Cells The Basic Unit of Life Sections 3

Cells The Basic Unit of Life Sections 3. 1 and 3. 2

Cell History n n Cytology- study of cells 1665 English Scientist Robert Hooke Used a microscope to examine cork (plant) Hooke called what he saw "Cells"

Cell History n Robert Brown n n Matthias Schleiden n n discovered the nucleus in 1833. German Botanist 1838 Concluded that all plants are made of cells Theodor Schwann n n 1838 Concluded that all animals are made of cells

Cell History n Rudolf Virchow 1855, German Physician n New cells could be produced only from the division of existing cells The combined work of Schleiden, Schwann, and Virchow make up the modern CELL THEORY. n n

The Cell Theory states that: 1. All organisms are composed of cells. 2. Cells are the basic units of structure and function in all organisms. 3. All cells arise from other cells.

Variety of Cells n n n Single-celled bacteria are the smallest. The largest cell is the ostrich egg. Cells exist in a variety of shapes. Structure is closely related to function. All cells contain a cell membrane, cytoplasm and genetic material.

Prokaryotic Cells n Prokaryotic cells lack membrane-bound organelles. n Single-celled n Bacteria

Eukaryotic Cells n n n Eukaryotic cells contain membranebound organelles. Single-celled or multicellular. Protists, fungi, plants and animals.

Compare and Contrast Prokaryotes Eukaryotes Nucleus Endoplasmic reticulum Cell membrane Golgi apparatus Contain DNA Lysosomes Ribosomes Vacuoles Cytoplasm Mitochondria Cytoskeleton

Cell Membrane—security gate n n Also called the plasma membrane Encloses a cell and separates its contents from its surroundings. Phospholipid bilayer embedded with proteins. Structure allows for the passage of materials into and out of the cell.

DNA and Chromosomes n n All cells contain DNA, the hereditary material. The DNA of eukaryotic cells is organized into chromosomes and contained in a nucleus. n n The DNA of prokaryotic cells is circular. It is found within the cytoplasm.

Ribosomes—assembly line workers n n Since DNA encodes for the formation of proteins, both eukaryotic and prokaryotic cells contain ribosomes. Ribosomes are the sites of protein synthesis.

Cell Wall—security fence n n n Functions to protect and support the cell. Prokaryotes, plants, fungi and some protists Cellulose – Plants Chitin – Fungi Peptidoglycan - Bacteria

Membrane-Bound Organelles n n n Tiny structures that perform specialized functions in the cell. Found in eukaryotic cells only. Work together like departments in a factory.

The Nucleus—manager n n n Contains the DNA that directs all of the activities of a living eukaryotic cell. Often the largest and most easily seen organelle. Many nuclei exhibit a darker area called the nucleolus, which is a region where ribosomes are made.

Endoplasmic Reticulum— transport system n n Series of membranes Function as the cell’s internal transport system. Smooth ER—important role in building lipids Rough ER—has ribosomes attached to it

Golgi Apparatus—shipping department n Responsible for the storage and packaging of chemicals that are eventually secreted from the cell.

Lysosomes—recycling center n n Loaded with strong enzymes Digest large particles found in the cell

Mitochondria—power station n n Release energy from the nutrients taken into the cell Composed of a series of two membranes, which greatly increases the internal surface area.

The Vacuole—storage area n n n Bubble-like organelles Store water, waste materials or food particles Many plant cells contain a large, central vacuole.

Chloroplasts--cooks n n Contain the green pigment, chlorophyll Sites of photosynthesis, or food production, in plants and algae

Cytoskeleton—interior walls n Network of protein fibers that reinforce the cytoplasm of eukaryotic cells n Support and shape cell n Anchor organelles to fixed locations

Centrioles—assembly line worker n n Function during cell division Move chromosomes

Section 7 -2 Plant vs. Animal Cell

Venn Diagrams Compare and Contrast Animal Cells Centrioles Plant Cells Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Wall Chloroplasts Large Central Vacuole