Exam 4 Flashcards
population
an interbreeding group of conspecific individuals existing in a particular place at a particular time
- spaciotemporal grouping
- most have limited geographic range which can change through time
geneticists
look at individuals as collectors of genes
gene pool
is the set of all different alleles at all loci in every living member of the group, pool is characterized by its gene frequencies
-phenotypic variation among all populations
evolutionary change
life-forms have evolved varying characteristics as they have adapted to varied animals
texas cougar and florida panther
florida panther had kink in its tail but not much other differences, so they interbreed which got rid of kink but evolutionary potential and variation was enhanced
guppies
- colorful when just living alone or with killifish
- plain when living with cichlids
protein variation
- no allele A in south america and a lot in canada
- allele B is not very common in americas
- O is very popular in south america
DNA sequence variation
- there are sets of 3 nucleotides that specify and amino acid
- can exist and be physiologically unimportant
3 requirements for evolution by natural selection
- phenotypic variation must exist among individuals
- phenotypic variation must be genetically inherited
- that variation must result in different numbers of viable offspring being produces
violations of HWE assumptions
- non-random mating-
- gene flow (genetic migration)-movement of alleles from one population, homogenize allele frequencies, the rate depends on:
- rate of movement and differences in frequencies between populations - selection- not everyone is able to survive equally
- avoiding predators and matching environment - genetic drift- instead of infinitive population
- has unpredictable effects - mutation
- meiotic drive
mummichogs
- LDH variation
- moving from up north to south, LDH goes down in frequency bc they do not need LDH in warm weather
directional selection
- selection eliminates one extreme from a phenotypic array
- push, if a bunch of smaller animals die then the next generation will be bigger and it will shift
natural selection
- you are either fit or you are not
- natural selection is the process, evolution is the outcone
- fitness differences among phenotypes lead to changes that shape population to become more fit
stabilizing selection
selection acts to eliminate both extremes from an array of phenotypes
disruptive selection
selection eliminates intermediate types
-beak types
industrial melanism
- peppered moth
- across 1800-1850 moths near cities shifted from white morph to dark
- soot was killing tree lichens
- J Tutt and B Kettlewell developed evidence that birds selectively eat white morphs
Skeletal Muscle
- striated, multinucleated, neurogenic
- extracellular Ca does not change Vm
- attached to tendons and bones so when muscles contact the bones move at joints
- moves skeleton
cardiac muscle
- striated, uninucleate, myogenic
- extracellular Ca does change Vm
Smooth muscle
- not striated, uninucleate, myogenic
- extracellular Ca does change Vm
neurogenic
individual cells have to be told to contract by nerves
origin and insertion
origin: part of bone that doesn’t move
insertion: does move
tendons
attachment to bones on both sides of joint
sliding filament model
-sarcomere- functioning unit
-thin filament made of actin
-myosin- thick filament
the actin is winched along the myosin by successive rounds of myosin heads pulling, each head independent
-thick filament, flat, hinge, head
what makes the sliding filament model
long muscle fibers that contract by myofibrils, highly ordered arrangements of actin and myosin filaments
light regions
- I bands (Z line is center of I bands)
- isotropic
- thin filaments
dark regions
- A bands
- thick filaments
sarcomere reticulum
sacs of calcium filaments
mechanisms of contraction
- Z lines get closer during contraction
- A band does not change in width
- I band gets narrower due to thin filament moving between thick filaments (not physically shortened)
- each I band divided in half by disc of protein
sarcomere
- From Z line to Z line
- smallest subunit of muscle contraction
- myofibrils contract (functionally shorten), ATP and Mg
Highly organized arrangement
- sets of six hexagons
- center of thick filament has more widely spread myosin molecules
- region in A band overlaps
- thick filament is able to interact with several thin filaments (series of interactions)
- thick filament change orientation during contraction to pull fibers together
Myosin Heads changing orientation
- Each head changes orientation independently
- pulls thin filaments closer
- makes I band narrower
- Z lines closer together
Contraction cycle
- myosin head has ATP, ADP, and inorganic phosphate
- head has high affinity for actin attachment
- ADP and Phosphate cause head to bind to actin
- myosin begin pulling, sharp change in orientation
- pulls thin filament toward sarcomere, releasing ATP and P
- head loses ATP and fiber dissociates
- ATP and phosphate on head shift head back to original binding sight
mechanisms of reproductive isolation
pre-mating: prevent wasting gametes
post-mating: prevent hybrids from surviving and reproducing
pre-mating mechanisms
- geographic
- habitat preferences
- seasonal differences
- physical differences
- behavioral isolation-different cells
post mating mechanisms
- genetic inviability
- hybrid inviability or sterility
allopatric speciation
most popular form of speciation (diversification)
- original population
- physical barrier
- reproductive contact
- differentiation/speciation (secondary contact)
buttercups in new zealand
the mountains made isolation and then they became different species
sympatric speciation
- Iris can pollinate with themselves
- apple maggot flies
- the influence of BMP4 on african cichlid jaws
Two views of speciation
- phyletic gradualism
- punctuated equilibrium
phyletic gradualism
due to an accumulation of differences that develop due to microevolutionary mechanisms (the same ones that cause change within a population)
Contraction Cycle extra
- hydrolysis of ATP causes change in orientation of the head
- actual movement of actin does not require ATP
- Mg is necessary for ATP->ADP
- -myosin heads act as ATPase (ATP->ADP)
role of Ca in contraction
- Actin and Myosin spontaneously contract without it
- tropomyosin-blocks myosin heads access to binding to actin
- doesnt directly help, uses NT
troponin
- actin on tropomyosin; when a muscle is relaxed myosin cannot bind to actin bc of tropomyosin
- for contraction to occur, troponin must move tropomyosin away from actin binding sites
- its complex shape is affected by Ca binding
Nerve Stimulate contraction
- somatic motor neurons stimulate skeletal muscle using action potential that goes to synaptic knob and opens voltage gated channels
- Release NTs from synaptic knob that interact with endplate
- axons from a single motor neuron synapse with a # of muscle fiber cells, a motor unit
- in the motor endplate or neuromuscular junction (synapse), the motor neuron releases acetylcholine onto myofiber cell
when fiber is stimulated at motor endplate
- LP is produces
- edges of endplate shift shift from ion-gated to voltage gated
- then an electrical impulse (AP) travels along the fiber cell membrane down to the transverse tubules (T tubules)
- voltage gated calcium and potassium channels changes orientation and polarization
- triggering release of Ca from sarcoplasmic reticulum
- the cytoplasmic Ca concentration is raised and Ca binds to troponin