1. Loci and the Human Karyotype
Biology
Unit 6

2. Chromosomes Karyotype: ordered display of an individual’s chromosomes.
Collection of chromosomes from mitotic cells.
Staining can reveal visible band patterns, gross anomalies.

3. Karyotyping
Meiosis KM

4. Karyotypes arrange chromosomes in order by size: Largest to smallest

5. Chromosomes
Some large like #1
Some small like #22

6. Homologous pairs Same Length Centromere in same location
Same bands (genes)

7. Centromere Position
The centromere is not exactly in the center of the chromosome
“p” arm: (p=petite) the shorter arm of the chromosome
“q” arm: the longer arm of the chromosome

8. Locus (plural=loci)
The position that a given gene occupies on a chromosome. (Its like an address for your genes)
Written like this: 15p23

9. Example: 15p23=Chrom 15 small arm, 23rd band from the centromere

10. Trisomy:
*Having 3 chromosomes of each kind instead of 2 *Normally trisomy results in death.
1 Example

11. Down Syndrome:
a genetic condition in which the individual has 3 copies of the 21st chromosome.
Genotype: 3 copies of 21st chromosome

12. Lt Olive 2p18 2q21 Ssss 2 Locus Allele My Geno. My Pheno Gene
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
Lt Olive
S = Dark
s= Light
SSSS= Dark
SSSs= Fairly Dark
SSss= Olive
Ssss = Light Olive
ssss = Lightest White
Skin Color
Polygenic
2p18
2q21
Ssss 2 S s s s

13. 4p20 4 Aa Some Acne Locus Allele My Geno. My Pheno A=Acne Acne
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
4p20 4
A=Acne
a=No Acne Aa
Some Acne
Acne
Polygenic
Incomplete Dominance
AA=Lots
Aa=some
aa= none A a

14. nn 4p19 Locus Allele My Geno. My Pheno No Cleft N = Cleft n= no cleft
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
N = Cleft
n= no cleft 4
Cleft Chin
Regular Dominance
4p19 nn
No Cleft n n

15. 7p15 Bb Locus Allele My Geno. My Pheno Light Brown 7 Eye color
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno 7
Eye color
Incomplete Dominance
7p15
B=Brown
b=Blue
Light Brown Bb
BB=Brown
Bb=Light Brown, Hazel, Green
bb=blue B b

16. 7p11 Hh Locus Allele My Geno. My Pheno Hair Color Incomplete Dominance
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
Hair Color
Incomplete Dominance
7p11
H=Brown/Black
h=blonde Hh
Light Brown 7
HH=Brown/Black
Hh=Light Brown
hh=Blonde H h

17. No CF FF 7q25 Locus Allele My Geno. My Pheno 7 Cystic Fibrosis
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno 7
Cystic Fibrosis
Autosomal recessive
7q25
No CF
F = No CF
f = CF FF F F

18. Aa 7q11 Locus Allele My Geno. My Pheno Some acne Acne 7 A= Acne
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
7q11
Acne
Polygenic
Incomplete Dominance 7
A= Acne
a = no Acne
Some acne Aa A a

19. o ii 9q34 Locus Allele My Geno. My Pheno IA=A Blood Type IB=B 9
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
IA=A
IB=B
i=O
Blood Type
A & B Codom.
O=Recessive 9
9q34 ii o i i

20. Rr Rh+ 9q30 Locus Allele My Geno. My Pheno 9 Rh Factor
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno 9
Rh Factor
Normal Dominance
9q30
R = +Rh
r = - Rh Rr
Rh+ R r

21. ff 12p5 Locus Allele My Geno. My Pheno Freckles Normal Dominance
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
Freckles
Normal Dominance
12p5
F = Freckles
f= no freckles 12 ff
No Freckles f f

22. cc 12q24 Locus Allele My Geno. My Pheno Hair Type Incomplete Dominance
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
Hair Type
Incomplete Dominance
12q24
CC= Curly
cc = Straight
Cc=Wavy 12 cc
Straight C C

23. No TS TT 15q23 Locus Allele My Geno. My Pheno Tay-Sachs T = No TS 15
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno
Tay-Sachs
Autosomal recessive
15q23
T = No TS
t = TS
No TS 15 TT T T

24. Dd 16p10 Locus Allele My Geno. My Pheno 16 Dimples Normal Dominance
Chrom #
Gene
Description
Locus
Allele My
Geno.
My Pheno 16
Dimples
Normal Dominance
16p10 Dd
D=Dimples
d = No Dimples
Dimples D d

25. XBY XAY Locus Allele My Geno. My Pheno 23 Color Blind Hemophilia Chrom#
Gene
Description
Locus
Allele My
Geno.
My Pheno
XBY
XAY
B= Not Colorblind
b = Colorblind 23
Color Blind
Hemophilia
A= No Hemophilia
a = Hemophilia B A