Genetics Biology

Incomplete Dominance definition:

Heterozygous phenotype is a blend of the two homozygous phenotypes.

Codominance definition:

Both alleles are fully expressed in the heterozygous phenotype.

sex linked traits definition:

Traits controlled by sex genes on the X or Y chromosome. can skip generations

where are X-linked recessive found?

More common in males (e.g., colorblindness, hemophilia).

where are X-linked dominant found?

Rare; affects males and females equally.

Where are  Y-linked found?

Only passed from father to son.

Dominant vs recessive traits:

Dominant traits mask recessive traits whereas recessive traits only appear if no dominant allele is present.

Pedigree symbols: what do squares and circles represent:

squares represent males, circles represent females

Pedigree symbols: what does shaded vs unshaded represent?

 Shaded represent affected, unshaded represent unaffected.

Pedigree symbols: what does half shaded represent?

Half-shaded represents carrier (for recessive traits).

what is Autosomal Dominant pattern?

Affected individuals in every generation; males and females equally affected.

What is Autosomal Recessive pattern?

Can skip generations; often appears when both parents are carriers.

What is X-linked Recessive pattern?

More males affected; often skips generations (e.g., carrier mothers pass to sons).

How many traits does monohybrid cross have?

1 trait (2×2 punnett square)

how many traits does Dihybrid cross have?

2 traits (4×4 punnett square)

Difference between phenotype and genotype"?

genotype is the set of genes that it carries whereas a phenotype is all of its observable characteristics

chromosomes of Klinefelter’s Syndrome

XXY, extra X chromosome in males

affects of Klinefelter’s Syndrome

Infertility, taller stature, learning disabilities.                              

Turners syndrome chromosomes?

X (missing X chromosome in females)

Turners syndrome affect?

Short stature, infertility, webbed neck.                                       

Chromosomes of Trisomy 21?

Extra chromosome 21

Effects of trisomy 21?

Down syndrome; intellectual disability, distinct facial features.             

sickle cell disease gene mutation?

Mutation in hemoglobin gene (HbS)

sickle cell disease affects

Abnormal hemoglobin; sickle-shaped red blood cells; resistance to malaria.

Mendels law of segregation definition?

Alleles for a gene separate during gamete formation, so each gamete carries only one allele.

Definition of Mendels law of Independent Assortment

Alleles for different genes are distributed independently of one another (if they are on different chromosomes).

what is a gamete?

Sex cells (sperm or egg) that carry one allele for each gene.

what gametes can a offspring with genotype AaBB produce?

AB, aB, AB, aB

allele vs gene definition?

A gene is a segment of DNA that determines a specific physical trait (like eye color). An allele is a variation of that gene (ex blue eyes)