Genetics:
Inheriting Traits
Chromosomes
• Chromosomes
________________
________________
____.
• You have ___sets,
from chromosome
____-____
• (______ total)
Genes and Traits
• Genes are
___________________
__________ of
chromosomes that code
for a _________.
(instruction manuals)
• Traits
___________________
___________________
___________________
• Types of traits:
1)_______________
• 2)_______________
• 3)_______________
Mr. Emery?
Question
1) How many different chromosomes do
you have?
2) How many sets of these
chromosomes do you have?
3) What are chromosomes made of?
Genotypes vs. Phenotypes
• Genotype:
____________________________________
_____. They are expressed in letters and
come in pairs (WW, Ww, ww).
• Phenotype:
____________________________________
_________________________________
(widows peak)
• [from Greek phaino- shining, from phainein to show]
• The individual letters are called alleles. (W) or (w)
(probably not on exam)
Dominant vs. Recessive Traits
• Dominant traits: When two different traits are
paired (widows peak vs. straight hairline)
____________________________________
_______.
• Dominant traits are usually expressed
genetically with an upper-case letter of
___________________________________
(W)
Dominant vs.. Recessive
Traits
• Recessive traits: are __________________
when paired up with a dominant trait.
• Recessive traits are expressed genetically
with a lower-case letter of the
____________________________________
____________________________________.
– Straight hairline is expressed with (w), not an (s).
The (w) matches the (W) for the dominant trait, a
widows peak.
Question
Widows peak is dominant trait over a
straight hairline .
1) If the genotype is (Ww), what
phenotype will be expressed?
2) If the genotype is (ww), what
phenotype will be expressed?
3) Why is (ss) not a good set of letters for
this trait?
Homozygous vs.
Heterozygous
• Homo: _______________
• Hetero: ______________
• Zygous: ______________
Homozygous vs.
Heterozygous
• Homozygous: ______________________
• (WW) and (ww) are both homozygous.
– (WW) is homozygous, and _____________
– (ww) is homozygous, and ______________
• Heterozygous:
__________________________ of genes or
trait
– Ww is ____________________________, that’s
it.
Question
Widows peak is dominant over a
straight hairline.
1) What is the genotype of a homozygous
dominant trait for widows peak?
2) If the genotype is heterozygous for
widows peak, which phenotype will be
‘hidden?’
3) What trait will be expressed if someone is
homozygous, recessive?
Twins
Identical twins vs. Fraternal twins
– Identical twins:
share
________________
________________
____.
– They come from the
same
__________and
________________.
Twins?
• Fraternal twins: Not identical genetically. They are
like brothers and/or sisters
______________________________________.
– By the way, these these two are NOT twins.
Cougar fans:
Same age vs. same time
(A)
#1
(B)
#2
Can you match the Cougar
Fans same age vs. same
time?
Question
•
These two Cougar fans are not fraternal twins.
1) Could their DNA be even more closely related than a pair of
fraternal twins?