7.1 - The Discovery of Cells - Associazione Dscholashare.dschola.it/lscattaneo/Per gli...

Ch 7: A View of the Cell

7.1 - The Discovery of Cells

Section 7.1

The History of the Cell Theory

The Cell Theory

2 Types of Microscopes

2 Basic Cell Types

Inside This Section...

The microscope was invented by

Anton van Leeuwenhoek

Dutch Scientist

First Microbiologist


Section 7.1


Section 7.1

The first person to see a cell (in cork)

was Robert Hooke.

Observed cells in Cork


Section 7.1

Matthias Scleiden Concluded that all

plants have Cells

German Botanist


Section 7.1

Theodore Schwann observed that

animals were also composed of cells


Section 7.1

3 main ideas:

All living things are composed of

one or more cells

The Cell is the basic unit of

organization of organisms

All cells come from preexisting cells

The Cell Theory

Section 7.1

Uses light and lenses

The Simple light Microscope

used one lens and natural light

(Leeuwenhoek)

The Compound light microscope:

Uses multiple lenses

Magnifies up to 1500 times

The Light Microscope

Section 7.1

Invented in the 1940s

Uses a beam of electrons

Magnifies up to 500,000 times

Two Kinds:

Scanning electron microscope (SEM):

Scans the surface of cells.

Transmission electron microscope

(TEM): Allows for study of structures

inside cells.

The Electron Microscope

Section 7.1

Microscope COmparison

Section 7.1

SEM

TEM

Two Basic Cell Types

Section 7.1

Prokaryotes: Cells lacking internal membrane-bound

structures

Eukaryotes: Cells containing internal membrane-bound

structures. The membrane-bound structures are called

organelles. Contains a nucleus: organelle that manages

cellular function. First observed by Robert Brown. Rudolf

Virchow concluded that it was responsible for cell division.

Section 7.1

Two Basic Cell Types

Section 7.1


The Cell Theory

2 Types of Microscopes

2 Basic Cell Types

In Review...

Section 7.1

Animal Cell Structure

Section 7.1

Plant Cell Structure


7.2 - The Plasma Membrane

Section 7.2

Maintaining a Balance

The Plasma Membrane

The Structure of the Plasma Membrane


The Plasma membrane is the

boundary between the cell and it’s

environment

Needs to let the good stuff (e.g.

nutrients) in and the bad stuff (waste)

out

The plasma membrane maintains

homeostasis.


Section 7.2

Section 7.2


Maintains Homeostasis: regulates internal environment

[Good in (but not too much), Bad Out]

Selective permeability: Allows some molecules into the cell

and keeps some out.

Some molecules can cross the plasma membrane (i.e.

water). Others must go through channels (i.e. Na, Ca, etc)

The Plasma Membrane

Section 7.2

Composed of a phospholipid bilayer.

A Lipid with a phosphate group

attached

Has only 2 fatty acid tails

Forms a sandwich

The phosphate group forms the polar

head

The fatty acid tails form the nonpolar

tail

Plasma Membrane Structure

Section 7.2

The membrane is fluid: It is flexible and phospholipids can move

in the membrane like water in a lake.

The membrane is mosaic: There are proteins embedded in the

membrane that also move (like boats in the lake)

The Fluid Mosaic Model

Section 7.2

Cholesterol: Helps stabilize the plasma membrane, and prevents

the phospholipids from sticking together.

Transport Proteins: Proteins that span the entire membrane and

form channels for specific molecules to enter and leave (like a

door).

Other Proteins and carbohydrates on the external surface: Helps

with identification.

Proteins on internal surface: Provides flexibility by attaching the

plasma membrane to the cell’s internal structure.

Other Components

Section 7.2

Section 7.2

Section 7.2


The Plasma Membrane

The Structure of the Plasma Membrane

In Review...


7.3 Eukaryotic Cell

Structure

Section 7.3

Cellular Boundaries

The Organelles

Support And Locomotion


Plasma membrane surrounds the cell

In plants, fungi, most bacteria and

some protists, the cell wall surrounds

the plasma membrane

Cellular Boundaries

Section 7.3

Cell Wall

Fairly rigid

Provides support and protection

Made up of the carbohydrate

cellulose

Has pores to allow molecules

through

Cellular Boundaries

Section 7.3

The Nucleus is the leader of the

cell

Gives directions for the making of

proteins

The master set of directions is in

chromatin

During cell division, chromatin

condenses to form chromosomes.

The Nucleus and Cell Control

Section 7.3

Inside the nucleus there is also the

nucleolus

Makes ribosomes

Ribosomes are sites where

proteins and other enzymes are

made, according to instructions

from DNA


Section 7.3

The Nuclear envelope is a double

membrane that surrounds the

nucleus.

Made up of 2 phospholipid

bilayers

Contains small nuclear pores


Section 7.3

Section 7.3

The Cytoplasm

• The Fluid

inside the

Cell

The endoplasmic reticulum: A

series of highly folded

membranes

Where cellular chemical

reactions take place

Like a large workspace

Assembly and Transport

Section 7.3

Some parts have ribosomes

attached (rough endoplasmic

reticulum - RER)

Others don’t (smooth

endoplasmic reticulum –

SER)


Section 7.3

RER: Proteins made in the

RER may:

form part of the plasma

membrane

be released from the cell

transported to other

organelles


Section 7.3

SER: involved in production

and storage of lipids.


Section 7.3

The Golgi apparatus: flattened

system of tubular membranes and

vesicles

Modifies proteins

Sorts and packages proteins

It’s kind of like the post office:

Sorts the mail and sends it to the

right place


Section 7.3

A vacuole is a sac surrounded by membrane

Used for temporary storage of

Food

Enzymes

Waste

Plant cells usually have one large vacuole, animal cells have

many smaller ones

Vacuoles

Section 7.3

Vacuoles

Section 7.3

Lysosomes are organelles that contain digestive enzymes

They digest food particles, organelles and engulfed viruses or

bacteria

Can fuse with vacuoles and digest the contents.

Can also digest cells that contain them.

i.e. tadpole’s tail

Lysosomes and Recycling

Section 7.3

For all the cellular processes to happen, energy is

needed

Two organelles provide that energy:

Choloroplasts (in plants)

Mitochondria (in animals and plants)

Energy Transformers

Section 7.3

Chloroplasts are organelles that

captures light energy and produces

food to store for later

Has a double membrane (like the

nucleus)

The inner membrane folds in to form

stacks of membranous sacs called

grana/thylakoids.

Chloroplasts

Section 7.3

In the thylakoid membrane there is

the green pigment called

Chlorophyll

Traps light energy

Gives leaves and stems their green

color

Chloroplasts

Section 7.3

Mitochondria produces

energy in a form that can be

used by the cell when

necessary.

Has an outer membrane and

a highly folded inner

membrane.

Provides large surface area.

Mitochondria

Section 7.3

Cytoskeleton: forms the framework

of the cell

Maintains shape

Composed of:

Microtubules: thin hollow

cylinders made of protein

Microfilaments: thin, solid protein

fibers

Support and Locomotion

Section 7.3

Cilia and flagella : Structures that aid in

locomotion and feeding.

Composed of pairs of microtubules, with

a central pair surrounded by 9 additional

pairs.

Cilia are short, numerous, hair-like

projections that move in a wavelike

motion

Flagella are longer projections, move in

a whip-like motion.

Support and Locomotion

Section 7.3

Section 7.3

Cellular Boundaries

The Organelles

Support And Locomotion

In Review...

7.1 - The Discovery of Cells - Associazione Dscholashare.dschola.it/lscattaneo/Per gli...

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