Bio Exam 4
How many polar bodies are produced during oogenesis?
3 polar bodies and 1 ovum
Trait
A characteristic that an organism can pass on to its offspring through its genes.
Aneuploidy
A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
Polyploidy
A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
alternation of generations
A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae.
ovum
A mature egg cell
incomplete dominance
A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.
Gene
A segment of DNA on a chromosome that codes for a specific trait
Epistasis
A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited.
Co-dominance example
AB blood type
Philadelphia chromosome
An abnormal chromosome produced by translocation of parts of the long arms of chromosomes 9 and 22.
dominant allele
An allele whose trait always shows up in the organism when the allele is present.
genetic map
An ordered list of the genetic loci along a particular chromosome.
Genotype
An organism's genetic makeup, or allele combinations.
Phenotype
An organism's physical appearance, or visible traits.
When does sporophyte mitosis and meiosis occur?
Diploid sporophyte cells undergo meiosis to produce haploid spores. Each spore goes through mitotic divisions to yield a multicellular, haploid gametophyte.
When & how does mitosis occur to produce multicellular gametophyte?
Diploid sporophyte cells undergo meiosis to produce haploid spores. Each spore goes through mitotic divisions to yield a multicellular, haploid gametophyte. Mitotic divisions within the gametophyte are required to produce the gametes.
sporophyte
Diploid, or spore-producing, phase of an organism. Makes haploid spores by meiosis.
characteristics of homologous chromososmes
Each carries the same genes in the same order, but the alleles for each trait may not be the same
diploid dominant life cycle
Early in the development of the embryo, specialized diploid cells, called germ cells, are produced within the gonads (e.g. testes and ovaries). Germ cells are capable of mitosis to perpetuate the cell line and meiosis to produce gametes. Once the haploid gametes are formed, they lose the ability to divide again. There is no multicellular haploid life stage. Fertilization occurs with the fusion of two gametes, usually from different individuals, restoring the diploid state .
homogametic
Females (XX)
gametophyte
In organisms (plants and some algae) that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. The haploid gametes unite and develop into sporophytes.
locus
Location of a gene on a chromosome
Law of Segregation
Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete
haploid dominant life cycle
Multicellular organism is haploid Haploid cells unite to form diploid zygote, then proceeds immediately through meiosis to make 4 haploid spores
Co-dominant alleles
Pairs of alleles that both affect the phenotype when present in a heterozygote
crossing over
Process in which homologous chromosomes exchange portions of their chromatids during prophase I meiosis.
genetics
The scientific study of heredity
Why was Mendell sucessfull?
Using a simple organism like the garden pea, Mendel was able to control pollination among his experimental plants, and most importantly, he used true breeding plants with easily observable characteristics, such as flower color and height
chromosomal translocation
When part of one chromosome breaks off and attaches to another non homologous, chromosome.
Random segregation
When the two chromosomes in meiosis are separated randomly to the reproductive cells gametes. There is no way of telling which chromosome will end up in each gamete.
chiasmata
X-shaped regions where crossing over occurred.
dihybrid cross
a cross between two different lines/genes that differ in two observed traits. According to Mendel's statement, between the alleles of both these loci there is a relationship of completely dominant - recessive traits.
reciprocal cross
a cross in which the phenotypes of the male and female are reversed compared with a prior cross
trihybrid cross
a cross involving three traits
Zygote
a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.
monohybrid cross
a genetic mix between two individuals who have homozygous genotypes, or genotypes that have completely dominant or completely recessive alleles, which result in opposite phenotypes for a certain genetic trait.
Gametes
a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
Lesch-Nyhan syndrome
a rare inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). This deficiency occurs due to mutations in the HPRT gene located on the X chromosome.
polar body
a small cell containing little cytoplasm that is produced along with the oocyte and later discarded
Meiosis
a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.
Epistasis example
albinism
independent assortment
alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.
recombinant phenotypes
an offspring whose phenotype differs from that of the true-breeding P generation parents
Homologues
chromosomes that are given the same number, but are of opposite parental origin
fungi reproduction and some protists reproduction
gametes fuse and form a diploid zygote, meiosis occurs without a multicellular diploid offspring developing. Meiosis produced not gametes but haploid cells that then divide by mitosis and give rise to either unicellular descendants or a haploid multicellular adult organism.
X-linked genes
genes that are considered recessive and located only on the X chromosome
x linked genetic disorders
hemophilia, color blindness, and Lesch-Nyhan syndrome
heterogametic
males (XY)
sex linkage
occurs when certain traits are determined by genes on sex chromosomes
Linkage
occurs when different traits are inherited together more often than they would have been by chance along; it is assumed that these traits are linked on the same chromosome
haploid multicellular organism
produces specialized haploid cells by mitosis that fuse to form a diploid zygote. The zygote undergoes meiosis to produce haploid spores. Each spore gives rise to a multicellular haploid organism by mitosis
incomplete dominance example
red flower + white flower = pink flower
How are genetic maps made?
researchers collect blood or tissue samples from members of families in which a certain disease or trait is prevalent. ... DNA markers don't, by themselves, identify the gene responsible for the disease or trait; but they can tell researchers roughly where the gene is on the chromosome.
Tetrad
structure containing 4 chromatids that forms during meiosis
Oogenesis
the development of mature oocytes (eggs), is a prolonged process in the human female. Immature eggs form in the ovary of the female embryo but do not complete their development until years, and often decades later.
Spermatogenesis
the formation and development of sperm, is continuous and prolific in adult males
synapsis
the pairing of homologous chromosomes during meiosis
multiple alleles
three or more forms of a gene that code for a single trait
cellular mosaicism
when a person has 2 or more genetically different sets of cells in his or her body.