3. GENOTYPE VS PHENOTYPE Flashcards
1
Q
- Do an organism’s traits always reveal its genetic composition?
Why?
A
- no
- this is because of the different effects that the
dominant and the recessive alleles have
EXAMPLE:
- Pp and PP have the same phenotype
(the purple flowers)
- Pp and PP have different genotypes
2
Q
- In which two forms can the genotype of a dominant phenotype show itself in an individual?
A
- the individual must have one dominant allele
- this can occur in a homozygous manner (PP)
- it can also occur in a heterozygous manner (Pp)
3
Q
- What method can we use to determine the genotype of a dominant phenotype that shows itself in an individual?
A
- we carry out a Test cross
4
Q
- What is a Test Cross?
A
- this is when we breed an unknown genotype individual with a homozygous recessive individual
5
Q
- We conduct a test cross, and the offspring display recessive phenotypes.
What does this mean with regards to the genotype?
A
- the genotype of the unknown parent must be
heterozygous
6
Q
- What did Mendel base his First Law
(the Law of Segregation) on?
A
- he based it on the inheritance pattern of 1 character
7
Q
- What can be said about the F1 offspring that were produced in the cross conducted on the Parental Generation?
A
- they were monohybrids
- they are heterozygous for 1 character
8
Q
- What is a Monohybrid cross?
A
- this is a cross between heterozygotes for 1 character
- these heterozygotes are called Monohybrids
9
Q
- How did Mendel identify his Second Law of
Inheritance (the Law of Independent Assortment)?
A
- Mendel observed the inheritance pattern of 2
characters at the same time - EG: seed colour (yellow or green)
- EG: seed shape (round or wrinkled)
10
Q
- Which kind of cross did Mendel use to develop the Law of Independent Assortment?
A
- Dihybrid Cross
11
Q
- Provide a definition for the Law of Independent Assortment?
A
MENDEL’S LAW OF INDEPENDENT ASSORTMENT STATES:
- that the alleles of two (or more) different genes are
sorted into gametes
- they are sorted independently of one another
WHAT THIS MEANS IS THAT:
- the allele a gamete receives for one gene does not
influence the allele the gamete receives for another
gene
12
Q
- What is a Dihybrid cross?
A
- this is the cross between F1 hybrids
- it determines whether 2 characters are transmitted to
offspring together as a package - OR whether the 2 characters are transmitted to the
offspring independently
13
Q
- What happens if 2 genes are located on the same
chromosome?
A
- the genes will most likely be inherited together
- this means that the Law of Independent Assortment
does not apply
14
Q
- What happens if 2 genes are located on different chromosomes?
A
- the genes will be inherited independently
- this means that the Law of Independent Assortment
does apply
15
Q
- What does the Law of Independent Assortment highlight with regards to Gamete Formation?
A
- each pair of alleles will segregate independently of
each other pair of alleles - this happens during gamete formation
16
Q
- What does the Law of Independent Assortment apply to?
A
- the law only applies to genes on non-homologous
chromosomes - these chromosomes are different from one another
- this law does not apply to genes on the same
chromosome
17
Q
- What happens to genes that are located near each other on the same chromosome?
A
- these genes tend to be inherited together
- this is the dependent assortment of linked genes
18
Q
- What laws govern Mendel’s Laws of Segregation and Independent Assortment?
A
- the laws of probability
- these laws have to do with multiplication and addition
19
Q
- Provide an example for Independent Events?
A
WHEN TOSSING A COIN:
- the outcome of one toss has no impact on the
outcome of the next toss
20
Q
- How do the laws of probability relate to alleles?
A
- alleles of one gene segregate into gametes
independently of another gene’s alleles
21
Q
- List the 3 situations in which a single gene may deviate from simple Mendelian patterns.
A
- When alleles are not completely dominant or
recessive - When a gene has more than 2 alleles
- When a gene produces multiple phenotypes
