1. Genetics
What DNA is telling us!

2. Learning Goals
The student will investigate and understand common mechanisms of inheritance and protein synthesis. Key concepts include:
prediction of inheritance of traits based on the Mendelian laws of heredity;
genetic variation (mutation, recombination, deletions, additions to DNA)
use of genetic information; and
exploration of the impact of DNA technologies.

3. vocabulary terms INHERITANCE or HEREDITY-
The genetic transmission of characteristics from parent to offspring

4. vocabulary terms
GENETICS
The study of the transmission of heredity

5. vocabulary terms
HOMOLOGOUS CHROMOSOMESA pair of matching chromosomes in an organism- with one inherited from Mom & one from Dad.

6. vocabulary terms AUTOSOME-
Any chromosome that is NOT a sex chromosome.
In humans there are 22 pairs

7. 1 gene from MOM + 1 gene from DAD = 2 genes (2 letters) for offspring
vocabulary terms
GENOTYPE- the genes present in the DNA of an organism. 
There are always 2 letters in the genotype because (as a result of sexual reproduction)
1 gene from MOM + 1 gene from DAD = 2 genes (2 letters) for offspring

8. Since WE LOVE VOCABULARY, each possible combo has a term for it.
vocabulary terms
Now, it turns out there are 3 possible GENOTYPES:
1. 2 capital letters (like "TT")
2. 1 of each ("Tt")
3. 2 lowercase letters ("tt").
Since WE LOVE VOCABULARY, each possible combo has a term for it.

9. Sometimes the term "PUREBRED" is used instead of homozygous.
vocabulary terms
HOMOZYGOUS: GENOTYPE has 2 capital or 2 lowercase letters (ex: TT or tt)
("homo" means "the same")
Sometimes the term "PUREBRED" is used instead of homozygous.

10. vocabulary terms
HETEROZYGOUS: GENOTYPE has 1 capital letter & 1 lowercase letter (ex: Tt)
("hetero" means "other")
A heterozygous genotype can also be referred to as HYBRID and sometimes the organism is called a CARRIER

11. vocabulary terms Let's Summarize:
Genotype- genes present in an organism
(usually abbreviated as 2 letters)
TT = homozygous = purebred
Tt = heterozygous = hybrid
tt = homozygous = purebred

12. What the organism LOOKS like
vocabulary terms
PHENOTYPE- how the trait physically shows-up in the organism; it is the observable traits present in an organism
What the organism LOOKS like
Examples of phenotypes: blue eyes, brown fur, striped fruit, yellow flowers

13. vocabulary terms
POLYGENIC INHERITANCE- a trait controlled by two or more genes that may be on the same or on different chromosomes
Examples of polygenic inheritance: eye color, skin color, and height

14. vocabulary terms
ALLELES- alternative forms of the same gene.  Alleles for a trait are located at corresponding positions on homologous chromosomes called loci.
ALLELES
Chromosome from MOM
A b C d e
Chromosome from DAD
A B c d E

15. Chromosome from DAD: P Chromosome from MOM: p

16. and the hidden allele is called RECESSIVE.
vocabulary terms
When 1 allele masks (hides) the effect of another, that allele is called DOMINANT
and the hidden allele is called RECESSIVE.

17. vocabulary terms Dominant alleles are represented by a CAPITAL letter
Recessive alleles are represented by a LOWERCASE letter

18. What are Dominant Genes?
Dominant Genes = one gene overshadows the other
Angus Cattle: black is dominant, red is not
Dominant: BB or Bb
Recessive: bb ONLY

19. What are Dominant Genes?
Hereford: white face is dominant
Dominant: WW or Ww
Recessive: ww ONLY

20. What are Dominant Genes?
Hampshire Hog: white belt is dominant
Dominant: WW or Ww
Recessive: ww ONLY

21. What are Recessive Genes?
The gene that is overshadowed by a dominant gene
Recessive genes can only express themselves if BOTH genes are recessive

22. What are Recessive Genes?
Horned is recessive to polled.
Dominant: PP or Pp
Recessive: pp ONLY

23. What are Recessive Genes?
Black wool is recessive to white wool.
Dominant: WW or Ww
Recessive: ww ONLY

24. What are Recessive Genes?
Some types of dwarfism are recessive to average size.
Dominant: DD or Dd
Recessive: dd ONLY

25. What are Recessive Genes?
Albinism (Albino) is recessive to pigmented.

26. What makes an organism the way that it is?
NATURE vs. NURTURE
· Traits that are expressed through genes can be inherited. Characteristics that are acquired through environmental influences, such as injuries or practiced skills, cannot be inherited.

27. Gregor Mendel (1822-1884) Austrian monk
Called the “Father of Genetics" for his study of the inheritance of 7 traits in pea plants.

28. Gregor Mendel ( )
The traits that Mendel chose to study were easily observable in 2 distinct forms.
EX.: Stem Height - tall vs. short
Pod Shape - round vs. wrinkled
Flower Color – white vs. purple
Seed Color – green vs. yellow

29. Gregor Mendel ( )
The significance of Mendel's work was not recognized until the turn of the 20th century
Its rediscovery prompted the foundation of genetics.

30. homozygous DOMINANT or purebred tall tall
Genotype Symbol
Genotype Vocabulary
Phenotype TT
homozygous DOMINANT or purebred tall
tall Tt
heterozygous or hybrid tt
homozygous RECESSIVE  or purebred short
short

31. Geneticists apply mathematical principles of probability to Mendel’s laws of heredity in order to predict the results of simple genetic crosses

32. Mendel’s laws of heredity are based on his mathematical analysis of observations of patterns of the inheritance of traits.
The laws of probability govern simple genetic recombinations.
To see this we use a Punnett Square

33. Punnett Squares
To complete a Punnett square, we use a letter to represent each allele.
We represent the dominant allele with a capital letter, and the recessive allele is given the same letter but in lowercase.
If there is only ONE TRAIT to look at the probability of occuring –this is a MONOHYBRID CROSS

34. Punnett Squares For the pea plant flowers: dominant: purple color = P
recessive: white color = p.
If both parents( P generation) are purebred, then the purple colored parent must be PP and the white colored parent must be pp.

35. Homozygous-recessive
How can we predict these results?
Homozygous-dominant
We complete the possible combinations. P P p P P p p p P P p p
Homozygous-recessive

36. These results show that all the F1 (1st filial generation) offspring are all purple colored hybrids.Pp
100% purple offspring

37. Heterozygous - hybrid
We can use another Punnett square to predict the F2 (2nd filial generation) offspring. P p
Heterozygous - hybrid P P P P p p P p p p

38. Heterozygous - hybrid
The results are always mathematically the same, a 3:1 ratio with 75% purple & 25% white offspring P p
Heterozygous - hybrid P P P P p p P p p p
Phenotypic ratio 3:1
Genotypic ratio 1:2:1

39. Heterozygous - hybrid
A genotype ratio is possible gene combination results you expect from a cross
Phenotypic ratio 3:1
Genotypic ratio 1:2:1 P p
Heterozygous - hybrid P P P P p
A phenotype ratio is possible appearance results you expect from a cross. p P p p p

40. Dihybrid cross You now are determining the probability for TWO TRAITS.
The Punnnett square NOW has 16 possible combinations so all the ratios are out of 16.
To determine the possible gamete combinations you have to FOIL, but I have a short cut, too.

41. Dihybrid cross

42. Dihybrid cross

43. Dihybrid cross

44. Dihybrid cross

45. Dihybrid cross
dihybrid cross practice

46. Dihybrid cross

47. Incomplete dominance
When both alleles are present, they are both expressed in the phenotype.
The hybrid is a blend of both alleles.
When expressing incomplete dominant alleles, both alleles are may represented by different capitalized letters. YOU NOW HAVE 3 possible phenotypes!!!!

48. Incomplete dominance : F1 generation
Homozygous R R W R W R W W R W R W
Homozygous

49. Incomplete dominance : F1 generation
100% pink offspring R R W R W R W W R W R W

50. Incomplete dominance :
F2 generation
Heterozygous R W R R R R W W R W W W
Heterozygous

51. Incomplete dominance : F2 generation
Heterozygous
A 1:2:1 ratio with 25% red, 50% pink & 25% white offspring R W R R R R W W R W W W
Heterozygous

52. codominance
When both different alleles are present, they are both expressed in the phenotype.
The hybrid EXPRESSES both alleles so both are clearly seen.
When expressing codominant alleles, alleles are may represented by different capitalized letters.

53. Codominance: in humans Blood Type: phenotypic ratio 1:1:1:1
1 type A
1 type B
1 type AB
1 type O IA IO IB IA IB IB IO IO IA IO IO IO

54. Codominance: in humans
Blood Type:
A & B are equally strong.
O is recessive
IAIO or IAIA is Type A
IBIO or IBIB is Type B
IAIB is Type AB
IOIO is type O

55. Codominance: in humans

56. Codominance: in humans

57. codominance
EX.

58. codominance
EX.

59. Sex-Linked Traits Boy or Girl? The Y Chromosome “Decides” Y chromosome

61. What are Sex Linked Traits?
In 1910, Thomas Morgan discovered traits linked to sex chromosomes in fruit flies.
Some genes are attached to the X and Y chromosomes
EXAMPLE: In humans, colorblindness and hemophilia are found on the X chromosomes

62. What are Sex Linked Traits?
Since it is usually on the X chromosomes, in Men, traits expressed anytime present
In Women, must have two genes to show trait
Sons can ONLY inherit sex-linked traits from their mothers since dads can only give the Y chromosome to their sons

63. Punnett Square: What sex will the offspring be?
50% chance of a male or a female child.

64. Colorblindness is carried by the mother
Phenotype:
25% colorblind males
25% carrier females
25% normal males
25% non-carrier females

65. If Dad is colorblind, will you be colorblind?
Phenotype:
0% colorblind males
100% carrier females

66. What if Mom is colorblind?
Phenotype:
100% carrier females
100% colorblind males

67. Genetic Diversity
The sorting and recombination of genes in sexual reproduction results in a great variety of gene combinations in the offspring of any 2 parents.
Do you look EXACTLY like your brothers & sisters?

68. Genetic Diversity
Genetically diverse populations are more likely to survive changing environments.
Greater variation within the species makes a population better suited to adaptation to changes in the environment.

69. Genetic Diversity
Leopard populations around the world are in danger because of inbreeding.

70. Genetic Diversity
There is very little genetic variation between any 2 individuals.

71. Genetic Diversity
This makes them VERY susceptible to disease & will likely lead to their extinction.

72. Genetic Diversity
Recombination and mutation provide for genetic diversity.
Inserting, deleting, or substituting DNA bases can alter genes.
An altered gene in a sex cell may be passed on to every cell that develops from it, and MAY cause an altered phenotype.

73. recombination Crossing-over
the physical exchange of chromosomal material between chromatids of homologous chromosomes during MEIOSIS.
Result: Generation of new combinations of genes (alleles).

74. recombination Occurs in prophase I of meiosis I Generates diversity
Creates chromosomes with new combinations of alleles for genes A to F.

75. recombination Letters denote genes Case denotes alleles A a a A B b bF F f f

76. recombination A a A a
Alleles have crossed over to produce new gene combinations B b B b C C c c D D d d E E e e F F f f

78. Chromosomal Errors
Sometimes entire chromosomes can be added or deleted by mistakes during anaphase, resulting in a genetic disorder such as Trisomy 21 (Down syndrome) or Monosomy X (Turner’s syndrome).

79. Chromosomal Errors
NONDISJUNCTION: the failure of chromosomes to separate properly in meiosis. Gametes with extra or too few chromosomes result.
Can cause diseases such as Down’s Syndrome, Turner’s and Klinfelter’s.

80. Chromosomal Errors
POLYPLOIDY: organisms with entire extra sets of chromosomes
Results in the death of the fetus in animals
Often occurs in plants and causes the fruits and flowers to be larger. EX.: bananas, lilies

81. A Karyotype is an Arranged Picture of Chromosomes At Their Most Condensed State
Note that almost all chromosomes come in homologous pairs.
Boy or girl?

82. Karyotype
Boy or Girl?

83. Normal or abnormal Karyotype? male or female?

84. Pedigrees
Pedigree charts show a record of the family of an individual.
It can be used to study the transmission of a hereditary condition.
It is particularly useful when there are large families and a good family record over several generations.

85. Autosomal Dominant

88. Genetics Quiz 5 –all responses in complete sentences
Using the proper vocabulary, describe a single gene cross between a homozygous dominant and a homozygous recessive organism for one trait.
Describe the survival benefits of an organism doing meiosis.
What are the reasons to study genetics?
What is a karyotype and what does it show?
What exactly is a Punnett square used for?

89. Ethical & Moral Concerns
The potential for identifying and altering genomes raises practical and ethical questions.

90. Ethical & Moral Concerns
Cloning is another morally charged issue facing us today.
Cloning is the production of genetically identical cells and/or organisms.

91. Ethical & Moral Concerns
Dolly was famous all over the world because of the way she was born, in She was the world's first cloned mammal.
Dolly the sheep

92. Ethical & Moral Concerns
Other cloned animals

93. Ethical & Moral Concerns
Transgenic organisms also known as Genetically modified organisms
These are organisms that have DNA from a different source or RECOMBINANT DNA
Much of our food is transgenic or GMOs genetically modified organisms, like corn, soybeans, mangos and strawberries

94. Ethical & Moral Concerns

95. Genetics in the News
Human Genome Project: a 1986 DOE and NIH project to identify and map the approximately 20,000–25,000 genes of the human genome completed in 2003

96. Genetics in the News
Medical or Criminal Forensics- because every organism has its own unique DNA…
DNA fingerprinting or profiling is done where the test sample is matched with actual DNA of humans and other organisms
This has been used as evidence in criminal cases and to determine relatedness between individuals

98. DNA Fingerprinting
Restriction enzymes cut unknown DNA into small pieces at certain points
The pieces are placed in wells at the top of a gel and electricity is run through it
A standard with known DNA sizes is placed in at least one well to compare
The different sized fragments (measured in number of base pairs) stop at certain points and the unknown is compared with the known samples

100. Genetics in the News PCR- polymerase chain reaction
A process that allows biotechnologists to make many copies of a small sample DNA in research or for identification in criminal cases when they use DNA fingerprinting.

101. Did you read all sections and understand all parts
Did you read all sections and understand all parts?…if not come and talk to ME ASAP