Cell Structure and Function

Cell Theory All living organisms are made of cells. Cells are small aqueous solution (cytoplasm) organelles (subcellular structures) “subunit of life!” Cells are of different size and shape Size and shape can be related to its specific function. Called specialized Cells What’s inside the cell? Are there different types of cells?

From Prokaryote to Eukaryote All living things come from a single cell born 3,500 million years ago (mya) – Simple organic molecules likely formed billions of years ago 1.A prokaryote “ate” another prokaryote 2.The inner prokaryote helped the outer prokaryote 3.They lived happily ever after Primordial Cell How did organelles get into simple cells? Endosymbiotic Theory

Prokaryotic Cells Prokaryotic Cells Examples? “Before membrane or nucleus” NO Nucleus Only ribosomes, DNA, and cytoplasm inside Extremely Simple BACTERIA

Examples? Eukaryotic Cells “TRUE membrane or nucleus” Nucleus and membrane bound organelles PRESENT DNA in nucleus Extremely COMPLEX Plants, animals, and Fungi

Unicellular vs. Multicellular Organisms Why unicellular? Why multicellular? Simplicity Quick Reproduction (Asexual) No need for circulatory system Complex Specialized Sexual Reproduction= genetic differences Need a circulatory system to get nutrients

Why don’t we have enormous unicellular organisms wondering around Walmart? It takes to long to get nutrients throughout the cell LAB TIME! Let’s see how the surface to volume ratio affects nutrient supply to the cell.

Outside Covers Plasma/cell Membrane Cell Wall Flexible membrane Phospholipid bilayer Controls what goes in and comes out All Cells! Rigid structure made of cellulose (carbohydrate) holds plants up Extra Protection Plant and bacterial cells (no animals)

Inner structures Nuclear Envelope Nucleus Nucleolus The outside covering of the nucleus Controls all cell activities Hold all genetic information (DNA) ”Brain of the cell” Inside the nucleus makes ribosomes and nucleic acids for the nucleus

Some cells lose their nucleus as they mature Ex/ RBC’s

Ribosomes Make proteins! – Assembled by their instructions in DNA “Ribs” are delicious protein Inner Structures

Cytoplasm Clear jelly-like fluid inside of a cell. Holds organelles in place Multiple chemical reactions take place here. Kept out of nucleus by nuclear envelope. Inner Structures

Endoplasmic Reticulum Folded membrane in the cytoplasm Has large surface area for more chemical reactions. Creates containment vesicles Studded with ribosomes Creates Proteins Smooth ER Rough ER

Golgi Apparatus Closely stacked, flattened membrane sacs Receive newly made proteins and lipids from the ER sends both to the plasma membrane and other organelles throughout the cell.

Vacuole Stores food, enzymes, and other materials needed by a cell. – A small percentage of vacuoles store waste products. – Vacuoles in plants cells are huge! Usually only one. – Animal cells can have many small vacuoles.

Lysosomes Contain digestive enzymes. Digest excess or worn out organelles, food particles, and engulfed viruses or bacteria Their membrane prevents harmful enzymes from pouring into the cytoplasm of the cell. “Everyone wants to get rid of lyce”

Mitochondria food molecules are broken down (glucose) to produce energy. – Shaped like tiny sausages. – Have their own DNA/Ribosomes – Inner membrane forms long, narrow folds called cristae.

Chloroplasts Photosynthesis takes place here Transforms light energy into chemicals to produce food In plants only! green pigment that traps light energy gives plants their green color. In the thylakoid membrane of the chloroplast. **What gives plants their green color** Contain Chlorophyll

Centriole Thick part of the cell membrane where spindles attach Helps in cell reproduction Helps in cell division

Structures for Support Cytoskeleton made of… provide support for organelles and helps the cell maintain its shape. – Microtubules: Thin, hollow cylinders of protein. – Microfilaments: Thin, solid protein fibers.

Structures for Movement “Hair-like projections” that beat together to create movement whip-like tail for motion – major method of locomotion in unicellular organisms. Cilia Flagella