Unit 10 Flashcards
Define Fertilization
the process in sexual reproduction where the male and female reproductive cells join
Define True-breeding
organisms that, if allowed to self-pollinate, would produce offspring identical to themselves
Define Trait
specific characteristic that varies among individuals
Define Hybrid
Offspring crosses between parents with different traits
define Allele
Different forms of a gene
Define Segregation
separation of alleles pairs during gamete formation
Define homozygous
organisms that have two identical alleles for a particular trait
define heterozygous
organisms that have two different alleles for a particular trait.
define phenotype
physical characteristics
define genotype
genetic makeup
Define independent assortment
alleles for a trait segregate independently
define incomplete dominance
cases in which one allele is not completely dominant over another
define multiple alleles
genes with more than two alleles
define polygenic traits
traits that are controlled by two or more genes
define homologous
chromosomes that have the same structure, function, and relative location
define diploid
cell that contain both sets of homologous chromosomes
define haploid
cell with only one set of chromosomes
define tetrad
the structure formed when chromosomes pair up with corresponding homologous chromosomes in prophase of meiosis I
define crossing over
exchange in portions of a chromatid
Define Nondisjunction
common error in meiosis where sister chromatids fail to separate
what Mendel’s law hereditary?
The principle of dominance states that some alleles are dominant and others are recessive.
The principle of probability can be used to predict the outcomes of genetic crosses.
The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes.
what are characteristics also influenced by?
environmental and nutritional factors
What is meiosis
a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.
explain interphase I
cells undergo a round of DNA replication, forming duplicate chromosomes.
explain prophase I
each chromosome pairs with its corresponding homologous chromosome to form a tetrad.
explain Metaphase I
Spindle fibers attach to the chromosome.
explain Anaphase I
The fibers pull the homologous chromosomes towards opposite ends of the cell.
Explain telophase I and cytokinesis
Nuclear membranes form. The cell separates into two cells.
explain Prophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original cell.
explain metaphase II
chromosomes line up like the similar way in metaphase I
Explain Anaphase II , Telophase II and cytokinesis
The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid daughter cells
what is gene linkage?
the tendency of DNA sequences that are close together on a chromosome to be inherited together
why are all x-linked alleles expressed in males?
because they only have one X-chromosome
what are 3 ways sexual reproduction is increases variation?
Independent assortment, random fertilization, and crossing over
