MUTATIONS
What is a mutation?
A change in the DNA sequence of an organism.
What is the difference between a organism's phenotype and its genotype?
is the physical appearance or observable trait of the organism brown eyes while genotype is the actual genetic makeup or combination of alleles
What are the three components that make up a single nucleotide, the building block of DNA?
A phosphate group, a deoxyribose sugar, and a nitrogenous base.
What is the main purpose of mitosis compared to meiosis?
Mitosis is used for growth and tissue repair by creating identical body cells, while meiosis is used to produce gametes
Question: What happens to the phenotype of a heterozygous individual in incomplete dominance?
The heterozygous individual displays a blend or intermediate phenotype that is a mix between the two homozygous parental phenotypes
What is the difference between a point mutation and a frameshift mutation?
A point mutation changes a single nucleotide base, while a frameshift mutation inserts or deletes bases, shifting the entire reading frame of the genetic code.
If a homozygous dominant plant (TT) is crossed with a homozygous recessive plant (tt), what percentage of the offspring will show the recessive phenotype?
0%
Which nitrogenous bases pair together in a DNA molecule, and what type of bond holds them together?
Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G). They are held together by weak hydrogen bonds.
How many daughter cells are produced in mitosis versus meiosis, and are they haploid or diploid?
Mitosis produces two identical diploid cells, whereas meiosis produces four genetically unique haploid cells.
How does codominance differ from incomplete dominance?
n codominance, both alleles are fully and distinctly expressed at the same time in the heterozygote, rather than blending together
Why are frameshift mutations usually more harmful than point mutations?
They alter every amino acid after the mutation site, completely changing the resulting protein, whereas a point mutation usually only changes one amino acid.
What term describes an organism that has two different alleles for a specific gene
Heterozygous.
What term is used to describe the twisted ladder shape of a DNA molecule?
A double helix.
What is "crossing over," and in which specific process and phase does it occur?
Crossing over is the exchange of genetic material between homologous chromosomes that creates genetic diversity. It occurs exclusively during Prophase I of meiosis.
What is a classic example of a human trait controlled by multiple alleles, and what are those alleles?
ABO blood type is controlled by multiple alleles
: What is a mutagen, and what are two examples?
A mutagen is an environmental factor that causes genetic mutations. Examples include UV radiation and cigarette smoke.
In a monohybrid cross between two heterozygous parents (Bb x Bb), what is the expected genotypic ratio of the offspring?
1:2:1
What two components make up the "sides" or the backbone of the DNA ladder?
Alternating sugar (deoxyribose) and phosphate molecules.
If a horse's skin cell contains 64 chromosomes, how many chromosomes will be found in its egg cell?
32 chromosomes. Skin cells are diploid (2n = 64), and egg cells are gametes, which are haploid (n = 32) and contain half the genetic material.
What defines a polygenic trait, and what is one example in humans?
A polygenic trait is controlled by the cumulative effect of two or more different genes, typically resulting in a wide range of continuous phenotypes. Examples include human skin color, height, and eye color.
Are all mutations harmful? Explain why or why not.
No. Some mutations are neutral (have no effect), and others are beneficial, introducing new traits that help an organism survive and evolve.
What do the letters written on the outside (top and left side) of a Punnett square represent?
The alleles of the parents' gametes (sperm and egg cells) formed during meiosis.
What does it mean that the two strands of a DNA molecule are "anti-parallel"?
It means the two strands run in opposite directions next to each other
What happens to the sister chromatids during anaphase in mitosis versus anaphase I in meiosis?
In mitotic anaphase, sister chromatids are pulled apart to opposite sides of the cell. In anaphase I of meiosis, homologous chromosome pairs separate, but the sister chromatids remain attached.
Why are males more likely to inherit and express X-linked recessive disorders, such as color blindness, than females?
Males only inherit one X chromosome (from their mother). If that X chromosome carries the recessive allele, they will express the trait because they do not have a second X chromosome to mask it.