Ch. 7 Cell Structure & Function Unit 3 Cells Ch. 7 Cell Structure & Function

The Discovery of the Cell Robert Hooke used compound light microscope to view cork, a plant material Cork had 1000’s of chambers in it - named the chambers “cells”

The Cell Theory Cells - the basic unit of life Developed the cell theory: All living things are made of cells Cells are the basic units of structure & function in living things New cells are produced from preexisting cells

Exploring the Cell

Prokaryotes & Eukaryotes Cells are in 2 broad categories depending on whether they have a nucleus Nucleus - a membrane-enclosed structure that contains the cell’s DNA Controls the cells activities

Prokaryotes & Eukaryotes Eukaryotes - cells that have a nucleus Prokaryotes - cells that do not have a nucleus

Comparing the Cell to a Factory Organelles - “little organs”, structures within a cell Cytoplasm - portion of the cell outside the nucleus

Nucleus Nucleus - contains cell’s DNA, & with it, the instructions for making proteins Nuclear envelope - membrane that surrounds the nucleus Nucleolus - center of nucleus, where ribosomes are formed

Ribosomes Proteins are made on ribosomes Ribosomes - small particles of RNA & protein found throughout the cytoplasm Site of protein synthesis (to make)

Endoplasmic Reticulum Endoplasmic reticulum - ER - site where proteins are assembled

Golgi Apparatus Golgi apparatus - function is to package proteins from the ER The “packaging center” of the cell

Lysosomes Lysosomes - small organelles filled with enzymes They break down (digest) lipids, carbohydrates, & proteins into molecules that can be used by the cell

Vacuoles Vacuoles - saclike structures that store materials like water, salts, proteins, & carbs.

Mitochondria & Chloroplasts Mitochondria - organelles that convert chemical energy stored in food to compounds that can be used by the cell The “powerhouse” of the cell

Mitochondria & Chloroplasts Chloroplasts - organelles that capture energy from sun & convert it into chemical energy, during photosynthesis Green structures, only found in PLANT cells

Cytoskeleton Cytoskeleton - a network of protein filaments that help the cell maintain its shape

Cell Membrane Cell membrane - regulates what enters & leaves the cell, also provide protection & support Contains lipid bilayer - 2 layers of lipids

Cell Boundaries Cell wall - found in plant cells, fungi, algae, & many prokaryotes (NOT in animal cells) Provides support & protection for the cell

Diffusion Through Cell Boundaries Every living cell exists in a liquid environment that it needs to survive Cells have a different concentration or amount of substances within them

Diffusion Through Cell Boundaries Diffusion - movement of molecules from an area of greater concentration to lesser concentration to create equilibrium Does NOT require energy Equilibrium - when the concentration of a substance is the same on both sides of a membrane

Osmosis Osmosis - diffusion of water through a selectively permeable membrane, until equilibrium is reached

The Effects of Osmosis on Cells

Facilitated Diffusion Facilitated diffusion - molecules that can’t diffuse across the cell’s lipid bilayer on their own, move through protein channels instead

Active Transport Active transport - requires energy moves against the concentration gradient from low to high

Unicellular Organisms Cells are the basic units of all organisms, but sometimes a cell is the organism A single-celled organism is also called a unicellular organism

Multicellular Organisms Organisms made up of many cells are multicellular Cell specialization - cells throughout an organism can develop in different ways to perform different tasks

Cell Specialization

Levels of Organization The levels of organization in a multicellular organism are individual cells, tissues, organs, & organ systems

Levels of Organization Tissue - a group of similar cells that perform a particular function Organ - many groups of tissue working together Organ system - a group of organs working together to perform a specific function