Chapter 7 - Cells

7-4 THE DIVERSITY OF CELLS

Compare and contrast the differences between different types

of specialized cells

Identify the levels of organization in multicellular organizations

How many different

types of cells are

there in the human

body?

Levels of Cellular Organization

Neurons• Receives and sends

messages

• Part of the nervous

system

Thermosensitive

Nerve Cells• Primary function is to

detect temperature

• Also detect pain

Muscle Cells

• Stretch and contract

to make body

movements

• Every movement in

your body is the result

of a muscle cells

contracting and

another set

expanding.

Sperm, Egg, Pollen

• Reproduction

Red Blood Cell

• Picks up oxygen from

the lungs and delivers

it around the body.

What do you see?

Cones

• Cell in the back of

your eye that

detects color.

• Cell in the back of

your eye that

detects light, but

aren’t sensitive to

color.

Rods

Skin Cells

• Provide protection

and a barrier to the

outside world

• The cells on the

outermost layer are

dead

Absorptive Cells

• These cells absorb

nutrients from food.

7-1 LIFE IS CELLULAR

Distinguish among prokaryotic and the two major groups of

eukaryotic cells

Cell Theory’s Main Points

All living organisms are composed of one or

more cells

Cells are the most basic unit for function and

structure of all organisms

All cells come from cells that already exist

Review of the Key Scientists

• Robert Hooke

• Anton van Leeuwenhook

• Matthias Schleiden

• Theodore Schwann

• Rudolph Virchow

Coined the term “cell” in

his publication about

microscopic structures

Contribution to Cell Theory

1632 -1723

A microscopy pioneer and naturalist

who formulated early descriptions of

bacteria and spermatozoa

He devoted his time to his hobby,

which was grinding lenses and

using them to study tiny objects

Matthias Schleiden1804 – 1881

1831

Recognized the importance

of the cell nucleus and its

connection to cell division

1838

Used his observations of

plant cells to state that

organisms consist of cells or

substances made by cellsContributions

to Cell Theory

Schw

ann’s

Dis

coveries

contributions to cell knowledge

Included

• cell origin

• tissue development of nails, tooth enamel

and feathers

Theodor Schwann1810 - 1882

all animals are made of cells

best known for his theory

Omnis cellula e cellula"every cell originates from another cell"

1858

Contributions to Cell Theory

• Proposes the

Endosymbiont Theory in

1970

– Several organelles found in

eukaryotic cells appear to

be of prokaryotic origin

– Evidence includes having

their own DNA and

reproduction that occurs

independently of the cell

Two Basic Kinds of Cell

• Prokaryotes

“Before Kernel”

– no nucleus

– no organelles

– single strand of DNA

– cell wall

(not like a plant)

– small size

• 0.1 to 1.0 µm

NEXT CHAPTER

• Eukaryotes

“New Kernel”

– nucleus

– organelles

– multiple chromosomes

– cell wall

(plants only)

– larger size

• 1.0 to 10.0 µm

FOCUS of this CHAPTER

Two Basic Kinds of Cell

• Prokaryotes

“Before Kernel”

NEXT CHAPTER

• Eukaryotes

“New Kernel”

FOCUS of this CHAPTER

Eukaryotic Cells – Two Types

Animal

Plant

How do we see the microscopic

world of cells?

• Light microscopes

• Electron microscopes

– Transmission

– Scanning

• Scanning probe microscopes

Light Microscopes

Electron Microscope

Table SaltTransmission Electron

Microscope

12/16/2015

Eye of an Ant

Spider

Human hair

7-2 EUKARYOTIC CELL

STRUCTURE

Describe the structure and function of the following:

cell wall, cell membrane, cytoplasm, nucleus, chromosomes,

ER, ribosomes, Golgi bodies, lysosomes, mitochondria,

microtubules, microfilaments, centrioles, cilia, flagella,

vacuoles, and plastids.

Start with…

The Cell Membrane

• Characteristics

– thin layer of lipid

and protein

– 5 to 10 nm thick

– flexible, bilayer

– surrounds the

outside of the cell

**all types of cells

have membranes**

cell membrane

Cytoplasm

• Characteristics

– semifluid substance

– two components

• Cytosol = primarily water

and dissolved organic

materials (50% of vol.)

• Everything Else = organelles

and the insoluble cellular

components

**all types of cells

have cytoplasm**

Cytoplasm

• Function

– suspends the organelles

– provides a medium for

dissolving and

transporting molecules

**all types of cells

have cytoplasm**

cytoplasm

Cytoskeleton

• Characteristics

– network of fibers and tubes

• microtubules

• microfilaments

• intermediate filaments

• Function

– supports cell

– transports organelles

– moves cell membrane

Cytoskeleton Fibers (filaments

and microtubules)

Nucleus

• Characteristics

– found in the center of the cell

– surrounded by a bilayer envelope with pores

• Function

– holds genetic information

– nucleolus makes ribosomes

**ONLY EUKARYOTIC CELLS**

Nucleus

Nucleolus

All the other stuff in a cell

What have we covered

already?

Nucleus

Nucleolus

Cell Membrane

Cytoplasm

Cytoskeleton

Fibers

Cell Organelles

• the following organelles are all found in

both types of eukaryotic cells

– Each organelle has a specific role (function)

**ONLY EUKARYOTIC CELLS**

Ribosomes

• Characteristics

– very small

– suspended in cytoplasm

– attached to rough

endoplasmic reticulum

– made up of two parts

• Function

– join amino acids to make

proteins

**Both EUKARYOTIC and PROKARYOTIC

CELLS but different types**

Ribosomes

Endoplasmic Reticulum (ER)

• Character

– contiguous

with the

pores of the

nuclear

membrane

– extensive

network of

membranes

ER – Rough and Smooth

• Function – Rough

– ribosomes are

embedded in the

membranes

• makes proteins and

new cell membrane

• Function – Smooth

– NO ribosomes

• makes lipids,

carbohydrates, and

modifies toxic

chemicals

Endoplasmic Reticulum

Golgi Apparatus –

Cell UPS Delivery

• Character

– series of membrane

bound sacs

– unique appearance

• like pancake stacks

Golgi Apparatus

• Function

– sorts, modifies, packages and distributes

macromolecules

– packages some molecules for secretion

Golgi Apparatus

Mitochondria – Cell Powerhouse

• Character

– double wall

membrane

– folded inner

membrane (cristae)

– inner space (matrix)

– 1000’s within a cell

Mitochondria

• Function

– breaks down food

molecules to produce

energy

– inner membrane contains

special structures for

producing large quantities

of energy

Mitochondria

Lysosomes

• Character

– saclike organelles

– contain digestive

enzymes

Lysosomes – Recycling Centers

• Function

– break down large molecules for transport and

disposal

– recycle worn out organelles

Lysosomes

Vesicles – Transport Containers

• Function

– transport of materials into and out of the cell

Vesicles – Transport Containers

• Transport

mechanism

– Vesicles travel

along cytoskeleton

structures

Vesicles

Centrioles

Plant Cells

Three Important Structures

• Cell Wall– Cellulose structure

• Central Vacuole– Large storage organelle

• Chloroplasts– Make carbohydrates!! Make

energy!!

Plant Cell Walls

• Important for holding

plants up!

– Special carbohydrate

called cellulose

• Very tough!

• Flexible enough, but

not too much

• Characteristic

appearance

http://www.ceres.net/AboutUs/Abo

utUs-Biofuels-Carbo.html

Plant Cell Wall Diagram

Central Vacuole

• Large storage organelle in the

center of plant cells

– Creates turgor pressure

– Helps store water

Chloroplasts

• Unique shape

• Found near surface

• Give plants their green color

• Make carbohydrates through

photosynthesis

• WE WILL CONTINUE THIS DISCUSSION

IN PHOTOSYNTHESIS

7-3

Cells and Their Environment

Explain how and why cells maintain a large surface to

volume ratio

Describe the roles of diffusion, facilitated diffusion, osmosis,

and active transport in maintaining homeostasis

Cell Membrane Structure

• phospholipid bilayer

– phospholipid has (a)

• hydrophilic head

• hydrophobic tails

– when placed in water

• head turns toward water

• tails turn away from water

Cell Membrane Structure

• embedded proteins

– 2 main types

– gate ports (transporters and channels)

– communication (receptor proteins)

Cell Membrane Model

• Fluid Mosaic Model

– phospholipids and proteins move around each

other freely

http://www.dnatube.com/video/360/Fluid-

Mosaic-Model

Maintaining Internal Conditions

• Cells use

– Active and passive transport to control

• Movement of water, food, ions and other

needed materials into and out of cells

Maintenance of these internal conditions

is called homeostasis.

Semi-permeable Membranes

• Cell membranes are

semipermeable

– They prevent the movement of certain

particles into and out of the cell

permeable =

allows molecules

to pass through

semi =

partial

Molecule Movement

• Can be controlled

– proteins

– carbohydrates

• large size

• Cannot be controlled

– water

• small size

• Small but controlled

– ions

• electrical charge

prevents movement

Transport Processes Through

Membranes

Passive Transport

• particles move down a conc. gradient from high to low

• includes– simple diffusion

– osmosis

Active Transport

• particles move against a conc. gradient from low to high

• used for transport of molecules to areas of high conc.

ENERGY

REQUIRED

NO

ENERGY

REQUIRED

Transport Processes Through

Membranes

Passive Transport Active Transport

ENERGY

REQUIRED

No ENERGY

REQUIRED

high

conc.

low

conc.

high

conc.

low

conc.

Passive Transport

• Includes Diffusion and Osmosis

• Start with Diffusion

– the random movement of particles from areas of high

conc. to low conc. without the input of energy

– two types of diffusion

• simple

• facilitated

REMINDER!! Concentration is

the proportion of

solute to solvent

Simple Diffusion

• rate of diffusion depends on

– temp. and size of molecules

– conc. gradient

FASTER movement

high temp.

small molecules

SLOWER movement

low temp.

large molecules

Passive

Transport

Facilitated Diffusion

• follows same rules for simple diffusion

– movement is passive down a conc. grad.

• facilitated carrier proteins help transport

the molecules across the cell

membrane

Passive

Transport

Osmosis

• special type of diffusion that results from

the passive movement of water across a

semi-permeable membrane

– follows rules of diffusion

• movement from

high WATER conc. to low WATER conc.

Passive

Transport

Word Parts for Osmosis:

• Hyper = more particles, less water

• Iso = equal particles, equal water

• Hypo = less particles, more water

• Tonic = particles in solution

Passive

Transport

Osmotic Environments

• Condition of the solution (environment) the

cell is in

– determined by comparison of the

concentration of solution

INSIDE and OUTSIDE

the cell

• three types of osmotic conditionsPassive

Transport

Osmotic Conditions

Passive

Transport

Whether or not something is HYPER,

ISO, or HYPOTONIC depends on what

you are comparing it with.

Make sure you know what you are

comparing your solution with.

For example:

The _______ is hypertonic to the

_______. Passive

Transport

Passive

Transport

Identifying Osmotic

Environments• When identifying an osmotic environment

you need to do two things:

– 1) identify the concentration

• of particles outside the cell

• of particles inside the cell

– 2) then compare and determine which

direction the water (!) will move BE

CAREFUL!!! Passive

Transport

Hypertonic Solution

• Solution

– lots of particles

– little water

• Water Movement

– out of the cell

Passive

Transport

Isotonic Solution

• Solution

– same particles

– same water

• Water Movement

– NO NET MOVEMENT

Passive

Transport

Hypotonic

• Solution

– few particles

– lots of water

• Water Movement

– into the cell

Passive

Transport

Active Transport

• Cells sometimes need

certain particles (molecules

or ions) that are already at

a high conc. inside the cell

• Need to move against the

conc. grad.

• Requires energy to move

particles Active

Transport

Movement of Large Particles

• Endocytosis

endo = into, cyto = cell

– Macromolecules or other

molecules are moved into the

cell

– Vesicles are formed from the

plasma membrane of the cell

Active

Transport

Three main types of endocytosis

1. Phagocytosis

2. Pinocytosis

3. Receptor-mediated Endocytosis

http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf

Active

Transport

Phagocytosis

• “cellular eating”

– Movement into the cell of large particles and

solids

– Can be used by white bloods cells to take in

bacteria for destruction

Active

Transport

Phagocytosis and Lysosomes

http://highered.mcgraw-

hill.com/olcweb/cgi/pluginpop.cgi?it

=swf::535::535::/sites/dl/free/00724

37316/120067/bio01.swf::Lysosom

es

Active

Transport

Pinocytosis

• “cellular drinking”

– plasma membrane encloses and pinches off

– small droplets of fluid are trapped in a vesicle

– liquid contents of the vesicle is then slowly

transferred to the cytosol

Active

Transport

Receptor-mediated Endocytosis

• Receptor proteins on the cell membrane

• Recognize specific molecules

• Receptors bind with molecule to bring it

into the cell

• Lysosomes bind with vesicle and release

contentsActive

Transport

Exocytosis

• The reverse process of endocytosis

– Used for

• Transporting wastes out of the cell

• Secretion of specific molecules

• Examples

– Tears are secreted salt and protein solution

– Cells in the pancreas secrete insulin to the

blood stream

END OF NOTES!

Study for your test!