Transcript 11-3 What is a cell - shssci

11-3
1. What is a cell (use notes
if necessary)?
GOAL SETTING:
1. Unit 2 Test grade = ____%
2. I prepared by…
3. Next time I will prepare by…
4. Goal for next time = ____
11-3
If you met your goal + got an A: You may maintain or
improve.
If you met your goal but did not get an A: You must
improve at least 1 percentage points.
If you did not meet your goal it stays the same.
Describe and interpret
11-3
relationships between structure and
function at various levels of
biological organization.
TODAY: Why are the shape and size
of cells important?
Owl Book Assignment
READ section 4.2 and answer
questions #s 1-6 on page 83
REVIEW
The cell theory states:
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What is the cell theory?
– 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.
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Cell Shape
Cell Diversity
– Shape reflects function
Function of
Nerve cell?
Shape?
Function of
Skin Cells?
Shape?
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Cell Size
Cell Diversity
– Cells vary in size
 Nerve cells in giraffe neck vs. Human egg cell size of a .
– Cell size is limited by it’s surface area to
volume ratio
What is the problem with increasing cell
size?
 Volume increases faster than surface area
as a cell grows
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– PROBLEM:
 needed materials can’t
get in fast enough
(O2, glucose) and
wastes out fast
enough (CO2)
 Notice SA increased
only 25 times and the
volume increase
125 times
Prokaryotic vs. Eukaryotic Cells
– Eukaryotes are cells that enclose their DNA
in nuclei.
– Prokaryotes are cells that do not enclose
DNA in nuclei.
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Prokaryote
– No nucleus
– No membrane bound
organelles
– Still have DNA mass
in center of cell
– Small / simpler than
eukaryotic cells
– Example:
 Bacteria
Cell Types
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Eukaryote
– 1 or more cells
– Have membrane
bound organelles
– Larger / more
complex than
prokaryotes
– Examples:
 plants, animals,
fungi, and
organisms
commonly called
“protists.”
Cell Types
11-4
1. At least two things that all
cells have in common? (use
notes if necessary)?
REVIEW
Describe and interpret
11-4
relationships between structure and
function at various levels of
biological organization.
TODAY: What organelles can be
found in a cell and what do they do?
Teach an organelle:
Groups of two w/ one laptop
Time to prepare = 10-15 minutes
Task: Prepare one ppt slide including a
student friendly def. + at least 1 picture.
1 student will present def to class + the
other will explain the picture(s) (I will
decide who does what so both of you
should be ready to do either!).
Presenting time = 45 seconds – 1 minute
…PRACTICE
When Done:
Save under dsto… (if you don’t know, ask)
Go to shssci.wikispaces.com
Go to CP Bio
Go to CP Bio Unit 3
Which do you think is older?
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Scientists think prokaryotic cells evolved
first, since they are less complex
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Endosymbiosis:
As prokaryotic cells evolved they engulfed
other prokaryotic cells, which eventually
became eukaryotic cells
Scientists think that this is how
mitochondria and plastids became
incorporated into plant and animal cells
Evidence?
Mitochondria and plastids have DNA that
varies from the rest of the cell
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Mitochondria have their own DNA and only
reproduce from division of preexisting
mitochondria
Plastid DNA is very similar to DNA of some
photosynthetic bacteria
Endosymbiosis
Endosymbiosis
How to remember prok vs euk cells
It’s all in a hand bag:
 Girls…when going to a wedding / fancy occasion
describe your purse

– Small, compact, just the stuff you NEED

The rest of the time,
what are most of
your purses like?
– Big. Lots of room,
extra stuff you may
not need
Cell Organelle PowerPoint –
Directions – 35 points
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You are going to create a PowerPoint that illustrates
information about each cellular organelle.
Each organelle must be identified with an image and
you must explain it’s function.
You must also identify plant organelles and compare /
contrast the differences they have from animal cells.
Your PowerPoint will be graded for the detail of it’s
information and pertinence of it’s images
You will submit your presentation to me (using a flash
drive) or you can post it to the wikispace.
Describe and find an illustration of these 25
organelles
 Cytoskeleton
 Plasma membrane
 Microtubule
– Phospholipids bilayer
 Microfilament
 Cytoplasm
 Cilium
 Cytosol
 Flagellum
 Nucleus
 Centriole
– Nuclear Pore
 Cell wall
– Nuclear Membrane
– Nucleolus
 Central vacuole
 Chromosome
 Plastid
 Nuclear envelope
 Chloroplast
 Ribosome
 Mitochondrion
 Chlorophyll
 Endoplasmic reticulum
 Golgi Apparatus
 Lysosome
Cell Organelle Review
Plant Cell

Plasma membrane
– Made of two layers of phospholipids (a
bilayer)
– Allows transport of molecule into / out of
the cell
– Helps protect cell from bacteria, etc
– Chemical communication with other cells
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(Review) Phospholipid – contains
hydrophobic tails and hydrophilic
head
Membrane contain lipids called
sterols (cholesterol)
– help make membrane more firm and
prevent freezing at lower temperatures
Organelles
Membrane Proteins:
 Integral proteins –
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– Proteins in the plasma
membrane that are
embedded or pass all the
way through the membrane
– Have carbohydrate attached
to act as marker or label
– Function:
 Communication
 Transporting materials into cell

Peripheral proteins –
proteins found only on one
side of the membrane
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Fluid Mosaic Model
– Idea that the phospholipids / lipids / proteins
can “flow” around each other
– Plasma membrane is more of a fluid than a
solid
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Cytoplasm –
– part of the cell including the fluid, the cytoskeleton
and all organelles except nucleus
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Cytosol –
– the cytoplasm that includes the ribosome's but not
the membrane bound organelles – 20% protein
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Nucleus –
– control center of cell– controlled by the code in your
DNA
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Nuclear Membrane / Envelope –
– double membrane that surrounds the nucleus
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Nuclear Pore –
– protein lined holes in the nuclear membrane that
allow RNA to enter / leave nucleus
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Nucleolus –
– where DNA concentrates to create ribosomal RNA
(ribosome's)
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Chromosome –
– DNA coils to form chromatin – chromatin coils to form
chromosomes
– Chromatin is how the cell’s genetic material is stored
when not replicating
– Chromatin coils to for chromosomes when replication
is occurring
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Ribosome –
– proteins that direct protein synthesis
– Consist of two subunits
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Mitochondria –
– takes organic molecules and makes ATP
(adenosine triphosphate)
– Phospholipid Membrane bound organelle
 Inner membrane has many folds for reactions to occur
(called cristae)
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Which cells would you think have the most
mitochondria?
– Muscle cells
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Endoplasmic reticulum (ER)
– “intracellular highway”
– Has a membrane and is composed of tubes and sacs
– Rough ER – contains ribosome's
 Thus produces proteins (some phospholipids)
 Proteins produced then surrounded by vesicle from the ER and then
transported around / out of cell
– Smooth ER – lack ribosome's
 Produce lipids and hormones in sex cells (estrogen & testosterone)
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Golgi Apparatus
– Flattened membranes and sacs
– Receive vesicles from ER and modify them as
the move through the Golgi (get “address
labels”)
– Vesicles then are sent to various locations
– Create lysosomes
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Vesicle –
– Used to carry contents around, into / out of
cell
– Vary in type
– Spherically shaped
– Surrounded by a membrane
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Lysosome – vesicle that contains digestive enzymes
produced by Golgi
– Digest organic materials, bacteria, etc
– Break down glycogen to get glucose
– Cytolysis or autolysis – lysosomes release enzymes to
destroy the cell (old or malfunctioning cells)
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Cytoskeleton –
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Microtubule –
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Microfilament -
– network of thin tubes / filaments that
supports the cell
– hollow tubes made of protein that hold
organelles in place and give the cell shape
– Smaller threads that contribute to changes in
cell shape
– Made of protein
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Intermediate filaments –
– Rods that anchor nucleus and other
organelles in place
– Maintain internal shape of the nucleus
– Make up most of your hair
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Cilium –
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Flagellum
– Hair like structures that extend from the
surface of cells
– Assist in cell movement
– Very numerous
– Whip like structure that assist in movement
– Usually less in number
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Centriole –
– short cylinders that organize microtubules for
cell division
– Not found in plant cells
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Cell wall –
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Central vacuole – large organelle that
stores water, enzymes, wastes etc
– rigid layer found outside plasma membrane
– Contain cellulose
– Take up a large amount of the plant cell
– If filled with water, how will plant stand?
 Upright – if they are lacking water, plant will droop
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Plastid –
– plant organelles that have their own DNA and
perform specific functions
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Chloroplast –
– plastid example – use light energy to make
carbohydrates
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Thylakoids –
– flat membranous sacs that contain chlorophyll (where
photosynthesis takes place)
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Chlorophyll –
– green pigment that absorbs light energy in plants
Cellular Organization
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Organelle
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Tissue
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Organ
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Organ system
– Intracellular structures with specific functions
– Group of similar cells with a specific funtion
– A groups of tissues with a particular job
– A group of organs that accomplish a task
– IE:
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Digestive system
Respiratory System
Nervous System
Endocrine System
Cardiovascular System
Warm Up 11-11
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What are two differences between
prokaryotic and eukaryotic cells?
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Today:
– Get out your microscope packets and get a
partner (or you can work by yourself)
– Microscope practice and questions
Warm Up 11-12
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What is depth of focus?
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Today:
– Observing cheek cell and Elodea cells
Warm Up 12-12
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What is the maximum total magnification
if the ocular lens is 10 x and the objective
lens is 40x
Warm Up 11-17
What is the function of the ER?
 Today:
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– Go over “Microscope Practice” lab
– Finish Observing Cells - Elodea, Onion Cell,
Cheek Cell Lab
 MAKE SURE YOUR DRAWINGS ARE DETAILED
ENOUGH
Warm Up 11-18
Draw either a Elodea (in pen or pencil)
and label the following: chloroplasts,
plasma membrane, cell wall, cytoplasm
 Today:
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– Cheek, Elodea and Onion cell labs due
– Looking at living protists under the
microscopes
Warm Up 11-19
Get out worksheet packet – answer
questions on pages 17 & 18.
 Today:
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– Review how organelles look
– Prepare for the test
– Homework:
 Finish Protist Lab
 Complete the pages of the worksheet packet
Warm Up 11-20
What is the function of the Golgi complex?
 Today:
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– Prepare for test Monday – Review sheets due
Monday
– Complete multiple choice on pages 21 and 23
of the new packet
Warm Up 11-23
Get out both your worksheet packets
 Turn in your protist lab
 Practice test:
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– #17 – 20  we didn’t discuss, but try them
anyway
– Short answer questions: Skip #24, 25 and
29.
Today 11-24
Test!
 Get out review sheets
 Get out a pencil
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11-25
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Check the grade sheet coming around
– Are you missing anything?
– Find it! Turn it in!
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Missing a lab?
– Today is the day to make it up
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Go over tests (maybe)
Warm Up 12-01
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Explain how our cells get food (make this
explanation in some detail – you will see a
similar question again
Light Microscopes and Cell Stains
A typical 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 of about 1000 times.
Light Microscopes and Cell Stains
Another 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.
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.
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.
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.
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.
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.