Genetics & Mendel 6.3, 6.4, 6.5
Name: ___________________________
KEY CONCEPT 6.3, 6.4, & 6.5
Mendel’s research showed that traits are inherited as discrete (individual) units.
Mendel laid the groundwork for genetics.
•
_________________ are distinguishing characteristics that are inherited. (eye color, hair
color)
•
__________________ is the study of biological inheritance patterns and variation.
•
______________________________ showed that traits are inherited as discrete units. (like
different colored marbles mixed together that can still be picked out separately)
Mendel crossed (mated) many pea plants and observed these ____________________ . His results
led to important conclusions about how traits/genes are inherited (more on that later).
Ratios are
all about
3:1…What
does this
mean?!
•
A _____________ is a piece of DNA that directs a cell to make a certain protein.
•
Each gene has a ________________, a specific position on a pair of
homologous chromosomes.
 An allele is any ________________________
occurring at a _________________________
Gene = pea shape
on a chromosome (gene=pea shape,
Allele=smooth or wrinkled
allele=smooth or wrinkled)
Locus = location
– Each parent donates one allele for
every gene.
-Genotype: The genetic makeup of a specific set of genes
-Phenotype: The physical characteristics of an individual – what you actually SEE
– _________________________ describes two alleles that are the
same at a specific locus. Ex: _________________
–
_________________________ describes two alleles that are
different at a specific locus. Ex: _________________
-Also called a hybrid
o __________________ can be represented using letters.
NOTE: Capital letters are used for
DOMINANT ALLELES, lowercase
letters are used for recessive
alleles.
Dominant = R
Recessive = r
– A _____________________ allele is expressed as a
phenotype when at least one allele is dominant.
– A _____________________ allele is expressed as a
phenotype only when two copies are present.
– Dominant alleles are represented by
___________________ letters; recessive alleles
by _____________________ letters.
Mendel used pollen to fertilize selected pea plants.
–
He crossed the _____________________ generation to produce
_______________________________________ generation.
He interrupted the self-pollination process in the plants by removing male
flower parts.
Punnett squares illustrate genetic crosses.
• The ________________________________ is a grid system for predicting all possible
genotypes resulting from a cross.
–
–
The ________________ represent the possible gametes of each ______________.
–
The ________________ show the possible genotypes of the _________________.
 The Punnett square yields the
_________________ of possible genotypes and
phenotypes
•
Mendel then allowed the resulting plants to ____________________________________.
–
Among the F1 generation, all plants had _______________________________ – this is
the ______________________________ (describes physical traits, what we can see)
–
F1 plants are all _____________________________ this is the
_____________________________ (describes the internal makeup of the genes, what
we cannot see).
A monohybrid cross involves one trait.
•
_________________________________ crosses examine the inheritance of only _______________
specific trait. (let’s do this one as an example).
Phenotype (parents):
Genotype (parents):
•
Among the ___________ generation, some plants had
_________________________________________________________________________.
•
Let’s do this cross and see how he got these results.
Phenotype:
Genotype:
•
Practice
•
What words would you use to describe the P generation (parents)?
•
What would the phenotype and genotype be of the F1 generation?
•
Both homozygous dominant and heterozygous genotypes yield a
_____________________________________________
Ex: _________________________________________
•
The only combination that shows the ____________________________________________________
is the genotype Ex: _________________________________
Mendel drew three important conclusions.
1. Traits are inherited as ___________________________________.
2. Organisms ________________________________________________ of each gene, one from each parent.
3. The two copies _________________________________ during gamete formation.
–
The last two conclusions are
called the _________________________________________________.