Asexual & Sexual Reproduction

Hierarchy: Cells make up tissues Tissues make up organs Organs make up organ systems Organ systems make up organisms ***FROM SMALL TO LARGE***

Examples Cells: Perform a specific function- skin cells, brain cells, etc. Tissues: A group of cells working together for a specific function- nervous tissue, muscle tissue Organs: A group of tissues working together for a specific function- heart, liver, lungs Organ Systems: A group of organs working together for a specific function- circulatory system, skeletal system Organisms: Several organ systems sustaining life for organisms Specialized Cells Tissues Organs Organ Systems Organism

Scientists Robert Hooke Anton VanLeewenhoek Discovered cells through a microscope Called them tiny boxes Used a microscope to discover single-celled organisms in pond scum. He called them animalcules

Scientists Matthias Schleiden Theodor Schwann Discovered all plant parts had cells in them Found that all animals are composed of cells

Scientists Rudolf Virchow- Concluded that cells come from other cells

Cell Theory 1. All organisms are composed of one or more cells (SCHLEIDEN AND SCHWANN) 2. The cell is the basic unit of life in all living things. (SCHLEIDEN AND SCHWANN) 3. All cells come from other cells. (VIRCHOW)

Asexual Reproduction Type of reproduction in which a new organism is produced from ONE parent and the offspring is identical to the parent. Occurs in most plants, bacteria, protists, and low invertebrates. The cells in our body reproduce asexually through a process called mitosis.

Asexual Reproduction One parent Offspring are identical to the parents. One Parent Identical Offspring

Asexual Reproduction Advantages – Identical to parent, so will get all good characteristics. Disadvantages – Identical to parent, so will also get bad characteristics and is less able to adapt to the environment.

Asexual Reproduction Types of Asexual Reproduction Regeneration – organism uses cell division to re-grow body parts. Example: starfish, salamander

Asexual Reproduction Types of Asexual Reproduction Runners– results in a new plant that is genetically identical to the parent plant (a clone). Examples: strawberry plant, vegetables, and crops.

Asexual Reproduction Types of Asexual Reproduction Budding – organism that produces a bud that breaks away to live on its own. Example: hydra

Asexual Reproduction Types of Asexual Reproduction Binary Fission – used by bacteria, an organism whose cells do not contain a nucleus copy then divide into two identical organisms Example: bacteria

Sexual Reproduction Two parents Offspring are a combination of both parents and are therefore different from each parent. unique / diverse offspring Two Parents

Sexual Reproduction Advantages – variety and/or diversity of offspring (color, shape, size, intelligence, ability, etc.), More able to adapt to environmental changes. Disadvantages – uniqueness, sometimes traits needed for survival are not passed on.

Sexual Reproduction Types of Sexual Reproduction Plants – when the reproductive cells of one plant fertilize (pollinate) the reproductive cells of another plant. This produces seeds that can grow into a new plant.

Sexual Reproduction Animals – when the reproductive cells of one animal fertilize the reproductive cells of another animal. This produces a baby (embryo).

Reproduction Processes Mitosis Meiosis

Mitosis VS. Meiosis produces two identical daughter cells The cells created from mitosis are diploid or 2n. produces four genetically different daughter cells The cells created from meiosis are haploid or n Diploid (2n) – two of each type of chromosome (in homologous pair – carry the same trait) Haploid (n) – one of each type of chromosome

Human cells have 46 chromosomes…. Diploid Haploid Therefore, the diploid number (2n) of chromosomes in humans is 46. The haploid number (n) of chromosomes in humans is 23.

Why does mitosis occur? To replace other cells that have been damaged or worn out To allow multicellular organisms to grow For asexual reproduction Because they get too big!

Why does meiosis occur? Meiosis results in four cells with half the number of chromosomes so that when the sex cells (sperm and egg) combine, the original or normal number of chromosomes will be restored

Where does it occur? Mitosis Meiosis Body cells Sex cells Ex- Skin Cells Sex cells Ex- Egg and Sperm only