17.1 Laying Foundations Flashcards
What is selective breeding?
The process of choosing and breeding specific organisms for particular physical features or behaviors
What was Aristotle’s view on Inheritance?
Egg and Sperm consist of particles from all parts of the body called pan-genes which develop into the parts of the body from which they are derived
What is Leeuwenhoek believe about inheritance?
He believed that sperm consisted of a single tiny human living in the head of the sperm
What do true breeding plants do?
Exhibit the same characteristics generation after generation
What is a mono-hybrid cross?
The offspring of a cross between two parent organisms with different inheritable traits
How did Mendel test traits?
He cross bred parental plants with other parental plants and observed the characteristics of the offspring and the offspring’s offspring
What is complete dominance?
An individual with one recessive and one dominant form had the same observable physical characteristics as an individual with two dominant forms
What generalizations did Mendel infer?
- Discrete genes determine individual traits
- Each individual organism has two copies of each gene
- When gametes are formed, the copies of each factor segregate so that each gamete receives one copy of each gene
- Eggs and sperm fuse randomly. The embryo that develops into a new individual has two copies of each factor -one copy from each parent
What is the law of segregation?
A summary of Mendel’s generalizations
Who coined the term Gene?
Danish Botanist and Geneticist Johannsen
What are the different forms of each gene called?
Alleles ex. Gene is seed shape alleles are round and wrinkled
What is used to represent a dominant allele and recessive allele?
The first letter in the description in upper case for dominant alleles and the first letter in lower case to represent recessive alleles
What is an individuals Genotype?
The combination of alleles for any given trait
What is an individuals Phenotype?
The outward expression of a trait -the physical expression you can observe
What does Homozygous mean?
An individual with two identical alleles for a trait ex. RR or rr
What does Heterozygous mean?
An individual with two different alleles for a trait ex. Rr
How did recessive traits randomly appear in the F2 generation?
When the plants produced gametes, the alleles segregate randomly and each gamete only receives one allele giving an equal chance to receive another recessive trait
What is a test cross?
A cross between an organism of an unknown genotype and a homozygus recessive organism
When is a test cross used?
When geneticists want to know if a pheotypically dominant individual is homozygous or heterozygous
What is a Dihybrid cross?
When plants that were true breeding for two different traits were crossed with plants that were true breeding for the opposite traits ex. TTGG x ttgg
What is Mendel’s second law?
The two alleles for one gene assort independently of the alleles for other genes during gamete formation
What is incomplete dominance?
A condition in which neither alleles for the same gene can completely conceal the presence of another
What is sickle cell anemia caused by?
A specific form of a gene that directs the synthesis of hemoglobin which distort the shape of the cells causing blockages that result in tissue damage
What is co-dominance?
When both alleles are fully expressed
What is the chromosome theory of inheritance?
A theory proposed by Walter Sutton that genes are carried on chromosomes
What were objections to Mendel’s and Suttons theories?
Many people believed that parental gens played a factor and environment played a role
