Genetics:

1
Genetics

• Inheriting Traits

2
Chromosomes

• Chromosomes are columns of coiled DNA.
• You have 2 sets from chromosome 1-23 (46 total)

3
Genes and Traits

• Genes are rows on the column of chromosomes that
  code for a trait. (instruction manuals)
• Traits are a notable feature or quality in a
  person. (physical, behavioral, medical
  conditions)

Mr.. Emery?
4
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?

5
Answers

• How many different chromosomes do you have?
• 23
• How many sets of these chromosomes do you have?
• 2
• What are chromosomes made of?
• Tightly wound columns of DNA

6
Genotypes vs. Phenotypes

• Genotype The type of genes that make up a trait.
  They are expressed in letters and come in pairs
  (WW, Ww, ww)
• Phenotype An observable trait (widows peak) or
  the expression of the genotype.
• from Greek phaino- shining, from phainein to
  show
• The individual letters are called alleles. (W) or
  (w)

7
Dominant vs. Recessive Traits

• Dominant traits When two different traits are
  paired (widows peak vs.. straight hairline) the
  dominant trait shows.
• Dominant traits are usually expressed genetically
  with an upper-case letter of the dominant trait
  (W)

8
Dominant vs.. Recessive Traits

• Recessive traits are hidden when paired up
  with a dominant trait.
• Recessive traits are most often expressed
  genetically with a lower-case letter of the
  dominant trait.
• Straight hairline is expressed with (w), not an
  (s). The (w) matches the (W) for the dominant
  trait, a widows peak.

9
Question

• Widows peak is dominant trait over a straight
  hairline .
• If the genotype is (Ww), what phenotype will be
  expressed?
• If the genotype is (ww), what phenotype will be
  expressed?
• Why is (ss) not a good set of letters for this
  trait?

10
Answers

• Widows peak is dominant trait over a straight
  hairline .
• If the genotype is (Ww), what phenotype will be
  expressed?
• Widows peak
• If the genotype is (ww), what phenotype will be
  expressed?
• Straight hairline
• Why is (ss) not a good set of letters for this
  trait?
• The letter representing the trait should be of
  the dominant trait.

11
Homozygous vs. Heterogygous

• Homo same
• Hetero different
• Zygous yoked, or joined

12
Homozygous vs. Heterozygous

• Homozygous same genes or trait
• (WW) and (ww) are both homozygous.
• (WW) is homozygous, and dominant
• (ww) is homozygous, and recessive
• Heterozygous different genes or trait
• Ww is heterozygous, thats it.

13
Question

• Widows peak is dominant over a straight
  hairline.
• What is the genotype of a homozygous dominant
  trait for widows peak?
• If the genotype is heterozygous for widows peak,
  which phenotype will be hidden?
• What trait will be expressed if someone is
  homozygous, recessive?

14
Answers

• Widows peak is dominant over a straight hairline.
• What is the genotype of a homozygous dominant
  trait for widows peak?
• WW, not ww
• If the genotype is heterozygous for widows peak,
  which phenotype will be hidden?
• Straight hairline
• What trait will be expressed if the someone is
  homozygous, recessive?
• Straight hairline

15
Twins Identical twins vs. Fraternal twins

• Identical twins share the same genetic code.
• They come from the same egg and sperm.

16
Twins?

• Fraternal twins Not identical genetically. They
  are like brothers and/or sisters born at the same
  time.
• By the way, these two are NOT twins, however they
  are brother and sister. These pictures were
  taken approximately the same time developmentally
  and in the same clothes.

17
Cougar fansSame age vs.. present
(A)
1
2
Can you match the Cougar Fans same age vs..
present?
(B)
18
Question

• These two Cougar fans are not fraternal twins.
• Could their DNA be even more closely related than
  a pair of fraternal twins?

19
Answer

• Yes, it is possible.
• And A1, B2