Download A. Gregor Mendel

A. Gregor Mendel was born in 1822 in Austria.
Growing up on his family’s farm he had a lot of
practice cultivating ____________ and _________
__________. As a young man he attended the
Institute in Olomouc. After completing his studies
he began work in a __________________. There he
changed his name from Johann to _____________.
In 1847, he was ordained as a ___________.
Mendel was inspired by both his professors and his
colleagues at the monastery that he started his own
work. He tried to unravel the mystery of
____________________________. He also studied
the ways __________________________________
_________________________________________.
Between 1856 and 1863 Mendel cultivated and
__________ some _____________ pea plants.
B. Mendel’s Research – Unraveling the Mystery
Mendel’s attraction to research was based on
his love of nature. He was not only interested
in plants, but also in ____________________
and the theory of _______________.
Mendel always wanted to find out how plants
obtained _______________ characteristics.
Mendel knew that sometimes the
_______________________________
seemed simple and sometimes they did not.
For example, sometimes a trait that appeared in first generation did not show up
in any of the offspring in the second generation. Interestingly, in the third
generation, the trait showed up again. Mendel also noticed similar patterns in
people and many other living things. How can this be?
C. Mendel’s Pea Plants
To simplify his investigation, Mendel decided to study only one kind of organism.
He had already done studies using the _______________________, so he chose
this as his subject.
Why did Gregor Mendel use pea plants? Garden peas were a good choice for
several reasons:
___________________________________
___________________________________
___________________________________
Self-pollinating plant:
Self-pollinating plants contains both _________ and ____________ reproductive
structures.
Pollen from one flower or plant can ________________________ of the same
flower or eggs of another flower ____________________________.
Pollination:
__________________________________
__________________________________
__________________________________
Fertilization:
__________________________________
__________________________________
__________________________________
__________________________________
D. MENDEL’S GAMEPLAN
After deciding to use pea plants as his
subject, he chose to study only
__________________________ at a time.
That way, it is easier to identify which
_____________ should be included or
eliminated.
These characteristics included:
__________
__________
__________
Mendel chose plants that had ____ forms
for each of the characteristics he studied.
Mendel’s plant characteristics that he studied:
Plant HEIGHT
Result
=
or
Plant SHAPE
Result
=
or
Plant COLOR
Result
=
or
The two forms for each characteristic above are called __________.
E. True-Breeding Plants & Cross-pollination
Mendel
was
very
careful
to
use
plants
that
were
_______________________ for each of the _________ he was studying.
True breeding (pure-bred) in plants:
____________________________________________________
____________________________________________________
____________________________________________________
Example: A tall true-breeding or pure-bred plant will always produce
offspring that are _________.
Mendel decided to find out what would happen if he ___________ or
__________ two plants that had different forms of a single trait. To do this,
he used a method known as ______________________________.
Cross-pollination in plants:
____________________________________________
____________________________________________
____________________________________________
____________________________________________
____________________________________________
This way, Mendel could have control of his experiments by selecting
which pollen would fertilize which plant.
*** PARENT GENERATION ***
WRINKLED SEEDS
ROUND SEEDS
*** F1 GENERATION ***
F. MENDEL’S FIRST EXPERIMENT
In Mendel’s first experiment, he performed
crosses to study seven different characteristics.
Each of the crosses was between the two traits
of each characteristic.
To study these different characteristics, he
performed a __________ (fertilization) between
plants that produce ______________ seeds and
plants that produce __________ seeds.
The offspring from this cross are known as the
_____________________. See figure to the left.
Write the result of the F1 generation to the left
In each of his crosses, Mendel observed similar
results. One trait always appeared, and the other
traits seemed to disappear.
To organize his observations he labeled the trait
that appeared as the ______________ traits.
Based on the F1 generation, which of the following
two traits are dominant? ____________
The trait that seemed to disappear he called the
_______________ traits. Which of the following
two traits are recessive? _______________
G. MENDEL’S SECOND EXPERIMENT
Mendel allowed the F1 or first generation from each of
the seven crosses to self-pollinate.
Mendel allowed the F1 or _______________________
offspring of the dominant trait for seed shape (which is
round) to self-pollinate.
The offspring from this self-pollinating cross is called
the _________________________________. In this
generation the trait for _______________________
showed up again. See figure on the right!
No matter which characteristic Mendel investigated, when the F1 generation
was allowed to self-pollinate, the recessive trait reappeared.
H. A FIRST TIME FOR EVERYTHING
For the first time recorded, Mendel did
something that no one else had done before:
He decided to
________________________________ with
each trait that turned up in the
__________________________.
He hoped
that this might help him explain his result. The
results can be seen to the right?
Mendel decided to calculate the _______ of
________________ traits to _____________
traits for each characteristic.
In the space to the right write the ratio for
each characteristic in the F2 generation?
__________ : __________
I. PUTTING IT ALL TOGETHER
Mendel realized that his results could be explained only if each plant had _______
sets of instructions for each characteristic. Even though, at the time, Mendel did
not know about DNA, he realized that a set of instructions are passed down from
the parents to the offspring.
In fact, each parent donates a
_____________________________ to the offspring.
These sets of instructions are called genes.
Genes:
Alleles:
To mathematically understand Mendel’s conclusions it is important to use a tool
called a ______________________.
Punnett Square:
______________________________________________
______________________________________________
______________________________________________
Punnett Squares use two different types of alleles. One
set comes from each parent’s ______ cells. The father
contributes ________ while the mother contributes an
______. To represent the allele from each parent,
___________ are assigned.
These letters represent the genotype of which
____________ you are looking for as a result of the
Punnett square.
Genotype:
J. How to write a Genotype:
All traits are shown with _____ letters. One set from each
parent’s sex cells _________ or ______. Letters are used
to represent different forms of genes called ___________.
Example of alleles
Some alleles are ________________ and are shown with
_______________________ [BB or B].
Some alleles are _______________ and are shown with
__________________________ [bb or b].
When writing a genotype always put the
_______________________ or capital letter first.
Example:
B = is a ______________ allele (form of gene) for
brown eyes
b = is any other eye color which is a ______________
allele (form of gene)
Answer the following questions:
If an individual has the genotype of BB or Bb they will have what color eyes?
If an individual has the genotype of bb, they will have what color eyes?
The prefix hetero means ______________.
Therefore, alleles written by [1] capital letter and [1]
lower case letter is called ____________________.
Example: Bb, Aa, Ss, Tt, etc… [ __________ ]
The prefix homo means ____________. Alleles represented by [2] capital letters
or [2] lower case letters are called __________________.
Example: BB, bb, AA, aa, SS, ss, etc... [_____________]
PRACTICE
For each GENOTYPE below, indicate whether the following alleles are heterozygous (He) or Homozygous (Ho).
ANSWERS LIE
NO
PEEKING
BEHIND THIS BOX
Using the chart above write which of the following are hybrids?
______________________________
Using the chart above write which of the following are purebreds?
___________________________
K. PHENOTYPES
A phenotype is ____________________________
_________________________________________
An organism’s phenotype is all of its observable
characteristics—which are influenced both by its
_______________ and by the ________________.
Remember: A change in the environment can
change an organism’s phenotype but not the
genotype. Flamingos turn pink because of the
food they eat and not by their genotype.
Genotypes (e.g. BB, Bb, bb) determine the visible
trait or phenotype (e.g. Brown, Brown, blue)
L. PUNNETT SQUARES
One way to visualize how genes combine is
through the use of _______________________.
By using Punnett squares you can work out the
___________________ that children of the
parents will have specific phenotypes and
genotypes.
Remember that ______________ alleles are
symbolized
with
capital
letters,
and
______________ alleles are symbolized with
lowercase letters.
Monohybrid cross:
_______________________________________
_______________________________________
_______________________________________
EXAMPLE:
Let’s say we cross a mother with a phenotype of blue eyes
(genotype bb) with a father who has the phenotype brown
eyes (Bb). Brown eyes are Dominant to blue eyes. What is
the chance that any of the offspring will have blue eyes?
Step #1: Draw a 4x4 box to setup your monohybrid cross.
Step #2: _______________________________
_______________________________
Step #3: _______________________________
_______________________________
Step #4: _______________________________
_______________________________
What % of the parent’s offspring will have blue eyes (bb)?
%