deep biological divisions within human species
- modern humans do not show evidence they have been isolated from each other long enough to form different races.
- other genetic evidence indicates that human groups have been missing for thousands of years.
traits that have become common in certain human populations due to the natural selection these populations have undergone
similarities among human populations may evolve as a result of natural selection. sickle-cell is selected for in populations in which malaria incidence is high and light skin in areas where UV light level is low.
define genetic drift
changes in allele frequency due to chance events such as founder effects or population bottlenecks
sexual selection
individuals, typically females, choose mates that display “attractive” quality, may be responsible for creating differences in human populations
positive assertive mating
individuals choose mates who are like themselves, can reinforce differences between human populations
Number of species estimated and why it is an estimate
estimated between 1.4 and 1.8 million. could be as high as 100 million
list three major domains of life
-bacteria: share common ancestor with archaea and eukarya while last two groupe are more closely related. Bacteria and archaea are prockaryotic organism without a nucleus or other membrane bound organelles. Eukarya are eukaryotes
endosymbiotic theory for the origin of eukaryotic cells
eukaryotes, cells with nuclei and other membrane organelles, probable evolved from symbioses among ancestral eukaryotes and prokaryotes
for major kingdoms of eukarya
Protista, animalia, fungi, and plantae
adaptive radiation
occurs when several new species appear quickly after the evolution of a new “way of life” or the death of a competing group.
-diversity of flowering plants may be due partly to adaptive radiation resulting from their production of defensive chemicals
virus
viruses are non living entities made up of genetic material in a transport container and can reproduce only by high jacking living cells
algae
protists that store food and thus are targets for predators. Make defensive chemicals against predators.
fungi
compete with bacteria for food. produce antibiotics
how are evolutionary classifications of living organisms created
phylogenies are created and tested by evaluating the shared traits of different species that indicate they shared a recent ancestory
epithelial tissues
epithelia line and cover organs, vessels, and body cavities. Tightly packed tissues with one free surface. Outer growths of epithelia form some glands. These tissues function in protection, secretion, and absorption.
6 types of connective tissue
loose tissue, adipose, blood, fibrous connective tissue, cartilage, bone tissue
loose connective tissue
connects epithelia to underlying tissues and holds organs in place. cellular component is fibroblasts, matrix rich in proteins, collagen, elastin which provide tensile strength and elasticity
adipose
connects skin to underlying structures and insulates and protects organs. cells synthesize and store fat and have little extracellular matrix
blood
type of connective tissue that transports oxygen and nutrients to body cells. Blood cells have a liquid matrix called plasma.
fibrous connective tissue
forms the tendons and ligaments. cells are fibroblasts and matrix is rich in collagen.
cartilage
flexible, shock-absorbing tissue composed of cells called chondrocytes that secrete a dense, collagenous matrix
bone tissue
provides support for the body. cells are called osteocytes and the matric is rich in collagen and minerals
Muscle tissues
skeletal, cardiac, smooth.
- can be voluntary or involuntary
- striated or smooth
skeletal muscle
attached to bones, responsible for voluntary movements, and striated
cardiac muscle
comprises the heart. It is involuntary and striated
smooth muscle
musculature of internal organs, blood vessels. smooth muscle, involuntary, not striate.
nervous tissues
found in brain and spinal cord, composed of neurons. senses stimuli and transmits signals throughout the body
what is an organ
group of tissues working in concert
organ system
suites of organs working together to perform a function for functions
liver
- composed of different tisses
- epithelial tissue of liver divided into lobes. lobes contain central vein that allows blood to reach hepatocytes, which function as filters to remove toxins and pathogens
- production of proteins and cholesterol, secretion of bile, storage of vitamins and glycogen
digestive system
mouth, pharynx and through esophagus to stomach to small intestine. digested nutrients absorbed into bloodstream and brought to cells.
- pancreas, liver , and gallbladder are accessory organs that secrete substances that aid in digestion
- digestive enzymes produced by the pancreas help break down food molecules. Bile produced by liver facilitates breakdown of fats, gallbladder stores and concentrates bile before it is released to small intestine.
homeostasis
ability to maintain a constant internal environment even when external environment changes
negative feedback mehanism
helps facilitate homeostasis. when negative feedback occurs, product of the process acts to turn down the process. Negative feedback negates change
positive feedback
less commonly used homeostatic mechanism. When positive feedback occurs, product of process intensifies the process. promotes change
respiratory system
air flows into body via mouth and nose enters respiratory system via the pharynx and trachea. Once in lungs, air flows through bronchi and into alveoli where gas exchange occurs
muscles involved in breathing
- air into and out of lungs depends largely on action of diaphragm (dome muscles sit below the lungs)
- contraction increases volume of chest cavity, decreases air pressure, air flows in. relaxation causes opposite to occur.
hemoglobin in gas exchange
blood flows through lungs, hemoglobin reversibly binds to oxygen there. In the body tissues hemoglobin releases some of the oxygen load to supply active tissues.
circulatory system
- blood
- veins and arteries
- heart
how does blood flow through circulation system of the heart?
heart is double pump consisting of four chambers-2 atria 2 ventricles. right side pump sends oxygen poor blood to the lungs; left side sends oxygen rich blood to the body.
-blood from lungs flows to heart where it is pumped into systemic circulation. after dropping of oxygen and picking up carbon dioxide it returns to the heart and is pumped to the lungs
cardiac cycle
heart can generate its own beat via the electrical activities of the SA node. signals from the SA node transmitted to the atria, causing chambers to contract and force blood into ventricles. signal carried by conductive fibers to the ventricles which then contract to force blood out of the heart and into circulation
urinary system
kidneys, bladder, ureter, urethra
urine excretion
- nephrons of kidneys, filtration forces most liquid but not cells or larger molecules, from plasma to kidney tubules. As filtrate travels through nephron water, glucose and other molecules are reabsorbed through active and passive transport. secretion occurs when waste materials that did not leave with filtrate are actively brought to nephron tubules from surrounding capillaries.
- hormones regulate blood pressure to control concentration of water in urine. urine collects in the renal pelvis, travels down ureters to be stored in bladder, during urination, urine is released from bladder through urethra and exits the body
smoking and respiratory system
- small particles of smoke enter lungs causing cell damage that leads to chronic bronchitis which can then lead to emphysema. Tiniest smoke particles drawn into alveoli where they remain for long periods , exposing cells to carcinogens.
- nicotine increases heart rate and blood pressure, putting strain on heart muscle. increase production of ldl (bad cholesterol). increases likelihood of blood clot
- toxins stored in urine within the bladder, leading to greater risk of bladder cancer in smokers.
bacteria
single celled organisms with no nucleus or membrane bound organelles. surrounded by a cell wall
viruses
nucleic acids encased in liquid and sometimes and envelop
bacterial replication
binary fission
viral replication
replicate their genome inside host cell. viral genome directs the synthesis of viral components.
first line of defense against infection
skin, mucous membrane secretions are nonspecific defenses
second line of defense against infection
nonspecific defense:
-white blood cells, inflammation, defensive proteins such as interferon help protect uninfected cells from becoming infected. complement proteins coat microbes and make them easier for microphages to digest
phagocytic macrophages
white blood cells that engulf and digest foreign cells
natural killer cells
white blood cells that release chemicals that disintegrate cell membranes of tumors and virus infected cells
lymphocytes
help compromise third line of defense in response to antigens on the surface of pathogens. exposure to antigens causes increased production of B and T lymphocytes.
B lymphocytes
secrete antibodies against pathogens
T lymphocytes
attack invaders
allergic reaction
immune system responding to antigenic substance that are not normally pathogens
process immune cells undergo to respond to millions of antigens
- lymphocytes produced during fetal development and allow immune system to respond to trillions of antigens
- antigen receptors on the surface of immune cells are produce by rearrangements of gene segments
process used to determine if cell is native or foreign
antigen receptors of b and t cells are tested for self reactivity, and those that react against self are eliminated
memory cells role in protecting against infection
memory cells carry copies of the antigen receptor and secrete antibody against a previously encountered pathogen
role of T helper cells in allowing infection by the aids virus.
aids is an immunodeficiency caused when HIV attacks helper T cells. Helper T cells increase immune response.
mechanism by which vaccines help confer immunity
vaccines contain parts of disease causing organism or entire organisms that have been inactivated. The immune system produces memory cells in response to vaccination, thereby affording protection in the case of actual infection
gene flow
spread of an allele throughout a species’ gene pool
gene pool
sum total of alleles found in all the individuals of a species’
founder hypothesis
establishment of a new species far from original population. species rapidly diversified into many species by taking advantage of many different resources
speciation
evolution of one or more species from ancestral form
single nucleotide polymorphism
SNP is a single base pair in the DNA sequence of humans that can differ from one individual to another
convergent evolution
traits that are shared by unrelated populations because they share similar environmental conditions
founder effect
gene pool of immigrants is rarely an exact reflection of the gene pool of the source population
adaptation s
traits that increase an individuals relative fitness in a particular environment
vestigial trait
similarities between functional traits in one organism and seemingly nonfunctional or greatly reduced features in another
molecular clock
rate of change in certain DNA sequences, due to accumulation of mutations that affect dna sequence but not the protein is relatively constant within a species.
hominims
humans and human ancestors
biodiversity
variety within and among living species
domains
modern species divided into domains. 3 large groups unified by similarities in cell structure. Bacteria, archaea, and eukarya
Kingdoms
within each domain are smaller groups called kindoms
eukarya kindoms
plantae, animalia, fungi, protista
Tissues
Groups of similar cell types that perform a common function. Four main types: epithelial, connective, muscle, nervous
endotherm
organisms with the ability to maintain a body temperature that is warmer than the surrounding environment
red blood cells
shuttle oxygen from lungs to rest of body. Packed with hemoglobin molecules
White blood cells
different varieties and essential to immune system function, attacking invading organism as well as removing toxins, wastes and damaged cells
pulmonary circuit
circulates the blood into the lungs to pick up oxygen and other components inhaled
systemic circuit
pumps blood to the rest of the body where it drops off oxygen and picks up carbon dioxide. picks up materials from digestive system and filters nongaseous wastes via the kidneys
eukaryotic pathogens
protozoans, worms, fungi. can cause diseases and sickness
phagocyte
white blood cell that indiscriminately attack and ingest invaders by engulfing and digesting the invader
microphage
phagocytic white blood cells that move through lymphatic fluid, clean up dead and damaged cells, digest invaders with enzymes, clean up old blood cells, dead tissue fragments. Much destruction of offending cells occur in lymph nodes
lymphocytes
white blood cells travel through body inbetween cll and tissue via blood and lymphatic system. triggered by proteins and carbs on the surface of pathogens or on cells infected by pathogens. produced from stem cells
B cells
white blood cell lymphocyte. recognize specific antigens. react to small, free living microorganisms such as bacteria and the toxins they produce. Secrete proteins called antibodies that bind and inactivate antigens
T cells
recognize and respond to body cells that have gone awry, such as cancer cells or cells that have been invaded by viruses, also respond to transplanted tissue and large organisms I.e. fungi and parasitic worms. Do not produce antibodies, directly attack invaders
helper t cells
boosters of immune response. alert both b and t cells that infection is occurring
protein hormone
cannot cross cell membrane. bind to receptor on surface of target cell and receptor stimulates series of other proteins to relay message to inside the cell
steroid hormones
fat soluble can cross cell membrane and bind to receptors inside target cell, causes cell to turn specific genes on or off
