BIO 1103 Unit 3 Practice Test

Which of the following are true statements about differentiated cells? - Only cells in the digestive system have genes for digestive enzymes - Brain cells and liver cells are genetically identical. - In our cells, gene expression can be controlled by numerous mechanisms beyond transcription factors or epigenetic tags. - Genes can be switched on and off in each particular cell type

- Brain cells and liver cells are genetically identical. - In our cells, gene expression can be controlled by numerous mechanisms beyond transcription factors or epigenetic tags. - Genes can be switched on and off in each particular cell type

Which of the following statements regarding epigenetics is true? Select all that apply. - Epigenetic changes may remain through cell divisions for the remainder of a cell's life. - There is no change to the underlying nucleotide sequence of the organism's DNA in epigenetics. - Genetic mutations cause the organisms' genes to express themselves differently in epigenetics. - Epigenetic effects may last for multiple generations.

- Epigenetic effects may last for multiple generations. - Epigenetic changes may remain through cell divisions for the remainder of a cell's life. - There is no change to the underlying nucleotide sequence of the organism's DNA in epigenetics.

Which of the following statements are true when describing gene expression? - Gene expression occurs as a result of epigenetic cues and in response to cellular signals in your body. - Gene expression dictates cellular behavior and production of proteins. - Gene expression is the specific combination of genes that are turned on or off within a cell. - Gene expression creates different DNA within each of your cell types.

- Gene expression occurs as a result of epigenetic cues and in response to cellular signals in your body. - Gene expression dictates cellular behavior and production of proteins. - Gene expression is the specific combination of genes that are turned on or off within a cell.

Studies examining epigenetic tags in twins have been useful in identifying variation in gene expression in humans. Which of the following patterns would you expect to be true based on epigenetics? - Identical twins have similar epigenetic tags late in life because they share similar interests and lifestyles with one another. - Identical twins will have the same epigenetic tags throughout their life because they are genetically identical. - Younger identical twins have more similar epigenetic tags on their DNA because they have more common life experiences.

- Younger identical twins have more similar epigenetic tags on their DNA because they have more common life experiences.

Identify which of the following are steps in the process of using a microarray to determine gene expression. Select all that apply. - collect all the mRNA in a cell - collect all the DNA in a nucleus of a cell - use a detector to measure the amount of fluorescence on the array - allow the labeled cDNA copies of mRNA to hybridize to the DNA on the microarray

- allow the labeled cDNA copies of mRNA to hybridize to the DNA on the microarray - use a detector to measure the amount of fluorescence on the array - collect all the mRNA in a cell

Which of the following would you expect to observe in a gene (like Agouti that causes yellow coat fur color) when it is marked for active transcription? Select all that apply. - loosely wound with few methyl groups - loosely wound with histones with many acetyl groups - tightly wound with many methyl groups - tightly wound with histones with few acetyl groups

- loosely wound with histones with many acetyl groups - loosely wound with few methyl groups

What is a nucleosome? - A complex of chromatin and proteins that controls import of molecules into the nucleus - A repeating unit of chromatin composed of DNA wrapped around histone proteins. - A membrane bound organelle that contains epigenetic information - Chromosomal DNA that is associated with the nucleolus and nucleotides

A repeating unit of chromatin composed of DNA wrapped around histone proteins.

Methylation is an epigenetic modification that turns off gene expression. Many cancers show evidence of hypermethylation (too many methyl groups) or hypomethylation (too few methyl groups) on key cancer causing genes. The two major classes of cancer causing genes are 1) oncogenes or genes that are normally used to speed up cell division, or 2) tumor suppressor genes that play a role in slowing down cell division. Predict the levels of gene expression for these two types of genes in cancerous and normal cells. Put responses in the correct input to answer the question. Select a response, navigate to the desired input and insert the response. Responses can be selected and inserted using the space bar, enter key, left mouse button or touchpad. Responses can also be moved by dragging with a mouse.

Cancer Cells: - Hyper (over) methylated tumor suppressors - hypo (under) methylated oncogenes Normal Cells: - Hypo (under) methylated tumor suppressors - Hyper (over) methylated oncogenes

Researchers look for chemotherapy agents that can affect methylation and acetylation of genes in cancerous cells. For each of the following drugs, indicate if genes would be on or off.

Gene On: - Resveratrol (RSV) removes methyl groups from DNA - Azacitidine prevents methylation of DNA Gene off: Thiazide sulfonamide prevents histone acetylation.

Researchers investigating a tumor are interested in 4 oncogenes (1-4) whose over-expression may be the cause of the excessive growth of the cells. Which gene shows characteristics that are consistent with over-expression?

Gene: 1 Methylation: Low Level Chromatin: Loosely wound mRNA transcripts: High Levels

Often cancer cells have modified epigenomes such that genes that should be turned off are instead turned on. For example, tumor suppressor genes often code for proteins that slow the cell's progress through the cell cycle, and they are usually turned on in cells. If the epigenome is changed, then the tumor suppressor gene might be turned off. One way that researchers are identifying cancerous cells is to detect the degree of methyl groups that are present on several cancer-causing genes. One gene, RSSF2, appears to be a tumor suppressor and produces a protein that is involved in stopping the cell from dividing. Doctors would expect to see ____levels of the RSSF2 protein in these abnormally dividing ovarian tumor cells because DNA for the gene had a(n) ______ in methyl groups

Lower, Increase

Researchers have long been intrigued by the idea that although all cells in the body contain all the same genes they do not make all the same proteins. For example, all cells have a gene such as lactase, but lactase protein is only made in specific cells, such as an intestinal cell, but is not made in another cell such as a skin cell. You can review how this is accomplished in this activity: Regulation of the Lactose Gene The reason for differences in the sets of proteins expressed in an intestinal cell compared to a skin cell of the same individual is that intestinal and skin cells contain different _____

Sets of regulatory proteins

Agouti mice display yellow coats and obese body size. However, when Jirtle supplemented the diet of Agouti pregnant mice with methyl donors like extra folic acid, vitamin B12, choline, and betaine. What did he observe in the pups? - The pups had darker coats and were thinner than the offspring of mothers who did not receive the supplements. - The offspring were obese if they were born to mothers who were supplemented. - Pups born to mothers who ate the supplements had lower levels of methyl groups on their Agouti gene. - The methylation levels of the Agouti gene changed as the offspring aged.

The pups had darker coats and were thinner than the offspring of mothers who did not receive the supplements.

Different cell types, for example a muscle or a blood cell in the same organism retain ___.

a complete set of their genes, and retain the ability to express those genes under certain circumstances into mRNA.

Cells that are unable to produce histones would likely - be unable to pack their DNA into the nucleus - see an increase in the size of RNA molecules made during transcription. - see an increase in mutations. - be unable to duplicate its DNA.

be unable to pack their DNA into the nucleus

Ants are social animals that benefit from division of labor. Most ants in a colony are workers foraging for food, others can grow incredibly large and become soldiers playing roles in colony defense, and usually one queen develops for egg laying. However, all the female embryos that the queen lays are identical and have the potential to become either queens, workers, or soldiers depending on nutrition, pheromones, and temperature. Scientists recently discovered that injecting a chemical in the brains of soldiers could turn off a gene called RCOR1 that is normally only expressed in worker or forager ants and transform their behavior. Based on your understanding of epigenetics, you might expect the chemical they injected to ____.

cause acetyl groups to be removed from histones.

One way that researchers are looking at to identify cancerous cells is to detect the degree of methyl groups that are present on several cancer-causing genes. One gene, RASSF2, appears to be a tumor suppressor and produces a protein that is involved in stopping the cell cycle. Doctors would expect to see _____ of the protein in ovarian tumor cells because the DNA for the gene had ______.

lower levels; an increase in methyl groups

Women are encouraged to take methyl-donating folate or choline during pregnancy to avoid neural tube defects. However, research in mice has shown that deficiencies in methyl donating groups late in pregnancy or in newborns can result in certain regions of the genome of the baby to be under-methylated for life. This is serious because ____. - without methyl groups genes cannot be transcribed into mRNAs. - the cells need methyl groups to synthesize nucleotides. - without these methyl groups genes can't be turned off - methyl groups are required to make new proteins.

without these methyl groups genes can't be turned off