bsc2011 dr. kraft unit 1 exam

What are the steps of fertilization in sea urchins?

1. Contact, 2. Acrosomal reaction, 3. Fusion of sperm and egg, 4. Calcium wave and cortical reaction, 5. Sperm enters egg, nuclei fuse

What are the four stages of embryonic development, and what mechanisms characterize these stages? What is the purpose/end result of each stage?

1. Fertilization: The formation of a diploid zygote from a haploid egg and sperm. Two main purposes of fertilization: 1. Restore chromosome number and 2. Egg activation. 2. Cleavage: a series of rapid cell divisions during early development that occurs in the absence of cell growth. 3. Gastrulation & Morphogenesis: Purposes of gastrulation: 1. Results in triploblastic gastrula embryo that will later form different tissues and organs in the embryo. 2. Creates a primitive digestive tract (archenteron). 3. Establishes a major body axes (head, tail) 4. Organgenesis: continued cell movement, communication, and differentiation resulting in the development of organs and organ systems.

How does the nuclear transplantation experiment relate to the process and issues associated with cloning?

An organism is grown within the egg cell, even though it has nuclear information from the embryo. Similarly to the clone process, which receives donor nuclear material and is an identical clone not offspring of the donor mother.

What determines the three body axes in a frog? Are some axes determined at random?

Anterior- Posterior axis (determined by animal/vegetal poles), Dorsal- Ventral axis (determined at random), Left-right axis (determined by first cleavage)

How do changes in cell movement relate to gastrulation?

Convergent extension: a block of cells converge and the block becomes longer (AKA extended)

What were the methods and results of the Nuclear Transplantation Experiment? How do the results from these experiments relate to the hypotheses?

Even though the nucleus was removed, it was replaced and therefore the information is still there. Differential expression of genetic material hypothesis is supported.

How do the sizes of the zygote and blastula at the end of cleavage compare?

HELP

What are the steps of neurulation in frogs? How do changes in cell shape affect development of the neural. tube? What is the significance of neural crest cells and somites?

HELP

What is a morphogen?

Morphogen: a signaling molecule that directs position of structures based on its concentration gradient.

Describe the two alternative hypotheses proposed to address how cells become more specialized in their structure and function during development.

Progressive loss of genetic material: nuclear material is progressively lost until the cell contains only the material necessary for the function of the differentiated cell (use it or lose it). Differential expression of genetic material: no nuclear material is lost; the mature cell only expresses the material necessary to its specialized function.

What were the methods and results of the Steward Carrot Experiment? How do the results from these experiments relate to the hypotheses?

The carrot cell is only able to produce identical, clone carrots. The cell cannot grow flowers, or other plants, only the identical carrot. Differential expression of genetic material hypothesis is supported.

What are Hox genes, and why are they important evolutionarily? Describe 2 ways that differences/mutations/duplications of Hox genes play a role in the evolution of animal forms.

There is evidence that the role of hox genes in evolution of body forms, that they evolved early in a common ancestor, and are valuable for life. differences region of hox genes may result in increased/decreased expression in the affected regions. Mutations may result in different functions of the genes (possible new species). Duplications can allow for greater structural complexity (possible new species).

What is the difference between a totipotent and pluripotent cell, and where can you find these cells in humans?

Totipotent: cells that have the potential to differentiate into an entire organism. ex) embryonic cells. Pluripotent: cells that are capable of differentiating into several cell types.

What is the difference between theory and hypothesis?

a theory is broad and a hypothesis is for a specific phenomenon.

What are the 3 embryonic germ layers, what is their relative location in the gastrula, and what tissues/organs arise from these layers?

a. Endoderm: inner layer Ex) SKIN b. Mesoderm: middle layer Ex) MUSCLE c. Ectoderm: outer layer Ex) DIGESTIVE TRACT

What is genomic equivalence?

all the different cell types in an organism have identical genomes (same DNA) because the all arose by mitotic cell division by the same zygote. But these cells expressdifferent genes!

What role does induction play in neurulation?

as a result of induction, the near plate, neural folds, and neural tube form.

Why is the gray crescent so important, and how does this relate to CDs and the dorsal lip?

cells with grey crescent cytoplasm cause the development of the dorsal side.

What is the central dogma, and how does this relate to gene expression?

central dogma is dna -> rna -> protein. the central dogma combined with cell division, cell differentiation, and morphogenesis is the process for gene expression.

What is organogenesis?

continued cell movement, communication, and differentiation resulting in the development of organs and organ systems.

What are cytoplasmic determinants, what is their function, and where are they located?

early embryonic cells differentiate via molecular maternal CDs that are distributed into daughter cells. the grey crescent contains cytoplasmic determinants.

What is the genetic code, and what are the 2 main properties of the genetic code we discussed?

genetic code is universal among all organisms, which means it supports the theory of evolution. additionally, the genetic code is redundant, meaning multiple codons code for the same amino acid.

What are haploid and diploid cells?

haploid egg and sperm combine to form a diploid zygote

What are the steps involved in gastrulation?

invagination, involution, and yolk cells internalized

What is induction? Describe two examples discussed in class.

molecular signals from one cell are received by a neighboring cell, setting up signal transduction pathways that change gene expression.

Why is it important for gamete recognition to occur during fertilization in sea urchins? What are the two ways urchin eggs prevent polyspermy, and why is this important?

polyspermy is prevented when the egg and sperm fuse, causing ion channels to open and therefore depolarizing the egg's plasma membrane (FAST) and when cortical granules harden the vitalize layer into a protective fertilization envelope (SLOW).

What is pattern formation? Describe all the ways this can be achieved.

process that governs the arrangement of organs and tissues in their characteristic places in the embryo. done by organizer regions, hormones, apoptosis, or master developmental genes.

What are the 3 main purposes of gastrulation?

purpose: 1. Results in triploblastic gastrula embryo that will later form different tissues and organs in the embryo. 2. Creates a primitive digestive tract (archenteron). 3. Establishes a major body axes (head, tail).

What are the 3 stages of cell signaling? Why do cells communicate? How does this relate to induction?

reception, transduction, response are the 3 stages. cells communicate to regulate cell activities and to communicate with neighboring cells.

what is science? What are two ways we can investigate concepts in science?

science is an approach to understand the natural world. we can investigate deductively (general->specific) or inductively (specific->general)

Why is the blastopore an important structure during gastrulation?

the blastopore is present at the beginning of gastrulation and will form into either the anus or the mouth.

What is cell differentiation?

the divergence in cellular structure and function as cells become specialized during development.

how does bicoid protein set up the anterior-posterior axis in fruit flies?

when bicoid protein is not present, there is no head development.