genetics

what is genetics

The study of how traits are passed from parents to offspring.

Who is known as the Father of Genetics?

Gregor Mendel.

What organism did Mendel use in his experiments?

Pea plants.

What happened in Mendel's F1 generation?

All offspring showed the dominant trait.

What happened in Mendel's F2 generation?

The recessive trait reappeared.

What phenotypic ratio did Mendel observe in the F2 generation?

3:1

What is the parental generation called?

P generation

What is the first offspring generation called?

F1 generation

What is the second offspring generation called?

F2 generation

What is a gene?

A segment of DNA that codes for a trait

What is an allele?

A different form of a gene.

What is a locus?

The location of a gene on a chromosome.

What are homologous chromosomes?

Chromosomes from different parents that carry the same genes.

What does homozygous mean?

Having two identical alleles.

What does heterozygous mean?

Having two different alleles.

What is a dominant allele?

An allele that masks another allele.

What is a recessive allele?

An allele expressed only when no dominant allele is present.

What is genotype?

An organism's genetic makeup.

What is phenotype?

An organism's physical traits.

What is the Law of Segregation?

Alleles separate during gamete formation.

What is the Law of Independent Assortment?

Genes on different chromosomes are inherited independently.

What is a testcross?

A cross used to determine an unknown genotype.

What is a dihybrid cross?

A cross involving two traits.

What phenotypic ratio is expected in a dihybrid cross?

9:3:3:1.

How are Mendel's laws explained?

By meiosis.

What causes the Law of Segregation?

Separation of homologous chromosomes during meiosis.

What causes the Law of Independent Assortment?

Random chromosome separation during meiosis.

What are linked genes?

Genes located on the same chromosome.

Can linked genes be separated?

Yes, by crossing over.

What is incomplete dominance?

Heterozygotes show an intermediate trait.

What phenotypic ratio is seen in incomplete dominance?

1:2:1

What is codominance?

Both alleles are expressed.

What is a common example of codominance?

ABO blood types.

How many alleles control ABO blood type?

Three (IA, IB, i).

What is pleiotropy?

One gene affects multiple traits.

What is epistasis?

One gene affects the expression of another gene.

What are polygenic traits?

Traits controlled by multiple genes.

Why do polygenic traits show continuous variation?

Because many genes contribute to the trait.

Can the environment affect phenotype?

Yes

Can genetic diseases be inherited?

Yes

What are the three main inheritance patterns?

Autosomal dominant, autosomal recessive, and X-linked recessive.

What is autosomal dominant inheritance?

One dominant allele causes the trait.

Can a heterozygous individual show an autosomal dominant trait?

Yes

Does an affected person usually have an affected parent?

Yes

What is autosomal recessive inheritance?

A trait appears only with two recessive alleles.

What is a carrier?

A heterozygous individual who carries a recessive allele.

Can two unaffected parents have an affected child?

Yes, if both are carriers

What chromosomes do human females have?

XX

What chromosomes do human males have?

XY

Which parent determines the sex of a child?

The father

What chromosome does every mother contribute?

X

What chromosome can the father contribute?

X

Which chromosome carries more genes, X or Y?

X

What gene determines maleness?

SRY gene

Where is the SRY gene found?

On the Y chromosome

Who is more likely to show X-linked recessive disorders?

Males

Why are males more affected by X-linked recessive disorders?

They have only one X chromosome

Can a son inherit an X-linked disorder from his father?

No

Why can't a son inherit an X-linked disorder from his father?

Sons receive a Y chromosome from their father.

What is a karyotype?

A picture of an individual's chromosomes.

What is a karyotype used for?

Detecting chromosome abnormalities.

What are common chromosome alterations?

Deletions, inversions, translocations, and duplications.

What is a pedigree?

A family chart used to track inheritance.

What can a pedigree determine?

Inheritance patterns and disease risk.