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Honors Biology: Unit 11 Gene Expressions - Learning Targets

Honors Biology: Unit 11 Gene Expressions - Learning Targets

1.   Explain the different purposes of the 3 types of RNA.

There are three types of RNA, which are mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA). The purpose of mRNA is to deliver the DNA code from the nucleus to the ribosomes; it is read in three base pairs, known as codons. The mRNA is complementary to the template strand of DNA and is used during both transcription and translation. The purpose of tRNA is to carry specific amino acids to the ribosome during translation and protein synthesis; it is read in a three base sequence called an anticodon. The purpose of rRNA is to read the amino acid sequence’s order and link them together; they make up the ribosomes along with the proteins. It attaches to the mRNA and helps build the protein (polypeptide chain).

2.   Explain that the information passed from parents to offspring is transmitted by means of genes that are coded in DNA molecules.  These genes contain the information for the production of proteins.

The information passed from parents to offspring is transmitted by means of genes encoded in DNA molecules. Genes are sections in DNA strands, as genetic material is stored in nucleic acids, or the long chains of nucleotides. DNA carries the genetic code to make proteins, according to the order of the base sequences.

3.   Explain how the DNA of different species would vary.

The DNA of different species would vary because of genetic variation. Technically, all species come from the same common ancestor, so mutations (changes in the sequence of genes in DNA) may occur, which would lead to different proteins being coded and thus different species. DNA sequences (of nucleotides) change over time, supporting the theory of evolution. Therefore, more closely related organisms will have more similar DNA sequences than those more distantly related. Additionally, the longer two species have survived and been separated from their common ancestor, the more distantly related they will become and thus their DNA will differ even more.

4.   Describe the process of transcription and translation and how they relate to each other in molecular

      Biology.

Transcription is the forming and synthesis of mRNA from the DNA template (with a nucleotide sequence) in the nucleus. There are three steps: initiation, elongation, and termination. For initiation, RNA polymerase attaches to the premotor site and transcription begins. With elongation, DNA unwinds and starts building RNA. With termination, RNA polymerase reaches the terminator region, and then releases the RNA polymerase along with the primary transcript, or pre-mRNA. Translation is the making of proteins using mRNA’s genetic information (in the form of nucleotide bases). It also involves three steps of the same name: initiation, elongation, and termination. During initiation, small ribosome subunits attach to mRNA at the start of the sequence, AUG (start codon). tRNA also attaches to the start codon at site P on the ribosome. The large ribosomal subunit attaches, and the A site will hold the tRNA carrying the next amino acid for the chain, the P site will hold tRNA with the growing polypeptide chain, and the E site will be the exit site where uncharged tRNA leaves to pick up the next amino acid. The sites follow the A-P-E sequence. The processes of transcription and translation relate to each other because they help DNA make RNA, which then makes proteins. DNA is copied to RNA in transcription, and RNA makes proteins in translation. RNA processing turns the primary transcript, or pre-mRNA, into usable RNA in the nucleus. The cap allows mRNA to attach to the ribosome and leave the nucleus. The tail prolongs the lifespan and allows the RNA to leave the nucleus. Introns are removed, which don’t code for DNA/RNA. Exons are spliced together, using splicing enzymes.

5.   Explain the difference between prokaryotic and eukaryotic transcription.

There is a difference between prokaryotic and eukaryotic transcription. In prokaryotes, transcription and translation must occur at the same time because there is no nucleus; both processes occur in the cytoplasm. In eukaryotes, RNA can be transcribed first in the nucleus, then translated into proteins in the cytoplasm. The DNA in prokaryotes has a small, circular shape and skips the introns step. The DNA in eukaryotes is longer.

6.   Predict the consequences that changes in the DNA composition of particular genes may have on an

      organism  (e.g. sickle cell anemia, other).

Changes in the DNA composition (known as mutations) of particular genes may have consequences on an organism. If the DNA is mutated on some genes, then the organism may develop a genetic disorder or other consequences of varying severity. This is because if the DNA sequence is changed, then the RNA sequence is altered as well, which may cause a frameshift or substitution in the reading of codons that code for specific amino acids. For example, sickle cell anemia is a genetic disorder caused by a mutation in both copies of one’s HBB gene. The protein of the red blood cell becomes a sickle shape instead of a rounded shape, making it harder for the cell to transport oxygen-carrying hemoglobin throughout the body. However, mutations may not always have a visible effect on an organism because most amino acids can be coded by two or more different codons. Mutations may also be beneficial because they may create a more helpful protein and phenotype that allows for a greater chance of survival or adaptation to the environment.

7.   Propose possible effects (on genes) of exposing an organism to radiation and toxic chemicals.

Exposing an organism to radiation and toxic chemicals may have effects on its genes. For example, they can damage the genetic material in cells, resulting in mutations that don’t result in the right protein type or number, or maybe no proteins are produced at all. Some mutations can have deadly effects, such as cancer because of uncontrolled cell division. For example, one can get skin cancer if they are exposed to radiation, or if they don’t use protection. Other effects include malformation, metabolic disorders, and immune deficiencies. If radiation or toxic chemicals cause mutations in reproductive cells, then they can be passed on to the offspring of the organisms.

8.   Demonstrate how different species generate different proteins using the same process of

      transcription and translation.

Different species generate different proteins, even though they all use the same process of transcription and translation. This is due to the fact that different species will have different DNA sequences to start with, resulting in different mRNA sequences (as part of transcription), resulting in different codons, which result in different proteins (as part of translation). For example, in the Lab 11A we conducted, our table group followed the same steps in transcription and translation. However, my partner and I got a different protein than the other subgroup within our group. That was because we were assigned different original DNA sequences, which led to different proteins being synthesized.

9.   Describe how inserting, deleting, or substituting DNA segments can alter a gene.  Recognize that altered genes may be passed on to every cell that develops from it and that the resulting features may help, harm, or have little or no effect on the offspring’s success in its environment.

Inserting and deleting DNA segments can alter a gene by changing its reading frame of codons (frameshift mutations). Oftentimes the stop codon is also changed, resulting in a shorter protein. Substituting DNA segments can either create a silent mutation (no changes in amino acids), a missense mutation (an important amino acid change), or a nonsense mutation (a new stop codon is created, creating a shorter protein). Substitution mutations are also known as point mutations.

10.   Explain how a gene mutation in a cell can result in uncontrolled cell division called cancer.

A gene mutation in a cell can result in uncontrolled cell division called cancer. A gene mutation can give rise to a faulty protein that has a role in the process of cell reproduction. Cells with too many mutations may stop functioning normally, or grow out of control, leading to cancer; mutations may also inhibit normal controls, such as cell cycle arrest or programmed cell death. Mutations in proto-oncogenes (causing it to become an oncogene), which normally help the cell grow, and tumor suppressor genes could lead to cancer, as the normal cell controls are inhibited. As cancerous cells grow, a tumor is developed.

11.   Explain how mutations in the DNA sequence of a gene may be silent or result in a phenotypic

      change in an organism and in its offspring.

Mutations in the DNA sequence of a gene can be silent because the base pair substituted may have produced a different codon that still codes for the “normal” amino acid. Therefore, the protein produced can still be the same. Mutations (frameshift ones) may also result in a phenotypic change in an organism and in its offspring because the reading frame of codons is altered from an insertion or deletion of a base pair, causing a different protein to be synthesized. Therefore, an organism’s phenotype will appear differently. The genotype is inherited from parents, which influences the phenotype of their offspring if mutations affect the gametes (sex cells; mutations are passed to offspring).


Honors Biology: Unit 11 Gene Expressions - Learning Targets

1.   Explain the different purposes of the 3 types of RNA.

There are three types of RNA, which are mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA). The purpose of mRNA is to deliver the DNA code from the nucleus to the ribosomes; it is read in three base pairs, known as codons. The mRNA is complementary to the template strand of DNA and is used during both transcription and translation. The purpose of tRNA is to carry specific amino acids to the ribosome during translation and protein synthesis; it is read in a three base sequence called an anticodon. The purpose of rRNA is to read the amino acid sequence’s order and link them together; they make up the ribosomes along with the proteins. It attaches to the mRNA and helps build the protein (polypeptide chain).

2.   Explain that the information passed from parents to offspring is transmitted by means of genes that are coded in DNA molecules.  These genes contain the information for the production of proteins.

The information passed from parents to offspring is transmitted by means of genes encoded in DNA molecules. Genes are sections in DNA strands, as genetic material is stored in nucleic acids, or the long chains of nucleotides. DNA carries the genetic code to make proteins, according to the order of the base sequences.

3.   Explain how the DNA of different species would vary.

The DNA of different species would vary because of genetic variation. Technically, all species come from the same common ancestor, so mutations (changes in the sequence of genes in DNA) may occur, which would lead to different proteins being coded and thus different species. DNA sequences (of nucleotides) change over time, supporting the theory of evolution. Therefore, more closely related organisms will have more similar DNA sequences than those more distantly related. Additionally, the longer two species have survived and been separated from their common ancestor, the more distantly related they will become and thus their DNA will differ even more.

4.   Describe the process of transcription and translation and how they relate to each other in molecular

      Biology.

Transcription is the forming and synthesis of mRNA from the DNA template (with a nucleotide sequence) in the nucleus. There are three steps: initiation, elongation, and termination. For initiation, RNA polymerase attaches to the premotor site and transcription begins. With elongation, DNA unwinds and starts building RNA. With termination, RNA polymerase reaches the terminator region, and then releases the RNA polymerase along with the primary transcript, or pre-mRNA. Translation is the making of proteins using mRNA’s genetic information (in the form of nucleotide bases). It also involves three steps of the same name: initiation, elongation, and termination. During initiation, small ribosome subunits attach to mRNA at the start of the sequence, AUG (start codon). tRNA also attaches to the start codon at site P on the ribosome. The large ribosomal subunit attaches, and the A site will hold the tRNA carrying the next amino acid for the chain, the P site will hold tRNA with the growing polypeptide chain, and the E site will be the exit site where uncharged tRNA leaves to pick up the next amino acid. The sites follow the A-P-E sequence. The processes of transcription and translation relate to each other because they help DNA make RNA, which then makes proteins. DNA is copied to RNA in transcription, and RNA makes proteins in translation. RNA processing turns the primary transcript, or pre-mRNA, into usable RNA in the nucleus. The cap allows mRNA to attach to the ribosome and leave the nucleus. The tail prolongs the lifespan and allows the RNA to leave the nucleus. Introns are removed, which don’t code for DNA/RNA. Exons are spliced together, using splicing enzymes.

5.   Explain the difference between prokaryotic and eukaryotic transcription.

There is a difference between prokaryotic and eukaryotic transcription. In prokaryotes, transcription and translation must occur at the same time because there is no nucleus; both processes occur in the cytoplasm. In eukaryotes, RNA can be transcribed first in the nucleus, then translated into proteins in the cytoplasm. The DNA in prokaryotes has a small, circular shape and skips the introns step. The DNA in eukaryotes is longer.

6.   Predict the consequences that changes in the DNA composition of particular genes may have on an

      organism  (e.g. sickle cell anemia, other).

Changes in the DNA composition (known as mutations) of particular genes may have consequences on an organism. If the DNA is mutated on some genes, then the organism may develop a genetic disorder or other consequences of varying severity. This is because if the DNA sequence is changed, then the RNA sequence is altered as well, which may cause a frameshift or substitution in the reading of codons that code for specific amino acids. For example, sickle cell anemia is a genetic disorder caused by a mutation in both copies of one’s HBB gene. The protein of the red blood cell becomes a sickle shape instead of a rounded shape, making it harder for the cell to transport oxygen-carrying hemoglobin throughout the body. However, mutations may not always have a visible effect on an organism because most amino acids can be coded by two or more different codons. Mutations may also be beneficial because they may create a more helpful protein and phenotype that allows for a greater chance of survival or adaptation to the environment.

7.   Propose possible effects (on genes) of exposing an organism to radiation and toxic chemicals.

Exposing an organism to radiation and toxic chemicals may have effects on its genes. For example, they can damage the genetic material in cells, resulting in mutations that don’t result in the right protein type or number, or maybe no proteins are produced at all. Some mutations can have deadly effects, such as cancer because of uncontrolled cell division. For example, one can get skin cancer if they are exposed to radiation, or if they don’t use protection. Other effects include malformation, metabolic disorders, and immune deficiencies. If radiation or toxic chemicals cause mutations in reproductive cells, then they can be passed on to the offspring of the organisms.

8.   Demonstrate how different species generate different proteins using the same process of

      transcription and translation.

Different species generate different proteins, even though they all use the same process of transcription and translation. This is due to the fact that different species will have different DNA sequences to start with, resulting in different mRNA sequences (as part of transcription), resulting in different codons, which result in different proteins (as part of translation). For example, in the Lab 11A we conducted, our table group followed the same steps in transcription and translation. However, my partner and I got a different protein than the other subgroup within our group. That was because we were assigned different original DNA sequences, which led to different proteins being synthesized.

9.   Describe how inserting, deleting, or substituting DNA segments can alter a gene.  Recognize that altered genes may be passed on to every cell that develops from it and that the resulting features may help, harm, or have little or no effect on the offspring’s success in its environment.

Inserting and deleting DNA segments can alter a gene by changing its reading frame of codons (frameshift mutations). Oftentimes the stop codon is also changed, resulting in a shorter protein. Substituting DNA segments can either create a silent mutation (no changes in amino acids), a missense mutation (an important amino acid change), or a nonsense mutation (a new stop codon is created, creating a shorter protein). Substitution mutations are also known as point mutations.

10.   Explain how a gene mutation in a cell can result in uncontrolled cell division called cancer.

A gene mutation in a cell can result in uncontrolled cell division called cancer. A gene mutation can give rise to a faulty protein that has a role in the process of cell reproduction. Cells with too many mutations may stop functioning normally, or grow out of control, leading to cancer; mutations may also inhibit normal controls, such as cell cycle arrest or programmed cell death. Mutations in proto-oncogenes (causing it to become an oncogene), which normally help the cell grow, and tumor suppressor genes could lead to cancer, as the normal cell controls are inhibited. As cancerous cells grow, a tumor is developed.

11.   Explain how mutations in the DNA sequence of a gene may be silent or result in a phenotypic

      change in an organism and in its offspring.

Mutations in the DNA sequence of a gene can be silent because the base pair substituted may have produced a different codon that still codes for the “normal” amino acid. Therefore, the protein produced can still be the same. Mutations (frameshift ones) may also result in a phenotypic change in an organism and in its offspring because the reading frame of codons is altered from an insertion or deletion of a base pair, causing a different protein to be synthesized. Therefore, an organism’s phenotype will appear differently. The genotype is inherited from parents, which influences the phenotype of their offspring if mutations affect the gametes (sex cells; mutations are passed to offspring).