Ch 19 BIO

Roles of transcription factors 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. 2. Transcription factors in one phase of development do not have any effect on the transcription factors involved in another phase of development. 3. Transcription factors direct the embryo to subdivide into regions that have properties of individual segments. 4. Transcription factors direct the formation of the body axes. 5. Transcription factors are nucleic acids. 6. Transcription factors are proteins

1. true 2. false 3. true 4. true 5. false 6. true

Stem cell differentiation 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 Cell

A. Embryonic Stem (ES) Cells Pluripotent B. Hematopoietic Stem Cells (HSC) Multipotent C. Fertilized Egg Totipotent D. Skin Cells Unipotent

The process by whereby a cell's morphology and function have changed is called?

Differentiation

positional information is important in determining the fate of a cell in a multicellular organism.Animal cells respond to positional information by

Dividing, migrating , derentiating , undergoing apoptosis.

Increase the likelihood of gene duplication/deletion. Study the figure below showing a duplication on one chromosome and deletion on the other. What characteristic would MOST increase the likelihood of this mutation? Picture A large poly-nucleotide region on the chromosome (e.g. 5' ...TTTTTTTTTTTTT...TTTTTTT... 3'). A region on the chromosome that contains 10-20 repeats of a tri-nucleotide sequence (e.g. 5' ...GCAGCAGCAGCA... 3'). Four, 20 base-pair regions scattered across one arm of a chromosome that have identical or very similar sequence Chromosomes that are highly acrocentric. All of these are equally likely to lead to gene duplications/deletions.

Four, 20 base-pair regions scattered across one arm of a chromosome that have identical or very similar sequence

Morphagens are

Molecules that convey positional information and promote changes in development

Gene duplication example Evaluate the following examples and determine which is most likely a result of a gene duplication. Many plant homeotic genes are transcription factors that contain a MADS domain, responsible for binding to the DNA. Many animal homeotic genes are transcription factors that contain a homeobox domain, responsible for binding to the DNA. Plant and animal homeotic genes are both transcription factors that contain DNA binding regions. Animals with a homeobox domain, and plants with a MADS domain. 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.

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.

A misaligned cross over between two homologous chromosomes A misaligned cross over between two homologous chromosomes usually results in a deletion in one chromosome and no change in the other. a deletion in one chromosome and a duplication in the other. deletions in both chromosomes. duplications in both chromosomes. no change in either chromosome.

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

the proper sequence for animal development is:

axes of the entire animal are determined, the animal is divided into segments,tissues & organs and other body structures in each segment are formed, cells become differentiated.

Compare determination and differentiation 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 differentiated/determined developed/determined differentiated/developed

determined/differentiated

Homologous genes are best described as genes that Homologous genes are best described as genes that have identical sequences. have a common ancestral gene. have similar functions. are on the same chromosome. are on homologous chromosomes.

have a common ancestral gene.

Analyzing a Drosophila mutant 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 maternal effect gene. There is a mutation in a gap gene. There is a mutation in a pair-rule gene. There is a mutation in a segment polarity gene. There is a mutation in a gene encoding a transcription factor. There is a mutation in a segmentation gene. There is a mutation in a homeotic gene.

here is a mutation in a gap gene. There is a mutation in a gene encoding a transcription factor.

Homologous genes within a single species are said to be Homologous genes within a single species are said to be orthologs. paralogs. metalogs. xenologs. homologs

paralogs.

what group of proteins plays a key role in controlling the program of developmental changes?

transcription factors

Stem cell characteristics Which of the following represents a characteristic(s) of ALL stem cells? They have the capacity to generate 8 first generation daughter cells instead of only two as in most other somatic cells All stem cells have the capacity to divide Their daughter cells can differentiate into one or more specialized cell types All stem cells express the same genes 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 ultilize the same transcription factors when differentiating into specialized cell types 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 out skin cells and red blood cells All human embryonic stem cells are totipotent All human stem cells are from the embryo or are germ cells

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 out skin cells and red blood cells

Evolutionary fate of organisms with duplicated genes 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. Gene duplications could be detrimental to the fitness of an organism, as proteins are produced in higher quantities than normal. Gene duplications allow for higher reproductive fitness, as there is more genetic information to be distributed among offspring. Gene duplications allow for faster growth and development, as there is more DNA to direct these processes. Gene duplications are mutations, so they will result in inviable offspring.

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

Characteristics of homeotic genes Which of the following statements are ACCURATE regarding homeotic genes and homeotic proteins? Check all that apply. In mammals, homeotic genes are randomly spread out on all chromosomes Homeotic genes encode transcription factors Homeotic proteins bind regulatory regions of genes important in development Animals contain homeotic genes, but plants do not Homeotic genes are found only in invertebrate animals, such as Drosophila In animals, the order of homeotic genes on a chromosome correlates with their spatial order of expression in the embryo The homeobox region of homeotic genes is found in the promoter 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 Hox genes are found in all animals Homeoboxes are only found in homeotic genes

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

An embryonic stem cell that can give rise to any type of cell of an adult organism but cannot produce an entire, intact individual is called

pluripotent