Pre-Lab Questions
What is a gene? Describe the function, structure, and location within the cell.
A gene is a subunit of a DNA that carry information and occupies a specific location in a chromosome.
Gene function carries hereditary information to be transmitted to the next generation and is involved in making proteins which determine the structure and function of a cell. They decide everything in a living organism and control all the functions.
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Genes are located in chromosomes at specific regions known as loci.
What are the three stop codons? What is the start codon?
The three stop codons are UGA, UAG, and UAA. A stop codon comprises of nucleotide sequences that code for termination during synthesis of an amino acid
Compare and contrast bacterial and eukaryotic ribosomes.
The main difference between prokaryotic and eukaryotic ribosomes is that prokaryotic are small with 70s ribosomes while eukaryotic ribosomes are large 80s ribosomes. Also, eukaryotic ribosomes are bound by a cell membrane while prokaryotic ribosomes occur free in the cytoplasm. Additionally, both ribosomes have large and small subunits. Also, each subunit in both ribosomes is made up of ribosomal proteins and r RNA.
EXERCISE 1: TRANSCRIPTION
Post-Lab Questions
How long are each of your peptide chains (how many amino acids are present)?
A polypeptide chain consists of a linear of amino acids of any length which are bound together amide bonds.
What differences exist between your two transcripts? What about your translated product?
A transcript can be defined as a single stranded RNA which is produced during DNA transcription. These transcripts can be divided into m RNA, t RNA and r RNA. After translation process, m RNA produces amino acids which are used to construct proteins.
Hb A represents a section of the 626 bases normal hemoglobin beta mRNA sequence. Hb S is from the sickle cell hemoglobin. Is the mutation found in sickle cell hemoglobin a point mutation or a frameshift mutation?
Point mutation
Does the sickle cell mutation result in a missense mutation, silent mutation or nonsense mutation? Why?
Missense mutation. A type of mutation where GAG codon is converted into GUG coding for valine rather than glutamic acid.
What is the resulting new trait for this mutation? What are the resulting symptoms in people with the HbS hemoglobin protein?
Sickle cell trait.
The symptoms among people with HbS hemoglobin proteins are fatigue due to an anemic condition. Yellow skin color as a result of jaundice. Also, white patches in the eyes known as icterus occurs when red blood cells undergo hemolysis. Additionally, this condition may be accompanied by swelling of feet and hand in a condition known as dactylitis (Kataoka et al., 2016) .
Do a web search to find another example of a disease caused by a mutation in a single gene. Do the resulting symptoms (new trait) make sense considering the role of the affected protein? Why or why not?
An example of a disease caused by a single gene mutation is cystic fibrosis.
Cystic fibrosis occurs as a result of mutations on chromosome 7. The mutation occurs due to changes in the gene that make a protein known as cystic fibrosis transmembrane regulator. An individual that produce these abnormal proteins is accompanied by symptoms such as thick and sticky mucus. Also, the condition is accompanied by persistent wheezing, lung infections, salty sweats, poor growth of height, fatigue, and regular sinus infections.
Exercise 2: Genetic Mutations
How does each of your mutations affect the amino acid sequences? Are the mutations missense mutations, silent mutations or nonsense mutations?
Point mutation is a form of missense mutation. A protein may lose its function to result in disease in an organism. The mutation occurs in three major forms. One form is substitution where a single base pair is substituted to another. Another form of point mutation is insertion due to additional base pairing, and the last one is deletion.
Frameshift-insertion
A frameshift mutation occurs as a result of insertions of nucleotides that are not multiple of three. This form of mutation results to changes in amino acids coding sequences which result in alteration of chemical composition, polypeptide length and also biochemical processes of a cell (Kataoka et al., 2016) .
Frameshift deletion
This mutation is similar to frameshift insertion. However, in this mutation, there is a deletion of nucleotides that are not multiple of three.
What differences did you notice between the point mutation and the frameshift mutations?
Point mutation occurs when a single nucleotide is replaced with another nucleotide. The mutation occurs at a single point in the DNA strand. Also, this mutation only affects the altered codon in the sequence. However, frameshift mutations occur as a result of deletion and insertion of nucleotides. This mutation has the overall effect of changing the DNA conformation and changes codons that occur before or after insertion and deletion. This reason makes frameshift mutation more dangerous than point mutation (Kataoka et al., 2016) .
Is it possible to determine the DNA sequence from the amino acid sequence Leu Pro Arg? Why or Why not ?
Yes. It is used in the genetic code table to read the amino acid coded.
Experiment 3: DNA Extraction
Post Lab Questions
Insert a picture of your results here:
What is the texture and consistency of the DNA?
After extraction, the texture is stingy consistence, gluggy, mucus-like, with slimy texture (Renshaw et al., 2015).
Why was salt used in the extraction solution?
Salt is used in DNA extraction to neutralize DNA phosphate-sugar charge. The purpose of adding salt is to make the DNA less hydrophilic.
Is the DNA soluble in the aqueous solution or alcohol?
DNA show solubility in aqueous solution but it is insoluble in alcohol. DNA is soluble in water because of the presence of a phosphate group that is highly charged.
What else might be in the ethanol/aqueous interface? How could you eliminate this?
Proteins are removed during extraction thorough protein precipitation. The removal is achieved by adding proteinase K.
Which DNA bases pair with each other? How many hydrogen bonds are shared by each pair ?
Purines bind to pyrimidines. Purines include adenine and guanine while pyrimidine includes cytosine, thymine, and uracil. Adenine bind to thymine forming three hydrogen bonds while guanine and cytosine to form 3 hydrogen bonds (Renshaw et al., 2015).
How is information to make proteins passed on through generations?
The information is passed down during fertilization. An organism undergoes meiosis process to produce haploids which fuse to become diploids.
Reference
Kataoka, M., Matoba, N., Sawada, T., Kazuno, A. A., Ishiwata, M., Fujii, K., ... & Kato, T. (2016). Exome sequencing for bipolar disorder points to roles of de novo loss-of-function and protein-altering mutations. Molecular Psychiatry , 21 (7), 885.
Renshaw, M. A., Olds, B. P., Jerde, C. L., McVeigh, M. M., & Lodge, D. M. (2015). The room temperature preservation of filtered environmental DNA samples and assimilation into a phenol–chloroform–isoamyl alcohol DNA extraction. Molecular ecology resources , 15 (1), 168-176.
