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Bio 190 > Chapter 18 > Flashcards

Chapter 18 Flashcards

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1
Q

What is the primary way prokaryotes and eukaryotes regulate gene expression?

A

In response to environmental conditions

This regulation triggers cell signaling.

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2
Q

What role does gene expression play in multicellular eukaryotes?

A

Regulates development and is responsible for differences in cell types.

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3
Q

What is one of the roles of RNA molecules in eukaryotes?

A

Regulating gene expression.

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4
Q

What do all organisms need to do regarding gene expression?

A

Regulate which genes are expressed at any given time.

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5
Q

Why is regulation of gene expression essential in multicellular organisms?

A

For cell specialization.

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6
Q

Fill in the blank: In eukaryotic gene expression, regulation occurs at many _______.

A

stages.

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7
Q

True or False: Gene expression does not affect cellular growth in eukaryotes.

A

False.

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8
Q

What process in cellular growth is mentioned in the context of gene expression?

A

Mitosis.

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9
Q

What is differential gene expression?

A

The expression of different genes by cells with the same genome

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10
Q

What do almost all the cells in an organism have in common?

A

They are genetically identical (totipotent)

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11
Q

What can abnormalities in gene expression lead to?

A

Diseases including cancer (mutations)

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12
Q

At what stages is gene expression regulated?

A

Gene expression is regulated at many stages

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13
Q

How does the structural organization of chromatin affect gene expression?

A

It helps regulate gene expression in several ways

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14
Q

What is typically the expression status of genes within highly packed heterochromatin?

A

Usually not expressed

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15
Q

Fill in the blank: Differences between cell types result from _______.

A

[differential gene expression]

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16
Q

True or False: All genes in an organism are expressed equally.

A

False

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17
Q

What role does gene regulation play in an organism?

A

It controls the expression of genes

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18
Q

What is histone acetylation?

A

The attachment of acetyl groups to positively charged lysines in histone

This process loosens chromatin structure, promoting the initiation of transcription.

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19
Q

How does histone methylation affect chromatin structure?

A

It can condense chromatin

The addition of phosphate groups next to a methylated amino acid can loosen chromatin.

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20
Q

What role do histone tails play in chromatin regulation?

A

They protrude outward from a nucleosome and are available for chemical modification

This allows for various modifications that can impact gene expression.

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21
Q

What is the effect of acetylated histones on chromatin structure?

A

They promote a loose chromatin structure that permits transcription

This contrasts with unacetylated histones, which result in a more condensed structure.

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22
Q

What is DNA methylation?

A

The addition of methyl groups to DNA

This process can lead to long-term inactivation of genes.

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23
Q

What is the significance of DNA methylation in cellular differentiation?

A

It can cause long-term inactivation of genes

This is crucial for the differentiation of cells.

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24
Q

What is genomic imprinting?

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A

The regulation of expression of either the maternal or paternal alleles of certain genes at the start of development

This process is influenced by DNA methylation.

25
What is epigenetic inheritance?
The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence ## Footnote This form of inheritance includes chromatin modifications that do not change the DNA sequence itself.
26
Do chromatin modifications alter the DNA sequence?
No, chromatin modifications do not alter DNA sequence ## Footnote However, they may be passed to future generations of cells.
27
What role do transcription factors play in gene expression?
Some transcription factors function as repressors, inhibiting expression of a particular gene ## Footnote They can use various methods to achieve this.
28
How do some activators and repressors influence transcription?
By influencing chromatin structure to promote or silence transcription ## Footnote This indirect action affects gene expression.
29
What plays multiple roles in controlling gene expression?
Noncoding RNAs ## Footnote Noncoding RNAs include various types such as microRNAs and small interfering RNAs
30
What fraction of DNA codes for proteins?
Only a small fraction ## Footnote This indicates that the majority of DNA does not directly code for proteins
31
What types of RNA are included in the small fraction of non-protein-coding DNA?
RNA and tRNA ## Footnote These are essential for protein synthesis and other cellular functions
32
What is the estimated amount of the genome that may be transcribed into noncoding RNAs?
A significant amount ## Footnote This highlights the importance of noncoding RNAs in the genome
33
At what two points do noncoding RNAs regulate gene expression?
* mRNA translation * Chromatin configuration ## Footnote These processes are crucial for the control of gene expression
34
What are microRNAs (miRNAs)?
Small single-stranded RNA molecules that can bind to mRNA ## Footnote miRNAs play a key role in regulating gene expression
35
What effects can microRNAs have on mRNA?
* Degrade mRNA * Block its translation ## Footnote This regulation can significantly affect protein synthesis
36
What percentage of human gene expression may be regulated by miRNAs?
At least half ## Footnote This indicates the widespread influence of miRNAs in gene regulation
37
What results from genetic changes that affect cell cycle control?
Cancer ## Footnote Cancer results from alterations in the normal processes that regulate cell growth and division.
38
What systems are involved in both cancer development and embryonic development?
Gene regulation systems ## Footnote These systems are responsible for controlling gene expression during development and can malfunction in cancer.
39
What can cause mutations in genes that regulate cell growth and division?
Spontaneous mutation or environmental influences ## Footnote Environmental influences include chemicals, radiation, and some viruses.
40
What are cancer-causing genes called?
Oncogenes ## Footnote Oncogenes can be found in some types of viruses and are linked to cancer development.
41
Fill in the blank: Cancer can be caused by mutations to genes that regulate _______ and _______.
cell growth and division
42
True or False: Mutations in cancer-related genes can only occur due to environmental influences.
False ## Footnote Mutations can occur due to spontaneous mutation as well.
43
What is the primary function of tumor-suppressor genes?
Help prevent uncontrolled cell growth ## Footnote Tumor-suppressor genes play a crucial role in regulating the cell cycle and maintaining normal cellular functions.
44
How can mutations in tumor-suppressor genes affect cancer onset?
They may decrease protein products of tumor-suppressor genes ## Footnote Such mutations can lead to a loss of function, contributing to the development of cancer.
45
What role do tumor-suppressor proteins play in DNA repair?
They repair damaged DNA ## Footnote This function is essential for maintaining genomic stability and preventing mutations.
46
What is one of the functions of tumor-suppressor proteins related to cell adhesion?
Control cell adhesion ## Footnote Proper cell adhesion is important for tissue integrity and preventing metastasis.
47
In what type of pathways do tumor-suppressor proteins act?
Cell-signaling pathways that inhibit the cell cycle ## Footnote These pathways help regulate cell division and prevent excessive proliferation.
48
What are common mutations found in human cancers?
Mutations in the ras proto-oncogene and p53 tumor-suppressor gene ## Footnote These mutations are frequently observed in various types of cancers.
49
What can mutations in the ras gene lead to?
Production of a hyperactive Ras protein and increased cell division ## Footnote This hyperactivity can contribute to uncontrolled cell growth.
50
What role does p53 play in the cell cycle?
Prevents a cell from passing on mutations due to DNA damage ## Footnote p53 is crucial for maintaining genomic stability.
51
What happens when there are mutations in the p53 gene?
Prevents suppression of the cell cycle ## Footnote This can lead to the propagation of genetic mutations.
52
Fill in the blank: _______ stimulates the cell cycle.
[Protein that stimulates the cell cycle]
53
What is the role of a transcription factor in cell signaling?
Acts as an activator for gene transcription ## Footnote This is essential for the expression of genes involved in cell division.
54
What are the components involved in the pathway of cell signaling?
Growth factor, receptor, G protein, protein kinases, Ras protein, transcription factor ## Footnote Each component plays a specific role in the signaling cascade.
55
True or False: Ras protein is inactive without a growth factor.
False ## Footnote Ras protein can be active with or without growth factor.
56
What is generally needed for full-fledged cancer development?
Multiple mutations ## Footnote The incidence of cancer increases with age due to the accumulation of mutations.
57
What is a characteristic of a cancerous cell at the DNA level?
At least one active oncogene and the mutation of several tumor-suppressor genes ## Footnote Oncogenes promote cancerous growth, while tumor-suppressor genes normally inhibit it.
58
True or False: The incidence of cancer decreases with age.
False ## Footnote The incidence increases with age due to the accumulation of genetic mutations.

Bio 190 (6 decks)

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