1. Define gene expression.
Gene expression is the process by which
information from a gene is used in the synthesis of
a functional gene product that enables it to
produce end products, protein or non-coding RNA,
and ultimately affect a phenotype, as the final effect
2. State the possible outcomes and location of
transcription.
Transcription takes place in the nucleus, and it
uses DNA as a template to make an RNA molecule
then leaves the nucleus and goes to a ribosome in
the cytoplasm, where translation occurs.
3. List and explain each of the steps of transcription.
Transcription has 3 steps: initiation, elongation, and
termination.
Initiation:
in the nucleus, RNA polymerase recognizes the
recognition site causing it to bind to the promoter
(start of the gene). The RNA polymerase then
separates the DNA into single strands so the
template strand can be read in the 3’ to 5’
direction.
Elongation:
pre-mRNA nucleotides are quickly paired with their
complementary bases which correspond with the
template strand of DNA. The pre-mRNA moves in
the 5’ to 3’ direction while the template strand
moves in the opposite direction 3’ to 5’. Pre-mRNA
does not contain thymine, instead uracil is used at
the complementary base to adenine.
Termination:
When the RNA polymerase reaches the terminator
it signals the RNA polymerase to stop and release from the DNA. Once separated, the two DNA
strands come back together and reform the double helix. The newly formed pre-mRNA molecule is
then released.
4. Explain the relationship between a gene and transcription.
Together, transcription and translation are known as gene expression. During transcription, the
information stored in a gene’s DNA is passed to a similar molecule called RNA in the nucleus.
Transcription is the first step in gene expression, in which information from a gene is used to
construct a functional product such as a protein. The goal of transcription is to make a RNA copy
of a gene's DNA sequence.
, 5. Explain how the “information” in DNA is transferred into RNA.
In the first step, the information in DNA is transferred to a messenger RNA (mRNA) molecule by
way of a process called transcription. During transcription, the DNA of a gene serves as a
template for complementary base-pairing, and an enzyme called RNA polymerase II catalyzes the
formation of a pre-mRNA molecule, which is then processed to form mature mRNA (Figure 1). The
resulting mRNA is a single-stranded copy of the gene, which next must be translated into a
protein molecule.
During translation, which is the second major step in gene expression, the mRNA is "read"
according to the genetic code, which relates the DNA sequence to the amino acid sequence in
proteins (Figure 2). Each group of three bases in mRNA constitutes a codon, and each codon
specifies a particular amino acid (hence, it is a triplet
code). The mRNA sequence is thus used as a
template to assemble—in order—the chain of amino
acids that form a protein.
1. Define cell cycle checkpoint and explain how it is
used in cell cycle control.
Cell cycle checkpoints are surveillance mechanisms
that monitor the order, integrity, and fidelity of the
major events of the cell cycle. These include growth
to the appropriate cell size, the replication and
integrity of the chromosomes, and their accurate
segregation at mitosis.
2. Explain the role of cyclin dependent kinases in the
cell cycle and how they promote mitosis.
Cyclin-dependent kinases (CDKs) are the families of
protein kinases first discovered for their role in
regulating the cell cycle. They are also involved in regulating transcription, mRNA processing,
and the differentiation of nerve cells. ... By definition, a CDK binds a regulatory protein called a
cyclin.
The formation of cyclin/CDKs controls the cell-cycle progression via phosphorylation of the target
genes, such as tumor suppressor protein retinoblastoma (Rb). The activation of cyclins/CDKs is
induced by mitogenic signals and inhibited by the activation of cell-cycle checkpoints in response
to DNA damage
3. Describe the relationship between mitosis and cancer.
If a chromosome doesn't separate (nondisjunction), it can cause cancer.
Mitosis is closely controlled by the genes inside every cell. Sometimes this control can go wrong.
If that happens in just a single cell, it can replicate itself to make new cells that are also out of
control. These are cancer cells.
Gene expression is the process by which
information from a gene is used in the synthesis of
a functional gene product that enables it to
produce end products, protein or non-coding RNA,
and ultimately affect a phenotype, as the final effect
2. State the possible outcomes and location of
transcription.
Transcription takes place in the nucleus, and it
uses DNA as a template to make an RNA molecule
then leaves the nucleus and goes to a ribosome in
the cytoplasm, where translation occurs.
3. List and explain each of the steps of transcription.
Transcription has 3 steps: initiation, elongation, and
termination.
Initiation:
in the nucleus, RNA polymerase recognizes the
recognition site causing it to bind to the promoter
(start of the gene). The RNA polymerase then
separates the DNA into single strands so the
template strand can be read in the 3’ to 5’
direction.
Elongation:
pre-mRNA nucleotides are quickly paired with their
complementary bases which correspond with the
template strand of DNA. The pre-mRNA moves in
the 5’ to 3’ direction while the template strand
moves in the opposite direction 3’ to 5’. Pre-mRNA
does not contain thymine, instead uracil is used at
the complementary base to adenine.
Termination:
When the RNA polymerase reaches the terminator
it signals the RNA polymerase to stop and release from the DNA. Once separated, the two DNA
strands come back together and reform the double helix. The newly formed pre-mRNA molecule is
then released.
4. Explain the relationship between a gene and transcription.
Together, transcription and translation are known as gene expression. During transcription, the
information stored in a gene’s DNA is passed to a similar molecule called RNA in the nucleus.
Transcription is the first step in gene expression, in which information from a gene is used to
construct a functional product such as a protein. The goal of transcription is to make a RNA copy
of a gene's DNA sequence.
, 5. Explain how the “information” in DNA is transferred into RNA.
In the first step, the information in DNA is transferred to a messenger RNA (mRNA) molecule by
way of a process called transcription. During transcription, the DNA of a gene serves as a
template for complementary base-pairing, and an enzyme called RNA polymerase II catalyzes the
formation of a pre-mRNA molecule, which is then processed to form mature mRNA (Figure 1). The
resulting mRNA is a single-stranded copy of the gene, which next must be translated into a
protein molecule.
During translation, which is the second major step in gene expression, the mRNA is "read"
according to the genetic code, which relates the DNA sequence to the amino acid sequence in
proteins (Figure 2). Each group of three bases in mRNA constitutes a codon, and each codon
specifies a particular amino acid (hence, it is a triplet
code). The mRNA sequence is thus used as a
template to assemble—in order—the chain of amino
acids that form a protein.
1. Define cell cycle checkpoint and explain how it is
used in cell cycle control.
Cell cycle checkpoints are surveillance mechanisms
that monitor the order, integrity, and fidelity of the
major events of the cell cycle. These include growth
to the appropriate cell size, the replication and
integrity of the chromosomes, and their accurate
segregation at mitosis.
2. Explain the role of cyclin dependent kinases in the
cell cycle and how they promote mitosis.
Cyclin-dependent kinases (CDKs) are the families of
protein kinases first discovered for their role in
regulating the cell cycle. They are also involved in regulating transcription, mRNA processing,
and the differentiation of nerve cells. ... By definition, a CDK binds a regulatory protein called a
cyclin.
The formation of cyclin/CDKs controls the cell-cycle progression via phosphorylation of the target
genes, such as tumor suppressor protein retinoblastoma (Rb). The activation of cyclins/CDKs is
induced by mitogenic signals and inhibited by the activation of cell-cycle checkpoints in response
to DNA damage
3. Describe the relationship between mitosis and cancer.
If a chromosome doesn't separate (nondisjunction), it can cause cancer.
Mitosis is closely controlled by the genes inside every cell. Sometimes this control can go wrong.
If that happens in just a single cell, it can replicate itself to make new cells that are also out of
control. These are cancer cells.
