Cell Structure and Function

The Discovery of the Cell Robert Hooke – first to see and identify cork “cells” using a microscope. www.nerdscience.com 7-1

The Cell Theory Cell Theory: All living things are made of one or more cells. Cells are the smallest unit of life. New cells are produced from pre-existing cells. Schleiden Schwann Virchow www.nerdscience.com 7-1

Basic Cell Substances The main ingredient of any cell is water. The structure of a water molecule makes it ideal for dissolving many other substances

Macromolecules Macromolecules form when many small molecules join The 4 types of macromolecules are: Nucleic acids- form when long chains of nucleotides join. Important because they contain genetic information Ex: DNA and RNA

Macromolecules 4. Proteins- Necessary for nearly everything cells do Made up of long chains of molecules called amino acids. Some help break down nutrient in food 3. Lipids- large molecule that does not dissolve in water Store energy Plays an important role as protective barriers in cells (membranes)

Macromolecules 4. Carbohydrates- Made up of one or more sugar molecules Store energy Provide structural support Used for communication between cells

Prokaryotes and Eukaryotes Cells can be grouped into 2 types: Prokaryotes – cells that do not contain nuclei. Ex: (Bacteria) Eukaryotes – cells that contain nuclei and have membrane-surrounded components called organelles which have specialized functions Ex: plants, animals, fungi, protist

Eukaryotic Cell Structure Organelles – structures in a cell that act like “little organs.” Cytoplasm – the jelly-like fluid where the organelles “float.” It contains salts and other molecules

The Nucleus Nucleus – large membrane-enclosed structure that contains the cell’s genetic information and directs cell activities Nuclear Envelope – membrane that surrounds the nucleus. Nuclear Envelope

Mitochondria Mitochondria – converts chemical energy stored in food into energy(ATP). “Powerhouse of the Cell!” Converts glucose and oxygen into ATP, Carbon Dioxide (CO2) and Water (Cellular Respiration) ATP- the fuel for cellular processes such as growth, cell division, and material transport www.nerdscience.com

Mitochondria Mitochondria

Ribosomes Ribosomes – Make Proteins! Found in a cells cytoplasm or attached to the endoplasmic reticulum (E.R) Ribosome

Endoplasmic Reticulum (ER) Endoplasmic reticulum –transports proteins to the Golgi apparatus and breaks down toxic material. Rough ER – has ribosomes Smooth ER – no ribosomes

Endoplasmic Reticulum (ER) Rough ER Smooth ER

Golgi Apparatus Golgi Apparatus (Golgi bodies)- prepares proteins and packages them into ball-like structures called vesicles Golgi Apparatus

Lysosomes Lysosomes – small organelles filled with enzymes that help recycle cellular components

Vacuoles Vacuoles – store food, water, and waste material Animal cells have small vacuoles Plant cells have large Central Vacuoles Vacuoles

Chloroplasts Chloroplasts – organelles that capture energy from sunlight and convert it into chemical energy. (Photosynthesis) Found only in plants. Chloroplast

Cytoskeleton Cytoskeleton – made of a network of threadlike proteins that are jointed to form a framework inside a cell. helps cell to maintain shape, move, and move organelles.

Cell Boundaries Cell membrane – thin, flexible membrane that surrounds the cell and protects the inside of a cell from the environment outside. Controls what enters and leaves the cell. Made of phospholipids (2 layers) and proteins. Two layers!

Cell Boundaries Cell wall – rigid layer around the membrane that provides structure and support. found only in bacteria, fungi and plants.

Cell Appendages Cell appendages are often used for movement. Flagella- long, tail- like appendage that whip back and forth and move a cell. Cilia- short hair like structures that can move a cell or move molecules away from a cell.

Moving Cellular Material

The exchange of materials between as cell and its environment takes place at the cell membrane. A cell membrane is semipermeable- it allows only certain substance to enter or leave a cell

Passive Transport Passive transport – the movement of substances through a cell membrane without using the cell’s energy Diffusion – movement of particles from an area of high to low concentration. Diffusion continues until the concentration of a substance is the same on both sides of a membrane. Osmosis – the diffusion of water through a membrane.

Osmosis Practice 90% H2O 10% NaCl Cell Concentrations are equal, so no net movement of water! 90% H2O 10% NaCl www.nerdscience.com 7-3

Osmosis Practice 80% H2O 20% NaCl Cell Concentration of water is greater in the cell than out, so water will move out! 90% H2O 10% NaCl www.nerdscience.com www.nerdscience.com

Osmosis Practice 90% H2O 10% NaCl Cell Concentration of water is greater outside the cell than in, so water will move In! 80% H2O 20% NaCl www.nerdscience.com 7-3

Active Transport 2. Active Transport- The movement of materials across a cell membrane with the use of energy Moves substances from areas of low concentration to areas oh high concentration Exocytosis – a cell’s vesicles releases their contents outside of the cell. Endocytosis – the cell surrounds a large particle and brings it into the cell

Cell Size and Transport For a cell to survive, its surface area must be large compared to its volume. As a cell grows, its volume increases faster than its surface area

Cells & Energy

CELLULAR RESPIRATION All living things need energy to survive Cellular Respiration – converts the energy in food molecules into a usable form of energy called ATP

CELLULAR RESPIRATION Step 1: Glycolysis- occurs in the cytoplasm of all cells Glucose is broken down into smaller molecules Step 2: Occurs in the mitochondria of Eukaryotic cells and requires oxygen Small molecules made during glycolysis are broken down Large amounts of usable energy called ATP are produced Water and Carbon Dioxide is given off

CELLULAR RESPIRATION www.nerdscience.com 7-3

FERMENTATION C6H1206 ATP + Lactic Acid C6H1206 ATP + Alcohol + CO2 Eukaryotic and prokaryotic cells use fermentation to obtain energy from foods when oxygen levels are low. It occurs in the cell’s cytoplasm Lactic- acid fermentation- Occurs in muscles C6H1206 ATP + Lactic Acid (Glucose) (energy) Some types of bacteria and yeasts make ATP during alcohol fermentation. C6H1206 ATP + Alcohol + CO2 (Glucose) (energy)

PHOTOSYNTHESIS Plants and some unicellular organisms obtain energy from light (radiant energy) Photosynthesis is a series of chemical reactions that converts light energy into chemical energy (Glucose)

PHOTOSYNTHESIS In plants light energy is absorbed by pigments called chlorophyll Photosynthesis occurs in the chloroplasts Uses CO2 that is released during cellular respiration to make food energy and release oxygen.