Download What Is Life? A Guide To Biology Second Edition Genes and Inheritance

Jay Phelan
What Is Life? A Guide To Biology
Second Edition
CHAPTER 7
Genes and Inheritance
© 2012 W. H. Freeman and Company
Mendel figured out the rules of genetics by working with
pea plants. Why were these plants a good tool for Mendel
to use to answer his questions about inheritance?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
ab
o.
..
e.
..
17
Al
l
of
t
he
de
fin
ly
ew
gr
Th
ey
In
di
vid
ua
lp
la.
qu
ic .
..
..
4.
25% 25% 25% 25%
ar
2.
3.
Individual plants could be self-fertilized or
cross-fertilized with other individuals.
They grew quickly (short generation time).
Clearly defined traits (yellow vs. green) were
observed.
All of the above.
Cl
e
1.
18
19
20
Three Ideas Mendel Used for
Explaining This Pattern of
Inheritance
1)
Each parent puts into every sperm or egg it makes a
single set of instructions for building the trait.
Three Ideas Mendel
Used for Explaining
This Pattern of
Inheritance
2)
Offspring thus find themselves with two copies of
the instructions for any trait (called alleles).
Three Ideas Mendel
Used for Explaining
This Pattern of
Inheritance
3)
The actual trait produced by an individual depends
on the two copies of the gene that they inherit
from their parents.
•
homozygous and heterozygous
Which example is the genotype of a truebreeding plant?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
16
he
of
t
co
p
Al
l
On
e
15
ab
o.
..
nd
yo
ft
2
20% 20% 20%
h.
..
so
f.
..
ie
co
p
o
Tw
Tw
o
co
p
ie
so
f.
..
20% 20%
1a
1. Two copies of the purple allele
2. Two copies of the white allele
3. One copy of the purple and one
copy of the white allele.
4. 1 and 2
5. All of the above
17
18
19
20
If an albino woman marries a man that is
heterozygous for albinism, what is the
probability that they will have an albino child?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
20%
17
20%
10
0%
20%
75
%
20%
25
%
20%
50
%
0%
25%
50%
75%
100%
0%
1.
2.
3.
4.
5.
18
19
20
If you are unable to roll your tongue,
what is your genotype?
25%
Rr
25%
25%
1o
r2
25%
rr
RR
Rr
rr
1 or 2
RR
1.
2.
3.
4.
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
17
18
19
20
If you have free earlobes, what is your
genotype?
25%
25%
25%
1o
r2
Ee
ee
EE
Ee
ee
1 or 2
EE
1.
2.
3.
4.
25%
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
17
18
19
20
You mate a pigmented male alligator to a female
albino alligator. The clutch of baby alligators
includes both pigmented and albino individuals.
What is the genotype of the father?
25%
25%
...
m
eq
1
an
d
2
ar
e
M
M
25%
m
25%
m
MM
Mm
mm
1 and 2 are equally
possible.
M
1.
2.
3.
4.
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
17
18
19
20
What is the genotype of the paternal
grandmother?
1.
Homozygous
recessive
Heterozygous
Homozygous
dominant
Cannot be
determined
2.
3.
4.
..
te
.
...
Ca
n
no
t
be
de
sd
om
oz
yg
ou
Ho
m
Ho
m
He
te
r
oz
yg
ou
sr
ec
..
oz
yg
ou
s
.
25% 25% 25% 25%
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
17
18
19
20
The gene for aldehyde dehydrogenase (ADH) is incompletely
dominant. A woman who is heterozygous for this gene (ADH+/ADH)
marries a man who is homozygous for the normal allele (ADH+/
ADH+). What is the probability that they will have heterozygous
children?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
25%
17
18
25%
25%
2/
3
1/
4
25%
3/
4
1/4
1/2
3/4
2/3
1/
2
1.
2.
3.
4.
19
20
• The sickle-cell allele is particularly common
among people of African descent
– It increases resistance against malaria
Close match between
distribution of sickle-cell
allele and malaria
If a male is colorblind, from whom did he inherit the condition?
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
er
25%
Au
nt
25%
fa
th
Fa
th
e
M
1
25%
r
25%
Gr
an
d
Mother
Father
Grandfather
Aunt
ot
he
r
1.
2.
3.
4.
17
18
19
20
In which example below will there
be a chance of a daughter being
colorblind?
25% 25% 25% 25%
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
. ..
an
d
s..
.
ha
Ch
oi
ce
s2
ho
A
A
A
m
m
al
al
ew
ew
ho
ho
ha
is
s..
.
.. .
4.
ew
3.
al
2.
A male who is colorblind marries a female who is a
carrier for colorblindness.
A male who has normal vision marries a female who is
a carrier for colorblindness.
A male who has normal vision marries a female who is
colorblind.
Choices 2 and 3 are correct.
m
1.
15
16
17
18
19
20
Color resembles snowy
background in winter
Some alleles are
heat-sensitive
Arctic foxes
make fur
pigment only
when the
Color resembles
weather is
tundra background
warm
in summer