What would be the result of a cytosine base being
substituted for a thymine base in a DNA segment during
DNA replication? (1 point)
The entire segment of DNA would be
affected.
The cytosine base would pair with adenine
when the DNA was replicated.
There would be no effect on the DNA.
The sequence could code for the wrong
amino acid during translation
The cytosine base would pair with adenine when the DNA was replicated.
What would be the result of a cytosine base being
substituted for a thymine base in a DNA segment during
DNA replication? (1 point)
The entire segment of DNA would be
affected.
The cytosine base would pair with adenine
when the DNA was replicated.
There would be no effect on the DNA.
The sequence could code for the wrong
amino acid during translation
The cytosine base would pair with adenine when the DNA was replicated.
Which statement is the first step of protein synthesis?
(1 point)
tRNA carries amino acids to the ribosome
and attaches them to the mRNA strand.
A ribosome attaches to the mRNA.
Amino acids are linked together with
peptide bonds.
DNA unzips between the base pairs
DNA unzips between the base pairs.
Which statement is true? (1 point)
The human body uses 20 amino acids to
form all types of proteins.
Amino acids do not need to be assembled
in a particular order.
Amino acids form a polypeptide chain via
carbon-carbon bonds.
tRNA is attached to specific proteins in the
cell’s cytoplasm.
The human body uses 20 amino acids to
form all types of proteins.
Hemophilia is a hereditary bleeding disorder that
primarily affects males. In 3–5 sentences, summarize
why this condition typically affects males more than
females. (4 points)
Hemophilia typically affects males more than females because it is an X-linked recessive disorder. The gene responsible for hemophilia is located on the X chromosome. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). If a male inherits a faulty hemophilia gene on his X chromosome, he does not have a second X chromosome to compensate for the defective gene. In contrast, females have two X chromosomes and can inherit a normal gene on one X chromosome, which can compensate for the defective gene on the other X chromosome. Therefore, females are more likely to be carriers of the hemophilia gene, while males are more likely to actually have the disorder.
The lactose (lac) operon in E. coli is an example of a
gene that is repressed when lactose is not available in
a cell. In 3-5 sentences, explain what this means, using
correct terminology. (4 points)
The lactose (lac) operon in E. coli is a cluster of genes involved in the metabolism of lactose. When lactose is not available in a cell, the lac operon is repressed, meaning that the genes within the operon are not actively transcribed and translated into proteins. The repression is mediated by a regulatory protein called the lac repressor. In the absence of lactose, the lac repressor binds to the operator region of the lac operon, preventing RNA polymerase from binding to the promoter region and initiating transcription of the genes. This ensures that energy is not wasted on producing proteins involved in lactose metabolism when lactose is not present in the environment.
Homozygous tall pea plants look the same as
heterozygous tall pea plants. Formulate a pollination
experiment to identify whether a tall pea plant is
homozygous or heterozygous. Explain your answer in
3-5 sentences. (4 points)
To determine whether a tall pea plant is homozygous or heterozygous, a pollination experiment can be conducted. First, select a genetically pure, short (homozygous recessive) pea plant. Use this short plant as the parent to cross-pollinate with the tall plant in question. If the tall plant is heterozygous, the resulting offspring will have a 1:1 ratio of tall to short plants, indicating Mendelian inheritance. However, if the tall plant is homozygous, all the resulting offspring will be tall plants. By observing the phenotype of the offspring and comparing it to the expected results based on Mendelian inheritance, it can be determined whether the tall plant is homozygous or heterozygous for the tall trait.
In 3–5 sentences, explain how genetic modification
helps provide food for a growing population. (4 points)