Quiz 1 (Ch. 2, 3, & 4) Flashcards
Where are genes found?
Within chromosomes
How many sets of chromosomes do humans have? How many do pea plants have?
Both humans and pea plants have two sets of chromosomes
Where do the two sets of human chromosomes come from?
One set of chromosomes is inherited via the sperm, and the other set is inherited via egg
What do the genes that offspring inherit affect?
Genes affect the traits of the offspring
What is an allele?
A version of a gene; Can be dominant or recessive
What is a haploid cell?
A cell which contains only one set of chromosomes
What occurs during the formation of a haploid cell?
i) The alleles of a gene segregate from each other
ii) The alleles of two different genes assort independently of each other
What three ideas of inheritance did Mendel’s experiments refute?
i) Pangenesis
ii) Preformation
iii) Blending hypothesis of inheritance
What organism did Mendel use for his experimental organism? Why did he choose this organism?
- Pea plants
- This organism was ideal because:
- –i) It existed in several varieties with distinct characteristics
- –ii) Its structure allowed for easy crosses where the choice of parental plants could be controlled
Definition: Hybridization
The mating or crossing between two individuals that have different characteristics
—Ex: Purple-flowered plant x White-flowered plant
Definition: Hybrids
The offspring that result from a hybridization mating
What does the anther of a plant contain?
The anther contains the pollen grains, where the male gametes (sperm) are produced
What does the ovule of a plant contain?
The ovule contains the female gametes (eggs)
What does the endosperm nucleus of a plant do?
The endosperm nucleus provides storage material for the developing embryo
Describe self-fertilization in pea plants
- Pollen & egg are derived from the same plant
- Naturally occurs in peas because a modified petal isolates the reproductive structures
Describe cross-fertilization
- Pollen & egg are derived from different plants
- Required removing & manipulating anthers
- Fig. 2.3
Definition: Characters
The morphological characteristics of an organism
Definition: Trait / Variant
Describes the specific properties of a character
—Ex: Eye color is a character, Blue eyes are a trait
Definition: True-Breeder
A variety of organism which produces the same trait over several generations
What seven characters did Mendel study?
i) Height (tall v. dwarf)
ii) Flower color (purple v. white)
iii) Flower position (terminal v. axial)
iv) Seed color (yellow v. green)
v) Seed shape (round v. wrinkled)
vi) Pod color (green v. yellow)
vii) Pod shape (smooth v. constricted)
Definition: Empirical approach ; How did Mendel use this?
- Using quantitative analysis to determine mathematical relationships
- In Mendel’s case, he believed that the he could find the mathematical relationships which govern hereditary traits
Definition: Single Factor Cross
- An experiment involving two variants of the same characteristic
- Only one characteristic of the organism is being observed
What are the four parts of Mendel’s Law of Segregation?
i) A pea plant contains two discrete hereditary factors for a given character, one from each parent
ii) These two factors may be identical or different
iii) When the two factors of a single character are different and present in the same plant, one is dominant and the other is recessive
iv) During gamete formation, the paired factors for a given character segregate randomly so that half of the gametes receive one factor and half of the gametes receive the other factor
Describe the term ‘Homozygous’ as it relates to alleles
An individual with two identical alleles
Describe the term ‘Heterozygous’ as it relates to alleles
An individual with two different alleles
Definition: Genotype
Refers to the specific allelic composition of an iindividual
Definition: Phenotype
Refers to the outward appearance of an individual
Punnett square
A grid that enables one to predict the outcome of simple genetic crosses
—Proposed by Reginald Punnett
