Loci and the Human Loci and the Human KaryotypeKaryotype

Honors BiologyUnit 52012-2013

ChromosomesChromosomesKaryotype:

◦ordered display of an individual’s chromosomes.

◦Collection of chromosomes from mitotic cells.

◦Staining can reveal visible band patterns, gross anomalies.

Meiosis KM 3

KaryotypingKaryotyping

Karyotypes arrange chromosomes in order by size: Largest to smallest

Chromosomes

Some large like #1

Some small like #22

Homologous pairsHomologous pairs

Same LengthCentromere

in same location

Same bands (genes)

Centromere PositionCentromere PositionThe 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

Locus (plural=loci)Locus (plural=loci)The position that a given gene occupies on a chromosome. (Its like an address for your genes)

Written like this: 15p23

Example: 15p23=Chrom 15 small Example: 15p23=Chrom 15 small arm, 23arm, 23rdrd band from the band from the centromerecentromere

Chrom

#Gene

DescriptionLocus Allele My

Geno.

My Pheno

2 Skin Color

Polygenic

2p18

2q21

S = Dark

s= Light

SSSS= Dark

SSSs= Fairly Dark

SSss= Olive

Ssss = Light Olive

ssss = Lightest White

SsssLt Olive

s

sS

s

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

AA=LotsAa=someaa= none

A=Acnea=No Acne

4p20Acne

PolygenicIncomplete Dominance

4 Aa Some Acne

A a

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

4 Cleft Chin

Regular Dominance

4p19 N = Cleft

n= no cleftnn No

Cleft

n n

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

Eye color

polygenetic

Incomplete Dominance

7 & (15)

7p15 B=Brownb=Blue

BB=Brown

Bb=Light Brown, Hazel, Green

bb=blue

Bb Light Brown

B b

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

Hair Color

Incomplete Dominance

7 7p11 H=Brown/Black

h=blonde

HH=Brown/Black

Hh=Light Brown

hh=Blonde

Hh Light Brown

H h

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

7 Cystic Fibrosis

Autosomal recessive

7q25 F = No CF

f = CFFF No

CF

F F

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

7 Acne

PolygenicIncomplete Dominance

7q11 A= Acne

a = no AcneAa Some

acne

A a

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

9 Blood Type

A & B Codom.

O=Recessive

9q34IA=A

IB=B

i=O

ii o

i i

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

9 Rh Factor

Normal Dominance

9q30 R = +Rh

r = - Rh Rr Rh+

R r

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

12 Freckles

Normal Dominance

12p5 F = Freckles

f= no freckles ff No

Freckles

f f

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

12 Hair Type

Incomplete Dominance

12q24 CC= Curly

cc = Straight

Cc=Wavy

cc Straight

C C

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

15 Tay-Sachs

Autosomal recessive

15q23 T = No TS

t = TSTT No

TS

T T

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

16 Dimples

Normal Dominance

16p10D=Dimples

d = No Dimples

Dd Dimples

D d

Chrom

#

Gene

DescriptionLocus Allele My

Geno.

My Pheno

23 Color Blind

Hemophilia

B= Not Colorblind

b = Colorblind

B

A

A= No Hemophilia

a = Hemophilia

XBY

XAY