Reproduction in Cells

One parent Creates clones Parent gives entire genetic make-up to offspring Examples: Binary Fission – Prokaryotes Mitotic Cell Division - Eukaryotes Asexual Reproduction

Mitotic Cell Division in Eukaryotes Budding Fragmentation Vegetative Reproduction Unfertilized eggs

Sexual Reproduction Two parents contribute equal # of chromosomes To do this need non-somatic cells – Gametes = reproductive cells (sperm and eggs) Produced by Meiosis Haploid cells (n) – Have 1 full set of chromosomes Fertilization creates a diploid cell (2n) – Have 2 full sets of chromosomes – homologous pairs = chromsomes have same sstructure and genes

Questions A cell has a diploid number of 16, what is the haploid number? A cell that has 12 chromosomes is going to divide to produce cells for sexual reproduction. How many chromosomes will the sex cells have? An egg cell for a certain species has 20 chromosomes. How many chromosomes will it have after it is fertilized?

Meiosis Review Activity

Meiosis

Prophase I Chromosomes condense Homologous pairs move together – Crossing over occurs (exchange of DNA between homologous chromosomes) allows genetic recombination and variation among species

Metaphase I Pairs move to center of the cell (metaphase plate) Anaphase I Homologous pairs separate

Telophase I Homologous chromosomes are completely separated Cytoplasm splits into two cells (cytokinesis) Haploid (n) cells

Prophase II Spindle forms No more crossing over Chromosomes move towards metaphase plate

Metaphase II Chromosomes line up in the middle of the cell Anaphase II Chromosomes split and move to opposite sides of the cell

Telophase II Chromosomes at opposite sides of the cell Nucleus reforms Cells divide (cytokinesis) – Four haploid gamete cells