Key Concepts Exam II - Purdue University · Key$Concepts$Exam$II$ •...
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Key Concepts Exam II • Chapter 20 Development and Evolutionary Change o Hox genes conserved homeotic genes found in vertebrates, Drosophila, and other animal groups. Hox genes contain the homeobox domain and specify pattern and axis formation in these animals o At sufficient concentration, bicoid stimulates transcription of the Hunchback gene. A gradient of that protein establishes the head. o Nanos mRNA is transported to the posterior end. Nanos protein inhibits translation of Hunchback. o Gastrulation: the process by which the three layers of the animal embryo are formed: ectoderm, mesoderm, and endoderm. o A major function of gastrulation of vertebrates is to bring mesoderm underneath the ectoderm on the dorsal side of the embryo, and then to form a notochord. o The notochord then sends a signal to the ectoderm, and causes it form a neural plate. This is called primary induction. o Stages in the process of neurulation – know these o Sonic hedgehog (Shh) is a protein secreted from notochord cells that activates a receptor in neural tube cells and directs motor neuron formation. o Know ectoderm, mesoderm, and endoderm differentiate into (different body systems) • Chapter 22 Reconstructing and Using Phylogenies o Phylogeny is the evolutionary history of relationships among organisms or their genes. It is portrayed in a diagram called a phylogenetic tree o Two species that are each other’s closest relatives are sister species. o Two clades that are each other’s closest relatives are sister clades. o Convergent evolution—independently evolved traits subjected to similar selection pressures may become superficially similar • Chapter 28, 29,37 o Bluelight receptors mediate effects of higherintensity blue light In isolated seedling tips, unilateral blue light causes the redistribution of auxin from the illuminated side to the shaded side. The auxin is then transported down the stem. The higher concentration on the shaded side of the stem causes cell elongation and thus curving. A blue light receptor called phototropin (PHOT1) was identified using o Facts about auxin in seedlings Chemically, auxin is indoleacetic acid. Auxin is made in the tip of the seedling and transported toward the root (apical to basal). It is also made at the tip of the root and transported upward. Auxin causes cell elongation. Auxin is responsible for the positive phototropic response of seedlings (the bending of seedling toward the light). o Key Points about Polar Transport of Auxin (IAA)
Transcript of Key Concepts Exam II - Purdue University · Key$Concepts$Exam$II$ •...
Key Concepts Exam II
• Chapter 20 Development and Evolutionary Change o Hox genes-‐ conserved homeotic genes found in vertebrates, Drosophila, and other
animal groups. Hox genes contain the homeobox domain and specify pattern and axis formation in these animals
o At sufficient concentration, bicoid stimulates transcription of the Hunchback gene. A
gradient of that protein establishes the head. o Nanos mRNA is transported to the posterior end. Nanos protein inhibits translation of
Hunchback.
o Gastrulation: the process by which the three layers of the animal embryo are formed: ectoderm, mesoderm, and endoderm.
o A major function of gastrulation of vertebrates is to bring mesoderm underneath the
ectoderm on the dorsal side of the embryo, and then to form a notochord. o The notochord then sends a signal to the ectoderm, and causes it form a neural plate.
This is called primary induction.
o Stages in the process of neurulation – know these o Sonic hedgehog (Shh) is a protein secreted from notochord cells that activates a
receptor in neural tube cells and directs motor neuron formation.
o Know ectoderm, mesoderm, and endoderm differentiate into (different body systems) • Chapter 22 Reconstructing and Using Phylogenies
o Phylogeny is the evolutionary history of relationships among organisms or their genes.
It is portrayed in a diagram called a phylogenetic tree o Two species that are each other’s closest relatives are sister species.
o Two clades that are each other’s closest relatives are sister clades. o Convergent evolution—independently evolved traits subjected to similar selection
pressures may become superficially similar
• Chapter 28, 29,37 o Blue-‐light receptors mediate effects of higher-‐intensity blue light
In isolated seedling tips, unilateral blue light causes the redistribution of auxin
from the illuminated side to the shaded side. The auxin is then transported down the stem. The higher concentration on the shaded side of the stem causes cell elongation and thus curving.
A blue light receptor called phototropin (PHOT1) was identified using o Facts about auxin in seedlings
Chemically, auxin is indoleacetic acid.
Auxin is made in the tip of the seedling and transported toward the root (apical to basal). It is also made at the tip of the root and transported upward.
Auxin causes cell elongation.
Auxin is responsible for the positive phototropic response of seedlings (the bending of seedling toward the light).
o Key Points about Polar Transport of Auxin (IAA)
Auxin moves only in one direction through plant stems: from apex (top) to base (bottom).
The entry of auxin into cells is not polarized. Entry is via two mechanisms: secondary active transport (IAA-‐ + 2H+) and passive
diffusion in the uncharged form, IAAH.
Efflux of auxin from the cells is via a carrier and the carrier is localized to the basal membrane of the cells. This is what gives auxin transport its directionality.
o Phytochrome mediates the effects of red light (Study Ch 37 carefully!)
Phytochrome is a photoreceptor pigment in the cytosol that exists in two
interconvertible forms.
The default or “ground” state (Pr) absorbs red light, and then is converted into
Pfr. The Pfr form absorbs far-‐red light; and is converted back to Pr. Pfr is the active form that triggers important biological processes.
The non-‐protein portion is the chomophore, the light-‐absorbing component.
• The domains of phytochrome: The protein includes a kinase domain
that, after exposure to red light (i.e. when the chromophore is in Pfr
form), allows the protein to autophosphorylate. The phosphorylation of phytochrome protein activates it.
o Seeds are dormant—the cells do not divide, expand, or differentiate.
o As the seed begins to germinate, it takes up water. The growing embryo obtains chemical building blocks by digesting the food stored in the seed.
o Until the seedling can photosynthesize, it depends on food reserves in the cotyledons or
endosperm. o In cereal seeds, ABA imposes dormancy. With germination, gibberellins diffuse through
the endosperm to surrounding tissue called the aleurone layer underneath the seed
coat. o Gibberellins trigger a cascade, causing the layer to secrete enzymes to digest the
endosperm.
o ABA imposes dormancy; GA has a role after germination is triggered
ABA is the central regulator of abiotic stress in plants and plays important roles
during plant growth and development. • Chapter 41-‐ Animal Hormones
o Steps in sympathetic stimulation of cardiac muscle
Norepinephrine is released. NE binds to the beta-‐adrenergic receptor Receptor is a 7 TMD protein, which activates a G-‐protein called Gs.
Activated Gs activates adenylyl cyclase, leading to the production of cAMP. cAMP activates protein kinase A
Protein kinase A phosphorylates a calcium channel, increasing its sensitivity to open.
o Calcium release in vascular smooth muscle cells can also be regulated by the alpha
adrenergic receptor. With sympathetic stimulus NE activates a receptor that is coupled
to a G protein that activates PLC and increases PIP2, resulting in Ca2+ release from
intracellular (SR) stores.
Same mechanism different diagram:
o Know relation between insulin and glucose and glucagon and glucose!
o • Chapter 43 Animal Reproduction
o LH increases testosterone: Increases growth rate and starts development of secondary sexual
characteristics o FSH and testosterone control spermatogenesis in the Sertoli cells.
Sertoli cells also produce inhibin, which exerts negative feedback on cells that
produce and secrete FSH. o The zygote undergoes cell division and becomes a blastocyst. o Know Acrosomal reaction!
• Chapter 44 Animal Development o A negative feedback of BMP signaling is responsible for the symmetry break of dpp and
chordin expression.
o • Chapter 45 Neurons and Nervous Systems
o Know the Nernst equation and how to solve
o Write down ion concentrations inside and outside the cell on your crib sheet o Know if opening certain channels will cause and influx or efflux of that ion
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o • Chapter 46 Sensory Systems
o Photosensitivity: Sensitivity to light. o A range of animal species from simple to complex can sense and respond to light. o All use same pigments—rhodopsins.
o Photoreceptor cells are metabotropic sensory cells that transform light into action potentials.
o Rhodopsin molecule sits in plasma membrane of a photoreceptor cell.
o Rod cell: A vertebrate photoreceptor, a modified neuron that has no action potentials.
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o • Chapter 47 Neurons and Nervous Systems
o Steps in parasympathetic inhibition of cardiac muscleNorepinephrine is released. ACh is released from postganglionic parasympathetic neurons
ACh binds to the muscarinic ACh receptor Receptor is a 7TMD protein that activates a G protein. A component of the activated G protein binds directly to a class of K channels,
opening them. This does not involve phosphorylation of the channel.
• Chapter 48 Sensory Systems
o Actin—thin filaments o Myosin—thick filaments
o Know muscle contraction cycle:
o o Skeletal Muscle Contraction Mechanism
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