Cells All living things are made up of cells. They are the basic units of structure and function in all living things.

Introduction to Cells

Living things can be Unicellular: -An organism made of only one cell -examples: amoeba, paramecium, bacteria Paramecium Amoebas Bacteria

Single-Celled Organisms

Or multicellular… -An organism made up of more than one cell, having various functions -example: animals, plants, fungus

Many-celled organisms

Animal vs. Plant Cells

The 2 main types of cells are: 1. Animals Cells

AND 2. Plant Cells

Cell Structure Most cells have three basic structures in common: 1. Cell membrane 2. Cytoplasm 3. Nucleus (Chromosomes/DNA)

Cell Membrane & Cell Wall

Cell Membrane Function: 1. To hold the cell together 2. Controls what goes in & out of the cell 3. Keeps cell’s contents separate from external environment

Cell Membrane Composition: Lipid Bilayer- Made of phospholipids

Hydrophilic: “Water loving” Hydrophobic: “Water hating”

Cell Wall 1. Pectin Layer: Outer 2. Primary Cell Wall: Middle 3. Secondary Cell Wall: Inner

Nucleus Instructions for cell function command center... Prokaryotes: No nucleus (bacteria)

Eukaryotes: Have a nucleus (all other cells) 1. Nuclear envelope: Pourous membrane that surrounds the nucleus 2. DNA: Deoxyribonucleic Acid-instructions for cell activity (located in the Nucleolus)

Cytoplasm A mix of protein, water & other particles -> organelles suspended in it Function: Where cell’s activity takes place.

Organelles within the Cytoplasm: 1. Energy Factories A. Mitochondria: Power-house of cell Function: Inner & Outer membrane breaks down food molecules so that cell can get energy (in the form of Glucose)

Mitochondria

B. Chloroplasts: Only found in plant cells Function: Stores chlorophyll used for photosynthesis

Chloroplasts

2. Ribosomes: Tiny structures floating in cytoplasm or attached to Rough ER Function: the place where protein is synthesized (made) with the help of mRNA (messenger RNA is formed in the nucleus)

Ribosomes

3. Endoplasmic Reticulum (ER): Network of membranes attached to nucleus. Function: A. Smooth ER: Creates steroids, collects and stores ions to keep correct levels of nutrients in the cell. B. Rough ER: Collects proteins, creates a bubble around them (vesicle), sends them to golgi apparatus or through cell membrane.

4. Golgi Apparatus: Made up of a stack of flattened out sacs (like pancakes) Function: -Collects vesicles from Rough ER… Takes the simple molecules and combines them together to make larger molecules, then packages them into packs called Golgi vesicles for exportation and lysosomes.

5. Lysosomes: Vesicles that Hold enzymes to break down food & old organelles.

6. Vacuoles: Bubbles that hold waste & food (larger in plant cells because it helps support cell wall). Function: to store and transport waste & food within the cell.

7. Cytoskeleton: Made up of proteins, can change their shape to move cell. A. Microtubules: help maintain shape, thicker than microfilaments & more abundant B. Microfilaments: helps maintain shape also, found in muscle cells… pulls & releases for relax and contracting of muscle.

Movement of materials through the Cell Membrane

Passive Transport 1. Diffusion: Molecules move from area of higher concentration to area of lower concentration while trying to reach equilibrium. 2. Osmosis: Movement of WATER through membrane to obtain equilibrium.

Facilitated Diffusion: Large molecules move through large proteins located in the membrane.

Active Transport 1. Phagocytosis: taking in “food” molecules from the external environment by pinching off cell membrane to create a vacuole. 2. Pinocytosis: taking in liquids by the same method as above. Endocytosis-

pinocytosis

Phagocytosis

* White blood cells use endocytosis to engulf harmful bacteria in our blood stream...

Exocytosis: 4. Exocytosis: Opposite of phago & pinocytosis- process of expelling waste molecules.

Levels of Organization Types of cells: 1. Muscle Cells-smooth cells, found in cardiac muscles, digestive, urinary, reproductive, and skeletal muscles as well as veins and arteries.

2. Nerve Cells: Axon, dendrite, body

3. Blood Cells: Red & White

4. Sex Cells: Sperm & Ovum

5. Epithelial: lining of organs, body cavities & skin

B. Tissues Similar kinds of cells that work together to perform the same function. Types of Tissue: 1. Epithelial3. Muscle 2. Nervous4. Skeletal

C. Organs A structure in the body made up of several types of tissues that work together to perform a particular task. Example: heart, skin, intestines, kidney, brain, etc.

D. Organ Systems Groups of organs working together to perform a specific task. Example: circulatory, nervous, reproductive, lymphatic, etc.

The highest level of organization is an ORGANISM: several organ systems working together to achieve homeostasis (balance).