Cells
An Introduction to Cells
Biology
1
Name things that are made
up of other things…





Schools
Buildings
Factories
Cars
Cities





Classrooms, people
Bricks, windows
Departments, lines
Engine, tires, hoses
Streets, hospitals,
people, parks
2
What do you
already know
about cells???
3
Microscopes were the key…

Robert Hooke: 1665
– Development of microscope
– Coined term “cellulae” from studying
slices of cork

Antoine van Leeuwenhoek: late
1600s
– Refined microscope, 1st to see living cells,
bacteria

Robert Brown: ~1830
– Further refinement of microscope
– Every cell contained a round structure,
“nucleus”
4
The Cell Theory

1839: Matthias
Schleiden & Theodor
Schwann
– 1. All organisms are
composed of cells.
– 2. The cell is the basic
unit of structure for all
organisms.

1855: Rudolf Virchow
– 3. All cells arise only
from preexisting cells.
5
Characteristics of Living
Things
Made up of cells
Homeostasis
Perform chemical activities =
metabolism
Grow & develop
Respond to environment
(Respsonsiveness)
Reproduce
Heredity
6
Cell Size



100 trillion cells in human body
Most 5-20 um in diameter
Limited in size due to SA/V ratio
– Small cells are more efficient
– Substances need to be able to enter & leave
cell in #s large enough to meet cell needs.
– Substances do not need to travel as far to
reach center of cell (in smaller cells).
• Ambulance in a city…NYC vs. Centerville
http://www.mhhe.com/biosci/genbio/biolink/j_explorations/c
h02expl.htm
7
2 Types of Cells
Prokaryotes & Eukaryotes
8
Common Features of both
cells…

Cell membrane
– Also called plasma membrane
– Outer boundary

Cytoplasm
– Interior of cell

Cytoskeleton
– Fibers in cytoplasm

Ribosomes
– Proteins made here

DNA
9
Prokaryotes





Smallest & simplest
1 celled (unicellular)
Oldest type of cell (3.5 billion years old)
No nucleus
Organelles lack membranes
– Limits specialized work in cell

Can grow & divide rapidly
 Can survive extreme conditions
 Cell wall around cell membrane
 May have capsule around cell wall, allows to
cling to things (teeth)
10
Cell Types
Prokaryotes
Eukaryotes
No nucleus, organelles
lack membranes
Has nucleus, organelles
surrounded by a membrane.
Bacteria
Protozoa, algae, fungi,
plants, animals
11
Both types of cells take in
food, change food to energy,
get rid of waste, and
reproduce.
These functions require
structures!
12
How would you describe…
Picture Provided By: http://www.jdaross.mcmail.com/endopl~1.htm
13
How do these compare?
Picture Provided by: http://www.nigms.nih.gov/news/science_ed/images2/endo2.gif
14
Animal Cell
15
Eukaryotic Cells are Made
Up of 3 Parts

Cell Membrane
– Surrounds cell to protect, support, & give
cell shape.

Nucleus
– Large oval shape, control center of cell.

Cytoplasm
– Region between the nucleus & cell
membrane.
16
Nucleus

Contains DNA & chromosomes
– Direct activities of the cell/genetics
• DNA provides instructions for making proteins, regulates
cell activities, & enables cells to reproduce.

Contains nucleolus
– Produces ribosomes

Surrounded by nuclear membrane
– Controls what enters/exits nucleus
– Has pores that serve as the passageway
17
Cytoplasm
Jelly-like substance
 Most all cell processes take place here.
 Composed of:

– Cytoskeleton—filaments & fibers that
support cell structure & cell movement
– Organelles—structures that perform
specific functions in the cell.
18
Cytoskeleton
Read pg. 59
 Holds cell together & keeps membrane
from collapsing.

– Actin fibers- anchor to cell proteins to help
determine shape of cell.
– Microtubules- highway system for
transport.
– Intermediate fibers- confines ribosomes &
enzymes to regions of cell.
19
Cell Organelles
Packages with specific jobs
that work together to
perform cell processes!
20
Mitochondria


Powerhouse of the cell.
Releases energy stored
in food.
– Site of cellular
respiration, provides ATP
to cell.

Has an outer
membrane & an inner
folded membrane.
 Contains own DNA
(mitochondrial DNA) &
own ribosomes.
Picture from:
http://biology.about.com/gi/dynamic/offsite.
htm?site=http://ntri.tamuk.edu/cell/mitocho
ndrion.html
21
Ribosomes



Assemble proteins.
Small, round structures.
Some are attached to
rough ER
– These proteins are
exported out of cell.

Picture Provided By:
http://www.jdaross.mcmail.com/endopl
~1.htm
Some float in
cytoplasm—”free”
ribosomes.
– These proteins remain
inside the cell.
22
Endoplasmic Reticulum- ER

Transports proteins
throughout the cell.
 Is all membrane- folded
network of tubes &
canals.
 Move proteins & other
substances through the
cell.
 Rough ER
– Ribosomes attached to
surface.
– Where proteins are
made.

Smooth ER
– No ribosomes attached.
– Transport within cell.
Picture Provided by:
http://www.nigms.nih.gov/news/science_ed/
23
images2/endo2.gif
Vesicles
As each protein is made on rough ER,
it crosses the ER membrane & enters
the ER. The part of the ER that
contains the completed protein pinches
off to form a vesicle.
24
Vesicle
Small membrane-bound sac.
 Transports substances in cells.

25
Golgi Bodies/Apparatus

Flattened membranebound sacs.
 Proteins travel from ER
to here in vesicles.
 Golgi then:
Picture from:
http://biology.about.com/gi/dynamic/offsite.h
tm?site=http://ntri.tamuk.edu/cell/mitochond
rion.html
– Alters proteins (with
enzymes)
– Packages proteins (in
new vesicles)
– Stores proteins
– Moves proteins on to rest
of cell
26
Lysosomes

One type of vesicle.
 Clean up crews.
 Use digestive
enzymes to break
down:
– Large food
molecules
– Waste products
– Old cell parts
Picture from:
http://biology.about.com/gi/dynamic/offsite.htm?site=
http://ntri.tamuk.edu/cell/mitochondrion.html
27
Proteins in the Cell






Ribosomes make proteins on rough ER.
Proteins are packaged in vesicles.
Vesicles take proteins from rough ER to Golgi
apparatus.
Golgi alters & packages the proteins in new
vesicles.
Vesicles move to cell membrane & release
contents outside of cell.
Other vesicles, some are lysosomes, remain
in cytoplasm of cell.
28
Vacuoles





Few in animal cells
In plants, referred to as
central vacuole.
Fluid filled sacs
When full, makes plant
rigid & plant stays
upright.
Temporary storage of:
– Water
– Food materials
(nutrients)
– Ions
– Wastes
Picture from:
http://www.mhhe.com/biosci/pae/botany/histology/ht
ml/vacuole.htm
29
Chloroplasts

Found in PLANTS,
algae, & some
bacteria
 Green color is from
chlorophyll.
 Chlorophyll traps
light energy from the
sun & converts H20
& CO2 to glucose.
(photosynthesis)
Picture from:
http://biology.about.com/gi/dynamic/offsite.htm?si
te=http://ntri.tamuk.edu/cell/mitochondrion.html
30
Chloroplasts & Mitochondria
Plants have both of these.
 They are similar:

– Both supply energy for the cell.
– Both have 2 membranes.
– Both contain their own DNA.
**cell membrane HO**
31
Other cell parts
Not organelles
32
Cell Wall
Not an organelle
 Surrounds the cell membrane.
 Supports, maintains cell shape, &
protects the cell in plants & bacteria.
 Made of proteins & carbohydrates
(cellulose).

33
Cilia & Flagella
Project out of cell membrane.
 In plant & animal cells.
 Flagella—helps cell to move.
 Cilia—moves materials surrounding the
cell.

– Cilia in our respiratory system sweeps
mucus out of our lungs.
34
Centrioles
Used for anchors in mitosis
35
Animal vs. Plant Differences





Do not have
chloroplasts
More likely to be altered
in shape as only has
cell membrane, more
flexible
Circular or irregular
shape
Have multiple, small
vacuoles
Lysosomes common





Contain chloroplasts
Have cell wall around
cell membrane, more
rigid (cell wall is not
living material, made of
cellulose)
Rectangular shape,
stacked
Typically have 1 large
vacuole
Lysosomes not
common
36
Similarities of A & P Cells
Cells are the basic unit of structure both
plants & animals.
 Cell membrane
 Cytoplasm
 Nucleus
 Most organelles are in common.
 Cell functions similar (except
photosynthesis)

37
Cell Membrane Functions
Surrounds cell to protect, support & give
shape.
 Controls what enters & exits cell

– Water, food molecules, oxygen, other
nutrients & waste products
38
Cell Membrane
Structure
See handout & model
directions!
Page 176
39
A cell membrane is
selectively permeable-Allows some materials to pass through
freely = permeable
 Other materials cannot pass through
freely = impermeable


Selectively permeable = allows some
through, but is selective
40
Recap…
Phospholipid—phosphate group & 2
fatty acid tails
 Lipid bilayer—2 layers of the lipids

– Each layer moves independently
– Proteins are embedded within
– Cholesterol within the layer holds it all
together
– Read page 176
41
Membrane Proteins

Proteins involved with the lipid bilayer have
various functions:
– Marker proteins: protein with carbohydrate chain
attached; identifies the type of cell
– Receptor proteins: bind specific substances
outside the cell; act like antennae for the cell,
collecting info about extracellular conditions
– Enzymes: proteins that assist in reactions inside
the cell
– Transport proteins: move substances in & out of
cell
– See page 177
42
Membrane is often referred
to as Fluid Mosaic Model
The proteins & phospholipids within the
membrane can move = fluid
 The bilayer is made up of various things
(phosphate, fatty acid tails, proteins,
carbohydrate chains) = mosaic

43
Cell Processes Involving the
Cell Membrane:

Diffusion

Osmosis

Active Transport
44
Levels of Organization in
Multicellular Organisms





Letters
Words
Lines/Sentences
Paragraphs
Story/Poem





Cells
Tissues
Organs
Organ Systems
Organism
45
Details…
Each level works as its own SYSTEM (a
cell performs its own functions)
 But each level is also a SUBSYSTEM,
part of a larger & more complex
SYSTEM

– cells work together as a
tissueorganorgan systemorganism
46
Study for test
Labeling cell diagram (10)
 Label microscope (10-12)
 Cell theory (3)
 Characteristics of life (7)
 3 main parts of Euk cell (1-3)
 Draw cell memb (4-5)
 An vs Plant cell diff/sim (9)
 Organelles functions (10)
 SI Units (4-5) KHDmdcm

47
Tah-Dah!
The end of Cell-A-Bration
is tomorrow—be ready for
the exam!
48
Last Unit/Experience
Current Unit
Next Unit
Dissection
Intro. To Cells
Genetics
Unit Schedule
1
Cell Theory &
Technology
2
Cell Parts
3
Quiz, Cell
Membrane
4
Cell Membrane
Models
5
Diffusion lab pt 1,
Cloning
6
Animal vs. Plant
Cells
7
Diffusion lab pt. 2,
Cell Size Lab
8
Surface Area
Manipulatives
9
Levels of
Organization,
Review
10
Exam
Basics
Cell
Theory
Cell
Parts
1) All organisms
are composed of
cells.
1) Nucleus
2) Cells are basic
unit of structure
& function in living
things.
3) Cell
3) Cells arise only
from other living
cells.
Key Questions:
How did technology affect our study of cells?
What are the characteristics of living things?
What are the cell parts?
What is the cell theory?
2) Cytoplasm
Membrane
or Cell Wall
Cell Size &
Organization
Cell
Tissue
Organ
Organ System
Organism
Science Process Skills:
Compare, communicate,
describe, observe, construct a
model, compare & contrast,
evaluate, calculate, measure,
identify
49
Diffusion
XXXXXXXXXXXXX
X X X XX X
XXXXXXXXXXXXXX
X XX X X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
XXXXXXXXXXXXX
XXXXXXXXXXXXXX
X
X
X
X
X
X
X X
X
X
X XX
X
X
X
X
X
XX
X X
X X X
X
X X
X
X X XX X X X
X X X X X X X
50
Diffusion:
Movement of a
SUBSTANCE from an area
of HIGH concentration to
an area of LOW
concentration.
51
Osmosis:
Movement of WATER from
HIGH concentration to
LOW concentration.
52
Diffusion & Osmosis…
Freebies—does not require energy
 Occurs when there are unequal
concentrations inside & outside of a cell.

53
What happens…

When cell needs substances that
cannot diffuse through the cell
membrane?
– Cell membrane is impermeable to
substance, or
– Concentration of substance outside of cell
is not high enough to diffuse into cell (or
vice versa)
– Substance is too large to “slip” through?
54
Active Transport
Energy-requiring process
that can “carry” a
substance into the cell.
55
Sources
Sources for pictures, cited within
 Sources for information:

– Biology, Upper Saddle River, New Jersey:
Prentice Hall, 2000.
– Exploring Life Science, Upper Saddle
River, New Jersey: Prentice Hall, 1997.
– Science Insights, Exploring Living Things,
Menlo Park, California: Addison-Wesley,
1996.
56