Meiosis
Chapter 13
Introduction to Heredity
Heredity
Inheritance
Transmission
of traits from one generation to the next
Variation
Occurs as a
result of the process of meiosis
Genetics
Study of
heredity and hereditary variations
Genes
hereditary
units
encodes the
expression of a particular trait
Asexual vs Sexual
Reproduction
Asexual
Reproduction
Like begets
like
single-celled
eukaryote
some
multicellular organisms (Hydra)
genetically
identical to the parent (clone)
Sexual
Reproduction
greater
variation
offspring
not genetically identical to either parent or to siblings
Overview of Meiosis
Introduction to Meiosis
Terminology and Process
Terminology
diploid cell
(2n)=> a cell with two sets of chromosomes.
haploid cell
(n)=> a cell with one set of chromosomes.
conjugation=>
bacterial
gene transfer
gametes (germ
cells)=> sperm and egg
gametogenesis=>
meiosis
+ maturation
Meiosis
Meiosis:
halves the chromosome number yielding four haploid cells.
Meiosis
is preceded by an interphase in which the DNA replicates.
Two
divisions of the genetic material.
Meiosis
First
division
46 to 23
chromosomes (diploid to haploid)
reduction
division
Meiosis I
Second
division
4 cells from
2 cells
equational
division
Meiosis II
Genetic Variation
Crossing
over
genetic
diversity
synpasis=> when homologs line up next to each other.
alleles=> different
forms of the same gene
homologs=> identical
chromosomes (one from mother, one from father)
Independent Assortment
random
arrangement of homologs
Mitosis
vs Meiosis
Mitosis
Diploid to
Diploid
Growth,
Repair
Somatic
Cells
1cell to 2
genetically identical cells
1 division
Meiosis
Diploid to
Haploid
Sexual
Reproduction
Germ Cells
1 cell to 4
genetically non-identical cells
2 divisions
