DNA basics
What does DNA stand for?
Deoxyribonucleic Acid
Who is known as the “Father of Genetics”?
Gregor Mendel
What is a genotype?
The genetic combination of an organism.
What is a monohybrid cross?
A genetic cross involving one trait.
What is a dihybrid cross?
A genetic cross involving two traits.
Which base pairs with adenine?
Thymine
What organism did Mendel study?
Pea plants
What is a phenotype?
The physical appearance of an organism.
Cross:
Tt × tt
What percentage of offspring will be short?
50%
How many gametes can YyRr produce?
4
(YR, Yr, yR, yr)
Name all 4 nitrogenous bases.
Adenine, Thymne, Cytosine, Guanine
State Mendel’s Law of Segregation.
Alleles separate during gamete formation, so offspring receive one allele from each parent.
What does homozygous mean?
Having two identical alleles.
Cross:
Bb × Bb
What is the phenotype ratio?
3:1
What is the common phenotype ratio for a dihybrid cross?
9 : 3 : 3 : 1
Which base pairs with Cytosine?
Guanine
Define independent assortment.
Different traits are inherited independently from one another.
What does heterozygous mean?
Having two different alleles.
In cats, long fur (f) is recessive.Cross:
Ff × ff
What percentage will have long fur?
50%
BbFf × bbff
What percentage will have white fur and straight ears?
25%
Explain one role of DNA in Inheritence.
DNA carries genetic information passed from parents to offspring.
Why were pea plants useful for genetics studies?
They reproduce quickly, have clear traits, and can self-pollinate or cross-pollinate.
What is a carrier in genetics?
A heterozygous organism carrying a recessive allele.
A homozygous dominant plant (PP) is crossed with a homozygous recessive plant (pp).
Describe the offspring.
All offspring will be heterozygous (Pp) and show the dominant trait.
Why do dihybrid crosses produce more variation than monohybrid crosses?
Because two traits assort independently, creating more allele combinations.