introduction to genetics life science. traits survey why causes these differences?
DESCRIPTION
Genetics- The study of heredity (how traits are passed on) x = orTRANSCRIPT
![Page 1: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/1.jpg)
Introduction to Genetics
Life Science
![Page 2: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/2.jpg)
Traits survey
Why causes these differences?
![Page 3: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/3.jpg)
Genetics - The study of heredity (how traits are passed on)
x =or
or
![Page 4: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/4.jpg)
The study of heredity started with the work of Gregor Mendel and his
pea plant garden
Mendel was an Austrian Monk that lived in the mid 1800’s
![Page 5: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/5.jpg)
Mendel noted that the size of pea plants varied. He cross-bred these pea plants to find some surprising results.
![Page 6: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/6.jpg)
Mendel’s cross between tall pea plants yielded all tall pea plants.
X =
![Page 7: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/7.jpg)
His cross between small pea plants yielded all small pea plants.
X =
![Page 8: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/8.jpg)
Mendels’ cross between tall pea plants and small pea plants yielded all tall pea plants.
x =
![Page 9: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/9.jpg)
Mendel then crossed these second generation tall pea plants and ended up with 1 out 4 being small.
x =
![Page 10: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/10.jpg)
Mendel’s work led him to the understanding that traits such as plant height are carried in pairs of information not by single sets of information.
Hereditary information (DNA) is carried in Chromosomes!
![Page 11: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/11.jpg)
![Page 12: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/12.jpg)
DNA
DNA is found in all living cells– It controls all functions
inside a cell– DNA stores all the genetic
information for a living organism
– Single cell like an amoeba– Multi cell like a human
![Page 13: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/13.jpg)
GeneticsSmall sections of DNA are responsible for a
“trait”. These small sections are called “Genes”.– Gene - A segment of DNA that codes for
a specific trait– Trait - A characteristic an organism
can pass on to it’s offspring through DNA
Gene
![Page 14: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/14.jpg)
Genes
There are two main kinds of genes:– Dominant - A gene that is ALWAYS
expressed and hides others– Recessive - A gene that is only expressed
when a dominant gene isn’t present (hidden)
![Page 15: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/15.jpg)
Dominant and Recessive Genes• A dominant gene will hide a
recessive gene!Example:• A “widows peak” is dominant, not
having a widows peak is recessive.• If one parent contributes a
gene for a widows peak, and the other parent doesn’t, the off- spring will have a widows peak.
Widows Peak
![Page 16: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/16.jpg)
Alleles
All organisms have two copies of each gene (one from female, one from male)
Homozygous- Two copies of the same geneHeterozygous - Two different genes
![Page 17: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/17.jpg)
Example:A Widows Peak, dominant trait, would be
symbolized with a capital “W”, while no widows peak, recessive trait, would be symbolized with a
lower case “w”.
Father - No Widows Peak - w
Mother - Has a Widows Peak - W
![Page 18: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/18.jpg)
Example:For the widows peak:
WW - has a widows peak Homozygous dominantWw - has a widows peak Heterozygousww - no widows peak Homozygous recessive
![Page 19: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/19.jpg)
Genotype vs Phenotype
• Genotype- Genes you haveEx: WW, Ww, or ww• Phenotype- physical features SHOWNEx: WW Widows peakWw Widows peakww NO widows peak
![Page 20: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/20.jpg)
Example:Since Herman has no widows peak, he must
be ______, since Lilly has a widows peak she could be EITHER ______ or ______.
ww WW or Ww
![Page 21: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/21.jpg)
Punnett SquarePunnett Square - A tool we use for predicting
the traits of an offspring– Letters used as symbols to represent genes– Capital letters= dominant genes– Lower case letters= recessive genes– Genes always exist in pairs
![Page 22: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/22.jpg)
Punnett SquaresWe can use a “Punnet Square” to determine
what pairs of genes Lilly has
Ww ww
Ww www
w
W w
Assume Lilly is heterozygous
Assume Herman is homozygous recessive ww
• A Punnet Square begins with a box 2 x 2
• One gene is called an “allele”
• One parents pair is split into alleles on top, the other along the side
• Each allele is crossed with the other allele to predict the traits of the offspring
Ww
![Page 23: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/23.jpg)
Punnett SquaresNotice that when Lilly is crossed with Herman,
we would predict that half the offspring would be “Ww”, the other half would be “ww”
Half “Ww”, Heterozygous, and will have a widows peak
Half “ww”, Homozygous, and will not have a widows peak
Ww ww
Ww www
w
W w
![Page 24: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/24.jpg)
Try it yourself!Create a punnett square assuming Lilly is
homozygous dominant (WW)
w
w
W WWhat is the chance of the offspring having a widows peak?
![Page 25: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/25.jpg)
Try it yourself!All of the offspring will have a widows peak!
Ww
Www
w
W W
Ww
Ww
100%
![Page 26: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/26.jpg)
GeneticsRecall that Herman and Lilly had another
offspring, Marylin. She had NO widows peak.
![Page 27: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/27.jpg)
Genetics
So which is true? Is Lilly homozygous dominant (WW) or is she heterozygous (Ww)?
Ww
Www
w
W W
Ww
Ww
Ww ww
Ww www
w
W w
![Page 28: Introduction to Genetics Life Science. Traits survey Why causes these differences?](https://reader035.vdocuments.us/reader035/viewer/2022062601/5a4d1bf67f8b9ab0599e8ca1/html5/thumbnails/28.jpg)
Genetics
Ww
Www
w
W W
Ww
Ww
Ww ww
Ww www
w
W w
If Lilly were heterozygous, then 1/2 of their offspring should have a widows peak, 1/2 shouldn’t
If Lilly were homozygous, all of their children will have a widows peak