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Background Information
Genetics is the study of heredity, the passing on of traits from parents to
children. Your biological traits are controlled by genes. A gene is a part of the
chromosome that produces a specific trait in an individual. In some cases a
particular gene from one parent is dominant and will become one of your more
obvious features, while the same gene from the other parent is recessive and
may not show up at all. You are like a ball of clay consisting of many colors in a
mixture. You have over 100,000 genes that make you who you are. We have a
different number of chromosomes than other organisms.
How many in each body cell? How many in each gamete cell?
The chromosomes are made of DNA, deoxyribonucleic acid. It is a very special
chemical that can reproduce itself. The nucleus of every cell contains this coded
genetic information. The coded information determines hair color, height and
over 100,000 things about you using only four symbols, ( A,T,C,G) These are
nucleic acids or chemicals that construct genes. They are: adenine (A), guanine
(G), thymine (T), and cytosine (C). Each chromosome contains a long sequence
of these four nucleic acids, represented by letters. Three letters in a row on a
DNA strand form a codon, a code for a different chemical. The chemicals formed
by the codons then link together to form a gene or trait, such as blond hair. The
DNA molecule has a very special shape, which was discovered by scientists
James Watson and Francis Crick. DNA is often described as a double helix and
closely resembles a twisted ladder with nucleic acids forming the rungs, or steps,
of the ladder.
Complete the following on this paper:
CTC ACA AAG ATG AAT AGA ATC ACG TTG CTC GCT CGG TTG AGA CAG TTG
ACC CCA ATC
1. From the strand of nucleic acids above decipher the coded DNA message.
2. Draw a vertical line after every third letter. This should divide your letters
into 19 groups of three letters.
3. Translate each three-letter code using the following code:
Codon
AAA
AAC
AAG
AAT
ACA
ACC
ACG
ACT
AGA
AGC
AGG
AGT
ATA
ATC
ATG
ATT
English
a
b
c
d
e
f
g
h
i
j
k
l
m
n
O
P
Codon
CAA
CAC
CAG
CAT
CCA
CCC
CCG
CCT
CGA
CGC
CGG
CGT
CTA
CTC
CTG
CTT
English
q
r
s
t
u
v
w
X
Y
z
A
B
C
D
E
F
Codon
GAA
GAC
GAG
GAT
GCA
GCC
GCG
GCT
GGA
GGC
GGG
GGT
GTA
GTC
GTG
GTT
English
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
Codon
TAA
TAC
TAG
TAT
TCA
TCC
TCG
TCT
TGA
TGC
TGG
TGT
TTA
TTC
TT
TTT
English
W
X
Y
Z
1
2
3
4
5
6
7
8
9
0
Space
Period
4. What does the message say? Write your response in the space below.
5. Define your understanding of the following terms.
a) Traitb) Genec) DNAd) Codone) Dominant genef) Recessive geneg) Genetics –
h) Heredity –
i) Double Helix -