Exam 3 Flashcards
Key stages of 1st few rounds of cell division
- Fertilized egg
- Four-stage cell
- Early Blastula
- Later Blastula
Fertilized egg
- Before 1st clevage division
- Surrounded by fertilization envelope
Four-stage cell
-After 2 clevage divisions
Early Blastula
- Embryo= multicellular ball
- Surrounded by Fert. envelope
- Blastoceol begun to form at center
Later Blastula
- Single layer of cells surrond blastocoel (fluid-filled cavity)
- Fert. envelope still present
Gastrulation
- A set of cells at or near surface of blastula moves to an interior location
- Cell layers are established
- Primitive digestive system formed
Steps of Gastrulation
- Single sheet of cells cover surface of blastula
- Group of cells buckle into blastoceol, forming shallow depression
- Continued invagination forms archenteron
- Open end of achenteron formed= blastopore
- Tip of archenteron reaches embryo surface–> complete formation of gut of embryo= gastrula
Diploblasts
- Gastrulation forms the two germ layers of the ectoderm and endoderm (one opening for mouth and anus)
- Blastopore becomes open end of gastovascular cavity
- Not monophyletic
Protostomes
- Ectoderm, endoderm, mesoderm
- Mouth forms from blastopore
- Anus forms when antercheron joins w/ other side
- Not monophyletic
Deuterostomes
- Ectoderm, endoderm, mesoderm
- Mouth forms opposite of blastopore (anus)
- Monophyletic
Fate Map
- Diagrams showing the structures arising from each region of an embryo
- Branch separation= cell division
Determination
- The progressive restricition of developmental potential in which the possible fate of each cell becomes more limited as the embryo develops
- Uses cytoplasmic determinants and Induction
Differentiation
-The process by which a cell or group of cell become specialized in structure and function
Cytoplasmic determinations
- Molecules inside cytoplasm of a cell
- Determine what cell will become
- Uses transcription factors
- Ex: P granules induce dtermination by migrating to one side of cell (active process_
Induction
- Cell signalling process
- Surrouning cells tell other cells what to become
- Influences determination
Hox Genes
- Shared homobox, 180 basepair region that is highly conserved
- Evidence of common descent= basepair is conserved, found in all species in variation
Etiolation
- Plant moropholical adaptations for growing in darkness
- Shoot response using signal transduction
- Ex: potatoes left in dark drawer
- Stem characteristics= White (no chlorophyll for photosynthesis), thick, extremely reduced leaves
De-etiolation
- The changes a plant shoot undergoes in response to sunlight (greening)
- Light is transduced into response of greening
Signal Transduction in De-etiolation
- Photochrome activated by light
* **A) cGmp= second messenger, activates protein kinase 1
* **B)Ca+ channel opens, activates protein kinase 2 - Transcription factor 1 (a) or 2 (b) is transcribed in nucleus (expression of genes for proteins that fxn in de-etiolation response)
- Translation–> de-etiolation (greening) response proteins
Tropism
-Movement towards a stimulus (+) or away from stimulus (-)
Phototropism
- The growth of a shoot towards light (positive) or away from light (negative)
- Adaptive bcuz difficult to reach light in crowded or shaddy environments
Thigmotropism
- Movement towards or away from touch
- Ex: venus fly trap
- Adaptive bcuz helpful when avoiding herbavores or sensing food
Gravitropism
- Statoliths sink to bottom of shoots in response to gravity
- Adaptive bcuz plant knows which way is up and down, knows which direction to grow in
Dendrites
-Highly branched extensions that recieve signals from other neurons
Cell body
-Neuron’s organelles, including nucleus, connects dentrites to axon
Axon
-Long branch off of cell body, transmits signals to other cells
Synapse
- The branched ends of an axon
- Transmit info to another cell at junction
- Use neurotransmitters to pass info to recieving cell
Membrane Potential
- Charge difference, or voltage, across the plasma membrane
- Positive Outside, Negative Inside (PONI)
- Changed by sodium potassium pump, sodium channel, and potassium channel
Hyperpolarization
- Increase in magnitude of membrane potential (away from 0 mV)
- Inside of membrane is more negative
- Open potassium channel, K+ moves outside
Depolarization
- Reduction in magnitude of membrane potential (towards 0 mV)
- Inside= more positive
- Open sodium channel, sodium moves inside
Resting State
Step 1
- Gated Na and K channels are closed
- Ungated channels maintain resting potential (PONI)
Depolarization Step
Step 2
- A stimulus opens some Na channels
- Na inflow through channels depolarize membrane
- If reaches threshold, triggers action potentional
Rising Phase of Action Potential
Step 3
- Depolarization opens most sodium channels
- Potassium channels= closed
- Na influx makes inside + with respect to outside
Falling Phase of Action Potential
Step 4
- Na channels inactivated by inactivation loop, blocks Na inflow
- Potassium channels open, permitting K outflow (inside neg again)
Undershoot
Step 5
- The sodium channels close
- Potassium channels still open
- When potassium channels close, sodium channels unblock (still closed)
- Membrane returns to resting state
Myelin Sheath
- The electrical insulation that surrounds vertebrate axons
- Produced by Schwann cells
Nodes of Ranvier
- Gaps in the myelin sheath
- Where voltage-gated sodium channels are restricted
- Signals jump from one to another
Myelin Sheath, Nodes of Ranvier and Conduction
- Allows for rapid saltatory conduction
- Action potential jumps from node to node bcuz cannot go through myelin sheath
Na+ in, K+ out
- Depolarizes (inside less neg, outside more +)
- Excites
Cl- in, K+ out
- Hyperpolarize (inside more neg, outside more +)
- Inhibits
Central NS
- The portion of the NS where signal integration occurs
- In vertebrate animals, brain and spinal chord
Peripheral NS
-The sensory and motor neurons that connect to CNS
Nerves
-A fiber composed primarily of the bundled axons of neurons
Brain
-Organ of the central nervous system where info is processed and integrated
Ganglion
-A cluster (functional group) of nerve cell bodies
Sympathtic NS
- Norepinephrine
- Pathway exits CNS midway along spinal cord through ganglia
- Bypasses CNS (reflex)
- Fight or flight responses
Parasympatheic NS
- Acetylcholine
- Nerves exit CNS at base of brain or spinal cord
- Rest and digest
Forebrain
- Cognition, decision making, learning, regulation of sleep, processing olfaction
- Parts: Cerebrum (cerebral cortex, basal nuclei), diencephalon (thalamus, hypothalamus, epithalamus)
Midbrain
- Sorting PNS signals and routing sensory input
- Parts: midbrain (part of brainstem)
Hindbrain
- Controls involuntary activities (blood circulation), coordinates motor activities (locomotion)
- Parts: pons (part of brainstem), cerebellum, medulla oblongata
Cerebellum
- Fxn: Coordinates movement and balance
- Helps in learning and remembering motor skills
- Location: Hindbrain
1 Year
- The Earth takes one full orbit around the sun
- Not a perfect circle, so the earth get less intensity of the sun than during the year
1 Day
- Earth rotates on its axes (23.5 degrees tilt)
- Because of the tilt, some parts of the Earth recieve more sunlight than other
- Each hemisphere spends half the year getting more sun than the other
Savanna
- Latitude: Near equator, between Tropics of Capricorn and Cancer
- Altitude: Varies from sea-level to 2,000 m
- Winds: seasonal, summer winds are SE, winter winds NE, wind stronger in winter( dry winds from North)
- Seasons= dry season of 8-9 months
- Ex: Africa
Temperate Broadleaf Forest
- Sun blocked by by heavy tree cover
- Lat: mid-lat northern hemisphere
- Wind: Strong winds knock down trees (decomp and disease)
- Water: community occurs near body of water, emphasizes different seasons
- Ex: Eastern US, Canada
Competition
(-/-) interaction that occurs when individuals of diff species compete for a resource that limits the survival and reproduction of each species
-Ex: two animals have same food source
Amensalism
(-/0) interaction between two organisms in which one is inhibited or destroyed and another is unaffected
-Ex: One animal eats all the food source of another animal, yet has other food to choose from
Antagonism
(-/+) interaction where one organism is benefitted, while the other is inhibited or destroyed
-Predation, parasite/host interactions, herbivory
Commensalism
(+/0) interaction btwn species that benefits one but neither harms nor helps the other
-Ex: clownfish get protection/ home from anemone
Mutualism
(+/+) interaction that benefits both species
-Ex: bird cleaning parasites off of animal
Niche
- The specific set of biotic and abiotic resources that an organism uses in its environment
- Where it lives, what it consumes (food, space, light)
- Two organisms cannot coexist if niches are identical
Fundamental niche
-The largest niche that an organism could theoretically occupy
Realized niche
-Subset of fundamental niche that an organism actually occupies under a particular set of circumstances
Character displacement
-An evolutionary response to a shifted realized niche, resulting in a change of the underlying fundamental niche
Species diversity
-The variety of different kinds of organisms that make up a community
Species richness
- The number of different species in a community
- Ex: frog, duck, bunny, lamb = 4
- Challenge bcuz doesn’t take into account abundance
- Can over look species if not careful
Shannon Diversity Index
- Takes into account species richness and abundance when calculating diversity
- H=-E(pi*lnpi)
- pi= (amount of 1 species)/ total # of species
- Ex: total= 20, 5 worms 5/20= .25= pi
Latitudinal Diversity Gradient
-Diversity increases as you aproach the equator
Why?
-Higher speciation rates
**More light and energy= faster reproduction, more mutations
**Species interactions less abiotic (environment), more biotic (each other)
-Lower extinction rates bcuz stable environemnt
Island Biography Theory
- On a smaller geographic scale, two basic variables can help explain differences in diversity between communities in same habitat type
- Variables= size of geographic area, distance from mainland
- Larger area means migrants more likly to find it
Size of Geographic area
- Bigger= increased diversity
- *Reduced competition
- *Diversity spacially in resources
- *More niches= lower extinction rate
Distance from Mainland of Similar Habitat
-Lower migration if further from mainland, diversty decreases
Trophic Level
- The positin an organism occupies in a food chain
- Ex: secondary consumer, primary consumer, primary producer
Secondary Consumer
-A carnivore that eats herbivores
Primary Consumer
- An herbivore
- Organisms that eats plants or other autotrophs
Primary Producer
- Autotroph
- Photosynthetic
- Make up the trophic level of an ecosystem that ultimately supports all other levels
MADS-box ABC model
- Sepal (green leaf, covers bud)= A activated, 1st
- Petal (showy)= A+ B activated, 2nd
- Stamens (male pollen)= B+C activated, 3rd
- Carpel (female ovules= C activated, 4th
- If one gene (A,B, or C) fails, you don’t see certain parts
Primary Succession
- A type of ecological sucession
- occurs in an area where there were originally no organisms present and soil has not formed
- Ex: Volcanic erruption
Secondary Succession
- A type of ecological sucession
- Exisiting community has been cleared by a disturbance that leaves soil or substrate intact
- Ex: Fire, flood, elephants
Pioneer stage
-1st community to establish from nothing
Climax stage
-Community that remains unchange w/o disturbances
Exponential growth
-Population that experiences such ideal conditions that it increases in size by a constant proportion at each instant in time Nt=N0e^rt Nt= current population size N0= initial pop size r= intrinsic pop growth rate t= time
Logisitic growth
-The per capita rate of population growth as it approaches 0 as population size nears carrying capacity (k)
Nt=N0e^rt *(K-N/K)
N= population
Carrying Capacity
- The maximum population size that a particular environment can sustain
- Ecological factors that prevent indefinite growth:
1. Competition
2. Predation
3. Disease
Time lags in population growth
-Most species do not reproduce instantaneously
**Eggs take time to hatch
**Reach reproductive maturity
Nt=N0e^rt(K-Nt-T0/K)
Nt-T= time lag
R-selected species
- High intrinsic reproductive rates
- Poor competitors
- Do not invest in offspring
- Ex: sea turtles
K-selected species
- Reproduce slowly
- Good competitors
- Large investment in offspring
- Ex: humans
Density dependent controls of population size
- Competition
- Territorality
- Toxic waste
- Intrinsic factors
Density independent controls of population size
- Stochastic events: treefalls, storms, mudslides
- Abiotic factors: temperature, moisture
- Interspecific interactions
Reasons for exponential growth in human population size
- Better healthcare–> decreased death rate
- Resource availability –> decreased competition
Consequences for human population growth
- Increased intraspecific competition
- Dividing finite resources among more people
Main carbon reservoirs
- Living things and soil
- Atmosphere
- Rocks and fossil fuels
- Ocean
Key mechanisms of moving carbon btwn reserviors
- Respiration (living things and soil–> atmosphere)
- Photosynthesis (atmosphere–>living things and soil)
- Weathering (rocks and fossil fuels–> atmosphere and ocean)
- Burning fossil fuels (rocks and fossil fuels–> atmosphere)
- Biological pump (ocean–> rocks and fossil fuels)
- Acid rain (atmosphere–>ocean)
- Mixing of air and water at ocean surface (ocean–> atmosphere)
Keeling Curve
- Positive relationship between time passing and atmospheric carbon in ppm
- Annual fluxuation (decreased during high photosynthesis and vice versa)
- Non-linear slope (accelerating)
Trend of atmospheric CO2 concentration
-CO2 concentration in the atmosphere has increased exponentially in the last 800,000 years
Ways scientists can estimate CO2 levels in the atmosphere
- Direct measurement from atmosphere
- Bubbles in ice core
How do CO2 levels affect the climate
-As CO2 concentration increases, temp increases (and vice versa)
Negative feedback loop involved in climate change
- Photosynthesis/ greening
- Increase atmospheric CO2–> increased photo–> decreased CO2
Positive Feedback loop involved in climate change
- Water vapor
- Increased temp–> increased evaporation–> more H2O vapor in atmosphere
Coral bleeching (ecological response to climate change)
- Photosynthetic microorganisms die (too hot from increased CO2)
- Leads to coral bleeching
- Spreads to other coral because they rely on each other
Extinction of polar bears and emperor penguins (ecological response to climate change)
-Ice melting due to increased temp from increased CO2, loss of habitat, species die
Ocean Acidification (ecological response to climate change)
- Increased CO2 absorbed into oceans
- As CO2 increased, temp increased, absorbtion decreased
- Ocean becomes more acidic, sensitive species like shellfish die
