A cell is the smallest basic unit of life
Answer:
1. The difference between the normal hemoglobin protein DNA sequence and the sickle cell hemoglobin DNA sequence is a base to base shift, in this case adenine (GAG) to thymine (GTG).
2. The difference affects the amino acid sequence of the protein by replacing glutamic acid (Glu) with valine (Val).
Explanation:
In sickle cell anemia, a change in the DNA nucleotide sequence is observed, where adenine is substituted by thymine, whose expression is the change in the amino acid sequence of globine β, incorporating valine instead of glutamic acid. This represents a molecular mutation - point mutation - by subtitution, which corresponds to missense mutation.
<u>Normal hemoglobin protein in a RBC</u>
DNA CTG ACT CCT GAG GAG AAG TCT
Amino acids Leu Thr Pro Glu Glu Lys Ser
<u>Sickle cell hemoglobin protein in a RBC</u>
DNA CTG ACT CCT <em>GTG</em> GAG AAG TCT
Amino acids Leu Thr Pro <em>Val</em> Glu Lys Ser
When GAG is transcribed to mRNA, the CUC codon is obtained, which codes for glutamic acid. Thymine substitution causes the DNA sequence to change to GTG, which is transcribed as CAC, the codon that encodes the amino acid valine. The <u>change from glutamic acid to valine in β-globin causes an altered hemoglobin, giving the abnormal erythrocytes observed in sickle cell disease</u>.
Answer:
A hypothesis is a possible explanation for a set of observations or an answer to a scientific question. A hypothesis must be testable and measurable. This means that researchers must be able to carry out investi- gations and gather evidence that will either support or disprove the hypothesis.
Explanation:
The correct answer is (a).
Both L-D and L-IND reactions take place in the chloroplast of the cell but in different parts or locations. L-D reactions take place in the chloroplast thylakoids while L-IND reactions take place in the chloroplast stroma.
Chloroplasts are chlorophyll- filled organelles mostly found in the leaves of green plants. Chloroplasts are surrounded by a double membrane called the thykaloid membrane that forms long folds within the organelle. In electron micrographs, the thykaloid membranes look like stacked coins. Chlorophyll is located within the thykaloid membranes.
Between the thykaloid membrane and the chloroplast membrane is a space. This space is what is called the stroma.
Answer:
Reptiles have scales, and their skin is dry. Amphibians do not, and their skin is often moist with mucus, which keeps them from drying up.