meiosis and genetic diversity, mendelian genetics Flashcards
genetics
study of heredity and heriditary variations
heredity
transmission of traits from one generation to the next
traits are passed from parent to offspring through
genes
genes
segments of DNA that code for basic units of heredity
asexual reproduction
single individual
no fusion of gametes
clones: offspring are exact copies of parent
mutations are the only source of variation
ca produce asexually through mitosis
sexual reproduction
two parents (male/female)
offspring are unique combinations of genes from parents
genetically varied from parents and siblings
homologous chromosomes
a pair of chromosomes (same size, length, centromere position) that carry same genetic information
karyotypes
display of chromosome pairs ordered by size and length
two types of chromosmes
autosomes
sex chromosomes
autosomes
chromosomes that do not determine sec (22 pairs)
sex chromosomes
x and y
eggs: x (humans: 22+x)
sperm: x or y (humans: 22+x or y)
meiosis
process that creates haploid gamete cells in sexually reproducing diploid organisms
meiosis results
daughter cells with half the number of chromosomes as the parent cell
mitosis vs meiosis
mitosis: occurs in somatic cells 1 division results in 2 diploid daughter cells saygheter cells are genetically identical
meisos: forms gametes 2 divisions results in 4 haploid daughter cells each daughter cell is genetically unique
key events in meiosis
prophase I: synapsis and crossing over
metaphase I: tetrads (homologous pairs) line up at the metaphase plate)
anaphase I: homologou pairs separate
meiosis I: interphase
cell goes through g1, s (DNA is copied), g2
synapsis
homologous chromosomes pair up and physically connect to each other to form a tetrad
crossing over (recombination)
occurs at the chiasmata and DNA is exchanged between the homologous pairs
anaphase I
pairs of homologous chromosomes separate
sister chromatids are still attached
telophase I and cytokinesis
nuclei and cytoplasm divide
there is now a hapoid set of chromosomes in each daughter cell
prophase II
no crossing over
spindle forms
metaphase II
chromosomes line up at metaphase plate
because of crossing over in meiosis I, the chromstids are unique
anaphase II
sister chromatids separate and move towards opposite poles
telophase II and cytokinesis
4 haploid cells
nuclei reappear
each daughter cell is genetically unique
homozygous
an organism that has a pair of identical alleles for a character
heterozygous
an organism has two different alleles for a gene
genotype
genetic makeup (alleles) of an organism
phenotype
an organisms appearance, which is determined by the genotype
testcross
help to determine if the dominant trait is homozygous dominant or heterozygous
monohybrid cross
cross between f1 hybrids
law of segregation
two alleles for the same trait separate during gamete formation and end ul in different gametes
law of independent assortment
genes for one trait are not inherited with genes if another trait
dihybrid cross
cross between f1 dihybrids
