Exam 1 Flashcards
Define
Development
It’s the set of processes by which a multicellular organism generates a complex phenotype of heterogenous cells arranged in a particular size a shape; the route by which genotype and environment produce phenotype
Define
Zygote
A fertilized egg cell
Define
Embryo
A developing organism prior to birth or hatching; usually refers to the early stages of development in humans
Define
Embryology
Ology=the study of
The study of animal development from fertilization to hatching or birth
Why is Aristotle important to developmental biology?
First known embryologist; undertook the first known study of comparative developmental anatomy; first figured out the functions of the mammalian placenta and umbilical cord
Define
Oviparity
EX: birds, amphibians, and most invertebrates
Young hatch from eggs ejected by the mother
Define
Viviparity
EX: placental mammals
Young are nourished in and born from the mother’s body rather than hatched from an egg
Define
Ovoviviparity
EX: some reptiles and sharks
Young hatch from eggs held within the mother’s body where they continue to develop for a period of time
Who concluded that all animals originate from eggs?
William Harvey
How did William Harvey progress embryology?
Saw the blastoderm of a chick embryo; first to notice “islands” of blood tissue form before the heart does; suggested that amniotic fluid functions as a shock absorber for the embryo
Who published the first microscopic account of chick development and when?
Marcello Malpighi in 1672
Define
Pattern Formation
The set of processes by which embryonic cells form ordered spatial arrangements of differentiated tissues
Define
Differentiation
The process by which an unspecialized cell becomes specialized into one of the many cell types that make up the body
Define
Morphogenesis
The organization of the cells of the body into function structures via coordinated cell growth, cell migration, and cell death
What makes an organism a good “model” for answering Developmental questions?
It must be possible to house a significant amount of breed adults in the lab; the time from embryo to reproductive adult has to be short, however the embryonic period has to be long enough for researchers to study it; they have to be able to see and work with the embryo; the organism needs to relate to the question they are asking; the organism needs to be appropriate for teh experiment approach needed to answer the question
Define
Fertilization
Fusion of male and female gametes followed by fusion of the haploid gamete nuclei to restore the full complement of chromosomes characteristic of the species and initiation in the egg cytoplasm of those reactions that permit development to proceed
Define
Gametes
Ex: Egg/sperm
A specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring
Define
Pronuclei
The male and female haploid nuclei within a fertilized egg that fuse to form the diploid nucleus of the zygote
Define
Genome
The complete DNA sequence of an individual organism
Define
Cleavage
A series of rapid mitotic cell divisions following fertilization in many early embryos; cleavage divides the embryo without increasing its mass
Define
Blastomeres
A cleavage-stage cell resulting from mitosis
Define
Blastula
Early stage embryo consisting of a sphere of cells surrounding an inner fluid-filled cavity, the blastocoel.
Define
Gastrulation
A process involving movement of the blastomeres of the embryo relative to one another resulting in the formation of the three germ layers of the embryo
Define
Gastrula
A stage of the embryo following gastrulation that contains the three germ layers that will interact to generate the organs of the body
Define
Germ Layers
One of the three layers of the embryo; ectoderm, mesoderm, and endoderm, in triploblastic organisms, or of the two layers, ectoderm and endoderm, in diploblastic organisms, generated by the process of gastrulation, that will form all of the tissues of the body exceot for the germ cells
Define
Organogenesis
Interactions between, and rearrangement of cells of the three germ layers to produce tissues and organs.
Define
Anterior-Posterior Axis
Primary body axis, defines the head verus the tail; sometimes used in reference to the limb to refer to the thumb (anterior)-pinkie (posterior) axis
Dorsal-ventral axis
Plane defining the back (dorsum) versus the belly (ventrum). When referring to the limb, this axis refers to the knuckles (dorsal) and palms (ventral)
Define
Right-Left axis
The body axis that specifies the lateral sides of the body
Define
Larva
The sexually immature stage of an organism, often of significantly different appearance than the adult and frequently the stage that lives the longest and is used for feeding or dispersal
Define
Germ cells
A group of cells set aside for reproductive function; germ cells become the cells of the gonads that undergo meiotic cell divisions to generate the gametes; contribute to the formation of a new generation
Define
Somatic Cells
Cells that make up the body i.e., all cells in the organism that are not germ cells; gives rise to the individual body
Define
Gametogenesis
The production of gametes
Identify
What cells does the Ectoderm form? What part of the embryo is it?
Produces epidermis and forms the brain and nervous system; covers outside of embryo
Identify
What cells does the Mesoderm give rise to? Where is it on the embryo?
In between the ectoderm and endoderm; generates blood, heart, kidney, gonads, bones, muscles, and connective tissues
Identify
What cells does the Endoderm give rise to? Where is it on the embryo?
Produces the epithelium of the digestive tube and its associated organs, including the lungs; on the inside of the embryo
Define
Blastopore
The invagination point where gastrulation begins. In deuterostomes, this marks the site of the anus. In protostomes, this marks the site of the mouth
Define
Neurula
Refers to an embryo during neurulation (i.e., while the neural tube is forming)
Define
Neural tube
The embryonic precursor to the central nervous system (brain and spinal cord)
Explain
What initiates amphibian metamorphosis, and what controls the speed?
thyroid hormones initiate metamorphosis, and environmental pressures control the speed at which it occurs
Define
Somites
Segmental blocks of mesoderm formed from the mesoderm next to the notochord; each contain major compartments: the sclerotome, which forms the vertebrae and ribs, and the dermomyotome, which goes on to form dermatome and myotome. The dermatoe forms the dermis of the back; the myotome forms musculature of the back, rib cage, and ventral body. Additional muscle originators detach from the lateral edge of the dermomyotome and migrate into the limbs to form the muscles of the fore and hindlimbs.
Define
Meiosis
Division process that occurs only in germ cells, to reduce the number of chromosomes to a haploid complement. Differs from mitosis in that germ cells undergo two cell divisions without an intervening period of DNA replication, and homologous chromosomes pair together and recombine genetic material.
Define
Alternation of generations
In plants, a life cycle in which a haploid multicelluar gamete-producing stage (the gametophyte) alternates with a diploid multicellular spore-producing stage (the sporophyte)
Explain
How is the development of plant embryos different from animal embryos? How is it the same?
Plant embryos develop three cell layers, but they don’t rearrange through gastrulation-like movements. Plant embryos also pause between the completion of embryogenesis and germination and growth, which can be extremely long
Define
Meristems
Tissue in plants that contains stem cells that are actively dividing. This is where the production of new plant tissue occurs. Different types of meristems give rise to different structures of the plant. The two main ones are the shoot and root apical meristems
Explain
Why is it important that plant zygotes divide asymmetrically?
The smaller apical cell generates the actual embryo, where the basal cell becomes the suspensor that supports the embryo; sets up the primary axis of the embryo
Define
Dermal tissue
Tissue that underlies the epidermis in animals and that makes up the outer layer of plants
Define
Ground tissue
In plants, all tissue that isn’t dermal or vascular; functions primarily in storage, support, and photosynthesis, and includes filler tissue called parenchyma and the more supportive collenchyma and sclerenchyma
Define
Vascular tissue
The conducting tissues in vascular plants that transport fluids and nutrients
Define
Xylem
In vascular plants, the conduits for bringing water and nutrients upward through the plant
Define
Phloem
In vascular plants, the conduits that carry sugars produced by photosynthesis, along with other metabolites, from sources to sinks; primarily from the leaves to the nonphotosynthetic parts of the plant
Define
Epithelial cells
Cells that are tightly linked together to form a sheet or tube (an epithelium) with little extracellular matrix
Define
Mesenchymal cells
Unconnected or loosely connected cells that can act as independent migratory units
Identify
What cellular processes bring about morphogenesis?
Direction and number of cell divisions, Cell migration, cell shape changes, cell growth and death, and changes in the composition of the cell membrane or secreted products
Define
Epithelial-to-mesenchymal transition
An orderly series of events where the cells of an epithelial sheet or structures are transformed into migratory mesenchymal cells. In this transition, a polarized stationary epithelial cell, which normally interacts with basement membrane through its basal surface, becomes a migratory mesenchymal cell that can invade tissues and form organs in new places. The converse is the mesenchymal-to-epithelial transition (MET), which occurs when mesenchymal cells coalesce and form epithelial structures
Define
Apoptosis
Programmed cell death. Apoptosis is an active process that prunes unneeded structures, controlls the number of cells in particular tissues, and sculpts complex organs; rapid apoptosis occurs when epithelial cells lose their attachment to the extracellular matrix
Identify
Which of these go through gastrulation? Animals, Plants, Fungi
Animals
Define
Epigenesis
The view supported by Aristotle and William Harvey that the organs of the embryo are formed from scratch at each generation
Define
What do the terms “Find it”, “Lose it”, and “Move it” mean?
Find it: association between one thing and another; Lose it: If cells destined to form limbs are removed, limbs won’t form; Move it: Are the cells moved sufficient for the process that carry out?
Define
Fate Map
Diagrams based on having followed cell lineages from specific regions of the embryo in order to “map” larval or adult structures onto the region of the embryo from which they arose. The superimposition of a map of “what is to be” onto a structure that hase yet to develop into these organs
Define
Vital Dyes
Stains used to label living cells without killing them. When applied to embryos, vital dyes have been used to follow cell migration during development and generate fate maps of specific regions of the embryo
Define
Fluorescent dyes
Compounds, such as fluorescein and green fluorescent protein (GFP), that emit bright light at a specific wavelength when excited with ultraviolet light
Define
Chimeric embryos
Embryo made from tissues of more than one genetic source
Define
Green Fluorescent Protein (GFP)
A gene that is widely used as a transgenic label for cells in developmental and other research, since cells that express GFP are easily identified by a bright green glow
Define
Transgene
Exogenous DNA or gene introduced through experimental manipulation into a cell’s genome
Define
Malformations
Abnormalities caused by genetic events such as gene mutations, chromosomal aneuploidies, and translocations
Define
Syndrome
Greek for “happening together”. Several malformations or pathologies that occur concurrently. Genetically based syndromes are caused either by (1) a chromosomal event (such as trisomy 21, or Down syndrome) where several genes are deleted or added, or (2) by one gene having many effects
Define
Disruptions
Abnormality or congenital defect caused by exogenous agents (teratogens) such as plants, chemicals, viruses, radiation, or hyperthermia
Define
Teratogens
Exogenous agents that cause disruptions in development resulting in teratogenesis, the formation of congenital defects
Explain
What are Von Baer’s laws of Vertebrate embryology?
- The general features of a broad group of animals appear earlier in development than do the specialized features of a smaller subgroup
- Less general characters develop from the more general, until finally the most specialized appear
- The embryo of a given species, instead of passing through the adult stages of lower animals, departs more and more from them
- Therefore, the early embryo of a higher animal is never like a lower animal, but only like its early embryo
Define
Phylotypic stage
The stage that typifies a phylum, such as the late neurula or pharyngula of vertebrates, and which appears to be relatively invariant and to constrain its evolution
Identify
What connects the invertebrate and vertebrate chordates?
The notochord
Define
Homologous
Structures and/or their respective components who similarity arises from their being derived from a common ancestral structure
Define
Analogous
Structures and/or their respective components whose similarity arises from their performing a similar function rather than their arising from a common ancestor
