APBIO Unit 5: Heredity

What is genetics the study of?

Heredity and hereditary variation.

Define heredity.

The transmission of traits from one generation to the next.

What are genes?

Segments of DNA that code for basic units of heredity.

Define asexual reproduction.

Reproduction involving a single individual with no fusion of gametes, resulting in clones.

What is the difference between somatic and gametic cells?

Somatic cells are diploid (2n) with two complete sets of chromosomes; gametic cells are haploid (n) with one set of chromosomes.

What is a karyotype?

A display of chromosome pairs ordered by size and length.

What is the role of meiosis in sexual reproduction?

It creates haploid gamete cells in sexually reproducing diploid organisms.

How does mitosis differ from meiosis?

Mitosis results in two genetically identical diploid daughter cells; meiosis results in four genetically unique haploid daughter cells.

What causes genetic variation during meiosis?

Crossing over, independent assortment of chromosomes, and random fertilization.

Who is Gregor Mendel?

An Austrian monk who studied inheritance and formulated the basic principles of heredity.

What is a Punnett square used for?

To predict the allele combinations of offspring from a genetic cross.

Define homozygous.

An organism that has a pair of identical alleles for a character.

What is a testcross used for?

To determine whether a dominant trait is homozygous dominant or heterozygous.

What does Mendel's law of segregation state?

The two alleles for the same trait separate during gamete formation.

Define dihybrid crosses.

A cross between F1 hybrids that examine the inheritance of two traits.

What is a pedigree?

A family tree that shows inheritance patterns of particular traits.

What is epistasis?

The phenotypic expression of a gene at one locus that affects a gene at another locus.

What are X-linked disorders?

Disorders linked to genes located on the X chromosome.

What is X-inactivation?

A process where one of the two X chromosomes in females becomes inactive.

What is linked genes according to genetic recombination?

Genes located near each other on the same chromosome that tend to be inherited together.

What does a linkage map show?

The relative distances between genes based on recombination frequencies.

How is mitochondrial DNA inherited?

Mitochondrial DNA is maternally inherited, as it is passed down from the egg only.

What is the chi-square test used for?

To compare observed results with expected results in a statistical analysis.

What does it mean if X² is greater than the critical value?

There is a statistically significant difference, and the null hypothesis is rejected.

What does phenotypic plasticity refer to?

The ability of the same genotype to exhibit different phenotypes in different environments.

What is Tay-Sachs disease?

An autosomal recessive genetic disorder caused by a mutation in the HEXA gene.

What is the result of nondisjunction during meiosis?

It can lead to chromosomal changes, such as Down syndrome.

Define polygenic inheritance.

The effect of two or more genes acting on a single phenotype.

What is the difference between dominant and recessive traits?

Dominant traits express their phenotype with one allele; recessive traits require two copies to express.

What is codominance?

A condition where both alleles in a heterozygote are fully expressed.

How are sex-linked genes inherited differently in males and females?

Fathers pass X-linked alleles to daughters only, while mothers can pass to both sons and daughters.

Define incomplete dominance.

A genetic situation where neither allele is fully dominant, resulting in a blended phenotype.

What is the role of environmental factors in genetics?

They can influence gene expression and lead to phenotypic changes.

What happens during crossing over in meiosis?

Homologous chromosomes exchange genetic material, producing recombinant chromosomes.

What are gametes?

Haploid cells (sperm and eggs) that are produced through meiosis.

What is the purpose of the Goodness of fit test?

To determine if observed experimental data fits the expected results.