Lecture 16. The Molecular Basis of Mendelian Genetics Flashcards
What is evolution ?
Descent with modification
What is genetics ?
Study of biological inheritance
What is a more specific definition of evolution ?
The process by which the genetic material of a population change over time
What is population ?
A group of organisms of the same species, in the same region, capable of mating freely with one another
What is a character ?
A feature of an organism
What is a trait ?
The state of a character in an organism
What is a phenotype ?
All the observable traits of an organism. These results from the interaction of its genotype with the environment.
What is population genetics ?
Study of the genetic composition of biological populations and changes to this composition
What is microevolution ?
Evolution within a species
What is evolutionary genetics ?
Broader study of how population genetic phenomena bring about long term evolutionary changes
What is macroevolution ?
Evolution above the species level
What are the laws that govern biological inheritance ?
- Inheritance of acquired traits
2. Blending inheritance
What is the Weismann barrier ?
Changes that occur in the body/soma cannot be passed on to the germ line
What does the weismann barrier show ?
Invalidates Darwin and Lamark theories of heridity but strengthened evolution by natural selection
Why was blending inheritance wrong ?
Advantageous traits would be blended away before selection could act
What was Mendels particulate inheritance ?
Traits are determined by discrete units that are inherited intact through the generations
What are Mendels laws of inheritance ?
- Law of segregation
- Law of independent assortment
- Law of dominane
What was Mendel’s idea about heritability ?
Heritability is mediated by discrete units or genes that can have alternate forms or alleles
What is the law of segregation ?
During gamete formation, the alleles for each gene segregates from each other so that each gamete carries only one allele for each gene. The allele is chosen randomly
What is the law of dominance ?
Some alleles are dominant while others are recessive, an organism with at least one dominant allele will display the effect of the dominant allele
What is violation of the law of dominance ?
- Some alleles do not show simple dominant/recessive relationship - incomplete dominance
- Codominance
What is incomplete dominance ?
Heterozygote phenotypes appear intermediate between the homozygote values
What is codominance ?
A new intermediate phenotype, both the recessive and dominant traits appear discretely alongside each other
What is the law of independent assortment ?
Genes for different traits segregate independently during gamete formation
What is a violation of the law of independent assortment ?
Genes do not always assort independently
What are Mendel’s assumptions ?
- Only two alleles exist for each gene
2. Each trait is controlled by one gene
What is the violation to Mendel’s assumption that only two alleles exist for each gene ?
Some genes are multiallelic
What is the violation to Mendel’s assumption that each trait is only controlled by one gene ?
Some traits are controlled by multiple genes (polygenic)
What is the chromosome theory of inheritance ?
The behaviours of chromosomes during cell division mirrors Mendels Laws
What was the conclusion of the chromosomal theory of inheritance ?
Genetic material was contained on the chromosome
What is the material of inheritance ?
DNA
What is the structure of DNA ?
Double helix
What is molecular genetics ?
The study of molecular material of heredity DNA
What is DNA replication important for ?
Universal to all life and essential for biological inheritance
What is homology ?
Similarity due to common descent
What is a mutation ?
An alteration in the DNA sequence
What are the two types of mutation ?
- spontaneous
2. Induced by mutagens
What are the major steps in studies of molecular evolution ?
- Identify homologous sequences
2. Indentify differences between them
What do shared mutations act as ?
Markers of shared descent
What is the genome ?
The complete set of genetic informationin an organism
What is chromosomal crossover ?
The production of gametes via meiosis involving genetic crossover
What does recombination promote ?
Independent assortment
What is linkage ?
The closer two genes are on a chromosome the less likely a recombination event will occur between then
