A framshift mutation is when an extra base is inserted into (or deleted from) a strand of DNA. When the DNA is transcribed, every codon downstream from the insertion is changed because the reading frame will be different. This will be the case for any mutations that affect a sequence of nucleotides that is not a multiple of three, for example a five-nucleotide deletion. Such mutations affect the three-nucleotide groupings for all codons following the mutation, and often result in a premature stop codon.

The correct answer is CGGTGAATAGGC  CGGTGAATCAGGC. In the original sequence, the codons are CGG-TGA-ATA-GGC. In the second, they become CGG-TGA-ATC-AGG-C. The other answers show either insertions or deletions that do not shift the reading frame, or single nucleotide polymorphism (changing a single nucleotide to another).

Note that the reading frame does not change in the following 3-nucleotide insertion. Though there is an extra codon, the downstream sequence is not affected.

CGG-TGA-ATA-GGC  CGG-TGA-AGA-CTA-GGC

A missense mutation is the substitution of one nucleotide for another in the DNA sequence, resulting in a different resulting amino acid. Essentially, one amino acid is replaced with another. This type of mutation will not alter the overall protein length.

A nonsense mutation results in a pre-mature stop codon, causing early termination of the protein product and a shorter protein. Frameshift mutations commonly cause pre-mature stop codons to arise, and at the very least will result in a highly altered protein product that is likely of a different length from the unaltered protein. Single-base addition and deletions will cause frameshift mutations.

Healthy RNA: 3'-AGG-UCG-UUA-GUC-5'

Missense:     3'-AAG-UCG-UUA-GUC-5'

Nonsense:    3'-AGG-UAG-5' (UAG stop codon)

Frameshift:   3'-AAG-GUC-GUU-AGU-C-5' (single-base addition)

Framshift:     3'-AGU-CGU-UAG-5' (single-base deletion, UAG stop codon)

Since the maternal oocyte would have two copies of chromosome 21, the normal 21 and the derivative chromosome, the normal addition of the sperm would lead to a zygote with a total of three copies of chromosome 21, or trisomy 21. Polyploidy is a tempting choice, but polyploid is a state characterized by extra copies of multiple chromosomes, as might be expected from more than one sperm fertilizing an egg.

First, you want to narrow down the answers to those with the fewest changes (1 base change). Next, you needed to select the single base change on the third base of the codon. A silent mutation (a DNA mutation that doesn't result in an amino acid change) is most likely to occur when the third base of a codon is changed.

Original sequence: 5'-CGA TGA ACG-3'

Unaltered mRNA transcript: 3'-GCU ACU UGC-5'

Note that the mRNA sequence is antiparallel, changing the orientation of the codons. mRNA is read in the 5'-to-3' direction by the ribosome, meaning that the third base in the codon will be to the left of the 3-base sequence. The given RNA sequence will be read as CGU UCA UCG.

Correct answer: 5'-CGA CGA ACG-3'

Altered mRNA transcript: 3'-GCU GCU UGC-5'

The sequence will be read as CGU UCG UCG.

The correct answer involves a mutation in the third nitrogenous base of the second codon. Both UCA (original) and UCG (altered) code for serine.

A silent mutation is a mutation that results in the inclusion of the same amino acid in the polypeptide product, despite a change in the DNA template sequence. Silent mutations generally involve the third nucleotide in the codon sequence, since this unit is often interchangeable due to the degeneracy of the coding sequence.

A missense mutation results in a different amino acid inclusion based on codon alteration. A nonsense mutation is the insertion of a new stop codon as a result of mutation, resulting in a truncated polypeptide and severely hindering functionality. An insertion or frameshift mutation can change the reading frame of the mRNA template, drastically changing the identity and primary sequence of the polypeptide product; these are the most dangerous type of mutation, as the product may be harmful as well as nonfunctional.

There are five conditions for Hardy-Weinberg equilibrium.

1. No natural selection
2. Large population
3. Random mating
4. No mutations
5. No migration

Hardy-Weinberg principle mathematically describes how inheritance does not change allele frequency in large populations. This helps explain why dominant and recessive alleles are both found in populations. A change in the predicted genotypes of a population may indicate evolotuion at work.

Hardy-Weinberg equilibrium is acheived when the gene frequencies in a population do not change over time. This means the population is not evolving. The five conditions for this are large population size, no mutations, random mating, no net migration, and equally successful reproduction potential for all genes in the population. Temperature is a directly important aspect of this.

The correct answer is "all of these." The choices listed are all required assumptions for a population to achieve Hardy-Weinberg equilibrium. "No natural selection" is another condition that is not listed here, bringing the total to 5 conditions.

The Hardy-Weinberg equilibrium expression says that p²+2pq+q² = 1.

We know that the incidence of q² (getting two recessive alleles, and thus being resistant) is 1/900 in a general population, and 1/25 in New Guinea. The recessive allele frequency, q, will be 1/30 and 1/5, respectively.

The carrier frequency is 2pq, where p = 1-q.

Using this information, we can find the respective carrier frequencies.

General population:

New Guinea: