Chapter 7
English scientist who used an early light microscope to study nature. Looked at cork (dead plant cells) under a microscope. He observed small geometric shapes, and named them cells.
Dutch trader that made simple light microscopes. His lenses were 10x more powerful than those that Hooke used. First person to observe living cells
Matthias Schleiden (1838) – all plants are composed of cells. Theodor Schwann (1839) – all animals are composed of cells. Rudolf Virchow – all cells come from other cells. These three observations helped form the cell theory
1. All organisms are composed of one or more cells 2. The cell is the basic unit of organization 3. All cells come from preexisting cells
Compound Light Microscope Electron Microscope Use a series of lenses to magnify objects. Magnify up to 1500x Uses a beam of electrons to magnify objects Magnify up to 500,000x their actual size Scanning electron (SEM) Transmission electron (TEM)
Prokaryotes – cells that do not have internal membrane-bound structures or a nucleus ex. Bacteria Eukaryotes – cells that have a nucleus and membrane-bound structures. ex. Animal cells and plant cells - the membrane-bound structures are called organelles
Prokaryotic CellEukaryotic Cell
The boundary between the cell and its environment. Controls what enters and exits the cell (selective permeability) - nutrients, wastes Cells, like our bodies, like constant environment. The process of maintaining this environment is called homeostasis.
Has two layers of phospholipids back-to-back (phospholipid bilayer) - polar heads face out (like water) - nonpolar tails face in (hate water) Cholesterol – helps stabilize the phospholipids (stops it from sticking together) Transport proteins – regulate which molecules enter and leave the cell. Carbohydrate chains – stick out from cell surface and helps cells identify each other.
Control center of the cell (contains directions to make proteins) Master set of directions for making proteins is contained in chromatin (strands of DNA) Inside the nucleus is another organelle called the nucleolus (makes ribosomes) Ribosomes exit through nuclear pores
Cytoplasm – clear fluid inside the cell Endoplasmic Reticulum (ER) – site of cellular chemical reactions - Rough ER (has ribosomes attached) - Smooth ER (no ribosomes) Golgi apparatus – modifies and packages proteins
Vacuoles – temporary storage of materials (food, enzymes, waste) Lysosomes – digest excess or worn out organelles, food particles, and engulfed viruses and bacteria Mitochondria – produce energy for the cell
Cytoskeleton – cells support structure made of microtubulues and micro- filaments. Cilia – short, hair-like projections that aid in movement and feeding Flagella – longer projections that move with a whip-like motion (movement)
Animal CellPlant Cell Centriole (only animal cells) Cell Wall Chloroplasts Large Vacuole