Final Exam Flashcards
gene pool
combination of all the genes (including alleles) present in a reproducing population or species
allele frequency
how common an allele is in a population. It is determined by counting how many times the allele appears in the population then dividing by the total number of copies of the gene.
genotype
the genetic makeup of an organism
phenotype
observable characteristics in an individual resulting from the expression of genes;
germ-line mutations
gene change in a body’s reproductive cell (egg or sperm) that becomes incorporated into the DNA of every cell in the body of the offspring. Germline mutations are passed on from parents to offspring.
somatic mutations
mutations that occurs in any other cells besides sex cells. They cannot be passed on to offspring
evolution
the change in the characteristics of a species over several generations and relies on the process of natural selection.
natural selection
the process through which populations of living organisms adapt and change.
Genetic drift
the change in frequency of an existing gene variant in the population due to random chance.
prezygotic mechanism
takes place before fertilization occurs between gametes and prevents different species from sexually reproducing
post-zygotic mechanism
a mechanism that blocks reproduction after fertilization and zygote formation
temporal separation
form of reproductive isolation in which two populations reproduce at different times.
ecological separation
reproduction is prevented because species live in distinct habitats and rarely encounter each other
allopatric speciation by dispersal
when a few members of a species move to a new geographical area
allopatric speciation by vicariance
takes place when a geographic barrier arises, disrupting the gene flow between subpopulations.
peripatric speciation by vicariance
new populations are formed by a small group of individuals that break off from the main group and form a new group on the periphery (outer border)
monophyletic taxon
a grouping of all species descended from a common ancestor, including that ancestor
paraphyletic taxon
A common ancestor and some of its descendants.
polyphyletic taxon
a grouping with no recent common ancestor.
homologous characters
characters in different organisms that are similar because they were inherited from a common ancestor that also had that character
analogous characters
having the same or corresponding roles (function) but do not share a common evolutionary origin.
How do fossils form, what type of organisms are most likely to be fossilized and why are fossils useful for phylogenetic analysis?
the soft parts of the animals body decompose leaving the hard parts, like the skeleton, behind. This becomes buried by small particles of rock called sediment. Fossilization usually occur in organisms with hard, bony body parts, such as skeletons, teeth, or shells. Fossils provide our only direct window into evolutionary events in the distant past.
What is significant about the fossil Lucy (Australopithecus afarensis)?
a 3.2 million-year old fossil skeleton of a human ancestor, it proved that our early human relatives habitually walked on two legs.
Where and how long ago did modern humans evolve? How do they(we) fit into the primate phylogenetic tree?
Evolved in Africa, 300,000 years ago, humans are primates and we are more closely related to all primate species than we are to any animals living today.
phototroph
an organism that can use visible light as a primary energy source for metabolism, a process known as photosynthesis
chemotroph
organisms that obtain energy by the oxidation of electron donors in their environment.
autotroph
an organism that can produce its own food using light, water, carbon dioxide, or other chemicals.
Heterotroph
an organism that eats other plants or animals for energy and nutrients.
Horizontal gene transfer can involve transduction, transformation or conjugation. What are these?
Transduction: DNA is transmitted from one cell to another via a bacteriophage.
Transformation:a DNA fragment from a dead, degraded bacterium enters a good recipient bacterium and exchanges for a piece of DNA of the recipient.
Conjugation: the process by which one bacterium transfers genetic material to another through direct contact.
Microbial mats: main types of metabolic activities as a function of depth.
often centimeter-thick multilayered structures of microorganisms, mainly bacteria, archaea, fungi, and sometimes these mats are enriched with protozoans.
Archaeons vs bacteria?
Bacteria contain peptidoglycan in the cell wall; archaea do not.
cytoskeleton
a network of fibers extending through cytoplasm that provides mechanical support & maintains the cell’s shape.
phagocytosis
the process by which white blood cells, known as phagocytes, engulf and digest cells - thereby destroying them
meiosis
A process in cell division during which the number of chromosomes decreases to half the original number
mitosis
Part of cell division in eukaryotic cells in which the nucleus divides eventually producing 2 daughter cells which are genetically identical to the parent cell.
polyploid
when an organism has more than two complete sets of chromosomes in its somatic cells.
haploid
the term used when a cell has only one set of chromosomes
diploid
a cell or organism that has paired chromosomes, one from each parent
endosymbiotic theory (mitochondria/chloroplast)
How eukaryotic cells evolved from a prokaryotic cell engulfing another prokaryotic cell. mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote)
What is (provide examples):
i) opisthokont. ii) archeplastid
i) a large supergroup of eukaryotes including metazoans and fungi ex.choanoflagellates
ii)the group containing essentially all of the primary algae ex.Rhodophyta
What is a choanoflagellate?
a globally distributed group of marine and freshwater protozoans ( one-celled animals)
bulk flow (provide examples)
the active transport of molecules throughout an organism’s body. Bulk flow is found in simple multicellular organisms, but not unicellular organisms. (frog,fish)
cadherins
transmembrane proteins that mediate cell–cell adhesion in animals.
plasmodesmata
membrane-lined passages that connect the cytoplasm of adjacent cells and allow small molecules to move freely between the two cells.
gap junctions
linkage of two adjacent cells consisting of a system of channels extending across a gap from one cell to the other, allowing the passage of ions and small molecules.
vascular plant, non vascular plant (examples)
vascular, which do actively control their hydration by drawing up water from the soil. Non-vascular plants lack a specialised vascular system for transporting water and nutrients.
crassulacean acid metabolism (CAM)
A number of plants have evolved a mechanism to limit water loss whereby they open their stomata to capture CO2 at night when the air is cool, which limits the rate of evaporation. CAM provides a system for overnight storage of CO2, converting CO2 into a form that will not diffuse away.
photorespiration
When O2 is the substrate, it results in a net loss of energy and release of CO2, a process called photorespiration.
cuticle
the outermost layer of plants, which protects plants against drought, extreme temperatures, UV radiation, chemical attack, mechanical injuries, and pathogen/pest infection.
transpiration
Evaporative loss of water vapor from leaves
xylem
The inner tissue that transports water from the roots to the leaves.
phloem
outer vascular tissue, called phloem, transports carbohydrates from leaves to the rest of the plant body.
shoot
The leaves, stem, and reproductive organs collectively form
root hair
To absorb water from in between soil particles. Epidermal cells in active areas of the root produce slender outgrowths
root Casparian strips
a thin band of hydrophobic material that encircles each cell.
angiosperms (main definition and example)
plants produce seeds encased in “fruits,” which include the fruits that you eat, but which also includes plants you might not think of as fruits, such as maple seeds
gymnosperms (main definition and example)
Plants that produce seeds that are not enclosed in an ovary. ex.pine tree
sporophyte/gametophyte/spores/gametes (as they apply to mosses, gymnosperms and angiosperms):
pollen – what is it?:
gametophyte is attached and nutritionally dependent on sporophyte. Sporophytes are diploid plants. Gametophytes are haploid plants. Sporophytes have two sets of chromosomes. Gametophytes have a single set of chromosomes. Sporophytes reproduce asexually.
dendrite:
a fiberlike extension from the cell body of a neuron that receives signals from other nerve cells or from specialized sensory endings; the input end of a nerve cell
cell body
contains the nucleus, and provides the life processes of the entire cell. also, integrates the information received by the dendrites
axon terminal
end of axon and beginning of junction with other cells where messages are transferred via chemicals called neurotransmitters; transfers to dendrite
axon hillock
the junction of the nerve cell body and its axon, which imitates an action potential
synapse
a junction through which the axon terminal of a nerve cell communicates with a neighboring cell
myelin
Glial cells form multiple lipid-rich layers or sheaths, Myelin gives many nerves their glistening white appearance
resting membrane potential
the cell’s membrane voltage is negative on its inside relative to its outside.
action potential
A brief membrane electrical signal transmitted from the cell body one or more axons. An action potential is a brief electrical signal transmitted from the cell body along one or more axon branches
