5.3 Common Ancestry Flashcards
_____ and ____ carry genetic information.
DNA, RNA
The genetic code is shared by ______.
All living systems
Gregor Mendel studied _____ and created two ____ that can be applied to the study of _____.
Inheritance, laws, genetics
Who was Gregor Mendel, what did he experiment on, and what did he discover?
- Austrian monk
- experimented on pea plants
- discovered the basic principles of heredity
Why did Gregor Mendel experiment on pea plants? (3)
- many varieties
- controlled mating
- relation short generation time
Mendel only tracked characteristics that came in two distinct forms. Give two examples.
- Colour (either purple or white)
2. Seed shape (round or wrinkled)
To help control his experiments, Mendel used _____
True breeding plants
What does the term “true breeding” mean?
- organisms that produce offspring of the same variety over many generations of self-pollination
Give an example of true breeding.
- true breeding purple plant will only produce purple offspring with self pollination
What is the P generation?
True breeding parental generations
What is the F1 generation? (2)
- first filial
- hybrid offspring of P generation
What is the F2 generation? (2)
- second filial
- offspring of the F1 generation
What are Punnett squares?
- diagrams used to predict the allele combinations of offspring from a cross with know genetic compositions
What does homozygous mean? Give an example for homozygous dominant and recessive.
- an organism that has a pair of identical alleles for a character
- dominant: AA
- recessive: aa
What does heterozygous mean? (2)
- hybrids
- organism that has two different alleles for a gene
- ex. Aa
What is a genotype?
The genetic makeup (alleles) of an organism
What is a phenotype?
- an organism’s appearance (physical) which is determined by the genotype
What do testcrosses help to determine?
- if the dominant trait is homozygous dominant or heterozygous
Mendel’s experiments allowed him to develop two fundamental principles of heredity. What are they?
- The law of segregation
2. The law of independent assortment
Mendel discovered that the cross between purple (P) and white (p) true breeding plants produced only purple F1 offspring. Did the white characteristic disappear? (2)
- no because the white pea flower characteristic comes back in the F2 generation
- he hypothesized that the purple flower must be a dominant trait to the white flower
Mendel performed the same crosses for each of the seven characteristics of pea plants and found the same result. What did he find?
The F2 generation was always a 3:1 ratio
To explain the 3:1 ratio, he observed the F2 generation and created a model with four concepts. What are these concepts?
- Alternative versions of genes (alleles) account for variations in inherited characteristics
- For each character(istic), and organism inherits two copies (two alleles) of a gene, one from each parent
- If two alleles at a locus (location on xmes) differ, then the dominant allele determines the appearance (phenotype) and the recessive ales has no noticeable effect
- Law of Segregation: the two alleles for the same trait separate during gamete formation and end up in different gametes
Why are somatic cells diploid? (2) what are alleles
- they contain 2 copies of each xmes
- alleles: alternate versions of a gene
State the Law of Segregation for the P generation. after, state if for true breeding.
- Each gamete for the P generation will contain one allele for flower colour
- True breeding plants (pure or homozygous) will have two identical alleles
Please see page 18 for a good example
