AP Bio Unit 7

What is a dominant allele?

Allele that produces the phenotype when 1 or 2 copies are in the genotype

What is a recessive allele?

2 copies of the allele are needed to produce the phenotype

What is true breeding?

When parents reproduce, offspring will have the same phenotype as parents

What is locus/loci

Physical location where gene occurs on chromosome

What is the law of segregation?

During gamete formation, the 2 alleles for a gene separate from each other so that each gamete carries only one allele for each gene

What is the law of independent assortment?

The inheritance of one trait is not influenced by the inheritance of another trait; occurs in metaphase I and metaphase II

What are multiple alleles?

Multiple alleles can exist that encode for same/similar phenotypes; bunny fur example/ABO blood type example

What is incomplete dominance?

Heterozygous shows an intermediate, blended phenotype; red flower and white flower might produce a pink flower

What is codominance?

Both alleles are fully expressed; red flower and white flower might produce red flower with white patches

What is polygenic inheritance?

Phenotype determined by 2 or more genes; height is determined by multiple genes and it is usually shown by a bell curve

What are autosomal chromosome?

Chromosomes that determine most of an organism's traits, excluding X & Y chromosome; 22 autosomal chromosomes and 1 sex determining chromosome

How is sex determined in humans?

Offspring always inherit an X chromosome from their mother and the father might contribute either his X or Y chromosome which determines the sex of the offspring

What are the male and female chromosomes?

XY = male, XX = female

What is the SRY gene?

The “male” chromosome that encodes for productions of male hormones

What are autosomal linked traits?

Autosomal linked traits occur on the autosomal chromosomes

What are sex linked traits?

Sex linked traits occur on X or Y chromosome

What is a carrier?

A person that carries the gene for an autosomal/sex linked disease but does not express the gene

What is linkage?

2 genes are found close together on the same chromosome; genes will travel together during cross over

What is a parental genotype?

Genotypes that result in the same phenotype of parents; offspring look the same as parents

What is a recombinant genotype?

Genotypes that result in different phenotypes of parents; offspring look different from parents

How do you find frequency of recombinants?

(total # of recombinants) / (total # of offspring); if value is close to 1, genes are less likely to cross over (linked)

How do you find genetic distance?

Turn the frequency of recombinants into a percent and that value is equal to genetic distance (centimorgan, cM)

What is polyploidy?

An organisms has more than 2 complete sets of chromosomes; common in plants, but not animals (Triploid [3n] = 3 sets of chromosomes, Tetraploid [4n] = 4 sets of chromosomes)

What is non-disjunction?

When homologous chromosomes (during anaphase I) or sister chromatids (during anaphase II) do not separate normally during meiosis

What is the result of non-disjunction?

Results in daughter cell receiving 2 of the same type of chromosome and another daughter cell receives no copy

What is euploidy?

The correct number of chromosomes for an organism

What is aneuploidy?

An abnormal number of chromosomes for an organism

What is a monosomic zygote?

Has only 1 copy of a particular chromosome

What is a trisomic zygote?

Has 3 copies of a particular chromosome

What is Pre-implantation Genetic Screening?

In IVF (eggs are fertilized in a lab), removing a cell from the embryo to test for aneuploidy before implantation in mother (early testing)

What is Amniocentesis testing?

Sample of amniotic fluid from uterus that has some of the baby’s cells (late testing)

What is Chronic villi sampling?

Sample of placenta that has baby’s cells

What are the 5 requirements for Hardy Weinberg Equilibrium (non-evolving population)?

No migration (no gene flow in or out), No mutations (no genetic change), Random mating (no sexual selection), No natural selection (everyone is equally fit), Large population (no genetic drift)

What is heterozygote advantage?

Individuals heterozygous for a certain gene have a survival or reproductive advantage over individuals who are homozygous for either of the two alleles