Lec 1-2 Flashcards
Individuals of genetics for individuals
Impact our traits and who we are
Susceptibility to disease/disorders
Importance of genetics for society
Food quality/supply
Drug development uses genetically engineered bacteria
Study of biology
History of heredity and genetics
Humans have been using genetics for thousands of years, even without a complete understanding of genetic material or heredity
Pangenesis
Each part of the body contains genetic info for only that particular part
Specific particles, called gemmules, carry info from parts of the body to reproductive organs
Then passed to the embryo at the moment of conception
Different parts of the body do express different genes
Inheritance of acquired characteristics
Jean-Baptiste Lamark (1744-1829)
Traits acquired incorporated into hereditary information and passed on to offspring
Inheritance of acquired characteristics
Jean-Baptiste Lamark (1744-1829)
Example
People who developed musical ability through study would produce children who were innately endowed with music ability
Inheritance of acquired characteristics
Jean-Baptiste Lamark (1744-1829)
Problem
Disregard for the influence of early development, environment, diligent practice on ability
Preformationism (17th-18th century)
Inside the egg or sperm exists a fully formed miniature adult
Simply enlarges throughout development
Offspring inherit solely from mother or father
Preformationism
Problem
Counter to observations that individuals possess mixture of traits from both parents
Blending inheritance
Traits of offspring are a blend of parental traits
Like colored paints
Rise of the science of genetics started in the
19th century
Disproving inheritance of acquired characteristics
August Weismann
Tested idea of inheritance of acquired characteristics by cutting off the tails of mice for 22 consecutive generations
This did not alter tail length in the mice
Thus no evidence supported inheritance of acquired characteristics
August Weismann
Germ-plasm Theory
Cells in reproductive organs carry a complete set of genetic information that is passed to the egg and sperm
Gregor Mendel
Discovered the basic principles of heredity by examining pea plants
Laid the foundation for our modern understanding of heredity
Gregor Mendel
Basic Principles of heredity
The law of independent segregation
The law of independent assortment
The law of dominance
The law of independent segregation
Each individual carries two copies of an inherited traits, which segregate equally in the following generation
The law of independent assortment
Different inherited traits sort independently of one another
The law of dominance
For a trait, one allele is dominant and appears in a 3:1 ratio
Identification of dominant and recessive genes
What are the rules of heredity
Charles Darwin
Traits can be inherited
Variation of traits within the population exist
Offspring with traits that increase their probability of survival survive to reproduce
Put forth the theory of evolution through natural selection
Charles Darwin: Evolution
Weakness
Lack of understanding of heredity
Was not aware of Mendel’s work
Weissman’s Germ-Plasm theory and Mendel’s principles led to the discovery of
Something in sperm/egg that is heritable and control traits
Insights about genetics came from
Cytology-study of cells
Schleiden and Schwann Cell Theory
All life is composed of cells
The cell is the fundamental unit of structure and function in living organisms
New cells arise from pre-existing cells
Discovery of the Nucleus and Chromosomes
Robert Brown described the cell nucleus
Walther Flemming observed chromosomes/mitosis
Examined salamander embryos
Published description of mitosis
Solved the separation of chromosomes from mother to daughter cells
His observations that chromosomes double is significant to the later-discovered theory of inheritance
Theodor Boveri and Walter Sutton (1888-1902) discoveries
Sperm and eggs contribute the same number of chromosomes
Behavior of chromosomes (highly organized, appear the same in daughter cells, and doubles before cell division) during cell division can explain Mendel’s laws of inheritance
The Boveri-Sutton Chromosome Theory: Genes are located on chromosomes
Drosophila (fruit fly) Genetics and Thomas Morgan (1910)
Mechanism of Mendalian Heredity (1915)
Linked the heritable information for eye color to X sex chromosome- first sex linked trait
Discrete pairs of factors located on chromosomes bear hereditary information
Thus, linking traits to chromosomes, confirming Mendel’s laws of inheritance and Sutton Chromosomal Theory that the heritable information is present in chromosomes
James Watson, Francis Crick, Rosalind Franklin, Maurice Wilkins
Described DNA in 1953 as inherited material
