in eukaryotic cells, a process of cell division that forms two new nuclei, each of which has the same number of chromosomes
(genetics) cell division that produces reproductive cells in sexually reproducing organisms
organic process consisting of the division of the cytoplasm of a cell following karyokinesis bringing about the separation into two daughter cells
The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, it exists as a mass of very long, thin fibers that are not visible with a light microscope.
Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.
a specialized condensed region of each chromosome that appears during mitosis where the chromatids are held together to form an X shape
series of events that cells go through as they grow and divide
the period of the cell cycle during which the nucleus is not undergoing division, typically occurring between mitotic or meiotic divisions
Located near the nucleus and help to organize cell division
dense masses of RNA and protein that manufacture ribosomes, several of these are located in the nucleus.
first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus
second phase of mitosis, during which the chromosomes line up across the center of the cell
the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles
the final stage of meiosis or mitosis, in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells form around the two sets of chromosomes
A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.
pinching of the cell ("drawstring"): develops in animal cells only
the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two
The first phase of meiosis I. the replicated chromosomes condense, homologous chromsomes pair up, crossing over occurs between homologous chromosomes, the spindle is formed, and the nuclear envelope breaks apart into vesicles. the longest phase of meiosis.
The third phase of meiosis I. the replicated homologous chromosomes are separated (the tetrad is split) and pulled to opposite sides of the cell.
The second phase of meiosis I. the paired homologous chromsomes (tetrads) align at the center of the cell (the metaphase plate).
The fourth of meiosis I. the number of chromosoms is now reduced by half. After this phase the cell is considered to be haploid. Note however, that the chromosomes are still replicated, and the sister chromatids must still be separated during meiosis II.
The first phase of meiosis II. identical to the mitotic step, except that the number of chromosomes was reduced by half during meiosis I.
The second phase of meiosis II. identical to the mitotic step, except that the number of chromosomes was reduced by half during meiosis I.
The third phase of meiosis II. the sister chromatids are finally spearated at their centromeres and puled to opposite sides of teh cell. is identical to mitotic anaphase, excep the number of chromosmes was reduced by half during meiosis I.
The fourth and final phase of meiosis II. the number of chromosomes was reduced by half during meiosis. I.
term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes
(genetics) an organism or cell having two sets of chromosomes or twice the haploid number
the side by side pairing of homologous maternal and paternal chromosomes at the start of meiosis
the paired chromosomes consisting of four chromatids
the interchange of sections between pairing homologous chromosomes during the prophase of meiosis
any cell other than a gamete, has 46 chromosomes, body cells
a fertilized egg
checks to see if cell size is adequate; chromosomes replication is successfully completed and checks for DNA errors
if condidtions are not apporpiate for the cell to divide or if it is not programmed to divide they are in this phase
asses if DNA replication has occured, go ahead signal triggers mitosis
Cyclin Dependent Kinases
cdk enzymes activate proteins to regulate the cell
factors that stimulate the cell to divide
Density Dependent Inhibition
The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.
the requirement that to divide, a cell must be attached to a solid surface.
one of two alternate forms of a gene that can have the same locus on homologous chromosomes and are responsible for alternative traits
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
Law of Independent Assortment
states that allele pairs separate independently during the formation of gametes
hybridization using a single trait with two alleles (as in Mendel's experiments with garden peas)
hybridization using two traits with two alleles each
creates a blended phenotype; one allele is not completely dominant over the other
a condition in which both alleles for a gene are fully expressed
three or more forms of a gene that code for a single trait (such as blood types)
A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited., One gene masks the expression of a different gene for a different trait
A single gene having multiple effects on an individuals phenotype (more than one phenotypic expression)
genes located on the same chromosome that tend to be inherited together in genetic crosses
Sex Linked Inheritance
Traits located on the sex cells. EX: Colorblindness, hemophilia.
During development, females inactivate half of their X gene elles in order to prevent producing double the amount of the protein.
error in meiosis in which homologous chromosomes don't separate; gametes end up with wrong number of chromosomes
condition in which an organism has extra sets of chromosomes
changes in a DNA sequence caused by substitution of one nucleotide for another
an abnormality involving a chromosome number that is not an exact multiple of the haploid number (one chromosome set is incomplete)(causes down sydrome and turners syndrome)
the appearance of the chromosomal makeup of a somatic cell in an individual or species (including the number and arrangement and size and structure of the chromosomes)
chromosomes that have the same sequence of genes, that have the same structured, and that pair during meisosis
a congenital disorder caused by having an extra 21st chromosome
condition seen in individuals carrying single X chromosome but no other sex chromosome (XO)
parental generation, the first two individuals that mate in a genetic cross
the first offspring from a cross of two varieties in the parental (P) generation
the second generation of offspring, obtained from an experimental cross of two organisms; the offspring of the F1 generation
a diagram that shows the occurrence of a genetic trait in several generations of a family
recessive, lipid build up, causes fat build up in brain. death by 2
syndrome in males that is characterized by small testes and long legs and enlarged breasts and reduced sperm production and mental retardation (XXY)
Sickle cell anemia
A human genetic disease of red blood cells caused by the substitution of a single amino acid in the hemoglobin protein; it is the most common inherited disease among African Americans.
sex-linked recessive disorder defined by the absence of one or more proteins required for blood clotting
a human genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consquent vulnerability to infection; fatal if untreated (4% whites are carriers - most common lethal genetic disease)
genetic disorder that causes progressive deterioration of brain cells. caused by a dominant allele. symptoms do not appear until the age of 30 or so
Autosomal Recessive , a hereditary condition characterized by a partial or total lack of melanin pigment (particularly in the eyes, skin, and hair)