Unit 6 Lesson 5: Gene expression and Gene Regulation

Question 1

What is gene expression

Answer 1

a process by which genetic information is converted into proteins

Question 2

Gene expression is the process by which..

Answer 2

Gene expression is the process by which information carried in the DNA of cells is decoded and used to build the proteins needed for those cells to survive.

Question 3

What are products of gene expression

Answer 3

Everything from eye color, organ function, and immune responses to viruses are products of gene expression.

Question 4

What is gene regulation

Answer 4

the mechanisms that activate or repress the expression of a gene

Question 5

How does gene rexpression and regulation occur in prokaryotes and eukaryotes

Answer 5

These processes occur differently in prokaryotes (cells that do not contain organelles, such as nuclei) and eukaryotes (cells that do contain organelles like nuclei).

Question 6

What are the difference betweeen prokaryotic and eukaryotic cells

Answer 6

First, prokaryotes do not separate their DNA from the cytoplasm using a structure called a nucleus like eukaryotic cells do.

Question 7

First, prokaryotes do not separate their DNA from the cytoplasm using a structure called a nucleus like eukaryotic cells do.
What does this mean

Answer 7

This means that the moment the enzyme RNA polymerase finishes transcribing DNA into mRNA, a ribosome can immediately attach to the mRNA and begin translating it into protein.

Question 8

RNA polymerase

Answer 8

an enzyme that copies a DNA genetic sequence into an mRNA sequence

Question 9

This means that the moment the enzyme RNA polymerase finishes transcribing DNA into mRNA, a ribosome can immediately attach to the mRNA and begin translating it into protein.
What happens becasue of this

Answer 9

Because of this, most gene regulation in prokaryotes focuses on regulating the process of transcription.

Question 10

prokaryotes tend to be what cellular organsims?

Answer 10

Furthermore, prokaryotes tend to be unicelluar organisms, which consist of only one cell.

Question 11

Why do prokaryotes need to ensure that genes needed to use the resources in the environment are active while conserving as much energy as possible.

Answer 11

prokaryotes tend to be unicelluar organisms, which consist of only one cell

Question 12

Because of this, prokaryotes need to ensure that genes needed to use the resources in the environment are active while conserving as much energy as possible. What does this require

Answer 12

This requires fine tuning their gene expression to only use the genes they need at that very moment to survive.

Question 13

Why are there many gene regulation mechanisms in prokaryotes that directly respond to environmental stimuli.

Answer 13

Because of this, prokaryotes need to ensure that genes needed to use the resources in the environment are active while conserving as much energy as possible. This requires fine tuning their gene expression to only use the genes they need at that very moment to survive. Because of this, there are many gene regulation mechanisms in prokaryotes that directly respond to environmental stimuli.

Question 14

What does an eukaryote’s nucleus do

Answer 14

Eukaryotes have a nucleus that separates their DNA from the cytoplasm.

Question 15

What allows eukaryotes to separate the process of transcription and translation

Answer 15

Eukaryotes have a nucleus that separates their DNA from the cytoplasm. This allows eukaryotes to separate the process of transcription and translation

Question 16

What ablity does separating the process of transcription and translation give eukaryotes

Answer 16

This allows eukaryotes to separate the process of transcription and translation, giving them the ability to manipulate and modify mRNA before translation

Question 17

Eukaryotes tend to be ?cellular

Answer 17

eukaryotes tend to be multicellular, multiple copies of the same starting cell.

Question 18

Why do all cells in an organism inheir the same copy of DNA

Answer 18

Because of this, all the cells in an organism inherit the same copy of DNA.

Question 19

Because of this, all the cells in an organism inherit the same copy of DNA. Where is this DNA nescssary

Answer 19

Part of this DNA is necessary in a specific cell type (such as a skin cell), but the other parts of the DNA are not necessary. For example, in humans, a liver cell uses specific genes within the DNA, and would not need the specific genes used by brain cells.

Question 20

Why led eukaryores to develop unique ways of packaging DNA t

Answer 20

. For example, in humans, a liver cell uses specific genes within the DNA, and would not need the specific genes used by brain cells. Because of this, eukaryotes have developed unique ways of packaging DNA to silence many genes at a time.

Question 21

What is chromatin remodeling

Answer 21

the process by which DNA is unwound from its associated protein to allow for transcription or replication

Question 22

What is the importance of chromatin remolding

Answer 22

chromatin remodeling, and it is an important step in the process of cell differentiation, during which a cell develops and matures into a certain type of cell, such as a liver cell or brain cell.

Question 23

Your digestive tract is filled with bacteria such as

Answer 23

Escherichia coli (E. coli)

Question 24

What is E. coli used for

Answer 24

E. coli has become one of the main model organisms that scientists use to study prokaryotes.Scientists have studied these bacteria to learn how gene regulation occurs in prokaryotes.

Question 25

How does E.Coil bacteria get energy

Answer 25

. E. coli bacteria use a wide variety of sugars to get the energy they need to digest the food you eat. The bacteria need different types of enzymes in order to be able to use each type of sugar found in the food you ingest.

Question 26

E. coli, like other prokaryotes, organize the genes in their genome into clusters called

Answer 26

Operons

Question 27

What are operons

Answer 27

a group of related genes that operates together as a functional unit in prokaryotic cells

Question 28

Opersons are the main way that prokaryotes regualte..

Answer 28

Operons are the main way that prokaryotes regulate gene expression at the transcriptional level.

Question 29

There are two main types of operons:

Answer 29

inducible and repressible.

Question 30

What are the most studeied inducible and repressible.

Answer 30

The most studied inducible operon is the lac operon, and the most studied repressible operon is the trp operon.

Question 31

Note the similarities between the two types of operons.

Answer 31

In both cases, binding of the repressor protein to the operator shuts down the operon. Also, binding of the repressor protein to a molecule related to the function of the operon causes a change in the shape of the repressor protein. This change in shape affects the binding of the repressor protein to the operator.

Question 32

repressor

Answer 32

a regulatory protein and/or small molecule that inhibits transcription

Question 33

How have prokaryotes, like E. coli, have become very efficient at using their resources.

Answer 33

By using operons, prokaryotes, like E. coli, have become very efficient at using their resources.

Question 34

Multicellular eukaryotes all start off as

Answer 34

zygotes

Question 35

What kind of cells are zygotes

Answer 35

Multicellular eukaryotes all start off as zygotes, which are single cells.

Question 36

how does zygote create more cells

Answer 36

This zygote then duplicates and copies its DNA to create more cells. This process is repeated until a single cell gives rise to all the cells within the body. Because of this, all the cells in a multicellular eukaryote, like humans, have the same DNA.

Question 37

If they all have the same DNA, then why does a brain cell behave so differently from a liver cell?

Answer 37

The answer comes from a unique form of gene regulation used by eukaryotes called chromatin remodeling or DNA packaging.

Question 38

Besides DNA packaging, eukaryotic cells, just like prokaryotic cells, can control how genes are…

Answer 38

transcribed into mRNA.

Question 39

What is DNA like in prokaryote cells

Answer 39

Recall that prokaryotes do not have a nucleus. The DNA of prokaryotes is in the cytoplasm of the cell. This allows ribosomes in the cytoplasm to immediately begin translating any mRNA that has been transcribed from the DNA. This prevents prokaryotes from modifying or manipulating their mRNA to affect its translation.

Question 40

What is DNA like in Eukaryote cells

Answer 40

Eukaryotes, on the other hand, have nuclei. This barrier separates the DNA from the cytoplasm. The mRNA produced by transcription must be transported out of the nucleus into the cytoplasm in order to be translated by the ribosome in the cytoplasm. This allows eukaryotes to modify and manipulate their RNA in a process known as RNA processing.

Question 41

RNA processing

Answer 41

a change RNA undergoes in the cell nucleus to become a mature mRNA molecule

Question 42

The DNA of eukaryotes is different from prokaryotes. Elaborate

Answer 42

In prokaryotes, the entire region of a gene that codes for a protein is translated into protein. In eukaryotes, on the other hand, the segments of the gene that will be expressed as protein are known as exons.

Question 43

exon

Answer 43

a portion of a gene that is expressed into protein

Question 44

What are between exons

Answer 44

Between these exons are segments of DNA that are transcribed into the mRNA initially, but they are removed before the mRNA is transported to the cytoplasm for translation. These regions that will not be made into protein are known as introns.

Question 45

What are introns

Answer 45

a portion of a gene that is not expressed into protein

Question 46

When must introns be removed

Answer 46

Introns must be removed from the initial mRNA, or pre-mRNA, before the mRNA can be transported to the cytoplasm for translation by the ribosome

Question 47

What is the porcess of removing introns called

Answer 47

The process of removing introns from the pre-mRNA is known as RNA splicing.

Question 48

RNA splicing does not always put all the exons of a gene back together. What happens in this case

Answer 48

This process can make different mRNAs from the same pre-mRNA by putting the exons together in different ways. This allows eukaryotes to produce several different mRNAs and, therefore, several different proteins from the same gene.

Question 49

Mutations in the gene near the boundary of exons and introns can cause problems with RNA splicing. Waht does this allow

Answer 49

This allows an intron to remain in the mRNA. Because of this extra mRNA, the protein that is translated from the wrongly spliced mRNA does not function correctly.

Question 50

After RNA splicing, two modifications are made to the mRNA in eukaryotes. Elaborte

Answer 50

First, a structure, known as a 5’-cap (pronounced “5 prime cap”), is added to the front of the mRNA. This cap interacts with the nuclear pores in the nuclear envelope of the nucleus, allowing the mRNA to be transported into the cytoplasm. Finally, adenine nucleotides are added to the end of the mRNA. This structure is known as the poly(A) tail. The number of adenines can vary, and this structure acts as a timer. When in the cytoplasm, there are enzymes that will slowly degrade these poly(A) tails. Once these tails are fully degraded, the mRNA is destroyed completely. Therefore, the cell can modify the length of this tail to make the mRNA last longer. Longer tails allow more time for translation, which results in more protein being produced from the mRNA.

Question 51

Regulation of gene expression at the translational and post-translational levels works similarly in both

Answer 51

Regulation of gene expression at the translational and post-translational levels works similarly in both prokaryotes and eukaryotes. The specific proteins and processes involved are, or course, different between the two types of cells, but there are similarities between the two.

Question 52

In order to prevent translation of the mRNA into protein what must be done

Answer 52

In order to prevent translation of the mRNA into protein once the mRNA has been transported to the cytoplasm, the cell must interfere with the ability of the ribosome to translate the mRNA.

Question 53

What are 2 ways a cells can prevent translation of the mRNA into the protein

Answer 53

There are two ways for the cell to do this: destroy the mRNA or prevent the mRNA from binding to the ribosome.

Question 54

What must be done to destroy the mRNA

Answer 54

In order to destroy the mRNA, both prokaryotes and eukaryotes have evolved systems that perform RNA silencing or RNA interference.

Question 55

RNA silencing

Answer 55

a way for the cell to control the translation of an mRNA using microRNAs; also known as RNA interference

Question 56

How is the process of RNA sliencing simialr in both prokaryotes and eukaryotes

Answer 56

. Although the exact proteins and enzyme involved in these processes are different between prokaryotes and eukaryotes, they both involve using small pieces of RNA called microRNA.

Question 57

What does microRNAs do

Answer 57

These microRNAs have specific sequences that allow them to bind to specific mRNAs in the cytoplasm. Once bound to the mRNA, they flag the mRNA for degradation by certain enzymes in the cytoplasm.

Question 58

What does the destruction of the mRNA do

Answer 58

The destruction of the mRNA prevents protein from being made by the ribosome from this mRNA.

Question 59

The second way involves preventing the mRNA from binding to the ribosome. Elaborate

Answer 59

e. Most mRNAs have a region, called the untranslated region or UTR, near the beginning and end of the molecule that is not translated into protein. These UTRs typically have binding sites for proteins that when bound can prevent the mRNA from binding the ribosome. This method of translational control is more reversible than the RNA silencing method described previously. The mRNA is not destroyed using this method. The cell can modify the protein bound to the mRNA so it will release the mRNA, allowing it to be translated.

Question 60

Post-translational control involves affecting the ability of the protein to perform its function or destroying the protein. There several ways a cell can affect the function of a protein. Explain

Answer 60

First, after an mRNA is translated into a polypeptide strand, that polypeptide strand must fold into a particular shape to become active. Because of this, the cell can take advantage of this to affect the function of the protein by either helping the protein fold correctly or preventing the protein from folding correctly. Second, many proteins require more modifications to become active. For example, some proteins involve multiple polypeptide strands that must come together to form a complex. Other proteins require the addition of chemical groups to be added before the protein becomes active. This is one of the more popular ways of controlling protein function, and one of the most popular chemical groups is the phosphate group, which is a phosphorus atom chemically bonded to four oxygens. The addition of a phosphate group typically activates the protein, while the removal of the phosphate group typically inactivates the protein. Finally, the cell can control when the protein becomes destroyed. This allows the cell to control the lifetime of the protein.

Question 61

What might happen if a eukaryotic cell could not regulate its gene expression?

Answer 61

The cell would make all the proteins that its DNA codes for. There would be no repression of gene expression. The cell would waste a lot of energy making proteins that it did not need.

Question 62

What are three ways a cell can regulate the proteins it produces?

Answer 62

transcriptional control, post-transcriptional control (which includes RNA processing), translational control (which includes RNA silencing or RNA interference), and post-translational control

Question 63

What is the difference between gene expression and gene regulation?

Answer 63

Gene expression describes the process by which genetic information is converted into proteins. Gene regulation describes processes by which the expression of a gene is induced, turned on, or repressed, turned off.

Question 64

What is a promoter, and what is its function?

Answer 64

A promoter is a noncoding part of a gene. It serves as the binding site for the enzyme RNA polymerase that will transcribe the gene into mRNA. This site typically has regulatory sites near it that either enhance or limit the ability of the RNA polymerase to bind to it.

Question 65

Suppose an mRNA molecule for an enzyme has been transcribed, and the mRNA is prevented from being translated into a protein. This is known as _______

transcriptional control
translational control
chromatin remodeling
RNA processing

Answer 65

B. translational control

Question 66

Explain how gene regulation results in the formation of specialized cells in multicellular organisms. How is this different in a prokaryotic cell, which is not specialized?

Answer 66

The cells of a multicellular organism do not make all the proteins that are coded for in their DNA. Instead, each kind of cell makes only those proteins that it needs for its specific functions. A prokaryotic cell must perform all the functions of the organism. It must make all the proteins that are coded in its DNA. To turn off certain proteins, the cells of a multicellular organism use a combination of the gene regulation techniques, including chromatin remodeling, transcriptional control, RNA processing, translational control, and post-translational control to only use some of the DNA.

Question 67

transcription factors

Answer 67

a class of proteins that regulates transcription in eukaryotes by interacting with RNA polymerase.

Question 68

promoter

Answer 68

a segment in DNA that binds with the enzyme RNA polymerase