BSC 120 Chapter 19

A cell is considered to be ______ when it is committed to becoming a particular cell type, such as an intestinal cell or a muscle cell. A cell is considered to be ______ when its morphology and function have changed, usually permanently, into a highly specialized cell type.

-determined/differentiated

Label the following structures associated with plant development

1Cotyledon1 4Root Merisetem 3Cotyledon Buds 2Shoot Meristem

On the left are phenotypic descriptions of several Arabidopsis floral mutants and of wild-type Arabidopsis; each whorl - from outer to inner - is listed. Review the ABC model of plant floral development, and the drag then appropriate mutant gene or combination of genes on the right to its matching phenotype. leaf-leaf-leaf-leaf NOT E sepal-sepal-carpel-carpel B carpel-stamen-stamen-carpel A sepal-petal-stamen-carpel WILD sepal-sepal-sepal-sepal NOT A/B sepal-petal-petal-sepal C carpel-carpel-carpel-carpel NOT A/B/C

Genes A and B defective Gene C defective Gene E defective Genes A, B, and C defective Gene A defective Gene B defective Wild type (no gene defective)

Drag the labels to the appropriate region of the shoot meristem

Peripheral zone Leaf bud Leaf bud Peripheral zone Central zone Organizing center

On a volcanic island, you discover a new species of fruit fly, and while investigating that species, you discover a novel morphogen that you call Morphogen A. When morphogen A is above the threshold concentration of 30 pM, the cells develop into anterior structures. You find a fruit fly oocyte with normal morphogen concentrations along its anteroposterior axis (a concentration gradient seen in wild type oocytes), but the resulting embryo does not properly develop a head, mouth, eyes, and other anterior structures. Which of the following is a reasonable explanation for the appearance of the headless mutant?

The headless mutant has a defect in a gene encoding a cell adhesion molecule.

Stem cells are categorized according to their developmental stage and their ability to differentiate. Match the following sources of stem cells with their appropriate ability to differentiate. A. Embryonic Stem (ES) Cells B. Hematopoietic Stem Cells (HSC) C. Fertilized Egg D. Skin Cells

UNIPOTENT -skin cells BIPOTENT UNDIFFERENTIATED TOTIPOTENT- fertilized egg PLURIPOTENT-embryonic stem cell MULTIPOTENT hematopoietic .

Which of the following statements best describes the evolutionary outcome of gene duplication events?

-Gene duplications allow for higher complexity in organisms, as genes can take on more specialized functions.

Which of the following statements are ACCURATE regarding homeotic genes and homeotic proteins? Check all that apply.

-Homeotic genes encode transcription factors -Homeotic proteins bind regulatory regions of genes important in development -In animals, the order of homeotic genes on a chromosome correlates with their spatial order of expression in the embryo -The homeodomain of a homeotic protein has an arrangement of alpha-helices that can bind DNA -Homeotic genes from plants do not contain a homeobox sequence -Homeotic genes found in mammals are homologous to homeotic genes found in Drosophila

The following are processes that apply to either plant development or animal development or both. Please classify them accordingly. -animal development -plant development -both

-Homeotic genes involved in development BOTH -Pattern formation occurs in four general stages ANIMAL -Pattern formation BOTH -Cell migration ANIMAL -Transcription factors regulate pattern formation BOTH -Entirely new individual can be regenerated from many cell types of somatic cells. PLANT -Development that does not rely on morphogens PLANT -First cell division is asymmetric PLANT .

Development in animals proceeds through 4 main phases. Please complete the statements below regarding these stages of development. differentiate four characteristics three segments limbs body axes

-Morphogens determine the formation of the BODY AXES and control the expression of transcription factors of phase two. -Transcription factors cause the embryo to become subdivided into regions that have properties of individual SEGMENTS . -They also control transcription factors of phase THREE.. -Transcription factors cause each segment and groups of segments to develop specific CHARACTERISTICS . They also control other transcription factors. -Transcription factors cause cells to DIFFERENTIATE into specific cell types such as skin, nerve, and muscle cells.

Evaluate the following examples and determine which is most likely a result of gene duplication.

-MyoD is a protein involved in muscle cell differentiation. Other proteins involved in the same process and possessing similar amino acid sequence are myogenin, Myf5, and MRF4. -MyoA, MyoD, and MyoH are all genes that are expressed exclusively in muscle cells. Only MyoD is capable of causing fibroblasts to differentiate into muscle cells. -Plant and animal homeotic genes are produce transcription factors that contain DNA binding regions, as exemplified by animals with a homeobox domain, and plants with a MADS domain.

Which of the following statements about plant development is/are ACCURATE?

-The basal cell produced by the first zygotic division is larger than the apical cell. -By the heart stage of embryonic development, the basic organization of the plant has been established. -Cotyledons are embryonic leaves that store nutrients for the developing embryo and seedling. -Meristems are present in a heart stage embryo. -The root apical meristem gives rise to the root.

You find a Drosophila embryo in which segments A1, A2, A3, and A4 are missing. Which of the following is accurate about the molecular defect in this mutant?

-There is a mutation in a gap gene.

Outcome of misaligned crossover

-a deletion in one chromosome and a duplication in the other.

Classify the following tissues as "plausible" or "implausible" source of stem cells.

-bone marrow PLAUSIBLE -spontaneously or voluntarily aborted fetuses PLAUSIBLE -hepatic (liver) cells IMPLAUSIBLE -fertilized egg PLAUSIBLE -human embryos produced from in vitro fertilization PLAUSIBLE -adult muscle tissue IMPLAUSIBLE -adult cardiac tissue IMPLAUSIBLE -adult mouse fibroblasts PLAUSIBLE .

Origin of homologous genes

-have a common ancestral gene.

Homologous genes within the same species

-metalogs. -xenologs. -paralogs.

Animal development occurs in four overlapping phases, and specific types of transcription factors are important in each phase. Match the correct description of each phase of development with the appropriate picture. Then identify which type of gene/s is/are important in each phase. -maternal effect genes -gap genes -establishment of body axes -pair-rule genes -cell-type specific transcription factor genes -homeotic genes -segment polarity genes -segmentation -cell differentiation -cell fate is determined

1. PHASE DEVELOPMENT: establishment body axes IMPORTANT GENES: maternal effects 2 PHASE DEVELOPMENT: not cell type IMPORTANT GENES: gap genes 3 PHASE DEVELOPMENT: cell fate IMPORTANT GENES: not pair rule 4 PHASE DEVELOPMENT: not segmentation IMPORTANT GENES: not segment polarity genes

Indicate if the following statements are true or false regarding the role of transcription factors in plant and animal development.

1. Transcription factors determine which genes are turned on and which genes are turned off during various stages of development. TRUE 2. Transcription factors in one phase of development do not have any effect on the transcription factors involved in another phase of development. FLASE 3. Transcription factors direct the embryo to subdivide into regions that have properties of individual segments. TRUE 4. Transcription factors direct the formation of the body axes. TRUE 5. Transcription factors are nucleic acids FALSE . 6. Transcription factors are proteins. TRUE .

Which of the following represents a characteristic(s) of ALL stem cells?

CHECK ALL THAT APPLY -All stem cells have the capacity to divide. -Their daughter cells can differentiate into one or more specialized cell types. -When a stem cell divides, one of the daughter cells can remain a stem cell, while the other can differentiate into a specialized cell type. -All stem cells from a given organism contain the same genome. -All stem cells have the capacity to differentiate into specialized cell types. -Stem cells replenish our skin cells and red blood cells.

Four outcomes are possible when an embryonic cell responds to positional information. Label the following illustrations with the correct outcome

Cell Migration Cell Differentiation Cell Death (Apoptosis) Cell Division .