MUTATIONS
Which of the following best describes a missense point mutation?
It change a single nucleotidebin a codon resulting in the subtitution of a different amino acid in the final pretein.
Which of the following best describes the relationship between a dominant allele and a recessive allele?
A dominant allele masks or covers up the expression of a recessive allele.
Which of the following three components make up a single nucleotide monomer of DNA?
A deoxyribose sugar a phosphate group and a nitrogennous base.
Which of the following best describes a fundamental difference in the end products of mitosis versus meiosis in humans?
meiosis produces four genetically unique haploid (n) daughter cells
If a homozygous red snapdragon (RR) is crossed with a homozygous white snapdragon (WW), all offspring in the (F_{1}) generation have pink flowers (RW). This pattern of inheritance is known as:
ncomplete dominance.
How does the insertion of a single nucleotide into a DNA sequence typically affect the resulting protein?
causes a frameshift mutation.
In pea plants, the allele for tall plants (T) is dominant over the allele for short plants (t). If a plant has the genotype (Tt), what is its phenotype?
tall.
According to Chargaff's rules and the standard Watson-Crick model, how do nitrogenous bases pair with each other across the DNA double helix?
through specific complementary rules and hydrogen bonding.
During which specific phase and process does homologous recombination (crossing over) occur to increase genetic variation?
pachytene substage of Prophase I in Meiosis I.
In certain cattle, the allele for red hair (\(R\)) and the allele for white hair (\(W\)) are both fully expressed in the heterozygous condition (\(RW\)), resulting in a "roan" coat with distinct patches of both red and white hairs. What is this inheritance pattern called?
codominance.
Down syndrome is most commonly caused by nondisjunction during meiosis. What does nondisjunction mean?
failure of homologous chromosomes or sister chromatids to separate properly during cell division.
.If you perform a monohybrid cross between a homozygous dominant parent (TT) and a heterozygous parent (Tt), what percentage of the offspring are expected to have the homozygous dominant genotype (TT)?
50%
How do purine bases structurally differ from pyrimidine bases in DNA?
Purine bases feature a double-ring structure (a six-membered ring fused to a five-membered imidazole ring with four nitrogen atoms), whereas pyrimidine bases feature a single six-membered ring structure (with two nitrogen atoms).
If a diploid organism's somatic cells contain 48 chromosomes, how many chromosomes will be present in each mature gamete produced by meiosis?
24 chromosomes
Human ABO blood types are determined by three different alleles (\(I^{A}\), \(I^{B}\), and \(i\)). Because an individual can only inherit two of these alleles despite three existing in the wider population, this genetic system exemplifies:?
multiple alleles.
A mutation changes a codon from UAC (which codes for Tyrosine) to UAA (which is a stop codon). What specific type of mutation is this?
nonsense mutation
In a cross between two heterozygous pea plants for plant height (\(Tt \times Tt\)), what percentage of the offspring are expected to exhibit the short (recessive) phenotype?
25%
What specific type of covalent bond links adjacent nucleotides together along the sugar-phosphate backbone of a single DNA strand?
phosphodiester bond.
How do the events of Metaphase I in meiosis differ from Metaphase in mitosis?
during Metaphase I of meiosis, homologous chromosome pairs (tetrads or bivalents) line up in pairs along the metaphase plate, whereas during Metaphase in mitosis, individual replicated chromosomes line up single-file.
Traits like human height and skin color show a wide, continuous range of variation rather than falling into distinct, clear-cut categories. This occurs because these traits are controlled by the cumulative effect of two or more genes. What is this phenomenon called?
polygenic inheritance
If a chromosomal mutation results in a segment of a chromosome being flipped backward 180 degrees, what is this mutation called?
chromosomal inversion
Two purple-flowered pea plants are crossed, and out of their offspring, some have white flowers (a recessive trait). What must be the genotypes of the two parent plants?
heterozygous (Pp)
.What does the term "antiparallel" mean in the context of the DNA double helix?
the two complementary strands run parallel to each other side by side, but they are oriented in opposite directions.
Which cellular event is shared by both mitosis and the second division of meiosis (meiosis II)?
separation of sister chromatids.
Marfan syndrome is caused by a mutation in a single gene that affects connective tissue, leading to tall stature, long fingers, lens dislocation, and heart problems all at once. When a single gene influences multiple, seemingly unrelated phenotypic traits, it is called?
pleiotropy (or pleiotropic effect)