BME 80H Lecture Notes - Lecture 5: Walter Sutton, Human Genome, Chromosome
11 Jun 2018
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5th lecture Introduction to Genomes, Chromosomes and Genes (chapter 1, p. 4-6;
chapter 2, p. 27-37/25-35; chapter 3, p. 54-55/52-53; chapter 6, p. 119-121/117-119)
V. Designating genotypes
A. A single factor defines each trait (Ockham’s Razor: Entia non sunt
multiplicanda praeter necessitatem. Latin translation = Entities must not
be multiplied without necessity) Keep it as simple as possible. It may not be
correct but it is the easiest to disprove.
- S smooth
- s wrinkly
B. Each plant carries a pair of factors (traits) for each characteristic.
gene pair
-pair of factors
alleles
-different versions of the characteristic
The genotypes for the P and F1 smooth seed-bearing plants:
P Smooth = SS (2 copies of the Smooth allele)
F1 Smooth = Ss (one Smooth allele and one wrinkled allele)
Can differentiate between the two genotypes through examination
of the offspring resulting from self-fertilization (figure 3.7/NA,
handout)
-used the F3 to determine the genotypes of the F2
-true-breeding or not
-remember they self-fertilized
F2 wrinkled = ss (2 copies of the wrinkled allele)
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If both alleles the same = homozygous (SS, ss)
If the alleles are different = heterozygous (Ss)
(1902) Walter Sutton and Theodore Boveri each independently proposed the
Chromosome Theory of Inheritance (table 3.2).
-Mendel’s factors (genes) are located on chromosomes and, through the separation
(segregation) of similar pairs of chromosomes are passed (transmitted) to daughter
cells (gametes).
Levels of genetics study:
gene
chromosome
genome
individual
family
population
Genetics is studied at all of these levels. The primary functional unit in every level
is the gene. Genes are located on chromosomes and the full complement of
chromosomes in an organism is known as its genome.
I. Human genome = 46 chromosomes (Karyotypes shown in figures 1.6 and 6.3/NA)
- diploid
-chromosomes are in pairs
-2n where n = haploid set = 23 chromosomes
- homologous pair
-chromosomes with similar, yet not identical, sequence along their
length
-same genes, but can have different alleles for the genes
- 22 pairs of autosomes and 1 pair of sex chromosomes
-autosomes are the numbered 1-22
-sex chromosomes are the XY male or XX female
find more resources at oneclass.com
find more resources at oneclass.com
