This presentation is suited for Grade 9 - Science for the topics about genes, chromosomes, solving punnett square and Non-Mendelian Inheritance(Co-dominance, incomplete dominance, multiple allelles and sex-related traits.

3. • They are the carriers of genes, the
unit determiners of hereditary
characteristics.
• They are located in the nucleus of
the each body cells.

4. Species Number of
Chromosomes
Species Number of
Chromosomes
Human 46 Earthworm 36
Gorilla 48 Puffer Fish 42
Donkey 62 Dog 78
Cat 38 Fruit Fly 4
Cow 60 Mosquito 6
Goldfish 94 Pea plant 14
Horse 64 Sunflower 34

5. • Each chromosomes is made up of
two long DNA molecule called the
blueprint of life or the genetic plan of
the organism. The entire DNA in the
body cells is called genome.

6. • From among the 46 chromosomes of
humans, 22 pairs have almost the
same size and shape and have the
same genes on them and they are
called homologous chromosomes.

7. • 1. Centromere – divides the
chromosomes into two arms.
• 2. q arm – the long arm region.
• 3. p arm – the short arm region.
• 4. Kinetochore – attaches to the
spindle fiber during cell division.

9. • Autosomes – aka body
chromosomes, are the first 22
pairs of chromosomes which are
the same in both female and
males.

10. • Sex Chromosomes – determine
the sex of the organism. The Y-
chromosome trigger the
development of specific male
characteristics.

11. • Females have XX chromosomes
(homogametic)
• Males have XY chromosomes
(heterogametic)
• They are not homologous because
X is bigger than Y chromosome.

12. • Genes are the determiners of
hereditary characteristics.
• They are the portions of DNA
molecule, the fundamental unit of
heredity.

13. • Through the Human Genome
Project, biologists found out that
humans have about 30,000 genes.
• Locus – the specific location of the
genes along the entire length of
the chromosomes.

14. • A member of homologous
chromosomes has the same pair of
genes. The member of each pair of
genes is called the allele.

15. • Linked Genes – genes that are
located on the same chromosomes
and are tend to be inherited
together at the same time.

17. • One allele is not completely
dominant over the other resulting
in the blending of characteristics.
• Common in Hibiscus and Mirabilis
jalapa.

18. P1 Red Flowers White Flowers
RR x WW
Formation of Gametes
(P2)
x
F1
Ratio Genotypic Ratio = 4:0 or 100% RW
Phenotypic Ratio = 4:0 or 100% Pink Flowers
R R
RW RW
RW RW
R R W W

19. P1 White Fur Black Fur
WW x BB
Formation of Gametes
(P2)
x
F1
Ratio Genotypic Ratio =
Phenotypic Ratio =
W W B B

20. P1 White Fur Black Fur
WW x BB
Formation of Gametes
(P2)
x
F1
Ratio Genotypic Ratio = 4:0 or 100% B
Phenotypic Ratio = 4:0 or 100%
B B
B B
B B
W W B B

21. • In some cases, the heterozygous
characteristics are fully expressed
in the F offspring resulting to both
traits to be expressed in the
organism.

22. P1 Red Flowers White Flowers
Rr x Ww
Formation of Gametes
(P2)
x
F1
Ratio Genotypic Ratio = 2:2 or 50% RW and 50% Wr
Phenotypic Ratio = 2:2 or 50% Pink and 50%
R r
RW Wr
RW Wr
R r W W

23. P1 Orange Fur(Incomp.Dominant) Black Fur
x BB
Formation of Gametes
(P2)
x
F1
Ratio Genotypic Ratio =
Phenotypic Ratio =
R
B B

24. P1 Orange Fur Black Fur
RY x BB
Formation of Gametes
(P2)
x
F1
Ratio Genotypic Ratio = 2:2 or 50% BR and 50% B
Phenotypic Ratio = 2:2 or 50% Dark Red and 50%
R
BR
BR
R Y B B

25. • There are some traits that are not
controlled by two alleles but by
multiple alleles.
• Common example is human blood
groups – A, B, AB and O.

26. Blood
Groups
(Genotypes)
Phenotypes Antigen
(Type of
Protein)
Antibodies
(Plasma of
the Blood)
lAlA or lAi Type A Antigen A Anti – b
lBlB or lBi Type B Antigen B Anti – a
lAlB Type AB Antigen A
and B
None
ii Type O None Anti a and b

27. G1 Blood Type A- Blood Type B-
lAi x lBi
Female Male
Formation of Gametes
(P1)
x
G2
Ratio Genotypic Ratio Phenotypic Ratio
lAlB Blood Type AB
lBi Blood type B-
lAi Blood type A-
ii Blood type O
lA i
lB lAlB
(Type AB)
lBi
(Type B-)
i lAi
(Type A-)
ii
(Type O)
lA i lB i

29. • Traits that are controlled by the
genes found in the sex
chromosomes. Sex-linked traits are
mostly recessive and can be
inherited from one or both
parents.

30. • Males are common to these traits
because they carry only one X-
chromosome inherited from their
mother. If that X-chromosome
carries a genetic disorder, it will be
expressed.

31. • In contrast, the two X-
chromosomes of the female
offspring should both carry the
disorder before it will be
expressed.
• Ex:Hemophilia and Color blindness

32. • Hemophilia – a recessive genetic
disorder wherein the blood does
not clot. Also known as bleeder’s
disease. This is because of lack of
genes that synthesizes protein for
blood clotting.

33. P1 ♀ Hemophilia Carrier ♂ Normal
XX x XY
F1
Ratio Genotypic Ratio = 1:1:1:1 Phenotypic Ratio = 2:1:1
only one X is affected

34. • Is carried by the autosomes not
the sex chromosomes. So, this trait
is not limited to male humans
alone. They are mostly recessive
but because of sex hormones it
acts like a dominant allele.

35. • For example if a male has an allele for
baldness, which is recessive, but since
he has testosterone, it will act as
dominant allele.
• If a female inherits an allele for
baldness it will remain recessive but
can still be passed on.

36. Male
Phenotypes Genotypes
Bald XBYb
Bald XbYb
Not Bald XBYB
Female
Phenotypes Genotypes
Bald XbXb
Not Bald XBXb
Not Bald XBXB

37. P1 ♀ Not Bald ♂ Bald
XBXb x XbYb
F1
Ratio Genotypic Ratio
♀ = 1:1
XBXb
XbXb
♂ = 1:1
XBYb
XbYb
Phenotypic Ratio
♀ = 1:1
Bald Not Bald
♂ = 2:0
Bald
Xb Yb
XB XBXb XBYb
Xb XbXb XbYb

38. • The trait is only expressed only in one
gender and does not appear in the
other. One typical example is production
of milk in lactating mothers. It is only
observable in females since they exhibit
the normal condition(well developed
breasts) for such effect to happen.

39. G1 Blood Type A Blood Type B-
lA lA x lBi
Female Male
Formation of Gametes
(P1)
x
G2
Ratio Genotypic Ratio Phenotypic Ratio
lAlB Blood Type AB
lAi Blood type A-
lA lA
lB lAlB
(Type AB)
lAlB
(Type AB)
i lAi
(Type A-)
lAi
(Type A-)
lA lA lB i

40. P1 ♀ Not Bald ♂Hetero Bald
XBXB x XBYb
F1
Ratio Genotypic Ratio
♀ = 2:0
XBXB
♂ = 2:0
XBYb
Phenotypic Ratio
♀ = 2:0
Not Bald
♂ = 2:0
Bald
XB Yb
XB XBXB XBYb
XB XBXB XBYb