Who was Jean Baptiste de Lamarck and what was his theory?
1. He was an early French taxonomist
2. He believed that species change because and individual uses a particular body part and then passes along the "better-developed" body part to the offspring
What did Charles Darwin believe about evolution?
1. Natural Selection:
Not all individuals in a species are identical
Some variations within the species are inherited
Every species produces more offspring that then environment can support
Individuals with inherited characteristics that allow them to survive in greater numbers will have more offspring (the species will change over time to select the most favorable characteristics)
What are the 3 observations of nature that support natural selection?
1. Organisms are varied, and some variations are inherited (no 2 individuals within a species are exactly alike)
2. More individuals are born than survive to reproduce
3. Individuals compete with one anther for the limited resources that enable them to survive.
What are the 2 inferences made from the observations of nature?
1. Within populations, the inherited characteristics of some individuals make them more likely to survive and produce fertile offspring
2. Because of the environment's selection against nonadaptive traits, only those with adaptive traits live long enough to transmit their genes to the next generation.
What is the fossil evidence for evolution?
1. Older fossils are very different from more recent fossils
2. More recent fossils more closely resemble modern species, suggesting a gradual change over millions of years.
3. Example: horse hoofs
What is the comparative anatomy evidence for evolution?
1. Homologous structures: Structures with very different functions show similar anatomy, suggesting common ancestor (radius, ulna, carpals, metacarpals, phalanges in humans compared to bats)
2. Vestigial structures: Structures that no longer have any significant use remain because they were useful for an ancestor (wings on an ostrich, tailbone in a human)
What is the embryological evidence for evolution?
Embryos show similar structures that develop into different organs with very different uses suggesting a common ancestor
1. Gill slits
3. Dorsal hollow nerve cord
4. Post-anal tail
What are the observations of species changing in modern times?
1. Species in captivity change over time when human breeders artificially select which individuals survive
2. Peppered moth: species changed from mostly light colored when tree trunks were light gray, to mostly dark when pollution darkened the tree trunks
3. Resistance to antibiotics among bacteria shows that these species are constantly changing because the environment now has more antibiotics in it
What is the biogeographical evidence for evolution?
1. Organisms in different parts of the world show similarities because they adapt to similar conditions even though they are not closely related (tall animals adapt to grasslands to see over the grass to detect predators and food)
2. Organisms on different continents sometimes resemble each other because the continents were once connected. After the continents separated, individuals evolved into different species when they were separated from their original populations
What is the biochemical evidence of evolution?
1. DNA and proteins of closely related species are more similar to each other than to the DNA and proteins of more distantly related species
2. Evolutionary theory predicts that mutations in DNA cause changes in offspring, which cause changes in proteins (similarity in DNA and proteins suggest a common ancestor)
What is the calculation to predict the unchanging% of alleles?
What is the big bang theory?
1. The origin of the universe
2. 13 billion years ago
3. All the matter of the universe was contained in a tiny area that exploded. The dust from the explosion collected to form stars and planets
When was the Earth formed and what were the conditions like?
1. 4.6 billion years ago
2. Very very HOT and contained no O2 in the atmosphere
What is the chemical evolution theory?
1. CH4 and CO2 in the atmosphere interacted with lightening, UV light, and volcanic activity to form amino acids, lipids/phospholipids, and nucleotide bases
2. Nucleotides may have formed primitive RNA to direct the synthesis of proteins
3. Phospholipids formed into double layer liposomes
4. Liposomes may have enclosed RNA and proteins to form a protective membrane to surround self-replicating RNA (evolved into the simplest prokaryotic cells)
5. Earliest evidence of biochemicals is 3.9BYA, earliest evidence of fossil cells is 3.8BYA
What is the endosymbiotic hypothesis?
1. Prokaryotic cells containing DNA and enzymes needed for ATP synthesis were engulfed by other prokaryotic cells, forming mitochondria
2. Prokaryotic cells containing DNA and chlorophyll engulfed by other prokaryotic cells formed chloroplasts. Allowed photosynthesis to produce O2 in the atmosphere
3. All organisms on earth use DNA, ATP and phospholipids. This suggests common ancestral single-celled organism.
What is Taxonomy?
The science of classifying organisms:
Domain: Bacteria, archaea, eukarya
Kingdom: Plant, animal, fungi, protista
What is that taxonomic classification of Humans?
What is the evolution of multicellular life?
1. The first multicellular fossils are 1.2 billion years old (5:45pm, if the earth's history is a 24hr day)
2. Jawless fish fossils are 450 million years old
3. First mammal fossils are 65 million years old
4. First hominid fossils are 6 million years old
5. Australopithecus (hominid fam) had several species now extinct
6. Homo neanderthalis became extinct 30,000 years ago
7. Modern humans evolved 200,000 years ago (a few seconds before midnight on 24hr clock)
What is a biological species?
A population who's members can interbreed and produce fertile offspring
What is speciation?
1. The formation of a new species
2. Occurs when members of a population can no longer successfully interbreed.
3. The species become reproductively isolated from each other
What are the pre-zygotic barriers that attribute to reproductive isolation?
1. Ecological isolation: different habitat preferences
2. Temporal isolation: different active/fertile times of the day or season
3. Behavioral differences: different mating calls/attractions
4. Mechanical isolation: male and female parts are not compatible; in plants, species have different pollinators
5. Gametic isolation: eggs of species 1 prevents fertilization of species 2
What are the post-zygotic barriers that attribute to reproductive isolation?
1. Hybrid inviability: hybrid offspring fail to reach maturity
2. Hybrid infertility: hybrid offspring reach maturity but cannot produce offspring
3. Hybrid breakdown: hybrid offspring are fertile, but the 2nd generation is abnormal
Evolution occurs in small incremental changes over many generations
Punctuated equillibrium speciation
Brief bursts of rapid evolution interrupting long periods of little change
1. Adaptive radiation: formation of several new species from a common ancestor in a short period of time
2. Occurs when new resources become available or when a group inherits a characteristic that gives them a key advantage
How does extinction occur?
A species dose not contain the alleles necessary to sustain the population
How long do species exist?
1. From 1 to 10 million years
2. Background extinction rate is between 0.1 and 1 extinction per million species
What caused the 5 major mass extinctions in the past?
1. Meteorites or asteroids
2. Movement of tectonic plates causing changes in the continents and oceans
3. Mass extinctions mark the change from one geological era to another
4. Humans causing the 6th major mass extinction?
What is a monophyletic taxonomic group (taxon)?
A group of organisms consisting of a common ancestor and all of its descendants
Describe the size of a virus
1. Smaller and simpler than other cells
2. Average virus is less than 1/10th the size of a bacteria (< 0.1um)
Describe the structure of a virus
1. Contains genetic information (DNA or RNA)
2. Genetic info is surrounded by a protein coat (capsid)
3. Some viruses also have lipid-rich envelopes
What are the ways a virus can infect a host?
1. The host might have a specific receptor for for the virus
2. Some viruses infect only a small type of cells in a particular organism (HIV)
3. Virus reservoir is the organism in nature where the virus exists that may or may not show symptoms
What are the similarities/differences between viruses and other living organisms?
1. Similarities: They both have have genetic material, they both evolve
2. Differences: Viruses are not considered alive, they do not respond to environmental stimuli, do not reproduce outside of other living cells
What are the stages of viral replication?
1. Attachment: Virus binds to receptor on host cell membrane
2. Penetration: Virus enters the host cell through endocytosis, pushed in by insects, or is injected by the virus itself
3. Synthesis: Multiple copies of viral DNA or RNA. Uses host DNA, tRNA, nucleotides, amino acids, and enzymes for the synthesis of viral proteins
4. Assembly: of protein subunits to form capsid, enclosing viral DNA or RNA
5. Release: Enzyme to break host's cell wall or exocytosis
What are the cycles of viral infection?
1. Lytic cycle: Causes host cell to burst and release multiple copes of the virus (lytic bacteriophages to treat bacterial infections)
2. Lysogenic cycle: virus is dormant in host for long periods of time without damaging the cell before entering the lytic cycle
What are the effects of viral infections (mild or severe)?
1. Viruses kill human cells (flu kills cells in lungs/throat)
2. Immune response is fever and localized inflammation
3. Viruses that linger for years as latent infection without symptoms (HIV, host cells divide rapidly in cancer)
How do antiviral drugs work?
1. They interfere with enzymes or other proteins unique to viruses, there are few medicines that inhibit viruses without damaging the host
2. Some viruses mutate so rapidly it is difficult to target them
3. Vaccines introduce an antigen that triggers the host's immune system without causing the serious effects of the disease
4. Antibiotics do not affect viruses because they lack the cell walls, ribosomes and enzymes targeted by abx
What are viroids?
Tightly wound circles of RNA without protein coats that may interfere with protein production in the host
What are prions?
1. Proteins with abnormal shape
2. Some cause spongiform brain diseases
3. Caused by eating infected brain tissue or from unclean medical procedures
Where does HIV originate?
Mutations from various Simian Immunodeficiency viruses