7.1 life is cellular - beachwood city schools 7 1 - 7 2 cell… · 7.1 life is cellular mrs....

The key to every

biological problem must

finally be sought in the

cell, for every living

organism is, or at some

time has been, a cell.

E.B. Wilson, 1925

7.1 Life is Cellular

Mrs. Baldessari

Biology

1

Cells are Us

2

Cells are Us

Cilia on a protozoan Sperm meets egg

3

Lesson Overview Life Is Cellular

THINK ABOUT IT

What’s the smallest part of any living thing that still counts as being

―alive?‖

Can we just keep dividing living things into smaller and smaller parts,

or is there a point at which what’s left is no longer alive?

As you will see, there is such a limit. The smallest living unit of any

organism is the cell.

4

Cells are Us

A person contains about 100 trillion

cells. That’s 100,000,000,000,000 or 1 x

1014 cells.

There are about 200 different cell types

in mammals (one of us).

nerve cell

Red and

white blood

cells above

vessel-

forming

cells.

5

CELL SIZE

• Smallest cell in the human body is the sperm cell

• Largest cell in the human body is the egg cell

6

http://av.rds.yahoo.com/_ylt=A9ibyJ699iRFcxUAFSKHBqMX;_ylu=X3oDMTBwanIybjRqBHBndANhdHdfaW1nX3Jlc3VsdARzZWMDc3I-/SIG=12h9l48d9/EXP=1160136765/**http%3a//www.mischost.com/uploads/[email protected]/ovum-lg.jpg

Most cells are small

1. Surface to volume ratio: cell has to be small enough to get

– Waste out

– Nutrients in

2. The nucleus can

only control a

certain size cell

7


The Discovery of the Cell

What is the cell theory?

The cell theory states:

- All living things are made up of cells.

- Cells are the basic units of structure

and function in living things.

- New cells are produced from existing

cells.

8

Early Microscopes

• Prototypes were developed in the late 1500’s by European eyeglass makers

• It was not until the

mid-1600s that

scientists began to

use microscopes to observe living things.

Early compound microscope 17th century 9

In 1665, Robert Hooke used an early compound microscope to look at cork

• Observed that cork was made up of thousands of hollow chambers

• Dubbed them cells since they looked like the monatsery’s tiny rooms called “cellula”.

• Today we know that living cells are not empty chambers, but contain a huge array of working parts, each with its own function.

10

Anton von Leewenhoek

• Late 1600’s- Dutch textile salesman

• Created different types of microscopes

• Discovered over 5,000 types of microscopic life

• Lenses were able to magnify up to 300X

• .

FIRST person to

OBSERVE and

DESCRIBE

MICROSCOPIC

ORGANISMS

and LIVING

CELLS

11


Early Microscopes

Anton van

Leeuwenhoek

examined pond water

and other things,

including a sample

taken from a human

mouth. He drew the

organisms he saw in

the mouth—which

today we call bacteria.

12

The Cell Theory

• In 1838, German botanist

Matthias Schleiden concluded: “plants are made of cells”

• The next year, German biologist Theodor Schwann stated that all: “Animals are made of cells”

Schleiden

Schwann 13

Cell Theory

1. All living things are made of cells.

2. Cells are the basic unit of structure and function

3. New cells come from preexisting cells.

*cells are different shapes and sizes based on their function

In 1855, German physician Rudolf Virchow concluded

that new cells could be produced only from the division of

existing cells.

14


Exploring the Cell

How do microscopes work?

Most microscopes use lenses to magnify the image of an object by focusing

light or electrons.

15

A Sense of Scale and Abundance – Bacteria on the Head of a Pin

16

1. There are

1) Light Microscope

•Allows light to pass through a specimen and

uses two lenses to form an image.

•The first set of lenses, located just above the

specimen, produces an enlarged image of the

specimen.

•The second set of lenses magnifies this image

still further.

•Because light waves are diffracted, or

scattered, as they pass through matter, light

microscopes can produce clear images of

objects only to a magnification from 40 – 1,000

times depending on objective being used

Exploring the Cell- 3 major types of

microscopes

17


1) Light Microscopes

• magnification from 40 – 1,000

• Eyepiece magnifies 10X

• Total magnification calculation: multiply the eyepiece by the objective being used. Example- eyepiece (10X) times low power objective (4X) = 40X

• Used to magnify objects that light can pass through.

• Uses slides

18

Dissecting Microscope

• Magnifies 10 to 30 times

• Eyepiece magnifies 10X

• Objectives: 1X and 2X (3X)

• Used to magnify objects that light cannot pass through

• Used mostly by research scientists and jewelers

• Advantage: objects are 3-D

• Disadvantage: can’t view small objects

19


Light Microscopes and Cell Stains

A problem with light microscopy is that most

living cells are nearly transparent, making it

difficult to see the structures within them.

Using chemical stains or dyes can usually

solve this problem. Some of these stains are

so specific that they reveal only compounds

or structures within the cell.

20


Light Microscopes and Cell Stains

Some dyes give off light of a particular color when

viewed under specific wavelengths of light, a property

called fluorescence.

Fluorescent dyes can be attached to specific molecules

and can then be made visible using a special

fluorescence microscope.

Fluorescence microscopy makes it possible to see and

identify the locations of these molecules, and even to

watch them move about in a living cell.

21


2) Electron Microscopes

Light microscopes can be used to see cells and cell structures as small as

1 millionth of a meter. To study something smaller than that, scientists need

to use electron microscopes.

Electron microscopes use beams of electrons, not light, that are focused by

magnetic fields.

Electron microscopes offer much higher resolution than light microscopes.

There are two major types of electron microscopes: transmission and

scanning.

22

Electron Microscope -Two types: Transmission and Scanning

• Uses electrons to illuminate objects

• Can magnify from 30,000 to 9 million times

• Mostly large institutions have them

• Costly to own and maintain

• Can only be used to look at dead specimens

• Used for cytology, forensics, and virology

23


Transmission Electron Microscopes

Transmission electron microscopes make it possible to

explore cell structures and large protein molecules.

Because beams of electrons can only pass through thin

samples, cells and tissues must be cut first into ultra thin

slices before they can be examined under a

transmission electron microscope.

Transmission electron microscopes produce flat, two-

dimensional images.

24

• Transmission Electron Microscope

•TEM- thin slices need to be made to have clear images,

images are 2-D

•Useful for studying internal structures

25

http://creationwiki.org/images/6/6e/Mitochondria_lung.jpg


Scanning Electron Microscopes

In scanning electron microscopes, a pencil-like beam of

electrons is scanned over the surface of a specimen.

Because the image is of the surface, specimens viewed

under a scanning electron microscope do not have to be

cut into thin slices to be seen.

Scanning electron microscopes produce three-

dimensional images of the specimen’s surface.

26

•SEM- samples do not need to be cut, are in 3-D

• Useful for studying external

structure

27


Electron Microscopes

Because electrons are easily scattered by molecules in

the air, samples examined in both types of electron

microscopes must be placed in a vacuum in order to be

studied.

Researchers chemically preserve their samples first and

then carefully remove all of the water before placing

them in the microscope.

This means that electron microscopy can be used to

examine only nonliving cells and tissues.

28

General info about cells

• Cells come in a variety of shapes

• Range in size from microscopic bacteria to giant amoeba

Chaos carolinensis – Giant amoeba,

approximately 1mm in length

Mycoplasma

pneumoniae 29

General info about cells

c. All contain DNA

d. All have a cell membrane- an outer, flexible barrier

Cell

membrane Nucleus-

containing

DNA

30

Two Main Categories of Cells

a. Eukaryotes- have cells that enclose their DNA in a nucleus

b. Prokaryotes- cells that do not enclose their DNA in a nucleus

31


Prokaryotes and Eukaryotes

How are prokaryotic and eukaryotic cells different?

Prokaryotic cells do not separate their genetic material within a nucleus.

In eukaryotic cells, the nucleus separates the genetic material from the rest of

the cell.

32


• Organisms whose cell contain a nucleus and other membrane bound organelles are called EUKARYOTES

• Organisms whose cells never contain (or lack) a nucleus and other membrane bound organelles are called PROKARYOTES

33

A rat liver cell (with color enhancement to show organelles) 34

It’s Crowded In There

An artist’s conception of the cytoplasm - the region of a

cell that’s not in the nucleus or within an organelle. 35

A micrograph showing

cytoskeleton (red),

ribosomes (green), and

membrane (blue)

It’s Crowded In There

36

Two Fundamentally Different Types of Cells

37



Cells fall into two broad categories, depending on whether

they contain a nucleus.

The nucleus is a large membrane-enclosed structure that contains the

cell’s genetic material in the form of DNA. The nucleus controls many of the

cell’s activities.

38



Eukaryotes are cells that enclose their DNA in nuclei.

Prokaryotes are cells that do not enclose DNA in nuclei.

39

Prokaryotes • Are generally smaller than eukaryotic cells

• Have no nucleus

• Carry out all of life’s processes

• Ex: bacteria

Bacillus anthracis 40

Eukaryotes a. Are generally larger and more complex than

prokaryotes

b. Contain dozens of membrane bound structures that are specialized

c. Nucleus separates DNA from rest of cell

41

Eukaryotes

• Come in a variety of shapes and size

• Ex: protists, fungi, plant, and animal cells

42


Eukaryotes • Eukaryotic cells are generally larger and more complex

than prokaryotic cells.

• Most eukaryotic cells contain dozens of structures and

internal membranes. Many eukaryotes are highly

specialized.

• There are many types of eukaryotes: plants, animals,

fungi, and organisms commonly called ―protists.‖

43

Us vs. Them -

Eukaryotes

and

Prokaryotes

44

7.2 Cell Structure

Cell organization

• Organelles- “tiny organs”; the specialized structures within the cell that perform a function

45

http://upload.wikimedia.org/wikipedia/commons/6/6e/Localisations02eng.jpg

Animal vs Plant cells

46

Animal and Plant Cells Have More

Similarities Than Differences

47

The cell as a factory

• The different organelles of a cell can be compared to a living version of a modern factory

• Cells, like factories follow instructions to produce products

48

Cytoplasm

Cytoplasm- the portion of the cell outside of the nucleus; the fluid that fills the entire cell

• Makes up about 70% of the cells volume.

• Most of the cells chemical reactions occur here

49

The

Nucleus

•Control center of

the cell

•Surrounded by a

nuclear envelope with

pores

•DNA is in the form

of chromatin which

condenses down

into chromosomes

•Prokaryotic cells lack

a nucleus, but they do

have DNA

50


The Nucleus

Most nuclei also contain a small,

dense region known as the nucleolus.

The nucleolus is where the assembly

of ribosomes begins.

51

Organelles that Store, Clean-up, and Support

1. Vacuoles- large sac-like, membrane enclosed structures - store water, salts, proteins, carbohydrates

2. Lysosomes- the “clean-up crew”; small organelles filled with enzymes

3. Cytoskeleton-The framework of the cell ; a network of protein filaments; made up of microfilaments and microtubules; some parts help in transport of materials

a. Centrioles - Are located near the nucleus; help organize cell division; not found in plant cells

52

Vacuoles

• large sac-like, membrane enclosed structures

• Function- store water, salts, proteins, carbohydrates

• Larger in plant cells

• Found in some unicellular

organisms and animal cells

• Ex: Paramecium

Contractile vacuole in paramecium cell

53

http://static.newworldencyclopedia.org/4/40/Paramecium_with_contractile_vacuole.jpg

Vacuoles

• Typically called vesicles in animal cells- store and move materials between cell organelles and to the cell surface

54


Vacuoles and Vesicles

• saclike, membrane-enclosed structures

that store materials such as water, salts,

proteins, and carbohydrates

• Larger in plant cells

55

Lysosomes- the “clean-up crew”; small organelles filled with enzymes

• Break down many types of materials

Lipids

Carbohydrates

Proteins

Cellular debri

• Found mostly in animal cells

56

The Lysosome

Recycling cellular components

Functions:

Digesting food or cellular

invaders

57


Lysosomes

• Lysosomes are small organelles filled with enzymes that function as the cell’s cleanup crew. Lysosomes perform the vital function of removing ―junk‖ that might otherwise accumulate and clutter up the cell.

• Found mostly in white blood cells

• Have been linked to diseases, such as Tay Sach’s

• Tay Sach’s is a disorder that is caused by a genetic defect that prevents the formation of an essential enzyme that breaks down lipids

• These lipids build up in the body and can cause nerve damage; prognosis is not good

58

The Lysosome

This

bacterium

about to be

eaten by an

immune

system cell

will spend the

last minutes of

its existence

within a

lysosome.

59

Many Diseases are Caused by Lysosome Malfunction

60

Cytoskeleton

• The framework of the cell ; a network of protein filaments

• Some parts help in transport of materials

• Aids the cell in movement

• Made up of microfilaments and microtubules

61

The name is misleading.

The cytoskeleton is the

skeleton of the cell, but it’s

also like the muscular

system, able to change

the shape of cells in a

flash.

Maintains the shape of

the cell

Aids in movement

The Cytoskeleton

An animal cell cytoskeleton

62

A Cytoskeleton Gallery

63

The Cytoskeleton in Action

Cilia on a protozoan Beating sperm tail at fertilization

Smoker’s cough is due to destruction of cilia linking the airways. 64

Cytoskeleton

• Microfilaments- threadlike structures made up of a protein called actin

• Help cell maintain shape and allow it to move

• Assembly and dissasembly are responsible for amoeboid movement

65

Cytoskeleton

• Microtubules- are hollow structures made up of proteins known as tubulins

• Important for cells in maintaining shape, as well as for cell division

• Help build projections from the cell surface

66

Centrioles

• Are located near the nucleus

• Function- help organize cell division

• Not found in plant cells

67

Organelles That Build Proteins

1. Ribosomes- are small pieces of RNA and protein; the worktable for making proteins

2. Endoplasmic Reticulum- Protein synthesis (about half the cell’s proteins are made here); Protein movement (transport)

3. Golgi Apparatus-Proteins produced in the rough ER move here for packaging

68

Organelles That Build Proteins

Ribosomes- are small pieces of RNA and protein

• Function- the worktable for making proteins

• Build proteins based on DNA’s coded instructions

•Located throughout the cell

69

Ribosomes and the Endoplasmic Reticulum

70

Ribosome

• Ribosomes Are Not Surrounded by a membrane. They are the site of PROTEIN SYNTHESIS (Production or Construction) in a cell.

71

Cystic Fibrosis

Click here to see the article. 72

http://www.hhmi.org/genetictrail/a100.html

http://www.hhmi.org/genetictrail/a100.html

Endoplasmic reticulum- “ER”

• Found in eukaryotic cells only

• Internal membrane system responsible for assembling lipids for the cell membrane

• Also assembles proteins for and other materials that are exported from the cell

• Two types- rough and smooth

73

The Rough Endoplasmic Reticulum

Protein movement

(transport)

Protein synthesis

(about half the cell’s

proteins are made

here).

Studded with ribosomes

74

The Rough Endoplasmic Reticulum • Rough ER- builds proteins; contains ribosomes

on its surface

• Rough ER chemically modifies the proteins made by the ribosomes

• Produces proteins that will eventually be secreted out of the cell

75

Smooth ER • IS NOT Covered with RIBOSOMES and

processes LIPIDS and CARBOHYDRATES.

• The Smooth ER is involved in the synthesis of steroids in gland cells, the regulation of calcium levels in muscle cells, and the breakdown of toxic substances by liver cells.

76

• Smooth ER- known as smooth because there are no ribosomes on its surface

• Contains enzymes that allow it to synthesize membrane and detoxify drugs

• Highly concentrated in liver cells

Right: rough er; Left: smooth er

Human liver cell 77

Golgi Apparatus

• Found in eukaryotic cells

• Proteins produced in the rough ER move here

• Appears as a stack of flat discs

• Function- modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or release outside the cell

78

Golgi Apparatus

• Processing, Packaging and Secreting Organelle of the Cell that is made of flattened SAC

79

Animal vs. Plant Cells – Chloroplasts Are a Big Part of the

Difference

80

Cells In a Leaf

81

Two Other Unique Features of Plant Cells

The central

vacuole

may occupy

90% of a

plant cell.

82

Organelles that Capture and Release Energy

1. Chloroplasts - Found in plant cells, algae, and some bacteria; Capture light energy and convert it into food that contains chemical energy ; Where photosynthesis occurs

2. Mitochondria-Found in all eukaryotic cell; “powerplant” of the cell; Converts the chemical energy stored in food into compounds that are more convenient for the cell to use (ATP)

83

Chloroplasts

• Found in plant cells, algae, and some bacteria

• Capture light energy and convert it into food that contains chemical energy

• Where photosynthesis occurs

84

http://en.wikipedia.org/wiki/Image:Chloroplast-new.jpg

http://en.wikipedia.org/wiki/Image:Chloroplasten.jpg

The Chloroplast

Think of the chloroplast as the solar panel of the plant cell.

Only plants have chloroplasts; they perform photosynthesis 85

Chloroplast Structure

• 2 membranes surround the organelle

• Stacks of membranes called grana are where chlorophyll occurs

• Chlorophyll- green pigment

86

Mitochondria

• Found in all eukaryotic cells

• Function- “powerplant” of the cell

• Converts the chemical energy stored in food into compounds that are more convenient for the cell to use (ATP)

87

The Mitochondrion

Think of the mitochondrion as the

powerhouse of the cell.

Both plant and animal cells

contain many mitochondria.

88

Mitochondrial Diseases

89

Mitochondria and Health

90


Cellular Boundaries

Cells are surrounded by a barrier known as the

cell membrane.

Many cells, including most prokaryotes, also

produce a strong supporting layer around the

membrane known as a cell wall.

91


Cell Membranes

All cells contain a cell membrane that

regulates what enters and leaves the cell

and also protects and supports the cell.

92

Cell membrane • The Cell Membrane is a complex barrier

separating the cell from it's external environment. The "Selectively Permeable" Membrane regulates what passes into and out of the cell.

93


Cell Membranes

The composition of nearly all cell

membranes is a double-layered sheet

called a lipid bilayer, which gives cell

membranes a flexible structure and forms

a strong barrier between the cell and its

surroundings.

94

Cell membrane-

• outermost boundary of the cell

• Is made up of a flexible double layer called a lipid bilayer

• Gives cell shape and holds cytoplasm in

Hydrophobic Tails Hydrophilic Head Lipid Bilayer

Receptor

Proteins

95

Cell membrane-

• Selective Permeability- some substances can cross over the cell membrane, some cannot

• Gets in: Oxygen, water, and Carbon Dioxide •Does Not Get in: Sodium, Potassium, Calcium, Chlorine, proteins (need active support), most large molecules

96

You will not be tested on the material

presented on the next 7 slides covering lipids and fluid mosaic model

– these slides do not appear in you powerpoint – this material is covered

in Honors Bio ad AP bio – I am presenting it for those who like to

understand how things work.

97


The Properties of Lipids that control how

a cell membrane works

Many lipids have oily fatty acid chains attached to chemical

groups that interact strongly with water.

The fatty acid portions of such a lipid are hydrophobic, or

―water-hating,‖ while the opposite end of the molecule is

hydrophilic, or ―water-loving.‖

98


The Properties of Lipids

When such lipids are mixed with water, their

hydrophobic fatty acid ―tails‖ cluster together

while their hydrophilic ―heads‖ are attracted to

water. A lipid bilayer is the result.

99


The Properties of Lipids

The head groups of lipids in a bilayer are

exposed to water, while the fatty acid tails

form an oily layer inside the membrane

from which water is excluded.

100


The Fluid Mosaic Model

Most cell membranes contain protein molecules

that are embedded in the lipid bilayer.

Carbohydrate molecules are attached to many

of these proteins.

101



Because the proteins embedded in the lipid bilayer can move around and

―float‖ among the lipids, and because so many different kinds of molecules

make up the cell membrane, scientists describe the cell membrane as a

―fluid mosaic.‖

102



Some of the proteins form channels and pumps that help to move material

across the cell membrane.

Many of the carbohydrate molecules act like chemical identification cards,

allowing individual cells to identify one another.

103


The Fluid Mosaic Model Although many substances can cross biological membranes, some

are too large or too strongly charged to cross the lipid bilayer.

If a substance is able to cross a membrane, the membrane is said to

be permeable to it.

A membrane is impermeable to substances that cannot pass across

it.

Most biological membranes are selectively permeable, meaning that

some substances can pass across them and others cannot.

Selectively permeable membranes are also called semipermeable

membranes.

104

Cell Wall • Plant cells have a cell wall.

• A Cell Wall DOES NOT REPLACE the Cell Membrane

• Cells with WALLS also have a CELL MEMBRANE.

• Plant Cells are covered by a Rigid Cell Wall that lies Outside the Cell Membrane.

105

Cellular Walls

• Cell Wall- a strong, supporting layer around the cell membrane

• Found in prokaryotes, plants, and fungi

• Not found in animal cells

106

• Function- supports, shapes, and protects the cell

• Porous enough to allow water, O2, and CO2 to pass through

• In plants, it’s made up of cellulose

Right: products made from

cellulose

107

Cellular Walls

The Central Vacuole

Controls Turgor Pressure

Flaccid – no water

Turgid – full of water 108

Cellular Anatomy

109

Plants vs Animals

• Chloroplasts

• Cell Wall

• Centrioles

Both

•Nucleus Cytoskeleton

•Nucleolus Vacuoles

•Mitochondria Ribosomes

•Golgi Apparatus Lysosomes

•ER Cytoplasm

110

Cell Structure Review

You must know the similarities and differences between plant and animal cells

• You must be able to locate the various organelles in a cell diagram

• You must know the function of each organelle

111

The Nucleus - review • The largest membrane-

bound organelle in the

eukaryotic cell

• Enclosed by the nuclear

envelope – contains pores

•Contains a “dark spot” -

the nucleolus – builds

ribosomes

•Contains chromatin (DNA

and proteins) – when coiled

forms chromosomes

http://www.daviddarling.info/images/cell_nucleus.jpg

112

http://www.daviddarling.info/images/cell_nucleus.jpg

Plasma Membrane - review • Composed of a phospholipid bilayer with

embedded proteins

• Provides a barrier that controls what enters and leaves the cell.

• All cells, both prokaryotic and eukaryotic, contain plasma membranes.

113

Cell Wall - review • Both prokaryotic and eukaryotic cells can have a cell

wall.

• Composed of cellulose in plant cells.

• A rigid, protective covering that provides structural support.

http://home.earthlink.net/~dayvdanls/ptcytok.

GIF

114

http://home.earthlink.net/~dayvdanls/ptcytok.GIF

http://home.earthlink.net/~dayvdanls/ptcytok.GIF

Cytoplasm - review

• Cell fluid which surrounds the organelles and contains many dissolved solutes.

• Site of many cellular chemical reactions.

http://www.jenningsk12.net/WE/peimann/Science/Cells/cell_amoeba.jpe

115

http://www.jenningsk12.net/WE/peimann/Science/Cells/cell_amoeba.jpe

Vacuole - review

• Bag-like storage structure

• Can take up to 90% of the volume of a plant cell

• Stores food, water, wastes, or other substances

• Animal cell vacuoles are much smaller

http://student.nu.ac.th/u46410320/vacuole%5B1%5

D.jpeg

116

http://student.nu.ac.th/u46410320/vacuole%5B1%5D.jpeg

http://student.nu.ac.th/u46410320/vacuole%5B1%5D.jpeg

Mitochondria - review • The site of cellular

respiration.

• Provides energy for the cell by producing a molecule called ATP.

• Has a highly folded inner membrane that provides increased surface area for chemical reactions.

http://micro.magnet.fsu.edu/cells/mitochondria/images/mitochondriafigure1.jpg

117

http://micro.magnet.fsu.edu/cells/mitochondria/images/mitochondriafigure1.jpg

Chloroplast - review • Site of photosynthesis.

• Contains the green pigment chlorophyll.

• Has a highly folded inner membrane that provides increased surface area for chemical reactions.

http://www.helpsavetheclimate.com/chloroplast1.gif

118

http://www.helpsavetheclimate.com/chloroplast1.gif

Ribosomes - review • Composed of RNA and protein

• Made up of two subunits

• Responsible for protein synthesis

• Found in both prokaryotic and eukaryotic cells

http://www.daviddarling.info/images/ribosome.jpg

119

http://www.daviddarling.info/images/ribosome.jpg

Other Organelles - review • Other organelles help to

carry out cell functions.

• ER – makes lipids and helps build new membrane.

• Golgi receives and modifies proteins and then ships them to new locations in the cell.

• Lysosomes digest worn out cell parts and food.

Golgi

Apparatus

Transport

Vesicle

Endoplasmic

Reticulum

Lysosome

http://www.answers.com/topic/endomembrane-system-diagram-no-text-nucleus-png

120














7.1 life is cellular - beachwood city schools 7 1 - 7 2 cell… · 7.1 life is cellular mrs....

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