deck_1141064 Flashcards
Evolution
Changes in the genetic make-up of populations of a species over generations.
Factors that cause evolution.
- Natural selection- Gene flow- Genetic drift- Bottlenecking- Non-random mating
Use and disuse
Belief that the environment modifies traits.E.g., a giraffe’s neck lengthens due to it stretching to reach leaves.
Inheritance of acquired traits
Belief that acquired traits are passed on to offspring.E.g., the aforementioned giraffe passes on this trait to its offspring.
Gene flow
The mixing of genes through immigration and emigration.
Genetic drift
When random changes occur in the genetic make-up of a population. Most significant in small populations.
Bottlenecking
When the original population has genetic diversity, but an event causes similar groups to be wiped out. The remaining population is very homogenous.
Non-random mating
Occurs through:- Inbreeding- Sexual selection
Hierarchy of biological order
- Atoms- Molecules- Organelles- Cells- Tissue- Organ- Organ System- Organism
Atom (e.g.)
Oxygen atom
Molecule (e.g.)
DNA
Organelles (e.g.)
Cell nucleus
Cells (e.g.)
Cardiac muscle cell
Tissue (e.g.)
Cardiac muscle tissue
Organ (e.g.)
Heart
Organ system (e.g.)
Circulatory system
Organism (e.g.)
Zebra
What are the smallest units of life?
Cells
Scientific method
- Observations- Question- Hypothesis- Prediction- Test (experiment or additional observation)If correct, retest. If incorrect, revise or replace hypothesis.
Charles Darwin
Discovered the mechanism for evolution and developed the theory of evolution through natural selection.- Carapace shape in Galapagos tortoises- Marine iguanas adapted to eat algae- The Origin of Species- A. Wallace developed same theory
Darwinian evolution
A gradual change in populations over time as a result of natural selection.
Species survival relies on the abilities to…
- Obtain resources- Survive- Reproduce
Modern synthesis of evolution
- Individuals that make up a population are not identical.2. Some of this variability is heritable, passing in genes.3. In most generations, more offspring are produced than can survive.4. Survival and reproduction are not random effects, but those best able to obtain resources, survive, and reproduce will pass on their genes.
Other causes of evolution
- Gene flow- Genetic drift- Bottlenecking- Non-random mating
Gene flow
The mixing of genes through immigration and emigration.
Genetic drift
Random changes in the genetic make-up of a population over time. These are most significant in small populations. E.g., eye color in people.Types:- Population bottleneck- Founder effect
Founder effect
When a small population of a colony breaks off and the genetic diversity of this smaller colony is much more homogeneous, misrepresenting its founder.
Non-random mating
- Inbreeding- Sexual selection
Microevolution
Evolution that does not result in a new species, but changes the genetic make-up of existing populations. - Most common
Macroevolution
Evolution that results in a new species. - Rare, requires special circumstances and a significant amount of time. - Also called “speciation.”
Artificial selection
Done by humans. E.g., crops and domestic animals.
5 Kingdoms
- Plantae (eukaryotes)- Fungi (eukaryotes)- Animalia (eukaryotes)- Protista (eukaryotes)- Monera (prokaryotes)
Spontaneous generation
Incorrect hypothesis that life originated from non-living things.
Biogenesis
Synthesis of organic compounds from inorganic precursors.
Inorganic compounds
Do not possess a carbon skeleton. May possess one carbon atom.
Louis Pasteur
Conducted experiments to show that life comes from life, supporting his biogenesis hypothesis. - Chicken broth in flasks with straw
The first life form was…
Anaerobic and prokaryotic
Protobiont
Abiotically formed cell.
Hypothetical steps to formation of the first cell
- Assemble simple molecules into building blocks for complex polymers2. Assemble polymers that can store information and catalyze reactions.3. Add membranes and an energy source to make a living organism.
Phospholipids
Form vesicles in water.
Organic compounds found in cells
- Proteins (amino acids)- Sugars- Fats- Genetic material (DNA/RNA)
Ribozyme
RNA molecule that was likely the first molecule to carry genetic information, replicate itself, and speed up chemical reactions.
Steps to abiotically formed cells
- Spontaneous formation of lipids, carbs, amino acids, proteins, and nucleotides.2. Formation of protein-RNA systems and lipid spheres.3. Self-replicating system enclosed in selectively permeable, protective lipid sphere.4. Membrane-bound protobionts5. Living cells (prokaryotic and eukaryotic)
History of life on Earth summarized
- Abiotic synthesis of small, organic molecules.2. Joining of molecules into polymers (chains of organic molecules)3. Origin of self-replicating molecules as genetic material.4. Packing of these molecules into protobionts, formed by many abiotically produced molecules.5. First cells anaerobic and prokaryotic, followed by aerobic and photosynthetic prokaryotic cells.6. Eukaryotic cells are formed, initially single-celled and then multicellular.
Prokaryotic cell structure
- No interior membrane for nucleus- May have flagella for locomotion- Pili for grip- Gelatinous outer capsule - Cell wall - Plasma membrane - Cytoplasm - Nucleoid + Contains genetic material - Plasmid + Carries resistance to antibiotics - Ribosomes
Prokaryote shapes
- Bacilli- Cocci- Spirochetes
Bacilli
Rod shaped
Cocci
Spherical
Spirochetes
Spiral shaped
Prokaryote
Single-celled (usually) organism that has neither a distinct nucleus with a membrane nor other specialized organelles such as mitochondria or chloroplasts.
In what order did prokaryotes and eukaryotes evolve?
- Heterotrophic prokaryotes2. Autotrophic prokaryotes (photosynthesis) a) Do not possess chloroplasts but may possess chlorophyll.3. Aerobic respiration4. Unicellular eukaryotes5. Multicellular eukaryotes
Endosymbiotic theory
Origin of eukaryotic cells: - Ancestral prokatyote’s plasma membrane unfolds to form the endoplasmic reticulum and nucleus.- This cell then engulfed aerobic heterotrophic prokaryote cells which developed into mitochondria. + These cells became heterotrophic eukaryotes. - Animals and fungi today.- Some of the cells also engulfed autotrophic prokaryote cells which developed into plastids, or chloroplasts. + These cells became photosynthetic eukaryotes. - Plants and algae today.
Eukaryotic cell structure
- Contains a nucleus with DNA as well as mitochondria and other organelles. + These organelles are membrane-bound.- Autotrophic eukaryotes will also possess plastids, or chloroplasts.- Contains a plasma membrane, cytoplasm, and other structures found in prokaryotes.
Monera
Prokaryotes- Bacteria- Archaea
Protista
Eukaryotes, mostly unicellular
Classification of life
- Domain + (Eu)bacteria, archaea, eukarya- Kingdom + Monera, protista, plantae, fungi, animalia- Phylum- Class- Order- Family- Genus- SpeciesMany biologists believe that kingdoms Monera and Prostista should be split into multiple kingdoms for different varieties of each.
Taxonomy
The study of species identification.
Binomial nomenclature
Invented by Linnaeus. Capitalized genus, lowercase species. Name must be underlined or italicized.
Archaea
Domain of unicellular microorganisms that lack a nucleus or membrane-bound organelles. Similar to bacteria but possess a few different qualities and evolved differently as well. - Thermophiles - Halophiles - Methanogens
Thermophiles
Heat-loving prokaryotes
Halophiles
Salt-loving prokaryotes
Methanogens
Methane-producing prokaryotes
Why is bacteria dangerous?
A bacteria cell’s metabolism allows it to release toxins.
What are the most common prokaryotes?
Bacteria
Autotrophs
Produce their own organic compounds from carbon dioxide. - Phototrophs - Chemotrophs
Phototrophs
Use light energy to produce chemical energy (ATP) to be used by the cell. - E.g., cyanobacteria.
Chemetrophs
Use energy from inorganic chemicals to produce chemical energy (ATP) to be used by the cell. - E.g., purple sulfur bacteria.
Heterotrophs
Must consume organic molecules for energy and as a source of carbon to produce their own organic molecules.
Oxygen requirements
- Obligate aerobes- Facultative aerobes- Anaerobes
Obligate aerobes
Microorganisms that require oxygen to perform cellular respiration and cannot grow without it.
Facultative aerobes
Microorganisms that grow in the presence of oxygen but will switch to anaerobe mode in the absence of oxygen.
Anaerobes
Microorganisms that do not require oxygen to produce chemical energy (ATP). - May die when exposed to oxygen.
Conjugation
Sexual reproduction in bacteria, accomplished by cell to cell contact or a bridge-like connection between cells to exchange DNA.
(Eu)bacteria
Major ecological roles:- Symbiosis + Mutualism + Commensalism + Parasitism/Pathogens- Photoautotrophs + Cyanobacteria- Decomposers + Break down organic molecules and recycle nutrients.
In eukaryotes, DNA is always found in the…
Nucleus
Regarding their chromosomes, eukaryote cells may be either…
Haploid or diploid
Haploid (n)
A cell with unpaired chromosomes, regardless of the number of chromosomes it has.
Diploid (2n)
A cell with paired chromosomes.
Mitosis
Process in which one cell splits to form two identical cells. - Haploid cell will produce 2 haploid cells and diploid cell will produce 2 diploid cells.
Cytokenesis
Process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis or meiosis to ensure that chromosome number is maintained from one generation to the next.
The cell wall of plants differs from other eukaryotes in that it is made of…
Cellulose
The only haploid cells in the human body are..
Sperm and egg
Meiosis
Necessarily for the reproduction of eukaryotes. Enables a diploid cell to split into 4 haploid daughter cells.
Types of sexual reproduction
- Isogamy- Anisogamy- Oogamy
Isogamy
Similar motile gametes
Anisogamy
Dissimilar motile gametes
Oogamy
One large, motile gamete (egg) and a smaller motile gamete (sperm).
Reproductive life cycle of Laminaria (unicellular green algae)
- Mature algae is a 2n sporophyte. Contains sporangia that undergo meiosis to create haploid zoospores. - These zoospores develop into gametophytes that are either male or female, and come together as sperm and egg to create a 2n zygote that continues to be supported by its haploid female half.- This zygote matures into a new sporophyte.- Oogamy reproduction
Meiotic types
- Zygotic- Gametic- Sporic
Zygotic
Zygote (2n) undergoes meiosis to form 4 cells (n) - Used by most fungi and some algae.
Gametic
Organism (2n) undergoes meiosis to form 4 gametes (n)- Used by animals
Characteristics of Kingdom Protista
- Mostly unicellular, filamentous, colonial and multicellular organisms (with simple structure), eukaryotic cells- Polyphyletic origin, meaning that have distinct origins and are unrelated.
Protists are grouped by…
Ecological role
Ecological roles of protists
- Producer (autotrophic/plant-like)- Consumer (heterotrophic/animal-like)- Both
Autotrophic protists
- Phylum Crysophyta- Phylum Phaeophyta- Phylum Rhodophyta- Phylum Chlorophyta
Phylum Crysophyta
“Golden brown algae”- Diatoms are found in this phylum- Mostly unicellular or colonial- Chlorophyll A & C plus other pigments- Cell wall made of cellulose or pectin
Diatoms
- Unicellular or colonial- Chlorophyll A & C plus other pigments- Cell wall made of silica or pectin- Limited locomotion- Significant source of oxygen- Great diversity of shells- Make up diatomaceous earth
Phylum Phaeophyta
“Brown algae”- Kelp and sargassum found in this phylum- Mostly multicellular- Chlorophyll A & C plus other pigments- Structure: holdfast (roots it), stipe (stem), frond (leaf division), vessel cells
Phylum Rhodophyta
“Red algae”- Mostly multicellular- Chlorophyll A & D and deep water pigments- Lack flagella- Cell walls of cellulose (deposits of calcium carbonate)- Coralline algae (looks like coral)/calcareous- Extracts: carragean and agar
Phylum Chlorophyta
“Green algae”- Unicellular, colonial or multicellular- Chlorophyll A & B- Cell wall: celluse and pectin- Locomotion: flagella- Ancestor of land plants- Chlamydomonas (unicellular), Volvox (colonial), and Ulva (multicellular), Caulerpa
Mixotrophic (autotrophic/heterotrophic) protists
- Phylum Euglenophyta- Phylum DinoflagellataFeed through photosynthesis as well as on other organisms.
Phylum Euglenophyta
- Mostly unicellular- When present, chlorophylls A & B- 2 flagella- Lack cell wall- Stigma (eyespot) + Used for light detection- Euglena genus belongs to this phylum
Phylum Dinoflagellata
- Unicellular- Possess 2 flagellum- When present, chlorophylls A & C and other pigments- Cellulose cell wall- Bioluminescent- Responsible for red tide and other toxins- Includes Pfiesteria (flesh eating bacteria) and zooxanthellae
Heterotrophic protists
- Kingdom Diplomonadida (animal-like)- Kingdom Parabasalia (animal-like)- Phylum Choanoflagellida (animal-like)- Phylum Kinetoplastida (animal-like)- Phylum Apicomplexa (animal-like)- Phylum Ciliophora (animal-like)- Phylum Rhizopoda (animal-like)- Phylum Actinopoda (animal-like)- Phylum Foraminifera (animal-like)- Phylum Oomycota (fungus-like)- Phylum Myxogastrida (fungus-like)- Phylum Dictyostelida (fungus-like)
Protozoans
Heterotrophic protists
Kingdom Diplomonadida
- Mostly parasites of guts- Unicellular- Multiple flagella- No plastids- No mitochondria- E.g., Giaridia lamblia (internal parasite)
Kingdom Parabasalia
- Mostly parasites or commensals of guts- Unicellular- No mitochondria- Multiple flagella- E.g., trichomonas vaginalis
Phylum Choanoflagellida
- Unicellular or colonial- Single flagellum encircled by collar- Feeds by creating a current with its flagellum to bring food into its collar.- May have given origin to animals
Phylum Kinetoplastida
- Contain a “kinetoplast” + Kinetoplast contains extra nuclear DNA- Single, large mitochondrium- Unicellular- Possess flagella- Symbiotic or pathogenic + Trypanosoma (African sleeping sickness, transmitted by the tse tse fly through protists in the bloodstream) + Chagas disease (bugs in mud houses) + Leishmania (feeds on cartilage)
Phylum Apicomplexa
- All species are parasites- Non-motile adults- Malaria + Main symptom is fever + Caused by mosquito (Plasmodium sp.) which occurs in 3 stages: - Sporozoite - Merozoite (in the liver, Cryoptozoite) - Gametocyte
Oocyst
A cyst containing a zygote formed by a parasitic protozoan such as the malaria parasite.
Phylum Ciliphora
- Unicellular- Surface covered by cilia- Specialized organelles + Contractive vacuoles + Complex cytoskeleton- Mostly free-living (not a pathogen/parasite)- Two types of nuclei + Macronucleus - Chromosomes found here + Micronucleus - DNA for sexual reproduction found here- Use binary fusion for reproduction- E.g., Parameciums & Ciliates + Parameciums feed on anything smaller than them and release waste into surrounding water.
Phylum Rhizopoda
“Amoeba”- Unicellular- No shell- Contain pseudopods + Lobed expansions of the body used for locomotion and feeding- Free-living or parasitic- E.g., Amoebas and Vampyrella
Phylum Actinopoda
“Amoeba-like with silica shells”- Unicellular- Contain actinipods + Ray-like pseudopods- Typically plankton- E.g., Heliozoans and Radiolarians- Covered in holes
Phylum Foraminifera
“Amoeba-like with calcium shells”- Unicellular- Chambered porous shells- Similar to Actinopoda but with chambers instead of holes
Phylum Oomycota
“Water and slime molds”- Commonly known as “blights”- Marine, freshwater, and terrestrial (require water)- Reproduce asexually and sexually- Reproduce through zoospores
Zoospores
Flagellated spores
Life cycle of Oomycota
Asexual:- Completely diploid- Zoospore develops into a cyst- Cysts develops germ tube- This forms into a zoosporangium- Zoosporangium releases new zoosporesSexual:- Release of zoospores from zoosporangium- 2n zoospores undergo meiosis to create egg nucleus and sperm nuclei, contained in the oogonium.- Fertilization occurs and 2n zygotes, called oospores, are released from the oogonium.- Zygote germination occurs and oospores develop into zoosporangium.- Release of zoospores from zoosporangium
Zoosporangium
A sporangium or spore case in which zoospores develop.
Oogonium
Contains egg nucleus and sperm nuclei of Oomycota
Oospores
Created by sexual reproduction of Oomycota
Phylum Myxogastrida
“Plasmodial slime mold”- Plasmodium (2n) + Single mass of cytoplasm with several nuclei with amoeboid movement (no cell wall)- Reproduction + Sporangium with spores (n)- Terrestrial- Locomotion: pseudopodia
Plasmodium
Single large cell with hundreds of nuclei that are all connected. - Grows sporangia in the absence of food or water. + Sporangia are reproductive structures that may release spores.
Life cycle of Physarum (plasmodial slime mold)
- Mature plasmodium develops young sporangium.- Sporangium matures and mature sporangium has a stalk. Undergoes meiosis to release (n) spores.- Spores germinate and develop into either a flagellated cell or amoebic cell.- Cells reproduce, but only flagellated with flagellates and amoebic with amoebic.- Both result in a 2n zygote.- Zygotes undergo mitotis to form a larger, feeding plasmodium.- Feeding plasmodium develops into mature plasmodium, able to fruit.
Phylum Dictyostelida
“Cellular slime mold”- Contain pseudoplasmodium + Similar to plasmodium but there is separation between cells.- Locomotion: pseudopodia- Sporangium- Utilize cAMP- Cell wall made of cellulose- May form multicellular colonies in the absence of food.- Colony grows “fruiting bodies” for the release of spores.
Life cycle of Dictyostelida (cellular slime mold)
Asexual (completely n):- Solitary (feeding stage) amoeba cells aggregate (come together to form a whole)- Aggregate cells develop into migrating colony- Colony develops stalks with bulbs on the end called “fruiting bodies”- Fruiting bodies release spores- Solitary amoebas emerge from sporesSexual:- Amoebas (n) released from zygote (2n) through meiosis- Amoebas aggregate- Amoebas fertilize one another to create new zygote
Feeding of fungus-like amoebas
Release enzymes outside of the body onto food source. Digestion takes place outside of the body and is then absorbed.
Three types of locomotion for heterotrophs
- Pseudopodia- Flagellum- Cilium
Syngamy
The fusion of two cells, or of their nuclei, in reproduction.
Pseudopodia
Cellular extensions used to move and feed.- Protists with these are usually amoebas.- Two types + Lobed - Short, bulbous lobes, typical of amoebas. - Called “lobopodia” - Found in Rhizopoda and Sarcodina + Thin - Long, thin pseudopods - Called “axopodia” or “actinopodia” - Found in Radiolaria and Heliozoa
Flagellum
Whip-like tail(s) for locomotion. - Microorganisms with flagellum are called “flagellates.”
Cilium
Short, hair-like extensions used for feeding and locomotion. - Microorganisms that have cilium are called “ciliates.”
How do slime molds feed?
Fungus-like feeding mechanism
