Chapter 18 study guide PDF

Preview

Summary

Download Chapter 18 study guide PDF

Description

Chapter 18 Study Guide

Palmtag Bio 1010C

1. What are the evolutionary and energetic advantages of an operon? Describe the following regions of an operon: regulatory gene, repressor protein, corepressor, promoter, operator, gene of operon. Focusing on the repressor protein and the corepressor, describe how an inducible operon is different than a repressible operon. In the lac operon, describe the role of the CAP protein. A single on-off switch can control the whole cluster of functionally related genes; these genes are under coordinate control. Operon: the entire stretch of DNA required for enzyme production for the tryptophan pathway, consists of the operator, the promoter, and the genes they control Regulatory gene- (trpR) located some distance from the trp operon and has its own promoter Repressor protein- protein that inhibits gene transcription, binds to the DNA in or near the promoter. Binds to control elements within enhancers, to activators or to other proteins in a way that blocks activators from binding to DNA Copressor- a small molecule that cooperates with a repressor protein to switch an operon off Promoter- a specific molecule sequence in DNA that binds to RNA polymerase profussing it to start transcribing RNA at the appropriate place Operator- the switch that controls ... Gene of operon- arranged sequentially after the promoter Inducible operon- usually off, but can be stimulated; the copressor is inactive and can activate by a copressor is usually the lac operon and the lac copressor is usually active by itself switching the lac operon (blank)repressible operon- has the transcription on but can be expressed when a small molecule binds alternatively to a regulatory protein (trp operon)CAP protein- an (blank) protein that binds to DNA and stimulates transcription of a gene if glucose is .... 2. What is morphogenesis? How does cell differentiation relate to morphogenesis? Morphogenesis- is the process that gives an organism its shape (operation of form) The cells become expressed into (tissues) and signals in a particular (blank) arrangement, which is followed by morphogenesis

3. Describe the capabilities of the following types of stem cells: totipotent, pluripotent, multipotent, oligopotent, and unitpotent. Totipotent- capable of constructing a complete organism, including the placenta Pluripotent- capable of becoming endoderm (gut, liver, and lungs), mesoderm (muscle, bone, kidneys, blood, gonads, and connective tissue), ectoderm (epidermal layer of skin). Basically every cell but the placenta. Multipotent- capable of becoming one of several cell types (blood stem cells) Oligopotent- capable of becoming one of a few cell types (osteoprogenitor- bone stem cell) Unipotent- capable of producing one cell type 4. What are cytoplasmic determinants, how do they relate to morphogenesis, what is their origin? One type of transcription factor. A cytoplasmic determinant is a maternal substance such as a protein or RNA, placed into an egg that influences the course of early development by regulating the expression of genes which in turn affect which type of stem cells the pre-stem cells will become. This will overall affect the developmental fate of all cells It relates to morphogenesis (parts that you see on the outside(can see that a starfish has 5 arms) 5. What are maternal effect genes, where are they transcribed into mRNA, where is the mRNA translated into protein? What effect on a developing egg do the proteins have on development? A gene, that when mutant in the mother, results in a mutant phenotype in the offspring regardless of that offspring's own genotype (cytoplasmic determinants). The mRNA is transcribed in the nurse cells and sent to the egg where it will be translated to protein. in a fruit fly, the mRNA or protein products of maternal effect genes are placed in the egg while it is still in the mothers ovary. the egg turns out to be defective and fail to develop properly 6. Describe the experiment that supported the hypothesis of “maternal effect genes”. What is the bicoid gene?

Nusslein-Volhar and Wieshcaus conducted an experiment where they looked for flies with lethal body mutations (two ended tail, no head). This was due to a mutation of the maternal effect gene known as the bicoid gene. Bicoid meaning "two-tailed" when expressed normally in an organism's mother will allow for normal development of the offspring, however when this gene is expressed as a mutation the offspring will be born with two tails 7. What are homeotic genes, what were some of the mutations observed in the homeotic gene experiment? Homeotic genes are regulatory genes that determine the location of where body parts should form. In the experiments Lewis was able to make a fly who's mutations were legs in place of antenna, and two sets of wings 8. How is gene expression ultimately determined? Regulation of gene expression is ultimately determined by the amount of functional protein that is synthesized 9. Eukaryotic gene expression can be regulated at any stage within a cell. The stages range from the properties of the chromatin to the functionality of the protein produced. Determine each level at which a gene can be regulated and describe an example of how genes are regulated at each of those stages.

10. One of the stages that you should have mentioned and described in the previous set of commands was regulation of transcription initiation. Describe how the following terms relate to this type of regulation: master regulatory gene, control element, enhancer region, activators, bending proteins, promoter, and transcription factors. How do this form of gene regulation relate to cell differentiation? Master regulatory gene- determines which activator proteins are produced. They are activated and deactivated during differentiation. Control element- is a segment of noncoding DNA that helps regulate transcription by binding to certain proteins. Enhancer region- is a unique sequence of DNA segments for each gene where the control elements are. Activator proteins- bind with enhancer sequences and tell which gene is to be expressed. Bending proteins- bend the chromosome allowing the enhancer sequence with the activators on it to bind to certain mediator proteins and general transcription factors, which helps them form an active transcription initiation complex on the promoter (where transcription then begins once RNA polymerase attaches). Depending on the specific transcription factors that are made in a cell will be the determinate of what specific genes are expressed. For example both liver cells and eye lens cells have the genes to produce the proteins crystalline (in our eyes) and albumin (in our liver), the transcription factors will determine which protein is actually transcribed 11. Describe how mutations, or chromosomal alterations, lead to changes in gene regulation, which lead to cancer. Proto-oncogenes are normal versions of cellular genes that play a role in the regulation of normal cell growth and division. When a proto-oncogene undergoes a genetic change of some sort the product is an oncogene or a cancer-causing gene. One way this can happen is through point mutations of the proto-oncogene. There are two types of point mutations that may occur. In one instance a promoter or enhancer controlling the proto-oncogene undergoes a mutation, which causes an increase in its expression creating an excess amount of growth-stimulating proteins. In the second scenario the coding sequence in the gene changes and in turn produces a hyperactive or a more degradation-resistant protein. Another way an oncogene can arise is if an especially active promoter is translocated next to a proto-oncogene, it will produce growth-stimulating proteins in excess (making it an oncogene). Also multiple copies of a proto-oncogene can create an excess amount of growth-stimulating proteins, leading to cancer....