Ch. 4 CellsCh. 4 Cells

Chapter 4 Cells

There are 100 trillion cells in the There are 100 trillion cells in the human bodyhuman body

A cell is a basic unit of life, and is the A cell is a basic unit of life, and is the smallest of all organismssmallest of all organisms

We need a microscope to see cellsWe need a microscope to see cells

-Many contributions to the cell were made by:

– Robert Hook– Robert Brown– Mathias Schleiden– Theodor Schwann– Rudolf Virchow– Anton van Leeuwenhoek- 1st

microscope

Cell TheoryCell Theory (3 parts) (3 parts)

1. all living things are composed of cells.1. all living things are composed of cells.

2. cells are basic unit of structure in living 2. cells are basic unit of structure in living thingsthings

3. all cells come from pre-existing cells.3. all cells come from pre-existing cells.

Cell Structure

• Cell Membrane is made up of lipids and proteins.

– It is selectively permeable and made of 2 layers. (lipid bilayer)

• Cell Wall (in plants) is around the outside and protects the cell.

• Organelles: perform a specific function.

– Nucleus: is the control center, or brain of cell

• Prokaryotes are: cells with no nucleus

• Eukaryotes are cells with a nucleus

• Nuclear Envelope surrounds the nucleus

• Nucleolus: in the nucleus. It produces ribosomes.

• Chromatin is: strands of DNA and protein

• Chromosomes are: densely packed, contain DNA and Protein for heredity.

• -Cytoplasm is located: within the cell membrane. Contains all the minerals, gases, and organelles.

• -Mitochondria: the power house of the cell. Provides energy to function.

• -Chloroplasts: (plants) trap energy from sun for plant to use.

• -Ribosomes: The site of protein synthesis

• Endoplasmic Reticulum (ER): passageway for transport of materials

– Smooth ER: synthesizes and regulates

– Rough ER: prepares proteins for export

• Golgi Apparatus: the post office. Prepares, and packs for secretion. Also Carb. Synthesis

• Lysosomes: Clean up crew. Has enzymes to digest.

• -Vacuoles: (plant) Storage of starch

• -Plastids: (plant) store food and pigments

• -Cilia: hair-like projection to sweep materials across and away from the cell

• -Flagella: whip like tail for motility.

• The level of Organization is:

• Cells

• Tissues

• Organs

• Organ Systems

• Organism

Cell Movement

• -Passive Transport

-Diffusion is: movement of molecules from greater concentration to lower conc.

example: oxygen in alveoli to the blood

Carbon dioxide in blood to the alveoli

* Some examples of diffusion in the body are:

-Equilibrium:

-Hypotonic solution: solutions with salt conc. Lower than cell.

-Hypertonic solution: conc. Higher than cells

-Isotonic solution: conc. are equal.

• Osmosis: diffusion of water through a selectively permeable membrane.

example: small intestines and kidneys

• Facilitated Diffusion: uses a carrier protein to move

• Molecules move through membrane from higher to lower concentration, but need help to do so.

• Example: The diffusion of glucose requires a Carrier Enzyme to bond to the glucose, making it soluble.

• Active Transport: ATP used to move a substance from an area of lesser conc. To an area of greater conc.

• Ex:-Sodium Potassium Pump

• -Endocytosis: cells ingest fluid

– Pinocytosis: When a stationary cell engulfs

something. Ex: cells in kidneys

– Phagocytosis: When a moving cell engulfs something. Ex: WBC in blood engulf bacteria

• -Exocytosis: The release of materials out of the cell.

• Filtration:

– Water and dissolved materials are forced through a membrane from higher to lower pressure.

– example: blood in tissues is forced through capillaries.