The Work of Gregor Mendel Flashcards
Heredity
the delivery and inheritance of characteristics from parent to offspring
Genetics
scientific study of heredity
What is important to understanding what makes each organism unique
study of genetics
What was Mendel known as
“Father of Modern Genetics “
Was Mendel recognized while he was still alive
no he was recognized after death
What did Mendel study?
cross breeding (cross-fertilization) by performing biological experiments on peas in his garden and the traits of pea plants
Why did Mendel choose to study pea plants?
bc they are small, easy to grow, true breeding, and self hereditary
True - breeding plants
Organisms that will always have the same traits; throughout all generations
Self Hereditary
plants that create their own sperm
Model System
systems that are convenient to study and may tell us how other organisms, including humans actually function
How many characteristics did each of the 7 traits that Mendel studied have?
2 (ex: yellow and green —- for color )
What is the first generation of plants called
paréntis (P)
[parents in latin]
What is the second generation of plants called
Filius (F)
[sons in latin]
What is the third generation of plants called
Filius 2
(F2)
Fertilization
when male and female reproductive cells join in sexual reproduction
In flowers, what contains sperm
pollen
In flowers, what contains the eggs
pistil
What does the pollen in the pistil create
an embryo encased in a seed
Another term for self hereditary
self pollinating
Trait
a specific characteristic (height, seed, color, etc.) of an individual
Genes
factors that are passed from parent to offspring and are formed by a pair of two alternative alleles
Alleles
the different forms of genes ( T, t ) that exist in pairs
How many traits of pea plants did Mendel study?
7
What are the unit factors in postulate 1
genes
Test Cross
technique used to determine if organisms are homozygous dominant or heterozygous dominant
Test crosses prevent ____-_____ and utilize _____-______
self-pollination; cross-pollination
How many steps does cross pollination in plants have?
2
How many parents does an offspring from cross pollination have?
2
What are the steps of cross pollination?
1) Cut pollen-bearing parts of flower
2) Dust pollen on a different organism’s pistils
Hybrids
the offspring of crosses between parents with different traits
All of Mendel’s F1 plants had the traits of ____ parent
one
Which postulate formed the current understanding of inheritance?
Postulate 1
Postulate 1
Genetic factors (TRAITS) are controlled by unit factors (GENES) that exist in pairs (ALLELES)
Postulate 1 is aka
Unit factors are formed in pairs
Postulate 2
some alleles are dominant and others recessive and
dominant traits always suppress the recessive from appearing.
What is postulate aka?
Dominant and Recessive
Dominant alleles
alleles which trait will always be expressed if present
Recessive alleles
An allele whose phenotypic effect is not observed in a heterozygote
Why are some alleles dominant and others recessive?
Because dominant alleles have more proteins than recessive
Segregation
separation of expression of alleles
Why does segregation occur?
The alleles for the different traits separated during the formation of gametes
At the end of segregation, each gamete carries ____ allele for each gene
one
Cross fertilization
the fusion of male and female gametes from different individuals of the same species
Hybridization
In genetics, the mating, or crossing, of two true breeding varieties (refers to organisms that produce offspring of the same variety over many generations of self-pollination).
Gene
the specific trait (like pea color, length, etc. etc.)
P
Parental generation
What kind of breeding did the P generation have
true breeding
F1 Generation
the first generation
True breeding
breeding with only homozygous traits
F2 generation
second generation
How many types of alleles are there and wht are they
2 (dominant and recessive)
Heterozygous
having two different alleles for one given gene
Homozygous
having 2 identical alleles for a given gene
Law of Segregation
during gamete formation, 2 ALLELES of 1 GENE will separate randomly into different gametes which means that each gamete will only get 1 ALLELE
the law of segregation deals with what
one trait (one gene)
Test Cross technique – how is it done
when an organism with an unknown genotype is crossed with a homozygougous recessive to see what the original genotype was
Monohybrid
an organism that is heterozygous with respect to a single gene of interest (in terms of hair its Bb)
All the offspring from a cross between parents homozygous for different alleles are ____
monohybrids
dihybrid
organism that is heterozygous with respect to two genes of interest (length and color – TtPp)
All the offspring from a cross between parents doubly homozygous for different alleles are _____
dihybrids
Law of Indendent Assortment
during gamete formation, the alleles of DIFFERENT genes segregate independently of each other
Significance of law of segregation
makes sure that each gamete only has one allele from a pair
when does the law of segregation occur
during meiosis when the homologous chromosomes separate
9:3:3:1
the phenotypic ratio that is typically ovserved in the offspring of a dihybrid cross
What do the numbers mean in 9:3:3:1
9 dom/dom, 3 dom/rec, 3 rec/dom, 1 rec/rec
Postulate 3
law of segregation
