Methods of Reproduction

Types of Reproduction There are two main ways in which reproduction occurs: –Asexual Reproduction –Sexual Reproduction

Asexual Reproduction: requires only 1 parent and the offspring are an exact copy of the parent---a clone

Asexual Reproduction: Organisms that reproduce asexually cannot develop much variety, because they are “copying” the original organism exactly.

Methods of asexual reproduction: Binary fission Budding Fragmentation

Binary fission Single-celled organisms (Amoeba, paramecium, euglena) which use asexual reproduction can do so simply by dividing into two equal halves. This is called binary fission.

When conditions are good, such as plenty of water, food, right temperatures, etc., binary fission is a very effective way of producing many, many offspring. For example, the cell of a Paramecium can divide, grow, and divide again in the space of 8 hours.

Budding- an offspring grows out of the body of the parent. Hydra Budding offspring Cactus Budding

Yeast - budding Budding In yeasts the cell does not divide equally in two halves; instead, there is a large mother cell and a smaller daughter cell.

Fragmentation In this form, the body of the parent breaks into distinct pieces, each of which can produce an offspring. Pieces of coral broken off in storms can grow into new colonies. A new starfish can grow from one detached arm.

Fragmentation- plant cuttings Some plants can grow from cutting them up and replanting them.

Green plants are quite sophisticated in their methods of asexual reproduction. Offspring may be produced by runners, bulbs, rhizomes or tubers.

What is sexual reproduction? Requiring 2 parents –male and female Offspring are different from the parent organism because it takes half the DNA from one parent and half from the other

Sexual Reproduction Sexual reproduction produces a greater chance of variation within a species than asexual reproduction would. This variation improves the chances that a species will adapt to his environment and survive.

Sexual vs. Asexual Reproduction Asexual reproduction results in offspring that are genetically identical to the parent organism. Sexual reproduction results in offspring that are genetically different from the parent organisms.

DNA – Chromosomes - Genes

DNA DNA: the chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms. The scientific name for DNA is deoxyribonucleic acid.

Chromosomes  A chromosome is one of the threadlike "packages" of genes and other DNA in the nucleus of a cell.  Different kinds of organisms have different numbers of chromosomes.  Humans have 23 pairs of chromosomes, 46 in all.  Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their fathers.

Gene A gene is the functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

Genome A genome is all the DNA contained in an organism or a cell, which includes the chromosomes plus the DNA in mitochondria (and DNA in the chloroplasts of plant cells).

Cell division and DNA replication Cells divide Growth, Repair, Replacement Before cells divide, they have to double cell structures, organelles and their genetic information

DNA replication – Mitosis & Meiosis

Videos Asexual Reproduction/Binary Fission – cqxI4 Budding in Yeast: – Y Regeneration: – GvA