BIO 2 Exam 1 Review

artificial selection can be achieved through

selective breeding

species

basic lower unit of classification of organisms

taxonomy

the science of classification of organisms

protozoa

single-celled eukaryotes, either free-living or parasitic ex:amoeba

porifera

sponges (think pores “pore” infera)

Why are insects so diverse?

Small body size - There are many opportunities for small organisms in a given environment

Why are insects so small?

1. It takes time to grow large - A long juvenile period increases the risk of mortality before reproduction
2. Oxygen limitation - Gas exchange becomes difficult at large sizes because of distance effects on oxygen diffusion

Tympana

A thin cuticular membrane that allows for hearing in insects also mating calls

Cnidaria

jellyfish, coral etc.

sound

Pressure fluctuation transmitted in a wave-form via movement of air or water

Hypothese on origins that have 4 overlapping stages

1. appearance of organic molecules
2. polymerization of molecules into RNA, DNA, or proteins
3. formation of protobionts
4. evolution of cell-like characteristics

minimal properties of life

reproduction, metabolism, evolution

hypotheses about how/where organic molecules originated

1. reduced atmosphere hypothesis
2. extraterrestrial hypothesis
3. deep sea vent hypothesis

Metabolism

Absorption of nutrients, waste excretion, energy acquisition and transformation, and cellular synthesis

Miller-Urey 1952 Experiment

Set up anaerobic atmospheric conditions and added an electrical discharge, resulting in the spontaneous formation of simple organic molecules

Extraterrestrial hypothesis

Meteorites brought organic carbon to Earth

Protobiont

Aggregate of molecules and macromolecules that acquired a boundary, allowing it to maintain an internal environment separated from its surroundings

What makes protobionts possible precursors to living cells?

1. A boundary separated external environment from internal contents
2. Polymers inside the protobiont contained information
3. Polymers inside the protobiont had enzymatic function
4. Protobionts capable of self-replication

living cells may have evolved from

coacervates-droplets that form spontaneously from charged polymers where enzymes trapped inside perform metabolic functions

liposomes-can enclose RNA

what is the first macromolecule of protobionts

RNA

what are functions of RNA

1. ability to store info
2. self-replication
3. enzymatic function (ribozymes)

Radioisotope dating

A common way to estimate the age of a fossil by analyzing the decay of radioisotopes within the rock (usually igneous rock)

Half-life

Length of time required for exactly one-half of original isotope to decay

Factors that affect the completeness of the fossil record:

1. anatomy
2. size
3. number
4. environment
5. time
6. geological processes
7. paleontology

fossil prokaryote

cyanobacteria

stromatolites

changes in living organisms due to

genetic changes and changes in environment which allow for new organisms and extinctions

Cretaceous

\- 144-65 MYA \n -Dinosaurs still dominant \n -Angiosperms - earliest flowering plants \n -Mass extinction at end wiped out dinosaurs and many other species

Macroevolution

The formation of new species or groups of related species

Lamarck

Proposed theory that organisms pass on traits they acquire in their lifetime. (Incorrect) i.e. Scars

Charles Darwin

English natural scientist who formulated a theory of evolution by natural selection

Darwin's Theory of Evolution based on:

1. Variation within a given species
2. Natural selection

Population genetics

The study of genes and genotypes in a population

Purpose of Population Genetics:

1. To know extent of genetic variation
2. Why it exists
3. How it is maintained
4. How it changes over the course of many generations

Phenotype

Physical appearance or observed traits due to genotype

Natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Reproductive success

Likelihood of an individual contributing fertile offspring to the next generation

Horizontal gene transfer

Transfer of genes between cells of the same generation

Permian-Triassic Extinction Event

252 MYA, the only known mass extinction of insects \n - 8 or 9 orders became extinct

Paleodictyopterida

An extinct superorder of beaked insects \n - Included 50% of all known Paleozoic insects

Ultrasonic pulses

Method by which echolocating bats detect prey

Phantom Echo hypothesis

Bat perceives clicks as multiple objects surrounding the moth

Ranging Interference hypothesis

Bat perceives clicks as a blurred target

Masking hypothesis

Bat perceives clicks as no target

Four periods of the Earth

Archaen, Proterozoic, Phanerozoic, Cenozoic

Life

An organized genetic unit capable of metabolism, reproduction, and evolution

Reproduction

Growth, duplication of all cellular components, division of discrete cells

Evolution

Variation, reproduction, and mutation

Origin of Life: Stage 1

Nucleotides and amino acids spontaneously produced prior to the existence of cells (Primordial soup)

Origin of Life: Stage 2

Nucleotides and amino acids became polymerized to form DNA, RNA, and proteins

Origin of Life: Stage 3

Polymers became enclosed in membranes, separating them from the environment

Origin of Life: Stage 4

Polymers enclosed in membranes acquired cellular properties

Reducing Atmosphere hypothesis

Atmospheric reactions with lightning, solar, and cosmic radiation

Deep-sea Vent hypothesis

Biologically important molecules may have been formed in the temperature gradient between extremely hot vent water and cold ocean water

Coacervates

Droplets that form spontaneously from the association of charge polymers

Liposomes

Vesicles surrounded by a lipid layer

Key functions of RNA:

1. Ability to store information
2. Capacity for self-replication
3. Enzymatic function

Sedimentary rock

Comprised of many layers. Sediments pile up and become rock

Stromatolites

Fossilized biofilms, form in layers. Can be used to extrapolate fossilized prokaryotes

Changes in living organisms are the result of:

1. genetic changes
2. environmental changes

Major environmental changes:

1. climate/temperature
2. atmosphere
3. landmasses
4. floods
5. glaciation
6. volcanic eruptions
7. meterorite impacts

Archaen

\-3.8 to 2.5 BYA \n -First cells are prokaryotic and heterotrophic \n -Little free oxygen, organisms were anaerobic \n -Autotrophs evolved as supply of organic molecules dwindled

Proterozoic

\-2.5 BYA-543 MYA \n -Multicellular eukaryotes arise 1.5 BYA \n -First animals are invertebrates \n -Bilateral symmetry facilitates locomotion

Cambrian

\- 543-490 MYA \n -Warm and wet with no ice at poles \n -Cambrian Explosion - abrupt increase in diversity of animal species (unknown cause) \n -All existing major types of marine invertebrates that no longer exist

Ordovician

\- 490-443 MYA \n -Diverse group of marine invertebrates including trilobites and brachiopods \n -Primitive land plants and arthropods first invade land \n -Towards end, abrupt climate change results in mass extinction (60% of marine invertebrates go extinct)

Silurian

\- 443-417 MYA \n -Coral reefs appeared \n -Large colonization by terrestrial plants and animals \n -Spiders and centipedes \n -Earliest vascular species

Devonian

\- 417-354 MYA \n -Ferns, horsetails, and seed plants (gymnosperms) \n -Insects emerge \n -Amphibians (tetrapods) emerge \n -Near end, series of extinctions eliminate many marine species \n -"Age of fish"

Carboniferous

\- 354-290 MYA \n -Rich coal deposits formed \n -Very large plants, trees, amphibians prevalent \n -First flying insects \n -Amniotic (terrestrially-adapted) egg emerges

Permian

* 290-248 MYA
\-Pangaea
* Amphibians prevalent, reptiles dominant
\-First mammal-like reptiles appeared
\-Largest known mass extinction event at the end (90-95% of marine species)

Triassic

\- 248-206 MYA \n -Reptiles plentiful \n -First dinosaurs and first true mammals \n -Gymosperms dominant land plant \n -Volcanic eruptions led to global warming and mass extinctions near end

Jurassic

\- 206-144 MYA \n -Gymnosperms still dominant \n -Dinosaurs dominant land animals \n -First known bird \n -Mammals present but not prevalent

Tertiary

\- 65-1.8 MYA \n -Mammals that survived expanded rapidly \n -Angiosperms became dominant land plant \n -Whales appeared \n -Hominoids appeared 7 MYA

Quarternary

\- 1.8 MYA to present \n -Periodic ice ages cover Europe and North America \n -Certain hominoids become more human-like \n -Homo sapiens appear 130,000 years ago

Geological Time Scale

1. Archaen - bacteria and archaea
2. Proterozoic - eukaryotes
3. Phanerozoic - Paleozoic (land colonized), Mesozoic (dinosaurs), Cenozoic (hominoids)

Ring of Cenotes

Modern-day signature of the subsurface Chicxulub crater

Chicxulub crater

Location of meteor impact that killed the dinosaurs at the end of the Cretaceous

Evolution

Heritable change in one or more characteristics of a population from one generation to the next

Microevolution

Changes in allele frequency in a population over time

Population

All members of a species that live in the same area and have the opportunity to interbreed

Linnaeus

Classified nature with a nested hierarchy (binomial nomenclature)

Observations of Evolutionary Change:

1. Fossils
2. Biogeography
3. Convergent evolution
4. Artificial selection
5. Homology

Biogeography

Study of the geographical distribution of extinct and living species

Convergent evolution

Two different species from different lineages show similar characteristics because they occupy similar environments

Artificial selection

Programs and procedures designed to modify traits in domesticated species

Anatomical homology

Fundamental similarity due to descent from a common ancestor (ex: human hands and bat wings)

Molecular homology

DNA sequences of related species tend to be similar

p53 proteins

Plays a role in preventing cancer

Molecular processes that underlie evolution:

1. Homologous genes
2. Gene duplication
3. Exon shuffling
4. Horizontal gene transfer
5. Genomic level changes

Homologous genes

2 genes derived from the same ancestral gene

Paralogs

Homologous genes within a single species

Exon shuffling

When an exon (parts of a gene that encode protein domains) and the flanking introns are inserted into a gene

Genomic level changes

Large changes in chromosome structure and number

Allele

A variant form of a gene

Genotype

Genetic makeup or hereditary information composed of multiple alleles

Allele frequency

\# of copies of an allele/total # of alleles in a population

Genotype frequency

\# of Indies with a particular genotype/ total # of indivs in a population

Hardy-Weinberg equation

p2 + 2pq + q2 = 1

Hardy-Weinberg conditions:

1. No new mutations
2. No natural selection
3. Large population - allele frequency doesn't change due to random sampling error
4. No migration between different populations
5. Random mating

How do changes happen?

1. Introduction of new genetic information (mutations)
2. Mechanisms that alter the prevalence of alleles/genotypes