__________________ ____________________ was an Austrian monk. While living at his
monastery, he became interested in the study of _______________ (botany). He used the
abbey _____________________ to perform his experiments.
Father of Genetics: The basic laws of ____________________ were first formed during the
mid ________________ by Mendel. His work laid the ________________________ to the
further study of heredity. He is often referred to as “The __________________ of Genetics”.
Mendel based his studies on garden _____________ __________________. They are easy to
grow, and have many ______________________ traits. In a relatively short time, Mendel was
able to see ___________________ in these traits over many ____________________ of
plants.
Pea plants have many visible traits such as: plant height, ______________ or
______________, seed color: ______________ or __________________, pod shape:
______________ or ___________________, pod color: ____________________ or
_________________, seed shape: _________________ or _____________________.
Mendel’s Experiments: Mendel noticed that some plants always produced
_________________ that had a form of a trait exactly like the parent plant. He called these
plants __________________ plants. For instance, purebred short plants
___________________ produced short offspring, and ____________________ tall plants
always produce _______________ offspring.
First experiment: Mendel crossed purebred plant with __________________ forms of a trait.
He called these plants the _______________________ ______________________________,
or P generation. For example, purebred tall plants were ________________ with purebred
short plants. Mendel observed that all of the offspring grew to be _______________ plants.
None resembled the short parent. He called this generation of offspring the
_________________ ________________, or F1 generation.
Second experiment: Mendel then crossed two of the offspring ______________ plants
produced from his first experiment. Mendel called this second generation of plants the
________________________________________. To his surprise, Mendel observed that this
generation had a mix of ________________ and ____________________ plants. This occurred
even though none of the F1 generation plants were short.
Law of Segregation. Mendel’s First law, the _______________ _____ _____________________
has three parts. Mendel concluded that: 1. Plant traits are handed down through
____________________ _______________________. 2. Because offspring obtain hereditary
factors from both parents, each plant must contain ______________ ________________ for
every trait. 3. The factors in a pair _________________ during the formation of sex cells.
Dominant and Recessive Genes. Mendel went on to reason that one ____________ (gene) in a
pair may mask, or hide, the other factor. For instance, in his first experiment, when he crossed
a ___________________________ tall plant with a _______________________ short plant all
of the offspring were _______________. Although all of the offspring had both tall and short
factors, they only displayed the _____________ factor. He concluded that the tallness factor
masked the shortness factor.
Today, scientists refer to these ‘factors’ as _______________. The different forms of a gene
are called __________________. Alleles that mask or hide other alleles such as the tall allele
are said to be ___________________.
A ________________ allele, such as the short allele, is masked or covered up whenever the
dominant allele is present.
Homozygous genes. What Mendel referred to as a “purebred” plant, we now know this to
mean that the plant has ____________ identical genes for a particular trait. For example, a
purebred tall plant has two genes for ____________, and a purebred short plant has two
genes for _______________. The modern scientific term for purebred is
_______________________. According to Mendel’s Law of Segregation, each parent donates
___________ height gene to the offspring. Since each parent had only short genes to donate,
all of the offspring will also have ____________ short genes (homozygous), and will therefore
be short.
Heterozygous genes. In Mendel’s first experiment, F1 offspring received one __________ gene
and one ______________ gene from the parent plants. Therefore, all offspring contained both
_______________, a short and a tall allele. When both alleles are present, the plant is said to
be a hybrid for that trait. The modern scientific term for hybrid is
________________________. Although the offspring have both a ___________ and a
____________ allele, only the tall allele is expressed and is therefore
______________________ over short.