Which body system is the most important in maintaining the homeostasis (and survival) of an individual organism?
Which body system is the most important in maintaining the survival of an entire species?
Reproduction • The life process by which an organism produces new individuals of the same kind. • This is essential for the survival of the species
Types of Reproduction • Asexual Reproduction • Involves ________ parent and results in one or more offspring that are genetically _________ to that parent. • Cells reproduce byMitosis one identical
Mitosis • A process where a cell divides and creates two daughter cells which are identicalto the parent • Cell Division happens by series of phases • Interphase, prophase, metaphase,anaphase, and telophase(cytokinesis) • I.P.M.A.T.(C).
I.P.M.A.T.C. Overview of mitosis interphase prophase PleaseMake Another Two Cells cytokinesis metaphase anaphase telophase
chromosomes in cell DNA in chromosomes cell 4 single-stranded chromosomes duplicated chromosomes nucleus duplicated chromosomes cell nucleus 4 double-stranded chromosomes DNA must be duplicated…
Mitosis: Dividing DNA & cells • Stage 1: cell copies DNA Copy DNA! DNA cell nucleus INTERPHASE
Mitosis: Dividing DNA & cells • Stage 2: DNA winds into chromosomes • Nuclear membrane disappears • Spindle Fibers/ Centrioles appear duplicated chromosomes Wind up! cell nucleus PROPHASE
double-strandedhuman chromosomes ready for mitosis
Mitosis: Dividing DNA & cells • Stage 3: Chromosomes line up in middle • attached to protein “cables” that will help them move Line up! duplicated chromosomes lined up in middle of cell METAPHASE
Mitosis: Dividing DNA & cells • Stage 4: Chromosomes separate • start moving to opposite ends Separate! chromosomes split & move to opposite ends ANAPHASE
Mitosis: Dividing DNA & cells • Stage 5: Cell starts to divide • Two nuclei • Chromosomes unwind Divide! TELOPHASE
Mitosis: Dividing DNA & cells • Stage 6: DNA unwinds again • cells separate completely (cleavage furrow) • now they can do their every day jobs Bye Bye! cytokinesis
Biology is the only subject in which multiplication is the same thing as division…
Examples of Asexual Reproduction Binary Fission • The cell splits into two identical cells, each containing an exact copy of the original cell's DNA. Nucleus and Cytoplasm divide EQUALLY!
Examples of Asexual Reproduction Budding- where the daughter cell grows out of the parent and gradually increases in size. Yeast cells Hydra Nucleus divides equally Cytoplasm divides unequally
Examples of Asexual Reproduction Spores • Reproductive cell that contains a nucleus and a small amount of cytoplasm • Spores are highly resistant to heat • Spores are capable of growing into a new organism when conditions allow • Produced by bread mold, mushrooms, mosses and ferns
Examples of Asexual Reproduction Regeneration • Development of a new organism from part of a parent • Whole organisms are produced – Starfish! • Replacement of lost body part
Examples of Asexual Reproduction Vegetative Propagation • Part of a plant (root, stem, leaves) grows into a new plant • Seedless fruits & vegetables • Commonly used by farmers = quick, easy & successful!
Sexual Reproduction • Offspring receive half of their genes from one parent and half from the other parent • The genes are carried on chromosomes in sex cells known as gametes • Male gamete is the sperm cell • Female gamete is the ovum (egg)
Sexual Reproduction • Joining of 2 sex cells (egg & sperm) • Do we make egg & sperm by mitosis? No! What if we did, then…. + 46 92 46 egg sperm zygote Doesn’t work!
Sexual Reproduction • Gametes are formed by Meiosis Meiosis (reduction division) • In series of divisions the number of chromosomes is reduced by half
46 23 46 23 Meiosis makes sperm & eggs • 46 chromosomes to 23 chromosomes • half the number of chromosomes egg meiosis diploid haploid sperm
Sexual Reproduction • Fertilization • Two gametes (Ovum and Sperm) join to create an offspring • Variation • Each offspring gets a unique combination of genes, therefore they are not identical to their parents or siblings.
Sexual Reproduction Meiosis (reduction division) • Spermatogenesis: Creates 4 sperm cells • Oogenesis: Creates 1 ovum and 3 polar bodies
46 46 46 46 46 46 46 46 46 46 23 23 46 23 23 Putting it all together… meiosis fertilization mitosis + development gametes meiosis egg zygote mitosis &development fertilization mitosis sperm
Meiosis & mitosis Meiosis to make gametes • sperm & egg Mitosis to make copies of cells • growth • repair • Development • replacement
Dad Mom The value of meiosis 1 • Consistency over time • meiosis keeps chromosome number same from generation to generation from Mom offspring from Dad
We’re mixing things up here! The value of meiosis 2 • Change over time • meiosis introduces genetic variation • gametes of offspring do not have same genes as gametes from parents • new combinations of traits from Dad variation from Mom offspring new gametes made by offspring
Adding to Variation… prophase 1 Crossing Over– Trading DNA! • During prophase 1, sister chromatids intertwine • homologous pairs swappieces of chromosome • DNA breaks & re-attaches tetrad
JonasBrothers Baldwin brothers Martin & Charlie Sheen, Emilio Estevez Sexual reproduction creates variability Sexual reproduction allows us to maintain both genetic similarity & differences.
CloningA form of asexual reproduction • The nucleus is taken from parent with a complete set of genetic information • Injected into an egg cell which has had its nucleus removed
Cloning cont. • The egg is implanted in a surrogate mother • Result is an organism which is 100% genetically identical to parent
Animals That Have Been Cloned Many more to come… Too many to list…