Genetics: The Science of Heredity
3.1 What is Heredity?
What did Mendel observe?
_____________________________: Known as the Father of Genetics, he unlocked the
key to understanding heredity using pea plants. He was able to obtain predictable,
repeatable results using plants that could both self-pollinate & cross-pollinate.
______________________ the passing of traits/physical characteristics from parents
to offspring
_____________________ the scientific study of heredity
___________________________ the joining of egg and sperm cell (the beginning of
the formation of new organism)
_____________ segments of DNA that carry hereditary instructions located on
chromosomes & passed from parent to offspring(factors that control a trait)
__________________ alternative forms of a gene that govern the same
characteristics (ex. eye color)
How do alleles affect inheritance?
An organism’s ______________ are controlled by the __________________ it inherits
from its parents. Some alleles are __________________________ , while other alleles
are ___________________________ .
______________________________________ trait observed when at least one
dominant allele for a characteristic is inherited
______________________________________ trait that is apparent only when 2
recessive alleles for the characteristic are inherited
____________________________/__________________________having 2 copies of the
same allele for a trait (ex. HH or hh)
_____________________________/___________________ having 2 different alleles for a
trait (ex. Rr or RW)
3.2 Probability & Heredity
How is probability related to Inheritance?
In a _______________ _____________ , the combination of _________________ that
____________________ can pass to an __________________________ is based on
_______________________________ .
_______________________________ the mathematical chance that an event will
occur/number that describes how likely it is that an event will occur
________________________________________ (designed by Reginald C. Punnett) a
chart that shows all the possible ways alleles can combine in a genetic cross
Parent generation (true breeding purple PP x true breeding white pp)
P
p
p
P
Pp
Pp
Pp
Pp
= _________________________
First generation (self pollination of the offspring from the parent
generation Pp x Pp)
P
P
p
p
PP
Pp
Pp
pp
= ________________________
________________________
(recessive trait reappears)
What are phenotype and genotype?
_________________________________ the inherited combination of alleles; genetic
make up
________________________________ an organism’s inherited appearance; visible
appearance
3.3 Patterns of Inheritance
How are most traits inherited?
Most traits are the result of ____________________ _______________________ of
____________________________ .
____________________________ both alleles for a gene are expressed equally (and
individually)
____________________________________ one allele is only partially dominant
(blending occurs)
___________________________________ three or more possible alleles determine the
trait (an organism can still only inherit 2 alleles for a gene, one from each parent,
but there are more possible genotypes with multiple alleles than with just 2
alleles)
__________________________________ more than one gene affects a trait (broad
range of geneotypes: human height, skin color, and eye color)
__________________________ traits organisms are born with (height, freckles, eye
color)
________________________________ traits organisms acquire (language a person
speaks, haircuts, piercings, tattoos)
How do genes and the environment interact?
_____________________________ factors can _______________________ the way genes
are __________________________________ .
List some examples of factors in your environment that can affect how genes are
expressed:
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Changes in _________________ ____________ cannot be passed to offspring. Only
changes in the sex cells - ____________ & ____________ can be passed to offspring.
3.4 Chromosomes & Inheritance
How are chromosomes, genes, & inheritance related?
According to the _____________________________ ___________________ of
______________________________ , genes pass from parents to offspring on
______________________________ .
__________________________________ coiled structure of DNA & protein that forms
in the nucleus during cell division; passed from one generation to the next
What happens during meiosis?
Meiosis
Meiosis produces new cells with _______the usual number of
chromosomes. This process creates ___________cells. The chromosomes
are copied/duplicated only__________ & nucleus divides ________________.