Mendel/Morgan Flashcards
What did Mendel discover?
The basic principle of heredity by breeding garden peas in a carefully planned experiment
What are the advantages of pea plants?
- many varieties with distinct heritable features variants (called traits)
- maturity of plants can be controlled
- each plant has sperm and egg producing organs
- cross pollination can be achieved
What is the P generation?
The true breeding parents of the first generation
What is the F1 generation?
Hybrid offspring from the P generation
When is the F2 generation produced?
When F1 individuals self pollinate
What did Mendel call a gene?
A heritable factor
What is the first law of segregation
3:1 ratio, with a dominant and recessive Alleles
What are the four related concepts in the first law of segregation?
- All alternative versions of genes account for variants
- For each character an organism inherits 2 Alleles, one from each parent
- Of the 2 Alleles at a locus differ, then one (dominant) determines the appearance, and the other (recessive) has no effect on appearance
- Now known as the law of segregation, states the 2 Alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
How many Alleles that are present in somatic cells of an organism to the sperm or egg get?
One of the 2
The segregation of Alleles corresponds to the distribution of what?
Homologous chromosomes to different gametes in meiosis
What’s the difference between genotype and phenotype?
Genotype is the genetic makeup and phenotype is its physical appraearance
What’s a cross between heterozygote monohybrids called?
Monohybrid cross
What does the law of independent assortment state?
That each pair of Alleles segregated independently of each other pair of Alleles during gamete formation
What’s the difference between the first law of independent assortment and the second law of inheritance?
First focuses on one trait where second focuses on 2
What are the degrees of dominance?
- complete dominance
- incomplete dominance
- codominance
What is complete dominance
Occurs when phenotypes of the heterozygote and dominant homozygote are identical
What is incomplete dominance
The phenotype of F1 hybrids is somewhere between the 2 parental varieties
What is co dominance
2 dominant Alleles effect the phenotype in desperate distinguishable ways
What are quantitative characters?
Those that vary in the population along continuum
Quantitative variation usually indicates what?
Polygenic inheritance, an addictive affect of 2 or more genes on a single phenotype
Which types of flys were mutant? Normal or wild?
Wild
With some traits why do only males get it?
Because it has to be located on the Y chromosome. Females need 2’copies of the allele
What is a gene located on either sex chromosome?
Sex linked gene (in humans usually on the X)
What are linked genes?
Genes located on the same chromosomes that tend to be inherited together
What is genetic recombination?
The production of offspring with combination of trait differing from either parent
What are parental types?
Offspring with a phenotype matching one of the parents
What’s s recombinant type/recombinant
Offspring with nonparental phenotypes (new combination of traits)
What percentage of frequency is observed for any two genes on different chromosomes
50%
What is crossing over
A process that breaks the physical connection between genes on the same chromosome
What is the genetic map?
An ordered list of the genetic loci along a particular chromosome
What is a linkage map
A genetic map of a chromosome based on recombination frequencies
How do the map units works
Distance between genes: one map unit=1%recombination frequency
How do genes that are far apart of the same chromosome behave?
Physically linked but not genetically linked, act as on different chromosomes
What is aneuploidy?
Results from the fertilization of gametes in which nondisjunction occurred
What is nondisjunction
Pairs on homologous chromosomes do not separate normally during meiosis
What is polyploidy? Triploidy?
A condition in which a organism has has more than 2 complete sets of chromosomes. Triploidy is 3 sets
Polyploidy is common in what?
Plants
What are the four types of changes in chromosome structure that come from breakage of the chromosome
- deletion-removes chromosome segment
- duplication-repeats a segment
- inversion-reverses segment
- reciprocal translocation- crossing of the sex chromosomes
