Cell Structure and Function Life Science

Two Categories of Cells: Prokaryotes: Small and simple cells Do NOT contain a nucleus Do NOT contain organelles All bacteria are prokaryotes Eukaryotes: Large and complex cells Contain a nucleus Contain organelles Animals, plants, fungi, etc.

Cell Structures

Prokaryotic Cell

Plant Cell

Animal Cell

Don’t forget that all cells have all these things!!! Cell membrane Cytoplasm Genetic material (almost all contain DNA) Have ribosomes, sites of protein synthesis (dehydration synthesis happens here!)

Cell Membrane Structure: Functions Phospholipid bilayer with proteins and carbohydrates Functions Thin, flexible barrier Separates cell from surroundings Regulates molecules into/out of cell (food, water, wastes, etc.) Selectively Permeable

Cell Wall Structure: Made of cellulose (a carbohydrate) and proteins Rigid wall outside of cell membrane Only in plants Function: Support and protect Allows water, oxygen, carbon dioxide and other substances to pass through * Found only in plant, fungi, and algae cells, NOT in animals

Nucleus Function: Components (Structure) Stores DNA (chromatin), hereditary info for cell Controls cell activities Components (Structure) Nuclear Envelope: bilayer lipid membrane that surrounds nucleus and has pores or holes to allow materials to move in/out of nucleus Nucleolus: Small dense region that makes ribosomes

Cytoskeleton Structure: Function: Network of long protein strands called microfilaments and microtubules Function: Microtubules: movement inside cells Microfilaments: Maintain shape and size of cell

Ribosomes Structure: Function: Most numerous organelle Made of RNA and protein Function: Synthesis of Proteins (make proteins)

Endoplasmic Reticulum (ER) Structure: Internal membrane system Stacks of flattened sacs Rough: has ribosomes- gives a bumpy appearance Smooth: no ribosomes- looks smooth Function: Intracellular highway—moves molecules around the cell Rough: prepares and sends proteins to Golgi for export Smooth: synthesizes lipids and cell membrane parts, detox (breaks down drugs and toxins)

Golgi Apparatus Structure: Function: Stacks of flattened membranes Processing, packaging, and secreting proteins Send proteins to their final destinations Works with Rough ER

Lysosome Structure: Function: Small sac which contains enzymes Not in plants Function: Breaks down food: digest proteins, carbs, and lipids, DNA or RNA in cell Removes debris: digests old organelle or viruses and bacteria

Vacuole Structure: Function: Large sac filled with enzymes, water, and wastes In plants: VERY large – takes up most of cell In animals: small – store extra materials Function: Storage Vesicles: small vacuoles involved in transporting substances within cells

Centrioles Paired cylindrical organelles near the nucleus Structure: composed of bundles of microtubules at right angles to each other Function: involved in cell division

Chloroplast Structure: Function: Saclike structure that contains chlorophyll (a green pigment) Function: Photosynthesis: Changes sunlight energy to organic chemicals (sugars) Found in plants, algae, and some bacteria NOT found in animals

Mitochondria Structure: Function: Has 2 membranes Cristae: folds of the inner membrane—increases surface area Function: “Powerhouse” of the cell Cellular Respiration: releases energy from food molecules to power cell (growth, movement, development, etc.)

Organelle DNA Chloroplasts and mitochondria contain some of their own genetic information or DNA Lynn Margulis – scientist who suggested that mitochondria and chloroplasts are actually descendants of ancient prokaryotes Endosymbiotic Theory – eukaryotic cells formed from a symbiosis among several different prokaryotic organisms

A Cell Is Like A City As a pair, match each structure with the city part that has the same function. Write 1-2 sentences for each structure to explain why you have made this analogy. Cell Membrane – ? Cell Wall – ? Nucleus – ? Ribosome – ? ER – ? Golgi Apparatus – ? Lysosome – ? Vacuole – ? Chloroplast – ? Mitochondrion – ? trucking company power plant recycling center storage company fence surrounding city post office factory border patrol city hall restaurant

A Cell Is Like A City Cell Membrane – Cell Wall – Nucleus – Ribosome – ER – Golgi Apparatus – Lysosome – Vacuole – Chloroplast – Mitochondrion – border patrol fence surrounding the city city hall factory trucking company post office recycling center storage company restaurant power plant