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Chapter 10: Meiosis and the Sexual Life Cycles (10.1 Offspring acquire…
Chapter 10: Meiosis and the Sexual Life Cycles
10.1 Offspring acquire genes from parents by inheriting chromosomes
genes:
a specific unit of hereditary information made of specific DNA or RNA sequences
locus:
space on a chromosome where a specific gene is located.
gametes:
meiosis produces haploid gametes (ova or sperm) that contain one set of 23 chromosomes.
When 2 gametes fuse, the resulting zygote is once again diploid, with the maternal and paternal parent each contributing 23 chromosomes.
asexual reproduction:
offspring are created by only one organism and the only genes inherited are an exact copy of the parent.
Clone:
a group of identical cells that are derived from the same cell.
Sexual reproduction:
when 2 parents make offspring that have unique combinations of inherited genes from parents via the gametes.
10.2 Fertilization and meiosis alternate in sexual life cycle
somatic cells:
any cell of a multicellular organism that is not a sperm or egg cell.
diploid:
a cell that contains 2 sets of chromosomes (1 from each parent)
haploid:
a cell with only 1 set of chromosomes that aren't paired
karyotype:
the visual appearance of chromosomes and organizing them by size and shape
homologous chromosomes/homologs:
a chromosome pair, one from each parents, that have similar length, position, and staining pattern
homologous pair:
when chromosomes pair up during meiosis, the chromosome pairs are homologous pairs
autosomes
: a chromosome not directly involved in determining the sex of an organism
sex chromosomes:
chromosomes that determine the sex of an individual organism. (X and Y)
Meiosis:
cell division that reduces the number of chromosomes by 1/2 and results in the formation of gametes
Fertilization:
a union of gametes that forms by fusion of nuclei
zygote:
the result of fertilization-gamete w/ 2 haploid sets of chromosomes with genes from paternal and maternal lines
life cycle:
is the generation-to-generation sequence of stages in the reproductive history of an organism from contraception of production
alteration of generations:
a life cycle where there is a multicellular diplod form and a multicellular haploid form
10.4 Genetic variation produced in sexual life cycle contributes to evolution
Recombinant chromosomes:
when the crossing over of DNA from the 2 parent cells combine to create a single chromosome
10.3 Meiosis reduces the number of chromosome sets from diploid and haploid
Meiosis I:
process that occurs after interphase I where proteins of eukaryotic cells are grown.
4 steps of meiosis I
metaphase I:
homologous pairs of chromosomes align at the center of the cell
anaphase I:
one chromosome of each homologous pair is pulled towards each pole
prophase I:
chromation is condensed into chromosomes
Crossing over:
occurs during prophase I and metaphase I. The exchange of different segments of homologous chromosomes to increase genetic diversity.
telophase I
synaptonemal complex:
protein structure that forms between homolgous chromosomes during meiosis
Synapsis:
paired homologs that become physically connected to each other along their lengths by zipper-like proteins
Meiosis II:
Second step of meiosis. Four stages will repeat again.
