Inheritance Flashcards
(23 cards)
What are genes?
Genes are short sequences of DNA that code for the production of certain proteins.
What is a trait?
A trait or characteristic is a feature of an organism, like eye colour or number of fingers.
What are alleles?
The different versions of a gene are called ALLELES
For example, there are 3 different alleles for eye colour (brown, green and blue)
What does it mean for an individual to be homozygous?
Having two copies of the same allele.
What does it mean for an individual to be heterozygous?
Having two copies of different alleles.
What is a ‘genotype’?
The alleles that an individual has in their chromosomes.
What is a ‘phenotype’?
The actual characteristics that the individual ends up with.
What is a dominant allele?
An allele that expresses its trait even if only one copy is present.
What is a recessive allele?
An allele that expresses its trait only if both copies are present.
Fill in the blank: A pea plant whose ________ is tall, could have the genotype TT or Tt.
phenotype
Fill in the blank: A tall pea plant with genotype TT is ________ dominant.
homozygous
Fill in the blank: A tall pea plant with genotype Tt is ________ dominant.
heterozygous
Fill in the blank: A dwarf pea plant with genotype tt is ________ recessive.
homozygous
Let B=black b=red
Write down the possible genotypes of a dog’s colour.
Black dogs: Bb BBbB
Red dogs: bb
A homozygous (pure breeding) black dog mates with a red dog.
Which alleles are found in the gametes of:
a. The black dog
b. The red dog
a. The black dog: BB
b. The red dog: bb
A homozygous (pure breeding) black dog mates with a red dog.
What will be the genotype (s) of the puppies?
Bb
A homozygous (pure breeding) black dog mates with a red dog.
What will be the phenotype (s) of the puppies?
Black
A dog with black fur (BB) is crossed with a dog with red fur (bb). What are the possible genotypes and phenotypes of their puppies?
Punnett Square:
B B b Bb Bb b Bb Bb
Genotype Ratio:
Bb: 100%
Phenotype:
All puppies will have black fur because black (B) is dominant.
If curly hair is recessive (s) and straight hair is dominant (S), what would be the expected genotype and phenotype ratios for a heterozygous straight-haired father (Ss) and a homozygous curly-haired mother (ss)?
S s s Ss ss s Ss ss
Genotype Ratio:
Ss: 50% ss: 50%
Phenotype Ratio:
Straight hair: 50% Curly hair: 50%
Explain how dominant and recessive alleles affect inherited traits.
A dominant allele only needs one copy to express a trait, while a recessive allele requires two copies. For example, the brown eye allele (B) is dominant, so a person with Bb or BB will have brown eyes. However, blue eyes (b) require the genotype “bb.”
What is a Punnett square, and how is it used?
A Punnett square is a diagram used to predict the probability of offspring inheriting specific traits based on the parents’ genotypes.
What is the difference between genotype and phenotype?
Genotype refers to the genetic makeup of an individual (e.g., Bb, BB, bb), while phenotype refers to the physical expression of that genotype (e.g., brown eyes or blue eyes).
How do organisms get traits?
Through inheritances due to your genes or through the environment
