CELLS Building Blocks of Life 7 th Grade

Cells the building blocks of life 1. 2. Cells are the smallest unit of living things that carry out all the activities of life. There are three parts of cell theory.

Cells the building blocks of life n The existence of cells was not known until 1665. What invention made their discovery possible?

Robert Hooke 1665 Built early microscope

Cork to “cells” n n Hooke looked at cork bark. The plant cell walls reminded him of monk “cells”, tiny rooms where monks sleep.

Cork Cells Monk Cells

Hooke’s book was Micrographia n Best seller n Contained his drawings

The Microscope is improved! Van Leeuwenhoek improved on the microscope. He observed and described small pond organisms.

“Animolecules”

Cell theory comes together Part 1 All living things are composed of one or more cells n Mathias Schleiden realized that all plants contain cells.

Cell theory comes together Part 2 The cell is the basic unit of life in all living things. n Theodor Schwann developed this idea in 1839 looking at animal cells

Cell theory comes together Part 3 All cells come from existing cells. Developed by Rudolf Virchow in 1858

Francesco Redi scientist) n Disproved the idea of spontaneous generation in the 1600’s by showing that maggots come from flies. Covered jars with gauze, lids and uncovered. (Italian

KINDS OF CELLS n There are two major ways scientists classify cells. Prokaryotic Very simple cells Bacteria are examples They do not have a NUCLEUS “Pro”- ahead of “karyote” nucleus

KINDS OF CELLS Eukaryotic Cells “Eu” New or true “Karyote” nucleus More complex cells These cells have a nucleus and many smaller organelles Two major types: Animal and Plant

Notice: These cells have a nucleus and many other small “organelles”. They are much more complex

Parts of a cell Organelles n n n Cells are composed of many smaller units called “organelles”. Each organelle has a specific function in keeping the cell alive and working. Organelle means “small organ”

Organelles Holding it all together Cell Membrane n n Cell Membrane Found in both animals and plants. Provides structure around the cell. The membrane does allow materials to move in and out.

Organelles Holding it all together Cell Wall n n Cell Wall Found ONLY in plants and plant like one celled organisms. Found OUTSIDE the cell membrane. Provides structure for the plant.

This is a piece of Algae. Notice the cell wall is clear.

Parts of a cell Cytoplasm n n Cytoplasm Thick, gel like substance that provides support for all the organelles

Organelles The Brains: Nucleus n n n The nucleus of the cell contains DNA. The nucleus directs and controls all functions of the cell. Think of the nucleus as a “brain” directing everything.

Nucleus

Organelles Ribosomes: Protein Factories n n n Ribosomes are the organelles that make protein. DNA in the nucleus sends instructions. Cells use proteins to reproduce and repair themselves.

Organelles Endoplasmic Reticulum (E. R. ) n n n The highway of the cell. E. R. transport proteins made by the ribosomes to vacuoles for storage or to other places for the cell to use. Often drawn as a curled up ribbon

Endoplasmic reticulum with ribosomes attached is called rough Endoplasmic reticulum without ribosomes is called smooth.

Organelles Mitochondria: Powerhouse n n n Mitochondria Large, oval organelles that are called the “powerhouse” of the cell. Mitochondria break down food and release energy for the cell to use.

Rough Endoplasmic reticulum (E. R. )

Organelle Chloroplasts: From sun to food n n n Chloroplasts are organelles found only plants and plant like single celled organisms. Photosynthesis, converting the sun’s energy into glucose occurs in them. They make the plant green.

Organelles Golgi Complex n n Golgi complex is the organelle that packages proteins for shipment. Looks like a stack of soggy paper plates.

Organelles Vacuole: Storehouse n n Vacuole: The cell’s storeroom. Food, waste, water and other substances are stored. Plant cells generally have 1 large vacuole. Animal cells may have more than one, but they are small.

Large vacuole in plant cell. Also seen are the nucleus and chloroplasts.

Organelles Lysosome: Packages of Destruction n Lysosomes are small, thick walled organelles that contain powerful chemicals, that the cell uses to break down old parts. Helps cells digest food. Helps the body “kill” foreign cells and viruses.

Flagella are used for movement!

Not all cells are the same! n n Cells become specialized to do their jobs. Living organisms have many different types of cells.

Muscle cells n n n Striated: Skeletal Muscle Cardiac: Found in your heart Smooth: Found lining blood vessels and organs.

Skeletal Muscle

Smooth Muscle

Cardiac Muscle

Nerve Cells n Nerve cells carry electrical impulses throughout the body

Epithelial Cells

Fat Cells n Provide a place to store excess glucose for later use.

Red Blood Cells n n n These cells carry oxygen to all other cells. These cells lose their nucleus and have soft sides so they can squeeze through capillaries. They are round.

White Blood Cell n n These blood cells move around and destroy foreign invaders such as bacteria and viruses. They change their shape to surround and destroy these organisms

White blood cell moving to kill a bacteria cell.

Cell to Organisms n n n Cell Tissue Organ System Organism