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75 Cards in this Set

  • Front
  • Back
The study of genes, how they work together to produce the variation we observe and how genes are transmitted from one generation to another.
Manipulation of human reproduction to create people with desirable traits.
Fundamental unit of inheritance; something within an organism that influences its appearance and passed onto progeny
An organism's genetic composition or makeup
What an organism looks like, function of both genotype and environment
Alternative forms of a gene
Dominant Allele
An allele that exhibits its phenotype in heterozygotes
Recessive Allele
Phenotype that is only observed in the homozygote
Dihybrid Cross
Cross between 2 heterozygotes at a particular loci. 9:3:3:1 ratio
How to tell if Recombinant
1. Determine expected based on the null hypothesis
2. Set up a table listing each with observed & expected values.
3. Determine degrees of freedom.
4. Use p table to determine if observed & expected values are due to chance.
Parental combination of alleles is found more frequently in gametes than the recombinant configuration.
Parental type
Configuration of alleles that were inherited from each parent.
Recombinant type
Alternative configuration.
2 Ways For Independent Assortment
1. Genes are on different chromosomes
2. Genes are so far apart on the same chromosome that there is a crossover between them in every meiosis.
A crossover in one interval on a chromosome decreases the probability of a crossover in an adjacent interval.
*Interference plays an important role in distributing crossovers throughout the genome so that every chromosome gets at least one.
Incomplete or Partial Dominance
The phenotype of the heterozygote is intermediate between homozygote.
Both alleles contribute equally to the phenotype of the heterozygote
The proportion of individuals of a given genotype that display the phenotype associated with that genotype
Maternal Imprinting
Gene is inactivated during oogenesis
i.e. Angelman Syndrome
Genomic imprinting
The expression pattern of a gene depends upon the parent from whom it was inherited
When the genotype at one locus masks the phenotype of a second locus
Gene Pool
The sum of all the total alleles in the breeding members of a population at a given time
Genotype Frequency
Proportion of individuals in a population that carry a particular genotype
Allele Frequency
Proportion of gene topics in a population that are given alleles
Chromatids condense
Sister chromatids align with kinetochore pointing to opposite poles of spindle
Cohesin destroyed, sisters pulled to opposite poles.
Multi-subunit ring structures that bind to DNA and hold sister chromatids together after replication.
A specialized cell division that reduces the chromosome number in half to produce gametes for sexual reproduction.
A meiosis specific subunit whose cleavage is regulated.
Meiotic prophase
Sister chromatids form a synaptonemal complex.
Chromosome architecture during meiotic prophase
Leptotene, Zygotene, Pachytene, Diplotene
Synapsed pair of replicated homologous chromosomes
Condensed pair of sister chromatids
Meiotic Anaphase I vs Meiotic Anaphase II
Anaphase I is when the arm cohesion is released, but Anaphase II is when the centromere cohesion is removed. These two events allow sister chromatids to segregate.
Chromosome architecture during meiotic prophase
Leptotene, Zygotene, Pachytene, Diplotene
Chromosomes that are the same in both sexes
Sex Chromosomes
Chromosome pair that differ between sexes
Gametes are the same with regard to a particular chromosome
Gametes are different with regard to a particular chromosome
Sex linkage
Different patterns of inheritance are observed in reciprocal crosses due to genes present in the sex chromosomes
SRY gene
Gene located on the Y chromosome which is sufficient to make a male
Pseudoautosomal Region (PAR)
Region of homology shared by mammalian X and Y chromosomes where cross overs occur during meiosis.
The failure of homologous chromosomes to separate normally during nuclear division.
Autosomal Dominant Characteristics

ex) Huntington's Chorea
1. Should occur in men & women with equal frequency
2. Should appear in every generation
3. 50% of affected offspring's children should be affected.
Autosomal Recessive Characteristics
1. Should occur in men and women with equal frequency
2. The appearance of the trait often skips a generation
3. An affected child can be born to unaffected parents
Pedigree Analysis
Study of human crosses
X Linked Dominant
1. Occurs in men and women
2. May appear in every generation
3. NEVER see father to son inheritance
4. All daughters of an affected man will be affected.
X Linked Recessive

ex) Hemophilia
*1. Shows up preferentially in males but women can be affected too
2. NEVER see father to son inheritance
3. Affected daughters should have affected fathers.
The breeding of related individuals within an isolated group
An individual who is heterozygous for a recessive mutation and doesn't exhibit phenotype but can transmit mutant allele to offspring.
Rare Trait Assumptions
1. People marrying into the family are assumed to be homozygous dominant for pedigrees that exhibit recessive inheritance.
2. Affected people are assumed to be heterozygous for dominant traits.
Sex Influenced Traits

ex) Pattern Balding
Are encoded by autosomal genes but the traits appear preferentially in one sex or another, because of the different hormonal environment provided by that sex.
Quantitative Traits
Follow a continuous distribution (in contrast with discrete traits)
Polygenic Traits
Affected by variation at many loci
Affected by environment as well as genetic variation
Quantitative Inheritance
Alleles make additive contributions to phenotype
Heritability Estimates
-Are properties of populations, not individuals.
-Depend on levels of environmental and genetic variation for the specific population under study
Complex Traits

ex) schizophrenia, heart disease.
-Often less quantifiable than metric traits, or not fully penetrant
-Often heterogenous (similar phenotypes with different causes)
Parental combination of alleles is found more frequently in gametes than the recombinant configuration
Parental Type
Configuration of alleles that were inherited from each parent
Recombinant Type
Alternative configuration
2 Ways for Independent Assortment
1. Genes are on different chromosomes
2. Genes are far apart on same chromosome
Cells that are able to grow at minimal medium because they can synthesize their own nutrients
Cells that require the addition of a specific nutrient to the medium to grow
If crossing over occurs BEFORE chromosome duplication...
Only 2 types of tetrads
If crossing over occurs AFTER chromosome duplication...
4 types of tetrads
Tetrads without recombination
Tetrads with 1 recombination
Tetrad containing 4 genotypes; 2 parental and 2 recombinant.
For linked genes, a single crossover produces a ___ tetrad. A 4 strand double crossover leads to an ____.
1) Tetratype
2) NPD
What are yellow twin spots on fruit flies?
Mitotic recombination - which happens to repair the cell when DNA damage occurs.
When patches of cells are homozygous for mutation in a heterozygous organism
Loss of Heterozygosity
If mutant allele becomes homozygous for a tumor suppressor gene.

ex) If people are heterozygous for Rb, they are predisposed to tumors.
What are some examples of aneuploidy?
Nullosomy, Monosomy, Double Monosomy, Trisomy, Tetrasomy