Looking at CellsLooking at Cells

Microscopes:Microscopes: A basic biology tool that A basic biology tool that allowed for the discovery of cells and cell allowed for the discovery of cells and cell parts.parts.

Simple microscopeSimple microscope-- hand lens hand lens Compound microscopeCompound microscope-- uses 2 or more uses 2 or more

lenses working together. The maximum lenses working together. The maximum useful magnification is 1200-1500x. useful magnification is 1200-1500x.

Electron microscope-Electron microscope- uses an electron uses an electron beam in place of light. These can magnify beam in place of light. These can magnify over 500,000x or half a million times.over 500,000x or half a million times.

Electron MicroscopesElectron Microscopes

SEMSEM- scanning electron microscope- - scanning electron microscope- used to view surfaces like cell walls used to view surfaces like cell walls and cell membranes.and cell membranes.

TEMTEM-transmission electron -transmission electron microscope- more powerful- used to microscope- more powerful- used to study tiny structures and organelles study tiny structures and organelles inside of cells.inside of cells.

STMSTM-scanning-tunneling microscope -scanning-tunneling microscope is used to view the structure of large is used to view the structure of large molecules.molecules.

OrganellesOrganelles OrganelleOrganelle- a structure inside a cell that is - a structure inside a cell that is

surrounded by a membrane. Each organelle has surrounded by a membrane. Each organelle has a specific function or job.a specific function or job.

MembraneMembrane- covering around cells or organelles. - covering around cells or organelles. They have several functions:They have several functions:

1. Membranes surround a cell or organelle and 1. Membranes surround a cell or organelle and define define its space. Separates living materials its space. Separates living materials from the from the environment.environment.

2. Membranes control materials that come and 2. Membranes control materials that come and go from go from cells or organelles.cells or organelles.

3. Serve to protect.3. Serve to protect. 4. Membranes are made mostly of lipids.4. Membranes are made mostly of lipids.

2 Types of Cells2 Types of Cells ProkaryotesProkaryotes- Kingdoms Eubacteria and - Kingdoms Eubacteria and

Archebacteria- all the bacteria, all the Archebacteria- all the bacteria, all the archebacteria and blue-green algae. The archebacteria and blue-green algae. The cells have no organelles & no nucleus.cells have no organelles & no nucleus.

All the cell chemistry is carried on in the All the cell chemistry is carried on in the cells cytoplasm. DNA floats in the cells cytoplasm. DNA floats in the cytoplasm in long strings or coils.cytoplasm in long strings or coils.

EukaryotesEukaryotes: have internal membrane : have internal membrane covered organelles. Also have a nucleus covered organelles. Also have a nucleus where DNA is found during most of the where DNA is found during most of the cells life. Kingdom Plantae, Animalia, cells life. Kingdom Plantae, Animalia, Fungi and Protista are eukaryotes.Fungi and Protista are eukaryotes.

Scientists of CellsScientists of Cells Robert HookeRobert Hooke- English- used microscope to view - English- used microscope to view

cork wood. Coined the term “cell”.cork wood. Coined the term “cell”. Anton van LeeuwenhoekAnton van Leeuwenhoek- Dutch- mid 1600’s, - Dutch- mid 1600’s,

An eyeglass lense grinder who built microscopes An eyeglass lense grinder who built microscopes and used them, and used them, The first scientist to describe living cells as seen through a simple microscope

Robert BrownRobert Brown- first wrote about the cell nucleus. - first wrote about the cell nucleus.

Rudolf VirchowRudolf Virchow first predicted that the nucleus first predicted that the nucleus contained genetic material and was responsible contained genetic material and was responsible for cell reproduction.for cell reproduction.

Matthias SchleidenMatthias Schleiden- German, 1830’s, proposed - German, 1830’s, proposed that all plants were made of cells.that all plants were made of cells.

Theodore SchwannTheodore Schwann- German, 1830’s, proposed - German, 1830’s, proposed that all animals are made of cells.that all animals are made of cells.

Cell TheoryCell Theory

Cell Theory- A cornerstone of Cell Theory- A cornerstone of modern biology! It has 3 Partsmodern biology! It has 3 Parts

1. All living things are made of cells.1. All living things are made of cells. 2. The cell is the basic unit of life.2. The cell is the basic unit of life. 3. All cells come from other living 3. All cells come from other living

cells.cells.

Hierarchy of Hierarchy of organization in living organization in living

things:things: CellsCells Tissues Tissues Organs Organs Organ Systems Organ Systems

OrganismOrganism Cells of similar function combine to form Cells of similar function combine to form

tissues: nerve tissue, muscle tissue, meristem tissues: nerve tissue, muscle tissue, meristem tissue in plants.tissue in plants.

Two or more tissues form an organ: muscle, Two or more tissues form an organ: muscle, nerve and epithelial tissue form the heart.nerve and epithelial tissue form the heart.

Two or more organs form an organ system: Two or more organs form an organ system: stomach, liver, small intestine, teeth are parts stomach, liver, small intestine, teeth are parts of the digestive system.of the digestive system.

An organism is several systems working An organism is several systems working together: a human and other vertebrates are together: a human and other vertebrates are made of 11 systems.made of 11 systems.

Plasma MembranePlasma Membrane

The The plasma membraneplasma membrane has several has several functions:functions:

1. It surrounds the cell material and 1. It surrounds the cell material and defines the cells space.defines the cells space.

2. It separates the cell from the 2. It separates the cell from the surrounding environment.surrounding environment.

3. It controls the movement of materials 3. It controls the movement of materials into and out of the cell. This helps into and out of the cell. This helps maintain a balanced living condition. maintain a balanced living condition. (Homeostasis)(Homeostasis)

Plasma MembranePlasma Membrane

The plasma membrane is made of 2 layers The plasma membrane is made of 2 layers of lipid with proteins inserted here and of lipid with proteins inserted here and there. This is referred to as a “lipid there. This is referred to as a “lipid bilayer”. The lipids also have phosphate bilayer”. The lipids also have phosphate groups attached so they are referred to as groups attached so they are referred to as “phospholipids”.“phospholipids”.

The inserted proteins are sometimes The inserted proteins are sometimes known as transport proteins because they known as transport proteins because they help move materials across the help move materials across the membrane.membrane.

Membrane Crossing Membrane Crossing

Things that must cross the plasma Things that must cross the plasma membrane:membrane:

Water, oxygen, waste products, Water, oxygen, waste products, glucose, food, carbon dioxide are glucose, food, carbon dioxide are some things that must commonly some things that must commonly cross the plasma membrane.cross the plasma membrane.

Osmosis- the movement of water Osmosis- the movement of water along a concentration gradient along a concentration gradient

High concentration

Equal concentration

Low concentration

Fluid Mosaic TheoryFluid Mosaic Theory The theory of the fluid mosaic model The theory of the fluid mosaic model

describes the structure of the plasma describes the structure of the plasma membrane and explains how and why it membrane and explains how and why it functions as it does.functions as it does.

Each cell membrane is composed of 2 Each cell membrane is composed of 2 opposing layers of phospholipids.opposing layers of phospholipids.

Each phospholipid molecule has a polar Each phospholipid molecule has a polar (water soluble) which is a phosphate.(water soluble) which is a phosphate.

This is also called the hydrophilic or water This is also called the hydrophilic or water loving end.loving end.

The other end of the phospholipids is made The other end of the phospholipids is made of nonpolar (oil soluble) fatty acids. This is of nonpolar (oil soluble) fatty acids. This is the hydrophobic or water hating end.the hydrophobic or water hating end.

These phospholipids in the membrane These phospholipids in the membrane line themselves up with the polar line themselves up with the polar phosphates facing outward toward the phosphates facing outward toward the water soluble environment and facing water soluble environment and facing inward toward the water soluble inside inward toward the water soluble inside of the cell.of the cell.

The nonpolar or hydrophobic ends of the The nonpolar or hydrophobic ends of the phospholipids move into the middle of phospholipids move into the middle of the membrane where there is no water.the membrane where there is no water.

Cholesterol molecules are found in Cholesterol molecules are found in between phospholipid molecules in the between phospholipid molecules in the membrane. Cholesterol keeps the membrane. Cholesterol keeps the membrane liquid and allows the membrane liquid and allows the phospholipids molecules to move phospholipids molecules to move around.around.

Two Types of proteinsTwo Types of proteins Transport proteins are found sticking thru Transport proteins are found sticking thru

the plasma membrane and allow movement the plasma membrane and allow movement of particles across the membrane. 2 types:of particles across the membrane. 2 types:

1. 1. Channel proteinsChannel proteins-these form openings -these form openings that allow material dissolved in water to that allow material dissolved in water to pass thru. This allows passive transport of pass thru. This allows passive transport of sugars, amino acids and ions to cross the sugars, amino acids and ions to cross the membrane. This simply forms an opening membrane. This simply forms an opening that allows these materials to move thru.that allows these materials to move thru.

2. 2. Carrier protein-Carrier protein- A protein molecule in the A protein molecule in the membrane that physically attaches to a membrane that physically attaches to a molecule or particles and pulls or pushes it molecule or particles and pulls or pushes it thru the membrane. A form of active thru the membrane. A form of active transport.transport.

Eukaryotic Cell StructureEukaryotic Cell Structure

Cell wallsCell walls: A solid covering around : A solid covering around cells of plants, fungi, bacteria and some cells of plants, fungi, bacteria and some protests. No animal cells have cell walls.protests. No animal cells have cell walls.

It provides support and physical It provides support and physical protection for the cell. It DOES NOT protection for the cell. It DOES NOT control movement of materials into or control movement of materials into or out of the cells.out of the cells.

Trees are able to grow to large heights Trees are able to grow to large heights because of the support given to their because of the support given to their cells by cell walls. Plants cell walls cells by cell walls. Plants cell walls contain cellulose as the main structural contain cellulose as the main structural material.material.

NucleusNucleus Nucleus: Nucleus: A fairly large membrane covered A fairly large membrane covered

organelle that controls the cell. It has several organelle that controls the cell. It has several parts: all materials in the nucleus are referred to parts: all materials in the nucleus are referred to as nucleoplasm.as nucleoplasm.

1. 1. nuclear membrane or nuclear envelope nuclear membrane or nuclear envelope surrounds the nuclear material and controls the surrounds the nuclear material and controls the movement of materials into the nucleus.movement of materials into the nucleus.

2. 2. ChromatinChromatin-- unwound DNA fibers inside the unwound DNA fibers inside the nucleus. The DNA contains the genetic code for nucleus. The DNA contains the genetic code for all the cells proteins. During cell division, all the cells proteins. During cell division, chromatin coils up into short spools called chromatin coils up into short spools called chromosomes.chromosomes.

3. 3. NucleolusNucleolus-- A small membrane covered area A small membrane covered area INSIDE INSIDE the nucleus that builds ribosomes for the the nucleus that builds ribosomes for the cells. cells.

Ribosomes Ribosomes build proteins for the cell.build proteins for the cell.

RibosomesRibosomes

The sites of protein synthesis. Makes proteins based on RNA

instructions.

Cytoplasm-Cytoplasm- a jelly like mixture of a jelly like mixture of water, proteins, Chemicals, and water, proteins, Chemicals, and organelles that make up all the cell organelles that make up all the cell except the nucleus. There are except the nucleus. There are several organelles.several organelles.

The clear fluid inside the cell.

ERER 1. 1. Endoplasmic reticulumEndoplasmic reticulum- layers of - layers of

many-folded membranes that act as many-folded membranes that act as transport canals. These folded membranes transport canals. These folded membranes act as sites for many chemical reactions. act as sites for many chemical reactions. Many ribosomes are found on the ER, so Many ribosomes are found on the ER, so lots of protein synthesis occurs there.lots of protein synthesis occurs there.

A folded membrane that forms a network of interconnected compartments in the cytoplasm

Smooth ER-areas with no ribosomes.Smooth ER-areas with no ribosomes. Rough ER- areas with ribosomes.Rough ER- areas with ribosomes.

Golgi bodiesGolgi bodies

Golgi bodies- similar in structure as the Golgi bodies- similar in structure as the ER. These “package” protein molecules ER. These “package” protein molecules that must be excreted from the cell. that must be excreted from the cell. This packaging allows the molecule to This packaging allows the molecule to cross thru the cells plasma membrane. cross thru the cells plasma membrane. Golgi bodies are very numerous and Golgi bodies are very numerous and active in cells that secrete proteins such active in cells that secrete proteins such as glands and digestive organs.as glands and digestive organs.

Closely stacked, flattened membrane sacs.

VacuolesVacuoles

VacuolesVacuoles- storage areas. Can store - storage areas. Can store food, chemicals, starches, proteins, food, chemicals, starches, proteins, almost anything. Plant cell often almost anything. Plant cell often have very large vacuoles.have very large vacuoles.

A membrane-bound, fluid-filled sac. Provides temporary storage of food,

enzymes, and waste products

LysosomesLysosomes

Lysosomes- Lysosomes- special vacuoles that special vacuoles that that breakdown or digest old, worn that breakdown or digest old, worn out organelles or food particles. out organelles or food particles.

This allows the cell to recycle This allows the cell to recycle materials.materials.

Digest excess or worn-out cell part, food particles, and invading viruses or bacteria

MitochondriaMitochondria

MitochondriaMitochondria- found in all eukaryotic cells, - found in all eukaryotic cells, these break down sugars and release energy. these break down sugars and release energy. It has a highly folded inner membrane that It has a highly folded inner membrane that serves as a “workbench” for enzymes. Cells serves as a “workbench” for enzymes. Cells that require a lot of energy will have many that require a lot of energy will have many mitochondria. Liver cells may have 2500 mitochondria. Liver cells may have 2500 each. each.

The structure of chloroplasts and mitochondria The structure of chloroplasts and mitochondria are very similar, but their function is directly are very similar, but their function is directly opposite: chloroplasts build sugars, opposite: chloroplasts build sugars, mitochondria break sugars apart.mitochondria break sugars apart.

Endosymbiontic theoryEndosymbiontic theory- proposed in the - proposed in the 1960’s by Lynn Margulis (p.392). The 1960’s by Lynn Margulis (p.392). The theory proposes that eukaryote cells theory proposes that eukaryote cells evolved as a result of a symbiotic evolved as a result of a symbiotic relationship between several types of relationship between several types of prokaryote cells.prokaryote cells.

In other words, organelles such as In other words, organelles such as chloroplasts and mitochondria were once chloroplasts and mitochondria were once free living prokaryotes, but became free living prokaryotes, but became absorbed into a larger prokaryote to form absorbed into a larger prokaryote to form a eukaryote cell.a eukaryote cell.

Endosymbiontic Theory

CytoskeletonCytoskeleton CytoskeletonCytoskeleton- a network of thin fibers that - a network of thin fibers that

give support, shape and structure to a cell. give support, shape and structure to a cell. There are 2 types of support materials:There are 2 types of support materials:

1. microtubules that are thin, hollow 1. microtubules that are thin, hollow protein tubes.protein tubes.

2. microfilaments that are thin, solid 2. microfilaments that are thin, solid protein fibers.protein fibers.

Imagine the cytoskeleton as the poles of a Imagine the cytoskeleton as the poles of a tent. It holds up the tent cover (plasma tent. It holds up the tent cover (plasma membrane) and provides space inside the membrane) and provides space inside the tent.tent.

Cell WallCell Wall

Firm, protective structure that gives the cell its shape in plants, fungi, most bacteria, and some protists.

ChloroplastsChloroplasts ChloroplastChloroplast-- found in plants, and some found in plants, and some

protests and some bacteria. This allows protests and some bacteria. This allows the cell to trap the energy in sunlight to the cell to trap the energy in sunlight to power a food making process called power a food making process called photosynthesis. These contain the photosynthesis. These contain the chemical chlorophyll which is a green chemical chlorophyll which is a green pigment that actually traps the light pigment that actually traps the light energy. It has 2 major parts :energy. It has 2 major parts :

1. The granum- which looks like stacks of 1. The granum- which looks like stacks of coins surrounded by a membrane. Each coins surrounded by a membrane. Each “coin” is called a thylakoid. It is in the “coin” is called a thylakoid. It is in the thylakoid that light energy is trapped. thylakoid that light energy is trapped.

2. The stroma- a fluid that surrounds the 2. The stroma- a fluid that surrounds the grana in the chloroplast.grana in the chloroplast.

Grana

LocomotionLocomotion FlagellaFlagella- a long tail like structure that is - a long tail like structure that is

used as a “paddle” to move a cell thru used as a “paddle” to move a cell thru water. A cell can have 1 or more of these.water. A cell can have 1 or more of these.

Cilia- Cilia- a short hair like structure that is used a short hair like structure that is used as a locomotion device (movement). Usually as a locomotion device (movement). Usually a cell will have many of these. Some body a cell will have many of these. Some body cells in animals have cilia on their surface so cells in animals have cilia on their surface so that as the cilia move, particles can be that as the cilia move, particles can be moved around in the organism.moved around in the organism.

Cilia cells in your respiratory system help Cilia cells in your respiratory system help move materials such as dust out of your move materials such as dust out of your lungs and into you throat. This helps keep lungs and into you throat. This helps keep the lung area clean.the lung area clean.