Cells And Their Organelles Biology Mr. Plazak

Intro

Discovery of the Cell 1665 - Robert Hooke examines a thin slice of cork with a microscope. He observes “a great many little boxes.” The first man to see dead cells. Notices that these little boxes look like jail cells – thus the name: CELL.

…more Discovery… 1673 – Anton van Leeuwenhook observes first living cells; called them animalcules. First to develop a “modern day” microscope: more of a hand lens and he even used water as a magnifier.

The Cell Theory The Cell Theory has three main parts. 1. All living things are composed of one or more cells. 2. Cells are the basic units of structure and function in living organisms. 3. Cells only come from the reproduction of existing cells.

Spontaneous Generation The cell theory (#3) also helps disprove the idea of Spontaneous Generation: living things (insects) can come from non-living things. Francesco Redi’s meat jars and flies experiment.

The Different Cells Eukaryotic Cells – have a nucleus and specialized organelles. Prokaryotic Cells – cells that do NOT contain a nucleus nor do they have organelles. DNA is free floating.

Prokaryotes Very primitive cells. DO NOT have a nucleus. All are bacteria. Use flagella/cilia for mobility and locomotion. DNA is free floating – gooey. First living things on earth.

Prokaryotes Pieces and Parts Has a cell membrane. Some have cell walls. Prokaryotes are so unique that they are in their own kingdom: Monera

Eukaryotic Cells and Their Size Why are cells so small? ****Cells are small because of their surface area – HAVE to exchange “stuff” with their environment.**** Cells take materials in and expel wastes – must be small or will starve or suffocate. ALL materials enter/exit through cell membrane.

Eukaryotic Cells Organelle – cell component that performs specific functions for the cell. Cell Membrane – entire cell is surrounded by a thin “layer” membrane….skin? The cell membrane is said to be selectively permeable - which means that some substances can cross easily, while others cannot cross the membrane at all.

Mitochondria Produce ATP. ATP is a molecule cells use for energy. Contain their own DNA. Numerous in cell. AKA Powerhouse of the cell.

Mitochondria Theory? Mitochondria are/were a key component to the Theory of Evolution. Evidence has led scientists to believe that a cell engulfed a mitochondria, didn’t digest it, and kept it inside of it. Cell then used mitochondria to make energy (ATP).

Ribosomes Most numerous organelle in most cells. Some ribosomes are free floating. Others are attached to the Endoplasmic Reticulum – the Rough E.R. Synthesize (Make) proteins!!!!!!! Proteins used in cytoplasm – made by free ribos. – Proteins put into membranes – E.R

Endoplasmic Reticulum AKA the E.R System of a series of membranes – an intracellular highway – molecules move from one part of cell to another. Rough E.R – ribosomes are attached to ER – in cells that make large amounts of proteins. Smooth E.R – no ribosomes on this E.R

Rough ER

Golgi Apparatus Associated with E.R – membranes Modifies proteins for export OUT of cell. Processes, packages and secretes for cell.

Golgi Apparatus

Cilia and Flagella Hair-like organelles that extend from surface of cell. Cilia are short – many. Flagellum are less numerous and longer…whipping mvmnt. Made of microtubules.

Lysosomes These are small, spherical organelles that contain digestive enzymes. Lysosomes can digest proteins, carbohydrates, DNA and RNA. Common in animal, fungal and protists but not in plants. Digest old organelles, VIRUS and bacteria.

Cytoskeleton Cytoskeleton maintains shape of cell just like  Network of long protein strands – helps cell move. Two major components Micofilaments MF Microtubules MT

The Nucleus Usually the most visible. Surrounded by a membrane – nuclear envelope. Chromatin is found inside DNA + Proteins. Stores heredity – your genes  DNA!! Nucleolus – dark spot – ribosomes are synthesized.

The Nucleus

The Plant Cell Very similar to the animal cells Plant cells have a cell wall Cell wall provide support and protection for the internal organelles Cell wall DOES have pores to allow for “stuff” to come in and out – cell membrane Distinguishing characteristic

Vacuoles Fluid – filled organelles store enzymes and wastes Usually quite large, can take up 90% of cell Sometimes stores toxic materials

Chloroplasts Contain their own DNA Convert sunlight into chemical energy Contain chlorophyll Is green

Chloroplast Theory ? Scientists are convinced that chloroplasts, like mitochondria, were once free living organisms. Evidence: Make their own “food” and they have DNA inside  could survive on their own.

Animal Cell

Prokaryotic Cell