Download Chapter 3 Continued How do genes determine traits?

Chapter 3 Continued
How do genes determine traits?
6th Grade Science
Mendel’s Work
Gregor Mendel
• ______________
- “Father of Genetics”
– A priest that conducted experiments in his garden
that revolutionized the study of heredity.
– ___________
- the passing of physical
Heredity
characteristics from parents to offspring
– Mendel used pea plants to observe _________
of
traits
pea plants.
traits
– _________
- a characteristic that an organism can
pass on to its offspring through its genes.
Mendel and Heredity
• Mendel experimented with hundreds of pea
plants to understand the process of ________.
heredity
• ________
- the scientific study of heredity.
Genetics
• Mendel “crossed” pea plants with contrasting
traits
________
and observed the outcomes of
traits in the offspring.
• Mendel started his experiments with
________
purebred pea plants or plants that have had
the same trait for many generations.
Crossing Pea Plants
Purebred
• __________
short pea plants come always
come from short parent plants.
Mendel’s Experiments
Mendel’s Conclusion
• Mendel’s Conclusions included:
genetic
– Individual factors or sets of _________
information controls the __________
inheritance of traits in
peas.
pairs - one
• The factors that control each trait exist in _____
female parent and one from the
from the _______
_______parent.
male
• One factor in each pair can mask or hide the other
factor.
Dominant and Recessive
• ________factors that control a trait.
Gene
• _____
Alleles - different forms of the gene
• Offspring inherit one _______
from each parent –
Allele
one could be tall and the other could be short,
both could be tall, both could be short – it
genetic
depends on the ________
information from the
parent.
• ____________
Dominant allele - the trait that always shows up in
the organism when the allele is present
• ____________
Recessive Allele - hidden whenever the dominant
allele is present
Alleles in Mendel’s Crosses
short
• Purebred
___________
- only pea plants that inherit
two recessive alleles for short stems will be
short.
• _________
- organism has two different alleles
hybrid
for a trait.
• ________
alleles.
Dominant alleles mask the ________
recessive
• A dominant allele is represented by a capital
______
letter. Recessive alleles are represented by
Lower case letters.
________
Sharing Dominance
• Not all gene pairs follow the dominant-recessive
pattern.
• Some traits show _____________of
a gene at
Both versions
work.
• Example – Erminette chicken has genes for both
black and white feathers. But neither color is
dominant. Instead the colors
___________________.
Share Dominance
• Selecting a few organisms with desired traits to
serve as parents of offspring is called
____________________
Selective breeding
Probability and Genetics
• Mendel was the first scientist to recognize
probability
that the principles of __________
can be used
Genetic crosses
to predict the results of ___________.
Punnett Square - a chart that shows all the
• ____________
possible combinations of ________
that can
alleles
result from a genetic cross.
• The boxes in the Punnett Square represent the
possible alleles that the offspring can
inherit
_______.
Punnett Square Examples
Meiosis and Punnett Square
Punnett Square
• _____________-show
the events that occur in
meiosis.
Chromosome pairs separate and go into
– When the _______________
Sex cells so do the _________
allele
two different ________,
carried on each chromosome.
– Punnett Squares show the possible allele
fertilization
combinations after __________.