BI 233 A&P Lab-Ex. 45

46 chromosome pairs contained in all human cells (except sperm/egg); maintained via mitosis

23 chromosomes contained in each gamete

Chromosomes which have the same genes, but possibly different alleles

Genes having a specific position on a specific chromosome, which code for a specific trait

Trait in which the pair of alleles (on the homologous chromosomes) differ

Trait in which the pair of alleles (on the homologous chromosomes) match/have the same expression

The element of a chromosome which provides the code for a particular trait

The allele which exerts its effects whether it is part of a hetero- or homo- zygous pair

Gene which will be suppressed in the case of a heterozygous pair

The genetic makeup of an individual;whether she is hetero- or homo- zygous

The manner in which a genotype is expressed (physical expression of a genotype)

The cross of a single genetic trait with two alleles

Gregor Mendel--and Austrian monk of the mid-1800s

Grid or diagram which provides a simple framework for determining a genotype by hand

• Condition in which the recessive gene is only partially repressed
• Condition in which both alleles express themselves in the offspring thus producing an intermediate phenotype
• Condition in which so-called dominant genes may be expressed differently in homo- and hetero- zygous offspring

Condition in which each cell or cell component "chooses" one or the other phenotype (e.g. variagated leaf; calico cat--orange, black, or white) or "chooses" both phenotypes (e.g. AB blood)

• Sickle Cell Anemia--disease produced due to incomplete dominance
• SS--(sickling gene absent) porduce normal hemoglobin
• Ss--(heterozygous) Sickle Cell Trait (SCT) produce both normal and sickling hemoglobin; develop anemia only in prolonged cases of O₂ deficit
• ss--(homozygous, exhibit SCA) produce abnormal hemoglobin which crystallizes and becomes sharp/spiky under O₂ deficit clumping, pain, possible death

• 22 of the 23 pairs of homologous chromosomes which determine most body (somatic) characteristics
• (do not determine sex, or sex-linked characteristics)

• 23^rd pair of homologous chromosomes which determine the sex of an individual
• XY=♂; XX=♀
• The Y chromosome, which determines maleness, is ~1/3 the size of the X chromosome and lacks many of the genes

• Genes present on either the X or Y chromosome, thus the phenotype requires only one recessive gene to present in males, but requires two (homozygous) recessive genes to present in females
• E.g. normal color vision (color blindness=recessive), normal clotting ability (hemophilia=recessive)

Genes which occur only on the Y chromosome and thus are only exhibited in males

• The father will always pass his X to a daughter and his Y to a son
• Males (XY) always inherit sex-linked conditions from their mothers
• Females (XX) may inherit sex-linked conditions from either their mother or father
• Males (XY) may inherit holandric conditions from their father
• Females (XX) may not inherit holandric conditions

An event with a probability of 1 is certain to happen

• Mathematical product of all individual events
• E.g. the probability of getting heads 4 times in a row