Bio Chapter 13

how are traits carried to offspring

egg is fertilized by sperm dna combines into parent and daughter chromosomes, splitting dna and giving it to offspring

somatic cell (diploid 2n)

every cell but sex cells

Gametes (haploid n)

sec cells. sperm and egg

Autosome

all other 22 chromosomes

Sex chromosmes

1 of 23 chromosomes. either x or y. male or female.

karyotype

the ordered display of chromosomes

meiosis role in sexual reproduction

reduces chromosomes in gametes to half the number of chromosomes in somatic cells.

meiosis 1

prophase 1- chromosomes pair and cross

metaphase 1- homologs line up microtubules

anaphase 1- creates spindle

telophase and cytokinesis 1- creates cleavage and spltis

meiosis 2

prophase 2- spindle forms

metaphase 2- microtubules attach to sister chromatids

anaphase 2- sister chromatids split to poles

telophase and cytokinesis 2- chromosomes go to poles and cell splits.

synapses

joins dna together

chiasmata

points of connection on non-sister homologs.

meiosis and double division

seperates twice in two different phases, 1 and 2

homologous chromosomes split during…

in anaphase 1

centromeres split…

in anaphase 2

sister chromatids split…

in anaphase 2

cohesions

proteins that hold sister chromatids

synaptonemal complex

zipper like structure that holds homologs together tightly.

tetrad

structure of four sister chromatids

crossover

produces recombinant chromosomes

independent assortment of chromosomes

sorts moms genes from dads genes

random fertilization

any sperm can fertilze the egg. fuzes gametes.