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)

(B)

#1 #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?