High School Biology : Genetics Principles

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #11 : Mutation

Which of the following mutations would be least detrimental to the function of a protein?

Possible Answers:

Silent

Missense

Frameshift

Deletion of two nucleotides

Nonsense

Correct answer:

Silent

Explanation:

Silent mutations change the nucleotide sequence of the DNA, yet the protein sequence is unchanged. This is due to the redundancy of the genetic code. Missense mutations involve substitution of one amino acid instead of another, which could change the folding pattern of the polypeptide. Nonsense mutations involve substitution of a nucleotide that results in a stop codon rather than the appropriate amino acid. This results in a truncated protein, which is nonfunctional. Frameshift mutations involve insertions, deletions and/or duplications of nucleotides. This shifts the reading frame on the mRNA, resulting in a nonfunctional protein. Note that frameshift mutations in which multiples of three nucleotides are inserted, deleted and/or duplicated are do not change the reading frame, and may still yield a functional protein. However, for example, a deletion of two nucleotides does change the reading frame and would lead to a nonfunctional protein.

Example Question #1 : Understanding Mutation And Evolution

Sickle cell anemia is a blood disorder in which the red blood cells are not shaped correctly and cannot carry oxygen as well as regular blood cells.

Sickle cell anemia is known to be caused by a single base mutation. What type of mutation is sickle cell anemia most probably caused by?

Possible Answers:

A missense mutation

A deletion

A nonsense mutation

A nondisjunction

An insertion

Correct answer:

A missense mutation

Explanation:

The red blood cells are still made, but their shape is different. This can be caused by a missense mutation, the replacement of one amino acid by another. A nonsense mutation would produce a truncated protein, which most likely would not be functional at all. An insertion or deletion could cause a frameshift mutation which could produce a completely different protein. Nondisjunction refers to meiosis, not DNA replication.

Example Question #681 : High School Biology

Which of the following is most likely to drive evolution?

Possible Answers:

A missense mutation

A frameshift mutation

A point mutation

An insertion mutation

All of these

Correct answer:

All of these

Explanation:

Evolution relies on genetic diversity. One source of genetic diversity is spontaneous mutation. One spontaneous mutation may be beneficial to an organism's fitness, increasing the chance of that mutation being passed to the next generation.

Example Question #71 : Genetics Principles

Which is incorrect regarding mutations? 

Possible Answers:

Many mutations are due to error in DNA replication 

Mutation is a process that produces new alleles and genes

Mutations lead to genetic variation

Mutations are always harmful 

Mutations can be beneficial 

Correct answer:

Mutations are always harmful 

Explanation:

Mutations are not always harmful as they can also be beneficial. Keep in mind mutations are also not always beneficial. Mutation simply is a process that produces new alleles in genes due to mistakes made during recombination, DNA replication or repair. 

Example Question #1 : Genes And Dna

The central dogma of molecular biology is the method by which cells transfer nucleic acids into functional molecules. Which of the following depicts the central dogma of molecular biology?

Possible Answers:

Correct answer:

Explanation:

The central dogma of molecular biology states that DNA is transcribed into RNA, which is then translated into protein.

Example Question #111 : Genetics And Evolution

A mutation occurs, changing the DNA sequence but leaving the final amino acid sequence unaltered. How is it possible that the underlying DNA sequence is different but the amino acid sequence remains the same?

Possible Answers:

Cells with mutated genomes will undergo apoptosis

The cell has a specific memory that corrects the DNA sequence before transcription

The genome encodes for "degenerate codons," indicating that more than one codon can encode for a particular amino acid

DNA checkpoints do not allow the cell to transcribe mutated genes

Correct answer:

The genome encodes for "degenerate codons," indicating that more than one codon can encode for a particular amino acid

Explanation:

The human genome can code for 64 different codons, but only produces 20 different amino acids. This results in some amino acids having multiple codes in order to use the remaining 44 available codons.

This ability of a single amino acid to have more than one possible codon is called "degeneracy." Occasionally when DNA is mutated, it will results in a codon that encodes the same amino acid. For example, a mutation from CUU in the mRNA sequence to CUG will still code for leucine.

Example Question #691 : High School Biology

What term describes the section of DNA that codes for a single protein?

Possible Answers:

Genotype

Gene

Allele

Locus

Correct answer:

Gene

Explanation:

DNA nucleotides are organized to form codes. When DNA is transcribed into RNA, these codes are read by the ribosomes to create proteins. Each gene refers to a sequence of DNA that codes for a specific protein. Mutation to a specific gene will affect that protein coded for by that sequence.

A locus is the location of a gene on a chromosome, and an allele is an alternative form of a given gene. A genotype is the description of the alleles for a specific set of genes.

Example Question #1 : Understanding Gene Coding

The first cross done between two individual parents is called the "Parental generation," or "P generation." What are the next two generations normally called?

Possible Answers:

G1 and G2

F1 and F2

F1 and G1

P1 and P2

Correct answer:

F1 and F2

Explanation:

Following the P generation is the 1st offspring generation, called F1. When the F1 generation is crossed, the result is the 2nd offspring generation, called F2.

G1 and G2 actually refer to periods of growth during the cell cycle, and are not related to genetics and inheritance.

Example Question #1 : Genes And Dna

What is the definition of an allele?

Possible Answers:

A portion of unreplicated DNA

A section of DNA that codes for a gene product

A location of a protein

A different version of the same gene, or group of genes

Correct answer:

A different version of the same gene, or group of genes

Explanation:

A gene codes for a certain protein product, which is often associated with a certain trait. Each gene is found at a specific location, or locus, on a chromosome.

Alleles refer to different forms of DNA that can appear at the same locus. In other words, an allele is an alternative form of a given gene. Different alleles often result in different phenotypes, such as changes in color or size.

Example Question #1 : Genes And Dna

In eukaryotic organisms, a DNA sequence of 10,000 nucleotides codes for a protein that is only 300 amino acids long. What is the best explanation of this phenomenon? 

Possible Answers:

The gene is a mutation

Three nucleotides correspond with one amino acid

The entire seqeunce is translated, and the cell cleaves the amino acid chain so that the desired protein remains

Certain nucleotides are skipped when the mRNA sequence is transcribed

Eukaryotic DNA is comprised of coding and non-coding strands

Correct answer:

Eukaryotic DNA is comprised of coding and non-coding strands

Explanation:

Eukaryotes possess coding (exon) and non-coding (intron) seqeunces that allow for incredibly long DNA sequences to correspond with relatively short peptides. Only the exons are translated after the mRNA sequence, which is transcribed fully from the DNA, undergoes mRNA splicing. Furthermore, while a codon (three nucleoties) does correspond with one amino acid, it does not account for the dramatic difference stated in the question. Also, the cell does not translate an entire unmodified mRNA sequence and cleave afterwards as that would be incredibly wasteful and potentially harmful to the cell. 

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