Download Sexual Reproduction

Sexual Reproduction
Meiosis
During sex reproduction…..
Fertilization occurs (sperm and egg come together)
Generally the egg and sperm come from different
organisms of the same species (e.g. male and female lion)
New cell is called a zygote
Types of Cells:
Body Cells vs.
Out number sex cells
Ex) brain, skin, bones,
muscle
Sex Cells
Only found in reproductive
organs
Chromosomes:
Humans have 46 chromosomes or 23 pairs!!!!
So each chromosome has a mate or one that is similar in size
and shape.
Chromosome 1
Has over 3000 genes
DIPLOID CELL (Have pairs of chromosomes)
All body cells are diploid cells
These cells have a similar pair of chromosomes
HAPLOID CELL
Include all sex cells
These cells only have HALF the number of chromosomes
Human sex cells only have 23 chromosomes
One from each of the 23 pairs
What is MEIOSIS?
This process produces HAPLOID sex cells!!!!!
Parent cell
Prophase 1: Nuclear
membrane disappears
Telophase 1: Two
daughter cells appear
Cells divide
Anaphase 1: pair of
twin chromosomes
move apart
NO INTERPHASE
HERE!!!!
Metaphase 1: Pair of twin
chromosomes line-up @
middle
Same as mitosis
except you know
have 4 new cells
Prophase 2; same as 1
Metaphase 2: same as 1
Anaphase 2:
same as 1
Telophase 2:
same as 1
Four genetically
different haploid
cells that contain
half the number of
chromomsomes as
the original parent
cell.
How can chromosome numbers be predicted?
Off spring get half of their genes from one parent and half from
the other parent
Think of this:
Donkey
Zebra
62 chromosomes
46 chromosomes
Zonkey
How many chromosomes would the zonkey receive from each parent?
23 from zebra and 31 from the donkey
What is the chromosome number of the zonkey? 54 chromosomes
What would happen when meiosis occurs in the zonkey’s
reproductive organs? Normal sex cells would not form…..8 unpaired chromosomes!!!!!