Cellular Transport And the Cell Cycle

DiffusionAt all temperatures above absolute zero,

the individual atoms that constitute any substance are always in movement. Indeed, the amount of this movement is what constitutes temperature itself.

Simply put, diffusion is the movement of particles from a region of high concentration to an area of lower concentration

Diffusion Cont. Particles of a

substance will move from a region of high concentration to a region of lower concentration.

The difference in concentration of atoms is know as a concentration gradient

As particles move in a given area, an equilibrium is reached where the space between the particles becomes fairly uniform.

This equal distribution of atoms is called dynamic equilibrium

Diffusion Cont.Follow link to animation of diffusion

The Diffusion AppletFollow link to tutorial of diffusion and

osmosis

Diffusion and osmosis tutorial

Plasma Membrane

Made up of two layers of phospholipids

Controls what moves into and out of the cell

Selectively permeable

Passive TransportTransport (diffusion) of particles across

the membrane without the use of energy by the cell

Particles move from a region of high concentration to a region of low concentration across the concentration gradient

Passive transport by proteins

Common method for moving sugars and amino acids across membranes

Driven by a concentration gradient (substances on both sides of the membrane are trying to reach equal concentration)

Facilitated Diffusion - Transport of materials across the plasma membrane with the aid of channel proteins

Passive TransportVideo

What is Osmosis?Osmosis – Diffusion of water

across a selectively permeable membrane

The plasma membrane does not limit the diffusion of water

In a cell, water always tries to reach an equal concentration on both sides of the membrane

Regulation of water flow through the membrane is important in maintaining homeostasis

What Controls Osmosis?Concentration gradient - Unequal

distribution of particles

Cells in an Isotonic Solution Isotonic Solution – when

the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside of the cell

Equal movement of water into and out of the cell, cell stays the same size

Cells in a hypotonic solution Hypotonic solution – when

the concentration of dissolved substances is lower in the solution outside the cell than the concentration inside the cell

Water is pulled into the cell, the cell swells and the internal pressure increases

Cells in a hypertonic solution Hypertonic Solution –

where the concentration of dissolved substances outside the cell is higher than the concentration inside the cell.

Water moves out of the cell, the cell shrinks, and internal pressure decreases

Water moves into a cell placed in a ___________________ solution.

A. Osmotic

B. Hypertonic

C. Isotonic

D. Hypotonic

Water moves out of a cell if it is placed in a _______________ solution

A. Hypotonic

B. Hypertonic

C. Isotonic

D. Passive

A cell moves particles from a region of lesser concentration to a region of greater concentration by _________________.

A. Facilitated Diffusion

B. Passive Transport

C. Osmosis

D. Active Transport

If a cell is placed in salt water, water leaves the cell by _____________.

A. Osmosis

B. Diffusion

C. Active transport

D. Phagocytosis

Pickles and Osmosis????• View the recipe for making pickles.

Dill Pickles• 15 pickling cucumbers or Kirbies

• Pickling Liquid: 3 cups water

2 cups white vinegar 1/4 cup coarse salt

2 tablespoons granulated sugar 8 garlic cloves, peeled

1 bunch dill 1 sprig thyme

• Bring a large stockpot water to a boil. Add cucumbers, immediately remove from heat, and drain in a colander. Rinse with cold water and reserve.

• Combine pickling liquid ingredients in a medium saucepan and bring to a boil. Place cucumbers in a large container with remaining vegetables and herbs.. Pour hot

pickling liquid over cucumber mixture and let cool. Tap down solids until liquid rises to top. Cover with plastic wrap and let stand at room temperature 1 day.

Transfer to a sealed container

After viewing the recipe above, explain the role of osmosis in making pickles. Be ready to share your answers!

Active TransportCells can move particles from a region

of low concentration to a region of high concentration, but it takes !

Active Transport – movement of materials through a membrane against the concentration gradient

Active Transport Cont.Proteins in the cell membrane (Carrier

proteins) bind with particles of the substance. When the right molecule binds to the right carrier protein, chemical energy allows the carrier protein to change shape so that the particle can be moved to the other side of the membrane

Transport of Large Particles Some cells can take in large molecules, groups

of molecules, or even whole cells Endocytosis – process by which a cell engulfs a

material and forms a vacuole inside of the cell Exocytosis – expulsion or secretion of materials

from the cell Used to get rid of waste, secrete hormones

Both endocytosis and exocytosis require cellular energy (Active transport)

Endocytosis and Exotytosis

Use the play dough to model the processes of endocytosis and exocytosis. Be able to explain the process. When you have finished, wait for Mrs. Johnson to come and check your work and hear your explanation.

Active TransportVideo

Release of waste or large cell products from inside to outside of cell _____________________.

A. Endocytosis

B. Exocytosis

C. Osmosis

D. Facilitated Diffusion

Type of cell transport which requires energy from the cell.

A. Osmosis

B. Facilitated Diffusion

C. Active Transport

D. Passive Transport

Active Transport is to carrier protein as _____________ is to channel protein.

A. Osmosis

B. Endocytosis

C. Exocytosis

D. Facilitated Diffusion

When cell engulfs a large particle

and forms a vacuole inside the cell

_____________________.

A. Endocytosis

B. Exocytosis

C. Osmosis

D. Facilitated Diffusion

Term for “cell eating”

A. Osmosis

B. Exocytosis

C. Pinocytosis

D. Phagocytosis

Cell Growth

Cells come in different sizes Red blood Cells = 8 µm Some nerve cells can be up to 1mm in

lengthThe yolk of an Ostrich egg measures 8cmMost living cells are between 2 and 200

µmGiven the wide range of cell sizes, why

can’t most organisms be just one giant cell?

What limits cell size?Diffusion

Diffusion is fast and efficient over short distances but slow and inefficient over larger distances

a mitochondrion at the center of a hypothetical cell with a diameter of 20 cm would have to wait months before receiving molecules entering the cell

What limits cell size? cont. DNA

The nucleus contains blueprints for the cell’s proteins (proteins are used throughout the cell by the organelles)

There is a limit as to how quickly the DNA (blueprints) can be copied

The cell can’t survive unless there is enough DNA to support the protein needs of the cell

Some large single celled organisms have developed more than 1 nucleus

What limits cell size? Cont.Surface area to volume ratio

As cell size increases, its volume increases faster than its surface area

If cell size doubles, the cell would require eight times more nutrients and would have eight times more waste to excrete. The surface area would increase only by a factor of four. The plasma membrane would not have enough surface area for nutrients, waste and oxygen to diffuse through

Surface area to volume ratio

1mm

1mm

2mm

2mm

4mm

4mm

Surface area = 6mm2

Volume = 1mm3

Surface area = 24mm2

Volume = 8mm3

Surface area = ??

Volume = ??Refer to PS lab 8.1 pg 209

Cell SizeVideo

To summarize…. Substances move into and out of cells

Passive transport Diffusion Osmosis Facilitated diffusion

Active transport Carrier proteins Endocytosis/Exocytosis

Cell size must be limited in order for a cell to function effectively

Video

The structure most responsible for maintaining cell homeostasis is the ___________.

A. Cytoplasm

B. Mitochondria

C. Cell Wall

D. Plasma Membrane

Which of the following explain why a cell’s size is limited?

A. Volume increases faster than surface area

B. Surface area increases faster than volume

C. Homeostasis is disrupted by a cell that is too large

D. Both a and c

As a cell grows, its ___________ increases more than its ___________.

A. Length, volume

B. Width, surface area

C. Volume, surface area

D. None of these

Cell Reproduction

Cell Reproduction (video clip)The cell theory states: all cells come from

preexisting cells We know that all organisms grow and

changeThroughout our lives, worn-out tissues are

repaired or replace by new cells All of this occurs through Cell Division

The process by which new cells are produced from one cell

Results in two cells that are identical to the parent cell

What are Chromosomes? Chromosomes – dark staining structures that

contain genetic material (DNA) Made up of DNA and protein

Chromatin – long strands of DNA wrapped around protein (resembles a tangled plate of spaghetti)

Before a cell can divide, the long strands of chromatin must be organized into a chromosome

http://www.sirinet.net/~jgjohnso/modchromosome.jpg

Chromosomes

http://www.uic.edu/classes/bios/bios100/labs/realchromo.jpeg

http://lhs.lps.org/staff/sputnam/Biology/U3Cell/chromosome_1.png

Video clip

The Cell CycleThe sequence of growth and division of

a cell

2 phases: Growth Division

The Growth Phase: Interphase

The majority of a cell’s life is spent growing and making more DNA, this period is called – Interphase During interphase, cell grows in size and the

chromosomes are duplicated G1 phase - rapid growth S phase – DNA synthesis and replication G2 phase – Centrioles replicate and cell prepares

for division

The Division Phase:Mitosis Cells undergo mitosis as they approach the maximum

cell size at which the nucleus can provide blue-prints for proteins and the plasma membrane can efficiently transport nutrients and waste into and out of the cell

4 phases of Mitosis:

ProphaseMetaphaseAnaphaseTelophase

The Cell Cycle

http://lhs.lps.org/staff/sputnam/Biology/U3Cell/cellcycle_1.png

Mitosis: Prophase 1st stage of mitosis

(longest stage) Chromatin coils up into

visible chromosomes Each duplicated

chromosome is made of 2 sister chromatids held together by a centromere

The nucleus begins to disappear

Centrioles migrate to opposite ends of cell

Spindle fibers become visible

Mitosis: Metaphase 2nd stage of mitosis

(short stage) Chromosomes

become attached to the spindle fibers by their centromeres

Chromosomes line up on the midline

Mitosis: Anaphase 3rd stage of mitosis Sister chromatids are

pulled apart the spindle fibers

attached to the centromere and the centriole begin to shorten pulling the chromatids from each other

Mitosis: Telophase 4th stage of mitosis Chromatids reach the

opposite poles of the cell Chromosomes unwind,

spindle begins to break down, nucleolus reappears and nuclear envelop forms around each set of new chromosomes

Mitosis

http://www.sirinet.net%2F%7Ejgjohnso%2Fmodchromosome.jpg&rurl=http%3A%2F%2Fwww.sirinet.net%2F%7Ejgjohnso%2Freprod.html&size=35.1kB&name=modchromosome.jpg&p=chromosome+structure&type=jpeg&no=85&tt=573&ei=UTF-8

Mitosis animation

Division of Cytoplasm Cytokinesis – division of

cytoplasm between the two newly formed cells

Different for plant and animal cells

Life Cycle of a Cell and Cell Division

Video clip

Among the following, the term that includes the others is ___________.

A. Interphase

B. Nuclear division

C. Mitosis

D. Cell Cycle

By the end of prophase, each of the following has occurred except ______________.

A. Tighter coiling of the chromosomes

B. Breaking down of the nuclear envelope

C. Disappearing of the nucleolus

D. Lining up of chromosomes in the cell

The longest phase of the cell cycle is ________________.

A. Prophase

B. Interphase

C. Metaphase

D. Mitosis

A chromatid is attached to a spindle fiber by the ________________.

A. Nucleolus

B. Deep furrow

C. Centromere

D. Centriole

The sequence of growth and division of a cell makes up ______________

A. Mitosis

B. The Cell Cycle

C. Chromosomes

D. Cytoplasmic Division

Identify the stage of mitosis

A. Anaphase

B. Metaphase

C. Prophase

D. Telephase

Identify the stage of mitosis

A. Anaphase

B. Metaphase

C. Prophase

D. Telephase

Results of Mitosis

So what’s the point?Mitosis guarantees that the two new

cells that are produced are genetically identical. The two new daughter cells will carry out the same cellular processes and functions as those of the parent cell and will grow and divide just as the parent cell did.

Control of the Cell CycleThe full story of how the cell cycle is

controlled is not fully understoodScientist do agree on some aspects of

what causes cells to divide

Enzymes

Enzymes Control the Cell CycleDifferent enzymes control different parts

of the cell cycleInterphase

growth (G1 phase) synthesis (S phase)getting ready (G2 phase)

mitosis (prophase, metaphase, anaphase, telophase)

Sometimes cells lose control of the cell cycle

Can result from: Not enough enzyme Too much enzyme Production of enzymes at the wrong time

Enzyme production is controlled by genes

Cancer Uncontrolled cell

division can result in cancer

Cancer is a mistake in the cell cycle

Cancerous cells form tumors

Tumors deprive normal cells of nutrients

Cancer cells can enter the blood stream and spread throughout the body (metastasis)

Causes of Cancer Genetic factors (Heredity) Viruses that cause damage to genes Environmental Factors that damage genes

Cigarette smoke Air pollution Water pollution UV exposure Radiation

Incidence of CancerPeople of different countries develop

different types of cancer Ex. Breast cancer is high in the U.S,

Stomach cancer is high in China

When people move from one country to another, cancer rates follow the pattern of the country in

which they are currently living

Cancer Prevention There is a clear link between a health lifestyle

and incidence of cancer Diet

Low fat, high fiber Fruits, vegetables, grains

Vitamins & Minerals Caratenoids Vitamins A, C & E Calcium

Exercise No tobacco use

Cell Aging and CancerVideo clip

Growth and Development in Multicellular Organisms

CellsTissuesOrgansOrgan systemsOrganism

Video clip

No matter how complex the organism, the cell is still the basic unit of organization