The Cell Mr. Ramos

Introduction to Cells The cell is life’s basic unit of structure and function. The cell is the smallest unit of living material that can carry out all the activities necessary for life. Two types of cells known: Eukaryotic and Prokaryotic Plant Cell

“Omnis Cellula e Cellula” Rudolf Virchow The Cell Theory All living things are composed of cells. Cells are the basic unit of structure and function in living things. New cells are produced from existing cells. “Omnis Cellula e Cellula” Rudolf Virchow

Pioneers of Microbiology Anton Van Leeuwenhoek: Father of microscopy and microbiology Built first practical microscope First to see & describe bacteria, yeast, & organisms in water. Robert Hooke: English father of microscopy Looked at a thin slice of cork under a microscope & noticed chambers, which he called “cells.”

The Compound Light Microscope A compound light microscope uses multiple lenses The nosepiece can holds 3 or 4 objective lenses with the power 4x, 10x, 40x, & 100x Total magnification (power): ocular lens X objective lens. 10x X 40x = 400x

Confocal Light Microscope Confocal Light Microscopes can observe living cells in 2D by scanning them with a laser beam.

Only for nonliving, preserved cells and tissues Electron Microscopes Electron Microscopes use beams of electrons to see things smaller than cells, such as cell membranes, chromosomes, organelles, and more. Transmission Electron Microscope (TEM): can see the internal structure of cells (e.g. organelles) Scanning Electron Microscope (SEM): can see the full details of the 3D surface of a specimen

Eukaryotes vs. Prokaryotes Eukaryotic Cells Prokaryotic Cells Nucleus Yes No Organelles Ribosomes DNA Size Generally bigger than prokaryotes Generally smaller than eukaryotes Examples Animal cells, Plant cells, Fungi, Protists Bacteria and Archaea

Prokaryotes No nucleus No membrane bound organelles Have DNA No membrane bound organelles Have a plasma membrane Most have a cell wall Have ribosomes Smaller size Bacteria Archaea

Eukaryotic Parts and Functions Organelles are little organs. Nucleus: cell’s command center (home of DNA) Nucleolus: ribosomal RNA is assembled (rRNA) Cytoplasm: area outside of the nucleus where the organelles are found Plasma Membrane: the cell membrane regulates what goes in and out of the cell Rough Endoplasmic Reticulum (RER): contains ribosomes & synthesizes proteins for cells to export Smooth Endoplasmic Reticulum (SER): does not contain ribosomes and is used to synthesize fats and detoxification of drugs

Eukaryotic Parts and Functions

Eukaryotic Parts and Functions Ribosomes: factories for making proteins Golgi Apparatus: modify, sort, and package proteins made in the rough endoplasmic reticulum. Mitochondria: makes energy for the cell & contains its own DNA Lysosomes: digest old organelles, macromolecules, and remove junk from the cell. Vacuoles: store materials, such as water, salts, proteins, and carbohydrates. They are like a closet or kitchen cabinet. Chloroplasts: converts sunlight into chemical energy & contains its own DNA

Eukaryotic Parts and Functions

Eukaryotic Cells: Plant Cell & Animal Cells Plant and animal cells are both eukaryotic cells. They contain a nucleus & most of the same organelles. Differences: Plants have a cell wall. Plants have chloroplasts. Plants have a large vacuole. Plants do not have centrioles.

Plant Cell vs. Animal Cell

Cell Membrane The cell membrane controls what goes into and out of a cell. All cells have a cell membrane. It is composed of two layers of phospholipids. phospholipid bilayer Cell membranes may also contain proteins & carbohydrates. Fluid Mosaic Model

Cell Wall Some eukaryotic cells and some prokaryotic cells have cell walls. Plants, fungi, algae, and prokaryotes (bacteria & archaea) Cell walls provide support and protection Plant cell walls are made of cellulose. Fungi cell walls are made of chitin.

Cytoskeleton The cytoskeleton is the skeleton of the cell Microtubules, Intermediate Filaments, & Microfilaments Microtubules contain the protein tubulin & they participate in cell division & cell movement Examples: Centrioles, Cilia & Flagella Microfilaments contain the protein actin and are found in muscle cells. They also support cells & help them move.

Cilia and Flagella Microtubules make up cilia and flagella.

Cell Transportation Cells need to get things in and out How things get in and out: Semipermeability of the cell membrane The size and charge of the particles Lipid molecules can easily go through the cell membrane Water may also go through the cell membrane, but not as easily as lipids.

Passive Transport: Diffusion Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. Diffusion does not use energy Passive Transport

Passive Transport: Osmosis Osmosis is the diffusion of water from an area of higher water concentration to an area of lower water concentration. In osmosis, it is water that moves, not the particles. Osmosis does not use energy Passive Transport

Active Transport Active transport requires energy. Movement from a lower concentration to a higher concentration Note: this is the opposite of diffusion & osmosis

Endocytosis and Exocytosis Endocytosis involves bringing things into the cell. Phagocytosis: cell eating Pinocytosis: cell drinking Receptor-mediated endocytosis: brings materials in along with cell receptors. Exocytosis involves taking things out of the cell. These terms are only used for larger molecules that cannot get in or out of the cell through diffusion or osmosis

Endocytosis & Exocytosis