DPR Exam 1 vocab Flashcards
Price chapters 1 -4 // campbell chp.6,7,11,18
Homologue
a gene or structure that is similar in different species since it was derived from their common ancestor during evolution
Line
a collection of organisms related by breeding that is relatively pure genetically because of continued inbreeding and artificial selection
Phenotype
the observable characteristics of an organism, such as its physical appearance or behavior
forward genetics
Working from phenotype to gene
reverse genetics
one starts with an interesting-looking gene and manipulates its activity to learn about its function.
Gain-to-function approach:
the genome is activated by the experimenter to discover what they do
Loss-of-function approach:
activating genetic inhibitors manufactured by the experimenter to produce a molecule that blocks the actions of a specific Drosophila gene
RNAi
RNA interference can be used to block gene function experimentally,
Process includes:
1.Inside normal cells, genes are transcribed to make single-stranded messenger RNA (mRNA) that is translated by ribosomes to generate specific proteins
2.To block gene function, antisense RNA molecules with sequences complementary to sense sequences of specific mRNAs are introduced into cells where they interact with their target mRNAs and block their translation
The Germ Layers
An outer layer called ectoderm
A middle layer called the mesoderm
An inner layer from the endoderm
Epithelium
a tissue that lines the external and internal surfaces, including internal cavities and organs and other free open surfaces of the body, of all animals and their immature developing forms
Gastrulation
is the formation of the germ layers once the repeated division of a fertilized egg has generated a collection of cells large enough to be rearranged
Neurulation
The process by which the neural tube is formed and acquires increasingly complex morphology
epiboly
Cells derived from the animal pole spread over the embryo with ectoderm ( epiboly is the process of which this is happening)
Fate
What the cell will do and what it will become
Homologous recombination
a phenomenon in which nucleotide sequences are exchanged between two similar or identical strands of DNA
Neuroectoderm
neurogenic region of the ectoderm
Gastrulation
formation of the germ layers occurs once the repeated division of fertilized egg has generated a collection of cells large enough to be rearranged
Blastomere
(mentioned in C.elegans development) any of the cells resulting from the first few cleavages of a fertilized egg during early embryonic development
Blastoderm
(mentioned in frogs and chicks)
the superficial layer of the early embryo in species whose eggs contain relatively large amounts of yolk; cell division occurs in this layer which surrounds the yolk in insects but is a flat disc at one pole of the egg in birds
Blastopore
(mentioned in frogs) Gastrulation involves the inward movement of cells from the embryo’s outer layer at a region
- organizer in frogs
Blastula
(mentioned in the frog) Before gastrulation, a fluid-filled cavity known as the blastocoel opens beneath the animal cap; the embryo is now
The first cells to move in migrating anteriorly from the dorsal lip of the blastopore
Their movement displaces the blastocoel anteriorly
Notochord
These cells form the endoderm which lines the primitive gut, the mesoderm of the future head, and the transient dorsal mesodermal structure
Blastocyst
(mentioned in mouse development)
- The mouse blastocyst comprises three tissues: the epiblast, situated at one pole of the embryo, the primitive endoderm beneath it, and the trophectoderm surrounding both tissues and the blastocoel cavity
- This is equivalent to the blastula of amphibians
Neuroblasts
(mentioned in drosophila) the formation of the CNS involves individual cells in the neuroectoderm enlarging and moving inside the embryo, a process called delamination
Neural Tube
The process of primary neurulation begins in the overlying neuroectoderm with the formation and folding of the neural plate to form the neural tube
Neural Plate
The neural plate is broader anteriorly and the folds it generates are larger than those made posteriorly.
Neural Crest
Originates from the lateral edges of the neuroectoderm; once these edges have joined to form the neural tube, neural crest cells end up dorsally along the line of fusion
Neurlation
occurs through rapid growth at rates that vary from region to region; cell movements; changes shape in cell
Primary Neurlation
the process by which a sheet of neuroectoderm called the neural plate rolls up as it grows to form the neural tube
Secondary Neurulation
achieves the same results as primary neurulation, but through a different process known as cavitation that involves the hollowing out of an initially solid rod of tissue
Animal cap
(mentioned in frog)
As cell division progresses the embryo’s dorsal region, called the animal cap, becomes packed with many small cells
Notochord
(mentioned in frogs) transient dorsal mesodermal structure
Ventral Nerve Cord
(mentioned in Drosophila) Neuroblasts are progenitor cells that divide many times to form numerous intermediate cells called ganglion mother cells (GMCs). Each GMC divides just once more to form neurons and glia. GMCs and their progeny pile up on the neuroblasts, forming the bilaterally symmetrical ventral nerve cord.
Primitive Streak
(mentioned in the chick)
As epiblast cells are produced they move posteriorly in the plane of the epiblast towards
Koller’s sickle from where they move anteriorly along the midline forming a structure called the primitive streak
Formation of the primitive streak involves the ingression of epiblast cells into the interior of the embryo
Hensen’s node
(mentioned in the chick)
As the primitive streak lengthens from posterior to anterior a bulge called
Hensen’s node appears at the anterior tip of the streak.
Hensen’s node is equivalent to the dorsal lip of the blastopore in frogs– the organizer in the chick
Epiblast
(mentioned in the chick) The pellucida area is transparent because there is a fluid‐filled cavity, initially cell‐free, between the yolk and an overlying single‐cell‐thick layer of epithelial cells. The epithelial layer is called the epiblast
- As in the developing chick embryo, gastrulation in the mouse embryo involves the movement of cells in the plane of the epiblast towards and through the primitive streak to form a new mesodermal layer between the outer endoderm and the inner ectoderm
Prechordal mesoderm
(mentioned in mouse development) The notochord grows anteriorly from the node, forming a narrow midline rod ending in the broader prechordal mesoderm under the future forebrain. The notochord comes to lie along the midline of the embryo beneath the part of the ectoderm that will form the nervous system, the neuroectoderm
Neural Induction
the inducing tissue tells the responding tissue to adopt a neural fate
The process often involves the binding of signaling molecules produced by one cell to receptor proteins on the surface of another
Hans Spemann and Hilde Mangold Experiment
Neural Induction concept:
Working on amphibian embryos, these scientists discovered that if the dorsal lip of the blastopore is transplanted to a new location in a different embryo, it induces the formation of a second body axis, complete with a second neural plate, which becomes a second neural tube and eventually a second mature nervous system
Neural Plate
becomes a second neural tube and eventually a second mature nervous system
Organizer
Might promote neural induction because it produces molecules that inhibit BMPs in the animal cap, preventing its cells from acquiring an epidermal fate
the dorsal lip of the blastopore in amphibians
Hensen’s node in birds, fish, and mammals
Default Model
the model came mainly from work on tissue that is induced to a neural fate in the blastula of amphibian embryos
Animal Cap
tissue that is induced to a neural fate in the blastula of amphibian embryos
BMPs
bone morphogenetic proteins; members of this family, including BMP2, BMP4, and BMP7, were found in the animal cap of the blastula
FGFs
FGFs were discovered during the 1970s and early work showed that they induced the proliferation of fibroblasts; there are over 20 FGF family members in mammals
FGFs rather than antagonists of BMPs are responsible for neural induction, suggesting that the default model has little if any relevance in these species
Wnts
there is evidence that neural induction requires activation of the canonical Wnt signaling pathway, resulting in the translocation of β‐catenin to the nucleus where it blocks the activation of the BMP gene
Signal transduction
Intercellular signaling involving the binding of a ligand to its specific receptor activates cascades of biochemical reactions within a cell
Intracellular signaling
signal transduction is achieved through the sequential catalytic activation of intracellular enzymes.
Regulatory elements
regions of the DNA where transcription factors bind which includes promoters and enhancers
Transcription factors
proteins that bind to DNA to regulate gene transcription
Patterning
the next step in neural development is to divide it up into areas that will lay the basis for regional specializations in the structure of the mature nervous system
Organizer
Signaling Source
Morphogen
a signal that provokes more than one cellular response depending on its concentration around the cell
Neurogenesis
formation of neural cells within the neuroectoderm
Gap genes
These different levels induce the expression of proteins encoded by the gap genes in broad AP domains. Gap genes are so named because when they are mutated the regions of the embryo that normally express them are missing.
Pair-rule genes
In the early embryo the number and position of segments is established when the gap gene products activate pair‐rule genes in a reiterated pattern of smaller domains
Hox genes
Instead of causing loss or malformation of body parts, mutations of these genes (now known generally as Hox genes) caused homeotic transformations in segment identity; that is a segment would be transformed perfectly to resemble another segment
Hox Code
As a result of the overlapping expression domains, each segment expresses a unique combination of Hox genes and it is thought that these combinations give different AP regions their identity.
Cytosol
inside all cells is a semifluid in which subcellular components are suspended
Cytoplasm
the region between the nucleus and the plasma membrane
Plasma Membrane
functions as a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell
Nucleus
contains most of the genes in the eukaryotic cell
Nuclear Envelope
encloses the nucleus separating its contents from the cytoplasm; double membrane
Nuclear Lamina
a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope
Chromosomes
the DNA is organized into discrete units; this structure carries the genetic information
Chromatin
the complex of DNA and proteins making up chromosomes
Nucleolus
a prominent structure within the nondividing nucleus, here ribosomal RNA is synthesized from instructions in the DNA
Ribosomes
complexes of ribosomal RNA and protein that carry out protein synthesis
Ribosomes Types
Free ribosomes are suspended in the cytosol
Bound ribosomes are attached to the outside of the endoplasmic reticulum or nuclear envelope
Endoplasmic Reticulum
an extensive network of membranes that accounts for more than half the total membrane in many eukaryotic cells
Smooth ER
outer surface lacks ribosome
Rough ER
studded with ribosomes on the outer surface of the membrane and thus appears rough through the electron microscope
Glycoproteins
Most secretory proteins are glycoproteins, proteins that have carbohydrates covalently bonded to them
Transport proteins
vesicles in transit from one part of the cell to another are called transport vesicles; we will discuss their fate shortly
Golgi apparatus
consists of flattened membranous sacs; many transport vesicles travel here
Lysosomes
a membranous sac of hydrolytic enzymes that an animal cell uses to digest macromolecules
Mitochondria
are the sites of cellular respiration, the metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats, and other fuels
Cristae
inner membrane folding
Mitochondrial matrix
enclosed by the inner membrane; contains many different enzymes
Cytoskeleton
a network of fibers extending throughout the cytoplasm
Microtubules
Microtubules shape and support the cell and also serve as tracks along which organelles equipped with motor proteins can move
Centrosomes
a region that is often located near the nucleus and is considered a microtubule-organizing center
Centrioles
- each composed of nine sets of triplet microtubules arranged in a ring
Basal Body
the microtubule assembly of a cilium or flagellum is anchored in the cell
Actin
microfilaments can form structural networks when certain proteins bind along the side of an actin lament and allow a new lament to extend as a branch; actin is a globular protein
Mysosin
myosin acts as a motor protein by means of projections that walk along the actin filaments
Intermediate filaments
anchor organelles and maintain nuclear shape and integrity
Flagella
microtubule-containing extensions that project from some cell
Cilia
microtubule-containing extensions that project from some cell
selective permability
allows some substances to cross it more easily than others.
amphiatic
meaning it has both a hydrophilic region and a hydrophobic region
Fluid Mosaic Model
membrane is a fluid structure with a mosaic of various proteins embedded in or attached to a double layer (bilayer) of phospholipids
Concentration Gradient
the region along which the density of a chemical substance increases or decreases
Diffusion
the movement of molecules of any substance so that they spread out evenly into the available space
Signal Transduction Pathway
the received signal is converted to a specific cellular response in a series of steps
Local Regulators
influence cells in the vicinty
Ligand
the term for a molecule that specifically binds to another molecule, often a larger one
Protein Kinases
an enzyme that transfers phosphate groups from ATP to a protein is generally known
Protein phosphatases
enzymes that can rapidly remove phosphate groups from proteins, a process called dephosphorylation
Second messengers
Many signaling pathways also involve small, non-protein, water-soluble molecules, or ion
Cyclic AMP
cytosolic concentration of a compound called cyclic adenosine mono-phosphate
Adenylyl cyclase
converts ATP to cAMP in response to an extracellular signal in this case, provided by epinephrine
Differential gene expression
the expression of different genes by cells with the same genome
Histone acetylation
acetyl groups are attached to lysines in histone tails; deacetylation is the removal of acetyl groups. When the lysines are acetylated, their positive charges are neutralized and the histone tails no longer bind to neighboring nucleosomes. Such binding promotes the folding of chromatin into a more compact structure; when this binding does not occur, chromatin has a looser structure
Epigenetic inheritance
- Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence
RNA interference (RNAi)
A growing understanding of the miRNA pathway explained a perplexing observation: Researchers had found that injecting double-stranded RNA molecules into a cell somehow turned off the expression of a gene with the same sequence as the RNA
