MUTATIONS
What is a mutation?
A random change in a DNA or RNA sequence that can alter the protein coded by that gene
In pea plants, purple flower color (\(P\)) is dominant over white flower color (\(p\)). If you cross two heterozygous purple-flowered plants (\(Pp \times Pp\)), what percentage of the offspring are expected to have white flowers?
25%
Which of the following correctly describes the three components that make up a single nucleotide in DNA?
A deoxyribose sugar, a phosphate group, and a nitrogenous base.
Which of coming the following best describes the primary function of mitosis in multicellular eukaryotic organisms?
Growth,tissue repair, and asexual reproduction.
If a true-breeding red snapdragon (\(R^{R}\)) is crossed with a true-breeding white snapdragon (\(R^{W}\)), all the \(F_{1}\) offspring are pink (\(R^{R}R^{W}\)). What phenotypic ratio would you expect in the \(F_{2}\) generation if these pink \(F_{1}\) plants are crossed with each other?
1 red: 2 pink: 1 white
What is a point mutation?
A change in a single nucleotide (base) within a DNA segment, such as a substitution, insertion, or deletion (e.g., sickle-cell anemia).
If you cross a homozygous dominant yellow seed plant (\(YY\)) with a heterozygous yellow seed plant (\(Yy\)), what is the expected genotypic ratio of the offspring?
1 YY : 1 Yy
According to Chargaff's rules and the standard Watson-Crick model of DNA, which of the following base pairs is correctly matched with its complementary partner?
Adenine pairs with Thymine.
How do the end products of mitosis and meiosis differ fundamentally in terms of chromosome number and cell type?
Mitosis produces 2 diploid somatic cells; meiosis produces 4 haploid gametes.
In certain cattle, coat color can be red (\(R\)), white (\(W\)), or roan (\(RW\)). Roan cattle have both red and white hairs intermixed equally in their coat rather than a blended intermediate color. Which term best describes this inheritance pattern?
Codominance
What is the difference between silent, missense, and nonsense mutations?
• Silent: Changes a base but codes for the same amino acid.
• Missense: Changes a base to code for a different amino acid.
• Nonsense: Changes a base to create a premature stop codon, ending protein synthesis early.
In snapdragons, flower color shows incomplete dominance. Cross-pollinating a red flower (\(RR\)) with a white flower (\(WW\)) produces pink flowers (\(RW\)). If you cross two pink flowers (\(RW \times RW\)), what is the expected phenotypic ratio of the offspring?
1 red: 1 pink: 1 white
How many hydrogen bonds typically form between a guanine (G) and cytosine (C) base pair, compared to an adenine (A) and thymine (T) base pair?
G-C pairs have 3 hydrogen bonds, while A-T pairs have 2 hydrogen bonds.
Which of the following events occurs in both mitosis and meiosis prior to the start of nuclear division?
Replication of DNA during interphase
A man with blood type AB and a woman with blood type O have a child. What are the possible blood types of their offspring?
What causes a frame shift mutation?
The insertion or deletion of nucleotides (not in multiples of three) that shifts the reading frame and alters every subsequent codon.
In human ABO blood types, alleles \(I^{A}\) and \(I^{B}\) are codominant, while \(i\) is recessive. If a person with type AB blood (\(I^{A}I^{B}\)) has children with a person who has type O blood (\(ii\)), what are the possible blood types of their children?
In the DNA double helix, the two strands run antiparallel to one another. What does "antiparallel" mean in this structural context?
One strand runs in the 5' to 3' direction, while the complementary strand runs in the 3' to 5' direction.
During which specific phase and process does crossing over occur to increase genetic diversity, and does it happen in mitosis?
Prophase I of meiosis; no, it does not occur in mitosis.
Red-green color blindness is an X-linked recessive trait. A color-blind male (\(X^{b}Y\)) marries a woman who is homozygous normal for vision (\(X^{B}X^{B}\)). What is the probability that their sons will be color-blind?
Which mutation can be passed on to offspring?
Mutations in germ cells (sperm or egg cells), unlike mutations in somatic (body) cells, which cannot be inherited.
A black-furred guinea pig is crossed with a white-furred guinea pig (\(bb\)). All 8 of the offspring produced from this cross are black-furred. What is the most likely genotype of the black-furred parent (\(B\) = black, \(b\) = white)?
BB (homozygous dominant)
The sugar-phosphate backbone of the DNA double helix is held together by covalent bonds known as phosphodiester bonds. Between which specific parts of adjacent nucleotides do these bonds form?
Between the 3' carbon of one sugar and the 5' phosphate of the next sugar.
How does the arrangement of chromosomes at the metaphase plate differ between Metaphase of mitosis and Metaphase I of meiosis?
Individual duplicated chromosomes line up singly in mitosis, whereas homologous pairs line up side-by-side in Metaphase I of meiosis.
A woman has blood type A and gives birth to a child with blood type O (\(ii\)). Which of the following men could not be the biological father of this child based strictly on blood type analysis?
A man with blood type AB (\(I^{A}I^{B}\))