Unit IV: Can You Divide?

Cell Reproduction All organisms REPRODUCE. Why? –This allows for growth, development and the survival of the species

There are 2 types of reproduction 1.Asexual Reproduction –Requires A single parent!!! (sorry, just ONE).

Asexual Reproduction (cont)… Results in the offspring having the same hereditary material (DNA)

In other words, the new cells are an exact copy of its parent (allow for little variation among species) Asexual Reproduction (cont)…

Types of Asexual Reproduction Fission – cell splits in half (ex: Amoeba)

Types of Asexual Reproduction (cont)… Budding – a new organism grows off from the side of an adult (ex: Hydra)

Types of Asexual Reproduction (cont)… Regeneration – a new organism grows from a severed body part (ex: starfish)

What is a chromosome? Structure found in the nucleus of a eukaryotic cell that contains hereditary material

The structure of a chromosome Chromosome Centromere Chromatid arm Gene

How do we replace old skin cells? Mitosis –The process in which the newly duplicated chromosome pairs are separated from each other

What happens to a cell before Mitosis starts? Interphase –Cell grows and develops –Chromosomes duplicate themselves –Centrioles appear

Steps of Mitosis Prophase –Nuclear membrane disappears –Centrioles move to opposite ends of the cell –Spindle fibers appear in the cell

Steps of Mitosis Continued Metaphase –Chromosomes line up in the center of the cell –Centromeres attach to the spindle fibers

Steps of Mitosis Continued Anaphase –Centromeres separate –The two strands of chromosomes are pulled apart by centrioles towards opposite ends of the cell

Steps of Mitosis Continued Telophase –Centrioles and spindle fibers disappear –Nuclear membrane begins to reappear

What happens to a cell after Mitosis is complete? Cytokinesis –Cell splits into two identical daughter cells with complete set of organelles

How did you get here? Sexual Reproduction –Reproduction in which two (2) parents are involved –Sex cells are called gametes (egg and sperm cells are gametes)

What is sexual reproduction? Sexual reproduction – starts with the formation of gametes and ends when one gamete joins another gamete. The joining of egg and sperm is called fertilization, resulting in the production of a zygote zygote

How are gametes produced? Meiosis –A process whose purpose is to reduce the chromosome number in the cells –Produces 4 new cells with half the number of chromosomes as the parent

Parent Cell 1 st Division Meiosis – two divisions of the nucleus 2 nd Division – 4 new daughter cells with ½ the # of chromosomes

Meiosis continued Diploid Cells: have two of every chromosome (body cells) Haploid Cells: have just one chromosome from each pair (gametes)