BASIC GENETICS
I.
Introduction
A.
Review mitosis
 Definition: nuclear duplication
 Purpose: to insure genetic continuity
 Definition: daughter cells will have the same number and kinds of
chromosomes as the Parents.
 Cell cycle – page 245
 Shows events during the life cycle of cell.
 Includes interphase and mitosis
 Interphase: DNA duplicates so the chromosome is double
stranded and has the appearance shown in figure 10-3
 Chromatids – compose duplicated chromosome
 Centromere – holds chromatid together.
Mitosis – page 246 – review events
 QUESTIONS: p. 257 #2-3-4-5-6-7-10-19
p. 259 #3-4
B.
Review meiosis
 Definition: reduction division
 Purpose: halves the # of chromosomes from 2N (diploid) to N
(monoploid)
 Diploid
 Monoploid
 Produces gametes, or sex cells:
 Egg
 Sperm
 Gametes have the N# or one member of the homologous pair
 Homologous chromosomes: chromosomes with the same size and
shape and the same kind of information
 Process: p. 276 – 277
 Creates variety
 The number of possible combinations in the gametes is 2n (n is the
monoploid number)
 Therefore 223 = 8 million combinations in the egg and sperm.
 If there are 8 million combinations in the egg and 8 million in the
sperm than the total number of combinations with fertilization is
64 trillion.
 Questions: p. 283 #7-8-9
p. 285 #1-3-6-9
II.
Mendel’s Work
A.
Introduction:
 Mendel’s life: 1858 – 1866
 Austrian monk
 Used pea plant – significant because it self-pollinates
B.
Mendel’s Experiments
 Figure 11-4 p. 265
Production of monohybrid
1. Definition: produced from two dissimilar parents
2. Significance of results: showed the Law of Dominance
 Dominant
 Recessive
C.
Mendel’s Hypothesis
 Page 266 – Law of Segregation
1. proved with test cross
 Terms:
 Homozygous
 Heterozygous
 Phenotype
 Genotype
 Alleles
 Punnett Square
D.
Mendel’s Dihybrid Cross
 Page 270 – figure 11-9
 Page 271 – figure 11-10
 Proved Law of Independent Assortment
Continuous Variation
A.
Definition – varying degrees of a characteristic
B.
Examples: quantitative traits such as height and skin tone
C.
Explained by multiple genes or polygenic inheritance
 Traits controlled by two or more genes
Incomplete Dominance
A.
Definition – the heterozygous condition results in an intermediate trait
B.
Examples: figure 11-11 p. 272

III.
IV.
Review: p. 283 #13-17
p. 285 #2-4