Chapter 7: Cell Structure and

Function7-1: Life is cellular7-2: Cell structures

7-3: Movement through the membrane

7-4: The diversity of cellular life

7-1 Life is cellular

7-1 Life is cellular

7-1 Life is cellularThe Cell Theory

All living things are made up of cells. All cells come from pre-existing cells. Cells are the basic unit and structure of

all living things.Contributors to the Cell Theory

Hooke – Named cells and observed cork Leewenhoek – Observed living cells Schliden – cell theory plants Schwann – cell theory animals Virchow – cell theory reproduction

A : Bacteria Cell

B : Plant Cell

C : Animal Cell

7-1 Life is cellularBasic Cell Structures:

Cell membrane – the thin barrier around all cells

Cytoplasm – the material inside the cell membrane

Ribosomes – small structures that manufacture proteins

7-1 Life is Cellular

Prokaryotes (bacteria)

Small Simple Contain DNA but no

nucleus Examples include:

Escherichia coli Staphylococcus aureus

Eukaroytes Large (in comparison) Complex with many

organelles – specialized structures that perform important cellular functions.

Contain a nucleus that contains DNA

Examples include: Plants Animals Fungi

Biologists divide cells into two basic categories: Eukaryotic cells or Prokaryotic Cells

Cells are Divided Into Two Categories

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Prokaryotic Cell

Eukaryotic Cell

Slides of Prokaryotes (Bacteria)

Prokaryote vs. Eukaryote (basic structures)

Cell membraneRibosomesCell wallDNACytoplasm

NucleusMany organellesBigPlantAnimal

DNASmallBacteria

Prokaryotic

Eukaryotic

Which group of cells would be considered prokaryotic?

A

B

C

7-2 Cell StructuresCytoplasm

Structure (What it’s made of):

Thick, jelly-like fluidFunction (What it does):

Holds all organelles Location of many cellular

chemical reactions

7-2 Cell StructuresNucleus

Structure: Nuclear envelope that

contains pores or holes Dark center called a nucleolus which manufactures ribosomes and contains RNA

Packaged DNA called Chromatin

Function: Controls all the cell’s activities Protects the cell’s information Brain of the cell

7-2 Cell StructuresCytoskeleton

Structure: Microtubules –

hollow tubes of protein

Microfilaments – thin narrow fibers

Function: Maintains cell’s

shape Highway system

for organelles

7-2 Cell StructuresCentrioles

Structure: Part of

cytoskeleton Only in animal cells Packs of

microtubulesFunction:

Helps cells to divide

7-2 Cell StructuresCilia/Flagella

Structure: Part of cytoskeleton Microtubules

Function: Movement

7-2 Cell StructuresRibosomes

Structure: Tiny No outer

membrane Found in both

eukaryotic and prokaryotic cells

Function: Make proteins!!!

Draw

7-2 Cell StructuresEndoplasmic Reticulum

Structure: Network of membrane

tubes Rough E.R. is covered

with ribosomes Smooth E.R. has no

ribosomesFunction:

Transports materials within the cell

Modify proteins Filters out toxins

7-2 Cell StructuresGolgi Apparatus

Structure: Stacks of

membranes Looks like

pancakesFunction:

Modify and package cellular materials

“Post office”

7-2 Cell StructuresLysosome

Structure: Membrane filled

with digestive enzymes

Only found in animal cells

Function: Trash compactor/

Stomach of cell Helps fight

infection

VacuolesStructure:

Membrane bagFunction:

Stores food, water and waste

Help give plant cells rigidity

7-2 Cell StructuresMitochondria

Structure: Peanut shaped Folded layers of

membrane inside called, cristae

Function: Powerhouse Cell Respiration

(makes energy)

7-2 Cell StructuresChloroplast

Structure: Green Contains stacks of

membranes Only in plants

Function: Photosynthesis A type of plastid (a

vacuole that contains pigment)

7-2 Cell StructuresCell Membrane

Structure: Phospholipid (fats) bilayer

Proteins Carbohydrates

Function: Creates a boundary

around the cell Regulates what goes

in and out of the cell

CARBS

PROTEIN

LIPIDS

7-2 Cell StructuresCell Wall

Structure:Only in plant cells and bacteria cells

Contains cellulose

Function:RigidityProtection

Organelle Structure Function

Nucleus DNA (chromatin) Nucleolus

Brain

Cell Membrane Phospholipid bilayer Regulates what goes in and out

Cell Wall Cellulose Protection/rigidity

Cytoplasm Jellylike Holds organelles cellular reactions

Cytoskeleton Microtubulesmicrofilaments

Supports the cell moves organelles

Ribosomes Tiny round structuresFound in ER and cytoplasm

Make proteins

ER Network of tubesRough or smooth

Transports proteins gets rid of toxins

Organelle Structure FunctionGolgi Apparatus

Stacks of membranes (pancakes)

Modify and package proteins and other cellular materials (post office)

Vacuoles Saclike structures Stores food, water, and waste

Mitochondria Peanut shapedFolded layers inside (Cristae)

Powerhouse (mighty!)

Chloroplast Only in plantsGreen bundles

Holds pigments and carries out photosynthesis

Lysosome Sac of digestive enzymes

Disposes of wastes (trashcan)

Centrioles Only in animal cells Helps cells divide

Cillia/Flagella Only in animal cellsHairlike projections

Movement of the cell

Centrioles

Nucleolus

Nucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrian

CellMembrane

Ribosome(free)

Ribosome(attached)

Figure 7-5 Animal Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrian

Cell wall

CellMembrane

Chloroplast

Vacuole

Figure 7-5 Plant Cell

Animal Cells Plant CellsLysosomesCentriolesSmall Vacuole

Cell membraneRibosomesNucleusEndoplasmic reticulumGolgi apparatusMitochondriaCytoskeleton

ChloroplastsCell WallLarge Vacuole

Animal Cells vs. Plant Cells

Identify the plant cells from the animal cells…

A

B

C

Match the Image to the Cell Type

PLANT

ANIMAL

7-3 Movement Through The MembraneParts of a Cell Membrane

Lipid bilayer: phospholipids

Hydrophilic head Hydrophobic tail

Proteins: On top/bottom Through Act as

passagewayCarbohydrates:

Cell Recognition

CARBSPROTEIN

LIPIDS

7-3 Movement Through The MembraneFluid Mosaic Model

Fluid mosaic model: the cell membrane is like a liquid

Phospholipids are constantly changing positions

Membrane is a mix/ mosaic of different chemicalsMembrane is selectively permeable - some things move through and some things do not

7-3 Movement Through The Membrane

Passive transport (high to low)

No energy needed.

Active transport (low to high)

Needs energy.

Diffusion is a type of Passive transportMolecules move down a concentration gradient (High to Low)Diffuse to reach equilibrium: concentration of molecules is the same throughout the space

Equili

brium

7-3 Movement Through The MembraneDiffusion

Boy am I confused!!!

Osmosis is a type of passive transport

Osmosis is the movement of water from a high concentration to a low concentration

Recall:Solute is the

substance being dissolved

Solvent is the substance doing the dissolving

7-3 Movement Through The MembraneOsmosis

Types of Osmotic SolutionsISOTONIC Solution:

Amount of water in and out of cell is equal Result: Even flow of water into and out of cell.

EX: Blood

HYPOTONIC Solution: More water outside than inside the cell. Result: Water rushes in and cell bursts

(cytolysis) or becomes firm (turgor pressure)

HYPERTONIC Solution: Less water outside than inside the cell. Result: Cell shrinks (plasmolysis)

Flash Movie

Animal Cells Only

Plant Cells Only

Plant Cells Only

7-3 Movement Through The Membrane

ISOTONIC

HYPOTONIC HYPERTONIC

Hypotonic Isotonic Hypertonic

Upper Left: ISOTONIC

Upper Right: HYPERTONIC

Lower Left: HYPOTONIC

How do you catch a unique rabbit?

Unique up on it!!!

Which direction are the molecules moving?

What is the net movement of molecules?

What direction will the molecules be moving at equilibrium?

What is the net movement of molecules at equilibrium?

Water 98%

NaCl 2 %

NaCl 6%Water 94%

Animal cells bursting of cells from a hypotonic environment = cytolysis (hypotonic)

Some cells can adapt to hypotonic environments with an organelle called a contractile vacuole – it fills with water and then squeezes it out of the cell.

Plant cells The rigid cell wall prevents bursting Turgor pressure is pressure that water

exerts against the cell wall (hypotonic) Plants without water wilt and die this is called plasmolysis (hypertonic)

7-3 Movement Through The MembraneOsmotic Pressure

Contractile Vacuole

Facilitated diffusion is a type of passive transportFacilitated diffusion is the movement of large molecules across a membraneCarrier proteins – facilitate (help) movement

Ex. Glucose moves through a carrier protein

7-3 Movement Through The MembraneFacilitated Diffusion

7-3 Movement Through The MembraneDiffusion vs. Facilitated Diffusion

Diffusion – High to low

Facilitated Diffusion – High to low with the help of a protein carrier

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7-3 Movement Through The MembraneActive TransportMolecule to

be carriedLowConcentration

CellMembrane

HighConcentration

Moleculebeing carried

LowConcentration

CellMembrane

HighConcentration

Energy Energy

Review Movie

Active Transport movement of molecules from low to high concentration

Energy is needed to do this!

Types: Vesicle Transport: Endocytosis – cell

eating/drinking Exocytosis – cell

spitting material out Protein Pumps – use

energy (ATP) to pump materials from low to high concentrations

7-3 Movement Through The Membrane Endocytosis and Exocytosis

Endocytosis Formation of a vesiclePinocytosis: cell drinkingPhagocytosis: cell eatingPhagocytes: eat and kill bacteria in our

bodyExocytosisVesicles fuse with the cell membrane to

release contents into external environment

7-4 The Diversity of Cellular Life

Cells in multicellular organisms are specialized, this mean each cell type has a specific job to keep the whole organism running.

For example: blood cells carry oxygen to all the cells of the body. Nerve cells have the ability to send electrical impulses

throughout the organism.The levels of organization in a multicellular organism are:

Individual cells (heart cell) Tissues (cardiac tissue) Organs (heart) Organ Systems (cardiovascular system)

Objectives Chapter 7Describe the structure of a membrane.Define the fluid mosaic model.Differentiate between passive and active transport.List and define the types of passive transport.Explain the effects of osmosis in different solutions (ex. iso, hypo, hyper.)Identify cells in isotonic, hypertonic, and hypotonic solutions.Explain how some cells/organisms respond to different osmotic environments.List and define the types of active transport.