Structure and FunctionChapter 4

What importance do cells have to life?

THE CELL

-Mid 1600’s Started using microscopes

-Robert Hooke- used the scope to look at cork-Coined the term cells, because of what the cork looked like under the scope.

-Van Leeuwenhoek- 1st to look at living cells.-Looked at pond water and saw organisms (very tiny) living in the water.

1. All living things are made of cells.2. Basic unit of structure and function.3. New cells come from existing cells.

The Cell Theory

- Use fluorescent labels to follow molecules through cells.

- Can build 3-D cells images of cells and their parts.

-Use light, electrons and high resolution scopes to see cells, structures, DNA, proteins and other molecules.

Exploring the Cell

CELL TYPES

Prokaryote1.1st to evolve2.Lacking

Nucleus3.Simple Cell4.Ex: Bacteria

Eukaryote1.Cells contain

Nucleus2.Larger and more

complex3.Highly

Specialized

BothHave DNA and CellMembranes

2 Parts1. Nucleus- Brain of the cell2. Cytoplasm- Entire cell outside of the nucleus.Holds organelles for cell.

Eukaryote Cell Structure

Animal Cell

Plant Cell

1. Cell Membrane--thin, flexible outer layer- lipid bilayer (2 layers of lipids)- Integral proteins(in membrane)- Peripheral Protein (touch membrane)-Mosaic because molecules in

membrane.

Cell Structures

Semi-Permeable Cell Membrane (fluid)

Gate Keeper- controls what comes in and out of cell. (picky)

2. Cell Wall- - Plant Cells- made of cellulose- rigid support for cell/plant- outside of the membrane

3. Cytoplasm-- area between nucleus and membrane-contains organelles-jelly-like substance

4. Nucleus- - brain of the cell- surrounded by the nuclear envelope

- double membrane- contains nuclear pores (sm holes)

- Main Function- store DNA in form of chromatin.- during cell division chromatin coils up to form chromosomes.

- Contains nucleolus- synthesizes and partially assembles

ribosomes.

5. Cytoskeleton-- framework of the cell, made of proteins- 2 structures:

1. microfilaments- (“threads”)- aid in movement and muscle

contraction2. microtubules- (“straws”)

- assemble/disassemble to form spindle fibers during cell division.

(extremely important to cells)

6. Cilia and Flagella-- hairlike- on cell surface- aid movement

Cilia- shorter and numerous (respiratory system)

Flagella- longer and less numerous(protists)

- small structures with specialized function- Found in the cytoplasm7. Mitochondrion- mitochondria (plural)- “powerhouse” of the cell- Converts energy from nutrients to ATP- Double membrane –inner membrane cristae- has its own DNA (from mother)-more in active tissue (muscle, liver)

Organelles

8. Ribosomes- - protein synthesis (proteins are made)- most numerous organelle- NOT membrane bound- synthesized and partially made in

nucleolus- finished being made in cytoplasm

when proteins are made.- may be “free-standing” or attached to

Endoplasmic Reticulum.

9. Endoplasmic Reticulum (ER)- “subway” of the cell- Transports material within cell- Rough ER- covered with ribosomes

and prepares proteins for transport.- Smooth ER- no ribosomes

- synthesizes steroids (glands)- regulates calcium (muscle)- breaks down toxins (liver)

10. Golgi Apparatus- - Made of a series of parallel

compartments.- Modifies/ repackages proteins- manufactures lysosomes- plays a role in secretion

11. Lysosomes-- most common in animals, not plants- contains digestive enzymes- help to break down carbs, proteins, lipids

12. Centrioles- - found in a pair- near nucleus- aid in cell division by aligning chromosomes

13. Vacuoles- - store food, water, waste (not at same time)- plant cells have a large central vacuole- animals have numerous, smaller

vacuoles - plant vacuoles perform lysosome job.

14. Chloroplasts- - exclusive to plants- have a double membrane- captures energy from sunlight and

converts it into chemical energy during photosynthesis.

- “solar power” in plants- contains green pigment called

chlorophyll.- Type of Chromoplasts- colored plastids

- orange- carotene

Plant Cells Animal CellsCell Wall No Cell Wall

Cell Membrane

Chloroplasts Mitochondria

NO Centrioles Centrioles

Single Large Vacuole Many small lysosomes

Oblong Shape Round/Irregular Shape

Nucleus not centrally located Nucleus usually centrally located

Endoplasmic Reticulum Endoplasmic Reticulum

Relationships Between Organelles1. Nucleus (DNA makes RNA)

- Nucleolus – Makes Ribosomes- Cytoplasm- Holds Organelles

2. ER- ribosomes attach, transports proteins3. Proteins modified by GOLGI4. Golgi manufactures LYSOSOMES5. Lysosome digest particles, worn out organelles6. Spare parts from lysosome, ready to use in future

from directions from NUCLEUS7. MITOCHONDRIA provides energy for ALL

7.3- Cell Boundaries

What is the cell boundary of animal cells?What is the cell boundary of plant cells?

What role do these structures have?

Cell Boundaries Functions

Cell Membrane- regulates what enters and leaves the cell.

Cell Wall- Provides support and protection for the cell.

2 Types of Transport

1. Passive Transport- movement of molecules/material through the cell membrane and requires NO energy.

2. Active Transport- movement of molecules/material through the cell membrane and REQUIRES energy.

Passive Transport1. Diffusion- movement of molecules from an

area of high concentration to low concentration.

2. Osmosis- movement of solutions across a membrane.

3. Facilitated Diffusion- form of diffusion which requires a carrier protein. Ex: Glucose

Diffusion- Concentration- amount of solute dissolved in a

solution- Concentration Gradient- difference in molecule

concentration across a space.- Movement of molecules from an area of HIGH

concentration to LOW concentration.- Ex: Match being lit.

- Movement is ‘with’ or ‘down’ the gradient- Molecules move to reach equilibrium.

Diffusion Continued

Movement from high Equilibriumto low Reached

Diffusion ContinuedKinetic Energy- powers diffusion

- energy of moving particles

Examples:- ink dropped into water- gas exchange in cells (oxygen)- fragrance of candles in a room

Osmosis- Movement of water (solutions)- Cell must have a selectively permeable

membrane.- Movement depends on concentration.

(use salt water as an example)- Hypertonic- more solute (salt) [OVER]- Hypotonic- less solute (salt) [Below]- Isotonic- same amounts of solute (equal salt in

the cell and outside of the cell)

Osmosis ContinuedOutside Outside Outside

Inside of Cell

Inside of Cell

Inside of Cell

Solutions are:

HYPOTONIC HYPERTONICISOTONIC - ate salt, need water - no salt to absorb water

Osmosis ExamplesPlants- “like” HYPOTONIC

- turgor pressure- membrane pushing against cell wall. Gives us crisp veggies.

Protists- often in HYPOTONIC environment.- contractile vacuole pumps out excess water

Animals- can be in HYPOTONIC environment.- cells take on water until they burst- CYTOLYSIS

If in HYPERTONIC environment- Plasmolysis- cells lose water and shrink.

Facilitated Diffusion- Form of diffusion- Requires a carrier protein (protein channel)- Carrier protein binds to molecule and

changes shape to carry molecule across.- Protein returns to normal shape when

finished.- No ATP (energy) used- Glucose is best example.

Active Transport1. Molecular Transport- movement of

molecules from area of lesser to greater concentrations.

2. Endocytosis- taking in of material into the cell by infolding of the cell membranes.

3. Exocytosis- forces material out of the cell through the cell membrane.

Molecular Transport-Movement of molecules from an area of lesser

concentration higher concentration- Movement is ‘up’ or ‘against’ the gradient

- Paddling up stream- Normally moves calcium, potassium, and

sodium ions across cell membrane.- Uses ATP- Ex: Na/K pumps

- moves 3 Na+ OUT and 2 K+ IN

EndocytosisEndocytosis- “infolding” to allow cells to bring molecules

into it. Cell membrane pinches around a molecule or fluid.

2 types1. Phagocytosis- membranes surround LARGE PARTICLES and pull it in.

2. Pinocytosis- membranes surround FLUIDS and pull it into the cell

Exocytosis

Exocytosis- cells release large amounts of material from the cell.- vacuole attaches to cell membrane and dumps its contents out of the cell.

7-4 Diversity of Cellular Life

- What are the different types of life found on Earth?

Living Organisms

Unicellular Organisms- a cell is the entire organism. 1 cell does everything multicellular organisms do.

Multicellular Organisms- made of many cellsCell specialization- cells develop in different ways to perform different tasks.

Cell Specialization

Animal Cells- Red Blood Cells- transport oxygen- Pancreatic Cells- produce proteins (enzymes)- Muscle Cells- humans ability to move

Plant Cells- Guard Cells- regulates how much carbon dioxide, oxygen, water vapor is released through the stomata.

Levels of Organization

Cells- Tissues- similar cells grouped into units that perform

a particular function. Ex: muscle, epithelial, nervous and connective

Organs- groups of tissues working together.Ex: heart

Organ Systems- group of organs that work together.Ex: Pulmonary system- heart and lungs