CHAPTER 11.1 REPRODUCTION

RECALL THE TWO IMPORTANT QUESTIONS WE ASKED…. What is the significance of Mitosis? Why do Chromosmes come in Pairs?

ASEXUAL VS SEXUAL REPRODUCTION

CHARACTERISTICS OF: ASEXUAL REPRODUCTION One Parent Genetic Continuity – Identical Offspring Many Offspring – Quickly Less Maturation Time Nuclear Division = MITOSIS

TYPES OF ASEXUAL REPRODUCTION

BINARY FISSION (SPLITTING IN TWO)

FRAGMENTATION - (PIECES) Fragmentation- A kind of reproduction where the “body” breaks into several pieces and the pieces develop into complete adults.

FRAGMENTATION - (PIECES)

BUDDINGBUDDING

BUDDING New individuals split off of the original organism.

CYTOPLASM DIVIDES UNEQUALLY bud

MULTICELLULAR BUDDING - SPONGE

PARTHENOGENESIS

Parthenogenesis = a process in which a female produces an egg that develops into an adult without ever being fertilized.

CLONING

MORE ABOUT CLONING DURING CHAPTER 15!

SEXUAL REPRODUCTION Requires two parents (cells) Union of special cells called GAMETES Sperm and Eggs or pollen and ovum Provides GENETIC VARIATION Usually mature more slowly

EGG & SPERM POLLEN & OVUM TYPES OF GAMETES

SEXUAL REPRODUCTION Advantages: Genetic variation Genetically diverse populations are able to withstand changes and disease better. Disadvantages: Need to expend energy looking for mate Produce fewer offspring.

HERMAPHRODITES Organisms with ovaries and testes Produce both eggs and sperm.

EARTHWORMS HAVE TESTES AND OVARIES

CHROMOSOME REVIEW A chromosome is an X shaped object that contains DNA. Within the DNA lies the codes for every characteristic of a living thing.

CHROMOSOME REVIEW Every chromosome consists of two identical halves called “sister chromatids” The chromosome has a backup copy of the DNA.

CHROMOSOMES Genes are located on located on chromosomes. Each chromosomes contains thousands of genes. A gene controls a specific trait such as your height or hair color.

CHROMOSOME NUMBERS Every species has a specific number of chromosomes. Humans have 46 chromosomes or 23 pairs of chromosomes.

CHROMOSOME NUMBERS Mosquitos have only 6 chromosomes in each cell. How many pairs of chromosomes does a mosquito have?

HAPLOID VS. DIPLOID CELLS Diploid cell- A cell that has two copies of each chromosome. This would include all somatic/body cells New cell will have an identical copy of DNA Diploid cells are produced by mitosis Mitosis is an asexual process. We call these cells “2N” cells. Examples would include: liver cells, etc.

HAPLOID VS. DIPLOID CELLS Haploid cells- Have only one (half) set of chromosomes. This includes ONLY GAMETES (egg/sperm). The two gametes will combine to create a new organism with full set of chromosomes (half from mom, half from dad). Haploid cells are created through meiosis. Meiosis is a sexual process. We call haploid cells “1N” or “N”

HAPLOIDS VS. DIPLOID CELLS SPECIESHAPLOID (N)DIPLOID (2N) HUMANS23 (# chromosomes in sperm/egg) 46 (# chromosomes in somatic/body cells) MONKEY42 CORN10 CATS38 FRUIT FLY4

HOMOLOGOUS CHROMOSOMES Homologous chromosomes- Each diploid cell has a pair of chromosomes known as homologous chromosomes. They are similar in shape size and genetic make-up. In each homologous pair one chromosome came from your mother and one from your father.

HOMOLOGOUS PAIRS

AUTOSOMES VS. SEX CHROMOSOMES Autosomes- Chromosomes with genes that do not determine the sex of an individual. Sex chromosomes- Chromosomes that do determine the sex of an individual.

AUTOSOMES VS. SEX CHROMOSOMES Sex chromosomes (Female)