Cells Review and Cell Organelles

Review: Two Types of Cells Prokaryotic cells –Have no nucleus –No membrane bound organelles –Evolved 3.5 billion years ago –Examples: Bacteria Eukaryotic cells –Have a nucleus –Membrane bound organelles –Evolved 1.5 billion years ago –Examples: Everything but bacteria

Prokaryotic & Eukaryotic Similarities Both types have: –A cell membrane –Cytoplasm – the liquid part of the cell –Ribosomes – organelles for making proteins

Plants vs. Animals Animal cells are typically rounded Plant cells are typically square or box like Plant cells have a cell wall made of cellulose. –Animal cells DO NOT Plant cells have chloroplasts –Animal cells DO NOT –Site of photosynthesis Convert sun energy  sugars

PRACTICE

Some organelles offer support The cell wall (not in animal cells), cell membrane, cytoplasm, cytoskeleton, and centrioles give the cell structure and shape which allows the other organelles to function properly

Cell Wall Provide protection, rigidity, structure. Never found in animal cells –Can be found in: –bacteria –Plants –Fungi

Cytoplasm Liquid part of the cell Suspends all other organelles Fills entire cell between the nucleus and the membrane

Cytoskeleton Network of fibers throughout the cytoplasm –Microtubules – hollow tubes of protein that give rigidity, shape, and organization –Microfilaments – thin protein rods that allow the cell to move and change shape

Centrioles Centrioles are important in cell division Organize spindles upon which chromosomes are pulled apart

Many organelles are involved in making and processing proteins The nucleus, nuclear envelope, endoplasmic reticulums, ribosomes, golgi apparatus, and vesicles play key roles in protein synthesis The nucleolus, inside the nucleus, plays an indirect role in protein synthesis

Nucleus “Control Center” of the cell Contains most of the cell’s DNA Info stored in the DNA directs activities of the cell DNA attached to certain proteins form long fibers called chromatin. Found inside the cell in the cytoplasm.

Nucleolus Ball like mass of fibers Contains the parts used to make ribosomes (which help build proteins) Found inside the nucleus

Nuclear Envelope Pair of membranes surrounding the nucleus Separates nucleus from remainder of cell Things moving into and out of the nucleus must pass through the nuclear pores found in the envelope.

Endoplasmic Reticulum Extensive network of membranes Located within the cytoplasm Connected to the nuclear envelope “Manufacturing & Transporting” Rough ER and Smooth ER –Two distinct regions –Two distinct functions

Rough ER Gets “Rough” name from ribosomes attached to the surface Ribosomes produce proteins that are immediately inserted into the ER. Proteins are packaged into vesicles.

Smooth ER Builds lipids Storage for proteins Intracellular pathway “Smooth” means no ribosomes on surface

Ribosomes The site for protein synthesis Made of proteins and nucleic acids in the nucleolus Some are bound to endoplasmic reticulum (ER) Some are suspended in the cytoplasm

Golgi apparatus Found in cytoplasm between ER and cell membrane. Modifies, stores, and routes proteins to their next destination. “Shipping & Receiving”

Other organelles have different functions in the cell Lysosomes, vacuoles, mitochondria, and chloroplasts have functions that are not directly related to protein synthesis

Lysosome Membrane bound sacs w/ digestive enzymes Fuse with food vacuoles Digest food Break down other organelles that aren’t working properly w/o killing entire cell.

Vacuole –Large membrane bound sacs in the cytoplasm –Can have several types Can store undigested nutrients, and remove from cell Contractile vacuole – removes excess H2O Central vacuoles – plants; store water, cause cells to expand Food vacuoles – hold food

Mitochondria Site for Cellular respiration –Release of energy (ATP) from sugars

Chloroplast Photosynthetic organelles found in some plants and algae Filled with chlorophyll