CHAPTER 7CHAPTER 7

Cell Structure and Cell Structure and FunctionFunction

7-1 Life is Cellular7-1 Life is Cellular

In 1665, English Physicist Robert In 1665, English Physicist Robert Hooke used one of the first light Hooke used one of the first light microscopes to look at plant tissue.microscopes to look at plant tissue.

- he looked at cork.- he looked at cork.

- he called the tiny chambers he - he called the tiny chambers he saw “cells”saw “cells”

CELL THEORYCELL THEORY

Other biologists made further cell discoveries and Other biologists made further cell discoveries and came up with statements about cells. came up with statements about cells.

The Cell Theory is a fundamental concept of The Cell Theory is a fundamental concept of Biology. Biology.

- The cell theory states the following:- The cell theory states the following:

1. All living things are composed of cells. 1. All living things are composed of cells.

2. Cells are the basic units of structure and 2. Cells are the basic units of structure and function in living things. function in living things.

3. New cells are produced from existing 3. New cells are produced from existing cells. cells.

Prokaryotes and EukaryotesProkaryotes and Eukaryotes

Biologists divide cells into two Biologists divide cells into two categories: eukaryotes and categories: eukaryotes and prokaryotes.prokaryotes.

- Eukaryotes, have a - Eukaryotes, have a nucleusnucleus

- Prokaryotes, no nucleus- Prokaryotes, no nucleus

Cell StructureCell Structure

Chapter 7 Sec 2Chapter 7 Sec 2

Found in plants, algae, fungi, and most Found in plants, algae, fungi, and most prokaryotes.prokaryotes.

Main function is to provide support and Main function is to provide support and protection to the cell.protection to the cell.

Made of fibers of carbohydrates called Made of fibers of carbohydrates called cellulose.cellulose.

Cell WallsCell Walls

NucleusNucleus Founded in 1831 by Scottish botonist Robert Founded in 1831 by Scottish botonist Robert

BrownBrown Controls most cell processes Controls most cell processes Contains DNAContains DNA Holds the coded info for making proteins and Holds the coded info for making proteins and

other required moleculesother required molecules ChromatinChromatin is visible in the nucleus is visible in the nucleus Chromatin is DNA bound to proteinChromatin is DNA bound to protein During cell division, During cell division, chromosomes chromosomes form when form when

chromatin condenses. chromatin condenses. Chromosomes hold genetic info which pass from Chromosomes hold genetic info which pass from

one generation to anotherone generation to another

The The nucleolus, nucleolus, a small dense region, a small dense region, is also found in most nuclei. is also found in most nuclei.

Ribosomes’ assembly begins in the Ribosomes’ assembly begins in the nucleolus. nucleolus.

The The nuclear envelope nuclear envelope is the double is the double membrane layer which surrounds the membrane layer which surrounds the nucleus. nucleus.

CytoskeletonCytoskeleton The The cytoskeleton cytoskeleton is a network of protein is a network of protein

filaments to support cell shape. filaments to support cell shape. Also aids in cell movement. Also aids in cell movement. Made up of microtubules and Made up of microtubules and

microfilaments. microfilaments. MicrotubulesMicrotubules are hollow tubes of protein. are hollow tubes of protein.

They give cell shape, and work as tracks They give cell shape, and work as tracks for organelle movement. for organelle movement.

Microfilaments Microfilaments are long, thin fibers that are long, thin fibers that function in support and movement of the function in support and movement of the cell. cell.

RibosomesRibosomes

RibosomesRibosomes are small particles made are small particles made of RNA (ribonucleic acid) and protein.of RNA (ribonucleic acid) and protein.

Proteins are assembled on Proteins are assembled on ribosomes. ribosomes.

2 Types of ribosomes:2 Types of ribosomes:

1. attached ribosomes1. attached ribosomes

2. free ribosomes2. free ribosomes

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

Found in Eukaryotic cellsFound in Eukaryotic cells It is an internal membrane structure.It is an internal membrane structure. The ER assembles components of the The ER assembles components of the

cell membrane and modifies some cell membrane and modifies some proteins. proteins.

Rough ER is involved in the synthesis Rough ER is involved in the synthesis of proteins. of proteins.

Smooth ER does not have ribosomes Smooth ER does not have ribosomes on its surface. on its surface.

Golgi ApparatusGolgi Apparatus

Proteins from the rough ER move into Proteins from the rough ER move into the stack of membranes known as the stack of membranes known as the the golgi apparatus.golgi apparatus.

Enzymes in the golgi apparatus Enzymes in the golgi apparatus attach carbs and lipids to proteins. attach carbs and lipids to proteins.

From the golgi apparatus, proteins From the golgi apparatus, proteins are sent to their final destination. are sent to their final destination.

LysosomesLysosomes

LysosomesLysosomes are small organelles filled are small organelles filled with enzymes.with enzymes.

Break down lipids, carbs, and Break down lipids, carbs, and proteins from food. proteins from food.

VacuolesVacuoles

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

ChloroplastsChloroplasts

Found in plantsFound in plants Uses energy from the sun to Uses energy from the sun to

complete the process of complete the process of photosynthesisphotosynthesis

MitochondriaMitochondria

Release energy from stored food Release energy from stored food moleculesmolecules

Uses energy from food to make high Uses energy from food to make high energy compoundsenergy compounds

Energy produced is used to power Energy produced is used to power growth, development, and growth, development, and movement. movement.

Known as the “power house” of the Known as the “power house” of the cellcell

Organelle DNAOrganelle DNA

Chloroplasts and mitochondria Chloroplasts and mitochondria contain some of their own genetic contain some of their own genetic information in the form of DNAinformation in the form of DNA

Biologist Lynn Margulis suggested Biologist Lynn Margulis suggested mitochondria and chloroplasts are mitochondria and chloroplasts are decendants of ancient prokaryotesdecendants of ancient prokaryotes

In humans, all of our mitochondria In humans, all of our mitochondria come from the cytoplasm of the egg come from the cytoplasm of the egg cell….thank you Mom!cell….thank you Mom!

The Cell as a FactoryThe Cell as a Factory The way proteins are made in a cell The way proteins are made in a cell

is similar to the way products are is similar to the way products are made in a factory:made in a factory:– Cell membraneCell membrane -Mitochondria-Mitochondria– Cell wallCell wall -Chloroplasts-Chloroplasts– NucleusNucleus -Cytoskeleton-Cytoskeleton– RibosomesRibosomes– Endoplasmic reticulumEndoplasmic reticulum– Golgi apparatusGolgi apparatus– LysosomesLysosomes– VacuolesVacuoles

Comparing CellsComparing Cells Prokaryotes have cell membranes Prokaryotes have cell membranes

but no nucleibut no nuclei Eukaryotes are much larger than Eukaryotes are much larger than

prokaryotes and contain nucleiprokaryotes and contain nuclei Eukaryotes have specialized Eukaryotes have specialized

organellesorganelles Plant cells (eukaryotes) contain large Plant cells (eukaryotes) contain large

vacuoles, cell walls, and chloroplastsvacuoles, cell walls, and chloroplasts Animal cells (eukaryotes) do not Animal cells (eukaryotes) do not

have cell walls or chloroplastshave cell walls or chloroplasts