Module 1 - BIOL 303

Question 1

syndactyly

Answer 1

failure of programmed cell death in the development of digits

Question 2

Development

Answer 2

The process of progressive and continuous change that generates a complex multicellular organism from a single cell.

Question 3

Support for epigenisis

Answer 3

Kaspar Friedrich Wolff (1767)
chick embryonic parts develop from tissues that have no recognizable adult counterpart

heart and blood vessels seen to develop anew

intestinal tube formation observed as folding of what was originally a flat tissue

Question 4

recapitulation

Answer 4

the idea that ontogeny (growth and development) occurs through a variety of stages that are representative of the evolutionary phylogeny of a particular species

Question 5

Fertilization

Answer 5

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.

Question 6

Gamete

Answer 6

A specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring; a sperm or an egg.

Question 7

Genome

Answer 7

The complete DNA sequence of an individual organism.

Question 8

Cleavage

Answer 8

A series of rapid mitotic cell divisions following fertilization in many early embryos; cleavage divides the embryo without increasing its mass.

Question 9

Blastomere

Answer 9

A cleavage-stage cell resulting from mitosis.

Question 10

Morula

Answer 10

Latin, “mulberry.” Vertebrate embryo of 16–64 cells;, precedes the blastula or blastocyst stage.

Question 11

Blastula

Answer 11

Early-stage embryo consisting of a sphere of cells surrounding an inner fluid-filled cavity, the blastocoel. Sometimes this single layer stage before and during gastrulation is known as the blastoderm.

Question 12

Gastrulation

Answer 12

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.

Question 13

Gastrula

Answer 13

A stage of the embryo following gastrulation that contains the three germ layers that will interact to generate the organs of the body.

Question 14

Zygote:

Answer 14

A fertilized egg with a diploid chromosomal complement in its zygote nucleus generated by fusion of the haploid male and female pronuclei.

Question 15

Embryo:

Answer 15

A developing organism prior to birth or hatching. In mammals, the term embryo generally refers to the early stages of development, starting with the fertilized egg until the end of organogenesis (embryonic period). After this, the developing mammal is called a fetus until birth, at which time it becomes a neonate.

Question 16

Embryology

Answer 16

The study of animal development from fertilization to hatching or birth.

Question 17

Germ layer

Answer 17

One of the three layers of the vertebrate embryo generated by the process of gastrulation, that will form all of the tissues of the body except for the germ cells

Question 18

Ectoderm:

Answer 18

“outside.” The cells that remain on either the outside (amphibian) or dorsal (avian, mammalian) surface of the embryo following gastrulation. Of the 3 germ layers, the ectoderm is the one that forms the nervous system from the neural tube and neural crest and also generates the epidermis covering the embryo.

Question 19

Endoderm:

Answer 19

Greek endon, “within.” The innermost germ layer; forms the epithelial lining of the respiratory tract, the gastrointestinal tract, and the accessory organs (e.g., liver, pancreas) of the digestive tract. In the amphibian embryo, the yolk-containing cells of the vegetal hemisphere become endoderm. In mammalian and avian embryos, the endoderm is the most ventral of the three germ layers, continuous with the yolk sack epithelium.

Question 20

Mesoderm:

Answer 20

Greek mesos, “between.” The middle of the three embryonic germ layers, lying between the ectoderm and the endoderm. The mesoderm gives rise to muscles and skeleton; connective tissue; the reproductive organs; and to kidneys, blood, and most of the cardiovascular tissue

Question 21

Organogenesis

Answer 21

Interactions between, and rearrangement of, cells of the three germ layers to produce tissues and organs.

Question 22

Metamorphosis

Answer 22

Changing from one form to another, such as the transformation of an insect larva to a sexually mature adult - or a tadpole to a frog.

Question 23

Germline cells

Answer 23

A group of cells set aside from the somatic cells (somatic cells form the rest of the embryo) for reproductive function. Consists of the cells of the gonads (ovary and testis) that undergo meiotic cell divisions to generate the gametes (egg and sperm).

Question 24

Somatic cells

Answer 24

Greek soma, body. Cells that form the body; all cells in the organism that are not germline cells.

Question 25

often first differenciation

Answer 25

The separation of the germline cells from somatic cells is often one of the first differentiations that occurs during animal development.

Question 26

Epithelial Cells

Answer 26

form sheets connected by junctional complexes

sheets act as a barrier

move in harmony

have a clear polar character from one side to another

basal lamina is a foundation contacts only one surface of the cell

Question 27

Mesenchymal Cells

Answer 27

loosely organized and loosely attached cells (more like bold individuals)

can migrate as individual cells

can also adhere in 3-dimensional clumps

basal lamina may surround the cells (muscle or fat cells)

Question 28

Morphogenesis:

Answer 28

The organization of the cells of the body into functional structures via coordinated cellular processes such as:

cell movement or migration
cell growth
cell death
cell division
cell shape changes
changes in composition of cell membrane or secreted products.

Question 29

cell growth

Answer 29

cell growth – some cells become smaller (sperm cells) or larger (egg cells)

Question 30

cell death –

Answer 30

cell death – programmed removal of superfluous cells or entire tissues

Question 31

cell division –

Answer 31

cell division – direction and amount of

Question 31

cell shape changes

Answer 31

cell shape changes (can also involve change in character from epithelial to mesenchymal – also occurs as cancer cells spread or metastasize)

Question 32

changes in composition of cell membrane or secreted products –

Answer 32

extracellular matrix can influence whether neighbouring cells migrate

Question 33

Fate Map:

Answer 33

Fate Map:
A map of the developmental fate of a zygote or early embryo showing the adult organs that will develop from material at a given position on the zygote or early embryo.

Question 34

Fate maps- direct observations

Answer 34

Some embryos have few cells and obvious differences in cytoplasmic pigmentation of early blastomeres.

Question 35

fate map constructed? – vital dyes

Answer 35

A vital dye is a stain that can be used on living cells without killing them – the old fashion method.

Question 36

fate map constructed? – fluorescent dyes

Answer 36

Fluorescent dyes are much better than vital dyes – sometimes injected and then photo-activated using a laser which allows a small group of cells to be “tagged” and their movements and lineage traced.

Question 37

cell fate – chimeric embryos

Answer 37

Le Douarin found that quail cells could be grafted into chick embryos. The distinctive large nucleolus of quail cells served as a marker in tissues that were fixed, stained, and examined by standard light microscopy.

Question 38

What is the function of the nucleolus?

Answer 38

Ribosome biogenesis

The nucleolus is the most prominent substructure within the nucleus.

It is the site of rRNA transcription and rRNA processing

a mammalian cell has 5-10 million ribosomes that are synthesized each time a cell divides

THE NUCLEOLUS IS A RIBOSOME PRODUCTION FACTORY it produces and assembles ribosomal subunits

Question 39

Homologous structures

Answer 39

Homologous structures are similar because they are derived from a common ancestral structure – our arms and the bat’s wings are homologous structures (but they do not necessarily perform similar functions).

As forelimbs, the bird and bat are homologous, because they shared a common ancestor with the typical forelimb structure.

Question 40

Analogous structures

Answer 40

Analogous structures are similar because they perform similar functions, but they do not necessarily share a common ancestral form – the bat’s wing and the butterfly’s wing are analogous structures (used in generating flight).

But as wings, the bird and bat wings evolved from the forelimb independently, and there was no common winged ancestor – thus as wings these are better considered as analogous.

Question 41

another word for gene mutation

Answer 41

aneuploidy

Question 42

Piebald syndrome

Answer 42

syndromes where a homologous gene in a model organism is mutated. (Mutation of the gene KIT in humans and mouse results in similar syndromes

Question 43

Down’s syndrome

Answer 43

aneuploidy

Question 44

Teratogen:

Answer 44

Teratogen: any agent that can disturb the proper development of an embryo or fetus (teratogens can result in birth defects or spontaneous abortion).

Question 45

Developmental abnormalities are characterized as

Answer 45

“malformations

Question 46

Developmental abnormalities if they are of a genetic nature

Answer 46

“disruptions” if they are associated with exposure to an exogenous agent such as a teratogen.

Question 47

syndactyly : a malformation or a disruption?

Answer 47

syndactyly : malformation – interestingly all kangaroos have syndactyly – in which case it I would say it is now part of normal development