Unit #3: Cells and Cell

Processes

(1) Compare and contrast prokaryotic and

eukaryotic cells.

(2) Investigate and explain cellular processes

including:

a) homeostasis

b) transport of molecules

c) synthesis of new molecules

(3) Examine specialized cells

a) roots, stems, leaves of plants

b) blood, muscle, epithelium of animals

Student Expectations

Cells All living things are composed of

one or more cells.

In 1665, the scientist Robert Hooke discovered plant cells in cork tissue.

Hooke coined the term "cells“ because the boxlike cells of cork reminded him of the cells of a monastery.

The cell is the considered the basic unit of life and organization of living things.

http://es.wikipedia.org/wiki/Robert_

Hooke

Hooke, Robert: cork cell structure and sprig of sensitive plant.

Photograph. Encyclopædia Britannica Online. Web. 26 Sep. 2010

Cell Theory Years after Hooke’s cell discovery, other

scientists continued to study cells and added

new information to the initial observations.

The major concepts surrounding cells are

now known as the cell theory.

It states:

All living things are composed of cells.

Cells are the basic units of structure and

function in living things.

New cells are produced from existing

cells.

Theory vs Hypothesis A scientific theory covers a broad range

of observations (Ex. The Cell Theory)

and is considered true until new data

arises.

A hypothesis is a tentative answer to a

scientific question (“an educated

guess”)

A hypothesis must still be tested

through experimentation.

Prokaryote vs EukaryoteProkaryoteEukaryote

*Cell

membrane

*Cytoplasm

*DNA

*Ribosomes

*Complex

*DNA surrounded by a

nuclear membrane (in a

nucleus)

*Mitochondria,

chloroplasts (in plants),

lysosome, etc. (membrane-

bound organelles) present

*Make up multicellular

organisms; but unicellular

species exist

*Plants, animals, fungi,

protists

*Simple

*Circular DNA free in

the cytoplasm NOT in

the nucleus

*Membrane-bound

organelles absent

*Unicellular only

*Bacteria!

Memory tool Pro-, NO (nucleus and membrane-

bound organelles)

Eu-, DO!

Prokaryotes

Prokaryotic cells are simply one cell holding genetic material.

They contain no nucleus (DNA is free in the cell).

They are unicellular organisms known commonly as

bacteria (they are not plants or animals).

Remember: Pro- rhymes with NO for No Nucleus

http://library.thinkquest.org/03oct/00520/gallery/photos/prokar

yote.jpg

Example:

Escherichia coli

(E coli) bacteria is

the common cause

of food poisoning.http://www.greenfacts.org/images/glossary/bacteria.jpg

Eukaryotes Unlike prokaryotes,

eukaryotic cells are much more complex.

They have membrane-bound internal structures called organelles (little organs).

Eukaryotes have a nucleus that holds the cell’s DNA and controls all the functions of the cell.

Remember: Both eukaryote and nucleus have the letters “E-U-”.http://www-micro.msb.le.ac.uk/109/Prokaryotes3.gif

Eukaryotes cont. Eukaryotes can be either unicellular (one cell) or

multicellular (many cells).

Eukaryotic

cells are

found in:

Animals

Plants

Fungus

Us!

http://content.answers.com/main/content/wp/en/thu

mb/e/e7/370px-Cytoskeleton-color.gif

Cell

Membrane:

The Fluid

Mosaic

Model The cell membrane is a thin double layer of lipids

(phospholipid bilayer), with proteins and carbohydrates interspersed in it.

It surrounds cell and regulates materials that go in and out of the cell to maintain homeostasis(stability/ equilibrium).

http://www.cs.utexas.edu/users/s2s/latest/cell1/src/images/cell_membrane.jpg

Phospholipid

bilayer

Below your notes of the cell membrane,

copy and label the following diagram.

The Cell

Membrane

Semi-permeable Cells have to move things in and out on a

regular basis (food, water, waste, etc.).

The cell membrane controls movement of molecules because it is selectively or semi-permeable.

Permeable means “can pass through”.

Impermeable means?

Selectively permeable means?

The cell membrane “screens” or “selects” what materials pass through.

DiffusionMolecules move from

areas of HIGH concentration (crowded) to areas of LOW concentration.

Diffusion is the movement of particles to reach equilibrium (the same or equal on all sides).

Smaller particles easilydiffuse through the cell membrane.

Sketch the diagram!http://www.okc.cc.ok.us/biologylabs

/Images/Cells_Membranes/diffusio

n.gif

Osmosis Water is one of the most

important items that cells need in order to function.

Osmosis is the diffusion of water through aselectively permeable (to permeate is to pass through) membrane.

Water will move easily, until the concentration is equal on both sides of the cell membrane.

SKETCH THIS! Small dots are water molecules. LABEL THEM.

http://www.okc.cc.ok.us/biologylabs/Ima

ges/Cells_Membranes/osmosis.gif

H2O

Types of Solutions - Isotonic An isotonic solution (or

“same strength”) is one where the concentration inside the cell matchesthe the concentration of the environment outside of the cell – there is little to no net movement of water.

Sketch the cells with the labeled arrows to show how water moves in both directions

Types of Solutions - Hypertonic

Hypertonic solution has a higher concentration of solute

so when a cell is placed inside a hypertonic solution,water will move out of the cell and it willshrink.

Sketch the cells with the labeled arrows to show how water moves out of the cell

H2O

Types of Solutions - Hypotonic

Hypotonic solution has a higher solute concentration

so when a cell is placed inside a hypotonic solution,water will move into the cell and it willswell.

Sketch the cells with the labeled arrows to show how water moves into the cell

Click on the simulations to view diffusion and osmosis.

Simulation #1

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Hyp”O”tonic Solutions –The cell gr”O”ws!

Hype”R”tonic Solutions –The cell sh”R”inks!

I”S”otonic Solutions

–The

“S”ame!

Memory tool

Concentration gradient

Materials traveling along a

concentration gradient move from an

area of high to low concentration.

Materials traveling against a

concentration gradient move from an

area of low to high concentration.

Passive Transport Passive transport is the spontaneous

movement of molecules from an area of

high concentration to an area of low

concentration (along a concentration

gradient).

No energy is required.

3 types of passive transport: simple

diffusion, osmosis, and facilitated diffusion.

Simulation #1

Facilitated Diffusion Larger molecules, like

glucose (C6H12O6),

cannot fit through the

phospholipid bilayer.

Instead, larger molecules

travel along the

concentration gradient

(from high to low

concentration) through

protein channels in the

cell membrane.

No energy is required.

Active transport In active transport,

particles move

against the

concentration

gradient (low to high

concentration)

through membrane

proteins.

Because of this,

energy is required.

Endocytosis The process by which a cell

takes material into the cell by

infolding of the cell membrane

(Endo- = in)

Examples:

1. Phagocytosis literally means

“cell eating”.

2. Pinocytosis means “cell

drinking”.

Is energy required for

phagocytosis and

pinocytosis?

YES!

Exocytosis

Process by which a cell releases

large amounts of material

Exo- = out or outer

Example:

Contractile vacuole – pumps out

excess water

Is energy required for exocytosis?

YES!

(1) Compare and contrast prokaryotic and

eukaryotic cells.

(2) Investigate and explain cellular processes

including:

a) homeostasis

b) energy conversions

c) transport of molecules

d) synthesis of new molecules

Student Expectations

The Microscope Antoine van

Leeuwenhoek invented

the first compound light

microscope.

We use a microscope to

study cells.

Microscopes magnify

cells to see more of the

structures and details

within them.

Cell Organelles

A structure inside the cell that performs a specific function is called an organelle (“little organ”).

All organelles are membrane-bound (surrounded by a membrane) EXCEPT for ribosomes.

Only eukaryotes have membrane bound organelles.

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Homeostasis This is the property of an organism to

regulate its internal environment so as

to maintain a stable condition or

equilibrium.

Cell membrane – regulates what goes

in and out of the cell

Lysosome – breaks down food and waste

Nucleus – controls cell’s activities

Energy Conversions

Mitochondria = Cellular Respiration Carbohydrate energy ATP Energy

Chloroplasts = Photosynthesis (light energy carbohydrate energy)

Transport of molecules

Cell membrane

Rough and smooth ER

Cytoskeleton/ Microtubules – moves

materials through the cytoplasm of the

cell

Synthesis of new

molecules

Ribosomes – protein

Smooth ER – lipids

Rough ER – proteins and lipids

Nucleolus – ribosomes

Nucleus – new DNA molecules, RNA (we’ll

learn more about this in another unit)

Viruses A virus is an infectious agent

made up genetic material (DNA

or RNA) and surrounded by a

protein coat.

They are NOT cells!

No nucleus

No Cell membranes

No organelles

They are parasites and have to

live off of other cells; that can

only survive and reproduce by

infecting living cells.

Common viruses include

influenza (flu), the common

cold, and HIV(causes AIDS).

http://oceanworld.tamu.edu/resources/oceanograph

y-book/Images/BacteriophageCartoon.jpg

DRAW THIS!

Cell boundaries Cell boundaries are structures that give a cell its

shape.

All cells are surrounded by a cell membrane. The

cell membrane controls the materials that go in and

out of the cell.

Some cells have an extra cell boundary called the

cell wall that surrounds the cell membrane.

Cell Wall

The cell wall is present in all plants, algae, fungi, and

prokaryotes (bacteria).

Animal cells have NO cell wall.

Its function is to provide support and protection for

the cell; it surrounds the cell membrane.

http://www.enchantedlearni

ng.com/subjects/plants/cell/

anatomy.GIF

Nucleus

The nucleus contains

the genetic

information (DNA)

and controls the cell’s

activities.

It is surrounded by a

double membrane

called the nuclear

envelope/ membrane.http://library.thinkquest.org/06aug/01942/plcells/thinkquest/nu

cleus.jpg

Ribosomes Ribosomes are found loose in cytoplasm or bound to

other organelles.

They produce (or make) proteins from instructions within

RNA.

http://www.biotechnologyonline.gov.au/images/co

ntentpages/cellwithlabels.jpg

Mitochondria Mitochondria convert

chemical energy from

carbohydrates and lipids

into cell energy;

Mitochondria are often

referred to as the

“powerhouse of the cell”. http://www.microscopy.fsu.edu/cells/mitochond

ria/images/mitochondriafigure1.jpg

Chemical Reaction

Food energy Cell energy

Chloroplasts Chloroplasts also

contain their own

DNA and capture

energy from

sunlight and

convert it to

carbohydrates

(photosynthesis).

They are found

only in plants and

algae

http://botit.botany.wisc.edu/images/130/Plant_Cell/Elodea/Ch

loroplasts_face_side_MC.jpg

Chemical Reaction

Sunlight Food Energy

Nucleolus The nucleolus is inside the nucleus where

ribosomes are produced.

http://micro.magnet.fsu.

edu/cells/nucleus/imag

es/nucleusfigure1.jpg

Lysosomes Lysosomes are

sac like organelles

filled with

enzymes.

Lysosomes help

to digest and

recycle materials

within the cell

They break down

carbohydrates,

proteins, and

lipids. lysosome: intracellular digestion. Art. Encyclopædia

Britannica Online. Web. 26 Sep. 2010

Endoplasmic Reticulum The ER is a folded

network of membranes.

Rough ER –

studded with

ribosomes

Smooth ER – no

ribosomes

Both rough and smooth

ER build lipids for the

cell.

Because rough ER, has

ribosomes, it can also

synthesize proteins.

http://fog.ccsf.cc.ca.us/~mmalacho/physio/oll/Lesson2/images/3

Slide11.GIF

Golgi Apparatus The Golgi apparatus

is a series of flat,

membrane-bound

sacs.

The Golgi apparatus

modifies, sorts and

packages materials

for storage or

transport outside

the cell.http://www.bact.wisc.edu/Microtext

book/images/book_4/chapter_2/2-

59.gif

Vacuoles Vacuoles are the storage

compartments for water,

proteins, lipids, and

waste within cells.

Plants often have 1,

large vacuole, while

animals have many

small ones.

Some forms of single-

celled life use vacuoles

to pump excess water

out of the cell (contractile

vacuole).

Flagella (1 flagellum) are long, whip like structures that some cells use for movement.

Some forms of single-celled life use flagella that spin like a propeller.

Mammalian sperm (eukaryotic) have these flagella (long tails) to help them reach an ova.

Some species of bacteria (prokaryotes) have flagella.

Flagella

Cilia Cilia (1 cilium) are tiny, hair like

projections on the surface of

some cells.

Some forms of single-celled life

use cilia for movement.

Cilia are found in the Fallopian

tubes of mammals to move ova

(egg cells) to the uterus. In the

respiratory system, cilia clean

debris and move fluid.

Cilia are found in eukaryotic

cells only.

Cytoplasm

Cytoplasm is the material

between the cell

membrane and nucleus.

It is a thick fluid made

mostly of water; jello like.

The function of the

cytoplasm is to contain

the organelles.

http://www.daylilies.org/ahs_dictionary/cytoplasm.gif

Cytoskeleton

The network of thread-like protein fibers (microfilaments)

and hollow tubes of protein (microtubules) extending

through cytoplasm is called the cytoskeleton (shown in

yellow).

This “skeleton” gives cell shape and support, helps

transport materials through cell, and sometimes enables

cell to move.

http://www.immediart.com/catalog/images/big_images/SPL_

6_P780110-Fibroblast_cells_showing_cytoskeleton.jpg

In Conclusion In this unit, we learned that all living things on the

planet are made of cells.

The two different types of cells are:

Prokaryotes (no nucleus)

• Bacteria

Eukaryotes (nucleus)

• All other life (Animals, Fungi, Plants, Protists)

Inside certain cells there are organelles that perform

certain functions.

Viruses are not living cells, but must infect living

cells in order to reproduce.