chapter 5 cytology

CYTOLOGY

CHAPTER 5

CELL MODELS

The idea of the hasn’t

always existed.

The invention of the

allowed

scientists to study plants and

animals in a new way.

What they saw

popular theories.

CELL MODELS

The idea of the cell hasn’t

always existed.


allowed



What they saw

popular theories.

CELL MODELS


always existed.


microscope allowed



What they saw

popular theories.

CELL MODELS


always existed.


microscope allowed



What they saw disproved

popular theories.

PREFORMATION

The idea that eggs and sperm

contain miniature that

increase in size after conception.

PREFORMATION

The idea that eggs and sperm

contain miniature people that

increase in size after conception.

MAJOR CONTRIBUTIONS TO THE CELL THEORY

Year Scientist Contribution

1665 Robert Hooke First used the term “cell” when looking at cork

under magnification. Beginning of cytology.

1682 Antonie van

Leeuwenhoek

Each cell had a central part. Living things

didn’t arise from nonliving materials.

1831 Robert Brown Named the nucleus.

1837 Matthias Schleiden

Theodor Schwann

Proposed that all plants and animals are

made of cells.

1855 Robert Remak Cells divide to produce new cells.

1858 Rudolf Virchow All cells come from preexisting cells.

MODERN CELL THEORY

1. Living things are composed of one or

more .

2. The cell is the basic unit of .

3. Cells come from cells.

The model we

use now!

MODERN CELL THEORY


more cells.

2. The cell is the basic unit of .


The model we

use now!

MODERN CELL THEORY


more cells.

2. The cell is the basic unit of life.


The model we

use now!

MODERN CELL THEORY


more cells.

2. The cell is the basic unit of life.

3. Cells come from preexisting cells.

The model we

use now!

CELL THEORY

Cell theory is a very reliable and predictable model that explains

the way cells work.

TRUE OR FALSE:

The cell theory is so foundational to biology that it may not ever

need to be changed.

CELL THEORY

Cell theory is a very reliable and predictable model that explains

the way cells work.

TRUE OR FALSE:

The cell theory is so foundational to biology that it may not ever

need to be changed.

FALSE

WHAT MAKES A GOOD MODEL?

A model is only useful if it can:

1. what we have already observed.

2. Make .

3. Be to account for new observations.



1. Explain what we have already observed.

2. Make .





2. Make predictions.





2. Make predictions.

3. Be modified to account for new observations.

WAYS TO CLASSIFY ORGANISMS

1. How the cells work together

organism- an

organism that is made of only

one cell.

Can fully function without help

from other cells.

Examples: bacteria, protozoans,

several algae and fungi


1. How the cells work together

Unicellular organism- an

organism that is made of only

one cell.

Can fully function without help

from other cells.

Examples: bacteria, protozoans,

several algae and fungi

UNICELLULAR ORGANISMS

Some unicellular organisms work

together in a .

cells take on specific tasks.

cells can break away from the colony

and function on their own.

algae

bacteria

UNICELLULAR ORGANISMS

Some unicellular organisms work

together in a colony.

cells take on specific tasks.

cells can break away from the colony

and function on their own.

algae

bacteria

MULTICELLULAR ORGANISM

Made of two or more cells that

on each other to

function.

Example: some algae and fungi, all

plants, animals, and humans.

Most cells are highly

and can’t function without the

support of other cells.

Example: blood cells, skin cells.



depend on each other to

function.



Most cells are highly






depend on each other to

function.



Most cells are highly specialized




Organization of cells in organisms

unicellular

colony

multicellular

tissue

organ

organ system

made of one cell made of more than one cell

cells work together in a cells work together to form a

which work together for a specific function in an

which work together for a specific function in an


2. By the kinds of parts

they have

The parts inside a cell are

called .

Many organelles are

surrounded by a .



they have


called organelles.

Many organelles are

surrounded by a .



they have


called organelles.

Many organelles are

surrounded by a membrane.

CELL ORGANELLES

An organism with cells that contain

membrane-bound organelles is

.

Examples: humans, animals, plants,

fungi, and protists.

An organism whose organelles

lack surrounding membranes is

.

Example: bacteria

CELL ORGANELLES



eukaryotic.





.

Example: bacteria

CELL ORGANELLES



eukaryotic.





prokaryotic.

Example: bacteria

PROKARYOTIC CELLS

1. CYTOPLASM

consists of everything within the cell

membrane except the nucleus

contains cytosol, the fluid in which the

organelles are suspended

has molecules used for building structures

in the cell

2. CYTOSKELETON

a system of fibers in the cytosol that helps

maintain the cell’s shape

provides protein motors and a track to

move substances around the cell in a

process called cytoplasmic streaming

3. CAPSULE

Found only in bacteria/prokaryotes

Located outside the cell membrane and

cell wall

Protects the cell

Contains water to keep the cell from

drying out, often making it feel slimy

4. NUCLEOID

Found only in bacteria/prokaryotes

Contains the genetic material for the cell

Floats freely in the cytosol (no membrane)

5. FLAGELLUM

extension of the cytoskeleton

usually only one or a few per cell

propels the cell through its

environment using a protein

motor

6. CHLOROPLAST

A type of pigmented plastid

Found only in plants and algae

converts light energy from the sun into

chemical energy

7. GRANUM

Found inside the chloroplasts

Made of stacks of thylakoids

Thylakoids contain the green pigment

chlorophyll to carry out photosynthesis

8. RIBOSOME

found in both prokaryotes and eukaryotes

because it’s not surrounded by a

membrane

contains protein and RNA

“reads” RNA and assembles amino acids

into proteins

either attached to the endoplasmic

reticulum or floating in the cytosol

9. ROUGH ENDOPLASMIC RETICULUM

transports compounds around the cell

helps maintain the cell’s shape

is studded with ribosomes

processes the proteins made by ribosomes

10. SMOOTH ENDOPLASMIC RETICULUM

transports compounds around the cell

helps maintain the cell’s shape

processes fats and breaks down toxic

substances in liver cells

11. CENTRAL VACUOLE

Found mostly in plants

Stores water, salts, sugars, and proteins

Maintains turgor pressure- the water pressure

inside the central vacuole that keeps the cell

rigid

12. LEUKOPLAST

A type of colorless plastid

found only in plants and algae

stores starches, lipids and proteins

13. CELL WALL

Found in plants, fungi, algae and

bacteria

Provides strength and rigidity to the cell

contains pores so that material can

pass through

1. NUCLEUS

found only in eukaryotic cells

“control center” of the cell

contains the cell’s genetic material

2. NUCLEOLUS

contains RNA and proteins

area of the nucleus where ribosomes

are assembled

3. CHROMATIN

the genetic material of the nucleus

contains DNA, RNA, and proteins

4. LIPID BILAYER

Lipids have a hydrophilic (water-loving) end

and a hydrophobic (water-fearing) end.

They arrange themselves into two layers

The hydrophilic ends face the watery

environments inside and outside the cell

The hydrophobic ends face each other to

escape the water

5. LYSOSOME

a type of vacuole found in humans, animals,

and protozoans

contains digestive enzymes that digest food, kill

bacteria and viruses, and recycle old cell parts

6. GOLGI APPARATUS

“post office” of the cell

receives substances from the ER and

packages them into membrane sacs

called vesicles

sends vesicles either to places within

the cell or to the cell membrane to

deliver their cargo outside the cell

7. CENTROSOME

found in animal and human cells

absent in plants and fungi

builds parts for the cytoskeleton

8. MITOCHONDRION

“powerhouse” of the cell

transforms energy from sugars into usable

energy for the cell (ATP)

Has an inner membrane that contains folds

(cristae) to increase surface area and

increase energy output.

9. CELL MEMBRANE

found in both prokaryotes and eukaryotes

surrounds the cell and protects it

allows certain materials to move through it-

semipermeable

10. CILIA

extensions of the cytoskeleton

often cover an entire cell or a portion of a cell

(many per cell)

shorter than flagella

propel the cell through its environment

move particles past the cell (mucus out of the

lungs)

smooth ER

chromatinnucleus

nuclear pore

nucleolus

cell membrane

lysosome mitochondrion

Golgi apparatuscilium

rough ER

TYPICAL ANIMAL CELL

ribosome

WHY STUDY CELLS?

The model of cells is still

developing.

The vesicle that makes unripe fruit

taste bitter was discovered in

2013.

There is much more to be

discovered about cells!

WHY STUDY CELLS?

It helps us to fulfill the Creation

Mandate and to love others.

BALANCE IN THE CELL

- the process by which a cell

maintains stable conditions in its internal

environment.

BALANCE IN THE CELL

Homeostasis- the process by which a cell

maintains stable conditions in its internal

environment.

- the

balance of changes and

motions in a system.

Dynamic equilibrium- the

balance of changes and

motions in a system.

What can affect homeostasis?

temperature

nutrition

illness

: ideal conditions, cells don’t have to work hard.

: cells can handle with extra work.

: beyond what cells can handle, cells die.

Examples: frostbite, sunburn

Optimal range: ideal conditions, cells don’t have to work hard.

: cells can handle with extra work.




Range of tolerance: cells can handle with extra work.




Range of tolerance: cells can handle with extra work.

Limit of tolerance: beyond what cells can handle, cells die.


How do cells regulate the speed of

processes?

How do cells start and stop

processes?

Signaling occurs through two

important processes:

feedback

feedback

Signaling occurs through two

important processes:

Positive feedback

Negative feedback

- occurs when a substance involved

in a cellular process causes the process to speed up.

Example: oxygen with hemoglobin

Positive Feedback- occurs when a substance involved

in a cellular process causes the process to speed up.

Example: oxygen with hemoglobin

- occurs when a substance

produced by a cellular process causes the process to

slow down or stop.

Example: ATP and Phosphofructokinase (PFK)

Negative Feedback- occurs when a substance

produced by a cellular process causes the process to

slow down or stop.

Example: ATP and Phosphofructokinase (PFK)

SOLUTIONS AND THE CELL

WHAT IS A SOLUTION?

A solution is a homogeneous of two or

more substances (solvent and solute).

A solution may exist in any (solid, liquid,

or gas).

WHAT IS A SOLUTION?

A solution is a homogeneous mixture of two or


A solution may exist in any (solid, liquid,

or gas).

WHAT IS A SOLUTION?

A solution is a homogeneous mixture of two or


A solution may exist in any phase (solid, liquid,

or gas).

SOLUTIONS

: the substance in a solution that does the dissolving.

Water is the universal solvent.

: the substance in a solution that is being dissolved.

SOLUTIONS

Solvent: the substance in a solution that does the dissolving.


: the substance in a solution that is being dissolved.

SOLUTIONS

Solvent: the substance in a solution that does the dissolving.


Solute: the substance in a solution that is being dissolved.

SOLUTIONS

- the amount of solutedissolved in a solvent.

- the spreading of solutes throughout a solution until they reach equilibrium. (Brownian motion)

SOLUTIONS

Concentration- the amount of solutedissolved in a solvent.

- the spreading of solutes throughout a solution until they reach equilibrium. (Brownian motion)

SOLUTIONS

Concentration- the amount of solutedissolved in a solvent.

Diffusion- the spreading of solutes throughout a solution until they reach equilibrium. (Brownian motion)

MEMBRANE

a membrane that allows some substances to

pass through it, but not others.

Example: The membrane

SEMIPERMEABLE MEMBRANE



Example: The membrane

SEMIPERMEABLE MEMBRANE



Example: The cell membrane

OSMOSIS

the diffusion of a through a semipermeable membrane.

OSMOSIS

the diffusion of a solvent through a semipermeable membrane.

DIFFUSION VS. OSMOSIS

Diffusion Osmosis

It involves movement of solute

molecules

It involves movement of solvent

molecules

Molecules move from higher

concentration of solute to lower

concentration of solute

Molecules move from lower

concentration of solute to higher

concentration of solute

Produces equal solution

concentrations

Does not produce equal solution

concentrations

Does not require a

semipermeable membrane

Requires a semipermeable

membrane

SOLUTIONS

: a solution that is more

concentrated than the cytoplasm of the cell.

: a solution that is less


: a solution that has the same

concentration of solutes as the cell.

SOLUTIONS

Hypertonic solution: a solution that is more


: a solution that is less




SOLUTIONS



Hypotonic solution: a solution that is less




SOLUTIONS



Hypotonic solution: a solution that is less


Isotonic solution: a solution that has the same


SOLUTIONS

same lower higher

TRANSPORT ACROSS THE MEMBRANE

- The movement of molecules across a

membrane without the use of chemical energy.

TRANSPORT ACROSS THE MEMBRANE

Passive Transport- The movement of molecules across a

membrane without the use of chemical energy.

PASSIVE TRANSPORT

The particle’s own natural motion causes it to

move from an area of concentration to an

area of concentration.

Cells don’t have to expend any energy to get

these particles across their membranes.

Examples:

Diffusion

Osmosis

Facilitated diffusion

PASSIVE TRANSPORT

The particle’s own natural motion causes it to

move from an area of high concentration to an

area of low concentration.

Cells don’t have to expend any energy to get

these particles across their membranes.

Examples:

Diffusion

Osmosis

Facilitated diffusion

PASSIVE TRANSPORT

Four factors determine whether a particle can be

passively transported across a membrane:

1. Particle size

2. Particle shape

3. Particle polarity

4. Membrane composition

PARTICLE SIZE

Very small particles can pass through the

pores of a cell membrane easily.

Examples:

water

oxygen

carbon dioxide

nitrogen

PARTICLE SHAPE

Even if a particle is small enough, it may still

not be able to pass through an opening in the

cell membrane.

A round particle will not fit into a square hole

and vice versa!

PARTICLE POLARITY The cell membrane only allows nonpolar molecules to

pass through easily.

Only very small polar molecules like water can pass

through the membrane using passive transport.

Ions cannot pass through the membrane passively.

MEMBRANE COMPOSITION

The lipid bilayer contains different

proteins and different-size openings that

affect what can get through a cell

membrane.

Example: liver cells have large openings in

their cell membranes to process toxins that

enter the body.

PASSIVE TRANSPORT- FACILITATED DIFFUSION

Molecules move through the cell membrane with the

help of without expending energy

(ATP).

Molecules are moved from areas of concentration

to concentration.



help of transport proteins without expending energy

(ATP).

Molecules are moved from areas of concentration

to concentration.



help of transport proteins without expending energy

(ATP).

Molecules are moved from areas of high concentration

to low concentration.

ACTIVE TRANSPORT- PROTEIN PUMP The movement of molecules across a

membrane using (ATP).

Molecules are moved from areas of

concentration to concentration.


membrane using chemical energy (ATP).

Molecules are moved from areas of

concentration to concentration.


membrane using chemical energy (ATP).

Molecules are moved from areas of low

concentration to high concentration.

ACTIVE TRANSPORT- ENDOCYTOSIS AND EXOCYTOSIS

Two kinds of active transport to handle large particles.

: the process by which large molecules are taken

into the cell using vesicles.

: Transportation of material from inside the cell to

outside the cell using vesicles.



Endocytosis: the process by which large molecules are taken


: Transportation of material from inside the cell to




Endocytosis: the process by which large molecules are taken


Exocytosis: Transportation of material from inside the cell to


chapter 5 cytology

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