pattern 2: autosomal dominant
again, autosomal traits affect males and females equally. an autosomal dominant
trait only requires 1 dominant allele for an individual to show the trait, so affected
individuals have a homozygous dominant or heterozygous genotype. unaffected
individuals will be homozygous recessive. expression of dimples, an autosomal dominant trait.
1. what is the genotype of individual ii - 1?
_________
2. write the genotypes of all the
unaffected individuals on the pedigree.
3. write the genotypes of individuals i - 1
and i - 2 on the pedigree.
4. write the genotype of individual ii - 4 on
the pedigree.
5. what are the two possible genotypes for individuals ii - 2 and ii - 3? ________
how could you be more sure of their genotypes?

pattern 3: sex - linked
sex - linked traits are usually carried on the x chromosome, so males will be affected more
frequently. females in a sex - linked pedigree can be affected (with 2 abnormal xs) or carriers
(with 1 abnormal x). carriers are shown with a half - filled circle.

1. write the genotype of individuals ii - 2, ii - 3 and iii - 1 on the pedigree. expression of red - green color blindness, a sex - linked trait.
2. make a punnett square to show the
offspring possibilities for individuals i - 1
and i - 2.

3. what is the only possible genotype for individual iii - 3? ________ how do you know? color her
circle correctly to show her genotype.

Question

pattern 2: autosomal dominant
again, autosomal traits affect males and females equally. an autosomal dominant
trait only requires 1 dominant allele for an individual to show the trait, so affected
individuals have a homozygous dominant or heterozygous genotype. unaffected
individuals will be homozygous recessive. 				expression of dimples, an autosomal dominant trait.
1. 	what is the genotype of individual ii - 1?
	_________
2. 	write the genotypes of all the
	unaffected individuals on the pedigree.
3. 	write the genotypes of individuals i - 1
	and i - 2 on the pedigree.
4. 	write the genotype of individual ii - 4 on
	the pedigree.
5. 	what are the two possible genotypes for individuals ii - 2 and ii - 3? ________
	how could you be more sure of their genotypes?

pattern 3: sex - linked
sex - linked traits are usually carried on the x chromosome, so males will be affected more
frequently. females in a sex - linked pedigree can be affected (with 2 abnormal xs) or carriers
(with 1 abnormal x). carriers are shown with a half - filled circle.

1. 	write the genotype of individuals ii - 2, ii - 3 and iii - 1 on the pedigree. 				expression of red - green color blindness, a sex - linked trait.
2. 	make a punnett square to show the
	offspring possibilities for individuals i - 1
	and i - 2.

3. 	what is the only possible genotype for individual iii - 3? ________ how do you know? color her
	circle correctly to show her genotype.

Accepted Answer

### Pattern 2: Autosomal Dominant (Question 1: Genotype of II - 1)
# Explanation:
## Step 1: Recall Autosomal Dominant Rules
In autosomal dominant inheritance, affected individuals have at least one dominant allele ($A$), so their genotypes are $AA$ (homozygous dominant) or $Aa$ (heterozygous). Unaffected individuals are homozygous recessive ($aa$).
## Step 2: Analyze Pedigree for II - 1
Individual II - 1 is unaffected (white circle). From the autosomal dominant rules, unaffected individuals must be homozygous recessive. So the genotype is $aa$.
# Answer:
$aa$

### Pattern 2: Autosomal Dominant (Question 2: Genotypes of Unaffected Individuals)
# Explanation:
## Step 1: Identify Unaffected Individuals
Looking at the pedigree, the white - colored shapes (circles for females, squares for males) are unaffected. These are II - 1 (white circle), the white square in the second generation (spouse of II - 4), and the white square in the third generation (offspring of II - 4 and her spouse).
## Step 2: Assign Genotypes
Using the autosomal dominant rule (unaffected = $aa$), all these unaffected individuals have the genotype $aa$.
# Answer:
II - 1: $aa$; the white square (spouse of II - 4): $aa$; the white square (offspring of II - 4 and her spouse): $aa$

### Pattern 2: Autosomal Dominant (Question 3: Genotypes of I - 1 and I - 2)
# Explanation:
## Step 1: Analyze I - 1 and I - 2 Phenotype
I - 1 (black circle) and I - 2 (black square) are affected (autosomal dominant trait). They have an unaffected offspring (II - 1, $aa$).
## Step 2: Determine Genotypes
For an affected individual to have an unaffected ($aa$) offspring, each parent must contribute a recessive allele ($a$). Since they are affected, they must also have a dominant allele ($A$). So their genotypes are $Aa$ (heterozygous), because if they were $AA$, they couldn't have an $aa$ offspring (as they would only pass on $A$).
# Answer:
I - 1: $Aa$; I - 2: $Aa$

### Pattern 2: Autosomal Dominant (Question 4: Genotype of II - 4)
# Explanation:
## Step 1: Analyze II - 4's Parents and Offspring
II - 4 is affected (black circle). Her parents (I - 1 and I - 2) are both $Aa$ (from question 3). She has an unaffected offspring (white square, $aa$).
## Step 2: Determine Genotype
To have an $aa$ offspring, II - 4 must pass on an $a$ allele. Since she is affected, she must have a dominant allele ($A$) as well. So her genotype is $Aa$.
# Answer:
$Aa$

### Pattern 2: Autosomal Dominant (Question 5: Possible Genotypes of II - 2 and II - 3)
# Explanation:
## Step 1: Analyze Parents' Genotypes
II - 2 and II - 3 are offspring of I - 1 ($Aa$) and I - 2 ($Aa$).
## Step 2: Use Punnett Square for $Aa\times Aa$
The Punnett square for $Aa\times Aa$ is:
$$
\begin{array}{|c|c|c|}
\hline
& A & a \
\hline
A & AA & Aa \
\hline
a & Aa & aa \
\hline
\end{array}
$$
Affected individuals (II - 2 and II - 3 are black squares, so affected) can have genotypes $AA$ or $Aa$ (since $aa$ is unaffected). To be more sure, we could look at their offspring. If they have an unaffected ($aa$) offspring, then their genotype must be $Aa$ (because $AA$ parents can't have $aa$ offspring).
# Answer:
Possible genotypes: $AA$ or $Aa$; To be more sure, examine their offspring. If they have an unaffected ($aa$) child, they must be $Aa$; if all their children are affected, they could be $AA$ (but in this pedigree, since their parents are $Aa$, $AA$ is less likely, but possible from the $Aa\times Aa$ cross).

### Pattern 3: Sex - linked (Question 1: Genotypes of II - 2, II - 3, III - 1)
# Explanation:
## Step 1: Recall Sex - linked (X - linked) Rules
For X - linked recessive (like color blindness), males have genotype $X^bY$ (affected) or $X^BY$ (unaffected). Females: $X^BX^B$ (unaffected), $X^BX^b$ (carrier), $X^bX^b$ (affected). Carriers are half - filled circles, affected females are fully filled circles, affected males are fully filled squares, unaffected males are white squares, unaffected females are white circles.
## Step 2: Analyze II - 2 (White Square, Male)
II - 2 is an unaffected male. So his genotype is $X^BY$ (since he has the dominant allele on the X - chromosome and $Y$ chromosome).
## Step 3: Analyze II - 3 (Fully Filled Circle, Female)
II - 3 is an affected female. For a female to be affected in X - linked recessive, she must have two recessive alleles ($X^bX^b$) (because she needs to inherit a recessive allele from both parents).
## Step 4: Analyze III - 1 (Fully Filled Square, Male)
III - 1 is an affected male. Males have one X and one Y. An affected male has the genotype $X^bY$ (he inherits the recessive allele on the X from his mother and $Y$ from his father).
# Answer:
II - 2: $X^BY$; II - 3: $X^bX^b$; III - 1: $X^bY$

### Pattern 3: Sex - linked (Question 2: Punnett Square for I - 1 and I - 2)
# Explanation:
## Step 1: Determine Genotypes of I - 1 and I - 2
I - 1 is a white circle (unaffected female), so her genotype is $X^BX^B$ or $X^BX^b$. But since she has a carrier daughter (II - 1, half - filled circle, $X^BX^b$) and an affected daughter (II - 3, $X^bX^b$) and an unaffected son (II - 2, $X^BY$), let's assume I - 1 is $X^BX^b$ (carrier? Wait, no, I - 1 is white circle, so unaffected. Wait, correction: I - 1 is white circle (unaffected female), so $X^BX^B$? But II - 3 is $X^bX^b$, so I - 2 (affected male, $X^bY$) must pass on $X^b$ to daughters. I - 1 (unaffected female) must pass on $X^b$ to II - 3, so I - 1's genotype is $X^BX^b$ (carrier, but the circle is white? Maybe the pedigree has a mistake, but following the logic: I - 1: $X^BX^b$, I - 2: $X^bY$.
## Step 2: Set Up Punnett Square
| | $X^B$ | $X^b$ |
| --- | --- | --- |
| $X^b$ | $X^BX^b$ (carrier female) | $X^bX^b$ (affected female) |
| $Y$ | $X^BY$ (unaffected male) | $X^bY$ (affected male) |
# Answer:
The Punnett square for I - 1 ($X^BX^b$) and I - 2 ($X^bY$) is as above, showing the possible offspring genotypes: $X^BX^b$, $X^bX^b$, $X^BY$, $X^bY$.

### Pattern 3: Sex - linked (Question 3: Genotype of III - 3)
# Explanation:
## Step 1: Analyze III - 3 (White Circle, Female)
III - 3 is an unaffected female. Her mother is II - 3 ($X^bX^b$) and her father is II - 4 (unaffected male, $X^BY$).
## Step 2: Determine Genotype
Her mother ($X^bX^b$) can only pass on $X^b$, and her father ($X^BY$) passes on $X^B$. So her genotype is $X^BX^b$ (carrier, but since she is unaffected, this is the only possible genotype as she gets a dominant allele from her father and recessive from her mother).
# Answer:
$X^BX^b$; We know because her mother (II - 3) is $X^bX^b$ (must pass $X^b$) and her father (II - 4) is $X^BY$ (must pass $X^B$), so she inherits $X^B$ from father and $X^b$ from mother, resulting in $X^BX^b$. To show her genotype, color her circle half - filled (since she is a carrier).

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QUESTION IMAGE

Question

Explanation:

Pattern 2: Autosomal Dominant (Question 1: Genotype of II - 1)

Step 1: Recall Autosomal Dominant Rules

Step 2: Analyze Pedigree for II - 1

Step 1: Identify Unaffected Individuals

Step 2: Assign Genotypes

Step 1: Analyze I - 1 and I - 2 Phenotype

Step 2: Determine Genotypes

Answer:

Pattern 2: Autosomal Dominant (Question 2: Genotypes of Unaffected Individuals)