Cell Structure and Function CHAPTER 7 Cell Structure and Function

7-1 Life is Cellular In 1665, English Physicist Robert Hooke used one of the first light microscopes to look at plant tissue. - he looked at cork. - he called the tiny chambers he saw “cells”

CELL THEORY Other biologists made further cell discoveries and came up with statements about cells. The Cell Theory is a fundamental concept of Biology. - The cell theory states the following: 1. All living things are composed of cells. 2. Cells are the basic units of structure and function in living things. 3. New cells are produced from existing cells.

Prokaryotes and Eukaryotes Biologists divide cells into two categories: eukaryotes and prokaryotes. - Eukaryotes, have a nucleus - Prokaryotes, no nucleus

Cell Structure Chapter 7 Sec 2

Cell Walls Found in plants, algae, fungi, and most prokaryotes. Main function is to provide support and protection to the cell. Made of fibers of carbohydrates called cellulose.

Nucleus Founded in 1831 by Scottish botonist Robert Brown Controls most cell processes Contains DNA Holds the coded info for making proteins and other required molecules Chromatin is visible in the nucleus Chromatin is DNA bound to protein During cell division, chromosomes form when chromatin condenses. Chromosomes hold genetic info which pass from one generation to another

The nucleolus, a small dense region, is also found in most nuclei. Ribosomes’ assembly begins in the nucleolus. The nuclear envelope is the double membrane layer which surrounds the nucleus.

Cytoskeleton The cytoskeleton is a network of protein filaments to support cell shape. Also aids in cell movement. Made up of microtubules and microfilaments. Microtubules are hollow tubes of protein. They give cell shape, and work as tracks for organelle movement. Microfilaments are long, thin fibers that function in support and movement of the cell.

Ribosomes Ribosomes are small particles made of RNA (ribonucleic acid) and protein. Proteins are assembled on ribosomes. 2 Types of ribosomes: 1. attached ribosomes 2. free ribosomes

Endoplasmic Reticulum (ER) Found in Eukaryotic cells It is an internal membrane structure. The ER assembles components of the cell membrane and modifies some proteins. Rough ER is involved in the synthesis of proteins. Smooth ER does not have ribosomes on its surface.

Golgi Apparatus Proteins from the rough ER move into the stack of membranes known as the golgi apparatus. Enzymes in the golgi apparatus attach carbs and lipids to proteins. From the golgi apparatus, proteins are sent to their final destination.

Lysosomes Lysosomes are small organelles filled with enzymes. Break down lipids, carbs, and proteins from food.

Vacuoles Vacuoles store materials such as water, salts, proteins, and carbs.

Chloroplasts Found in plants Uses energy from the sun to complete the process of photosynthesis

Mitochondria Release energy from stored food molecules Uses energy from food to make high energy compounds Energy produced is used to power growth, development, and movement. Known as the “power house” of the cell

Organelle DNA Chloroplasts and mitochondria contain some of their own genetic information in the form of DNA Biologist Lynn Margulis suggested mitochondria and chloroplasts are decendants of ancient prokaryotes In humans, all of our mitochondria come from the cytoplasm of the egg cell….thank you Mom!

The Cell as a Factory The way proteins are made in a cell is similar to the way products are made in a factory: Cell membrane -Mitochondria Cell wall -Chloroplasts Nucleus -Cytoskeleton Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles

Comparing Cells Prokaryotes have cell membranes but no nuclei Eukaryotes are much larger than prokaryotes and contain nuclei Eukaryotes have specialized organelles Plant cells (eukaryotes) contain large vacuoles, cell walls, and chloroplasts Animal cells (eukaryotes) do not have cell walls or chloroplasts