GENE MAPPING
G
WHAT GENES ARE AND WHAT THEY DO
Genes are units of DNA (the material
that controls the body’s growth,
structure, and functions) contained in
every cell. They exert their effects by
directing the manufacture of proteins.
All of a person’s genes come from
his or her parents. The physical
differences between people, such as
in eye, hair, and skin colour, arise from
slight differences in gene structure.
DNA PRINTOUT
Through painstaking laboratory
research, the exact structure of
many genes is now known.
HI n
n
» XX
n ànnnnn
xx
n
xs
xx
xx xx
13
14
15
16
17
18
n
XX
X X
XX
5 U
19
20
21
22
XY
Chromosomes
Genes are contained in the chromosomes
within the nuclei of a person’s cells. Each
chromosome contains a long strand of DNA
(deoxyribonucleic acid).
TTC-GAG-CAT-
TCA-TGT —
CCT-
TGA-TTA—CCG-
TAT-GAC-ACG-
CGG-TCA-CGC-
GGG-GAC-TCG-
CAA-GCG-AGT-
CGA—CGC—AGC-
TAT—ACC—TAC-
TTG-TTA-TGT-
ATG-AGC-GGA-
CTG-GGG-ATG
TCA-TCG-TTT
ACC —
CCA-TCG
CAA-GTT-CCG
ACG-TCA-TGT
TAA-TCA-CGT
TTA-AAT-AGA
TTT-GAA-TTC
TAA-CTG-TTA
GAT-GGG-TTA
GTG-CAT-TAT
DNA base sequence
This printout shows a small part ofthe
sequence in the gene that codes for the
protein trypsin, a digestive enzyme.
S t r u c t u r a l p r o t e i n s
S o m e p r o t e i n s a r e
u s e d a s s t r u c t u r a l
c o m p o n e n t s o f
c e l l s , t i s s u e s , a n d
o r g a n s .
P r o t e i n m o l e c u l e
T h e i n f o r m a t i o n in a g e n e is
d e c o d e d t o m a k e a p r o t e i n
m o l e c u l e , w h ic h i s f o l d e d a n d
c o n s i s t s o f a s t r in g o f a m i n o a c i d s .
- E n z y m e s
O t h e r p r o t e i n s a r e
e n z y m e s , w h ic h
r e g u l a t e i m p o r t a n t
c h e m i c a l p r o c e s s e s
v it a l t o b o d i l y g r o w t h
a n d fu n c t i o n in g .
334
previous page 333 BMA A Z Family Medical Encyclopedia   2004 read online next page 335 BMA A Z Family Medical Encyclopedia   2004 read online Home Toggle text on/off