Transcript Life Functions/Cells PowerPoint File

Unit 1: The Unity and Diversity of Living Things
“We are educated to be amazed by the infinite variety of life
forms in nature; we are, I believe, only at the beginning of being
flabbergasted by its unity.”
Lewis Thomas
author “The Lives of a Cell”
Biology
living/once-
“the study of”
living things
What determines if something is living?
There is no single definition of life. However, there is a
list of characteristics by which we determine if
something is living or not.
In order to be considered “living”, you need to display the
potential for all of the following life functions:
1. Nutrition- obtaining materials from the environment
and processing them for use within the
organism.
a. heterotrophs- organisms that consume food
ingestion- taking in food
digestion- breaking down food
egestion- removal of undigested or
indigestible food ex) corn, fiber,
throwing up
What must an oak tree do to stay alive
that both a fly and a human must also
do?
b. Autotrophs- “auto”= self, “trophic”= nutrition
*Photosynthesis:
chlorophyll
CO2 + H2O light
C6H12O6 + O2 + H2O
enzymes
*Chemosynthesis:
Some types of bacteria carry out the
process of making food by using energy
from inorganic compounds like CO2
rather than from sunlight.
•occurs deep in the ocean where
there is no sunlight
Hydrothermal vent clip
2. Transport- the absorption and circulation of materials
within an organism
•a. single-celled organisms (or any cell w/in an
organism… materials are diffused/absorbed
directly across the cell membrane
•b. multi-celled organisms-most cells aren’t in
contact w/the environment so a circulatory
system is needed
3. Respiration- The exchange of O2 and CO2 AND the
release of energy that is stored in food
molecules.
•a. anaerobic- does not use oxygen, produces little
energy
•b. aerobic- does use oxygen, produces lots of
energy, more efficient
C6H12O6 + O2
(glucose)
CO2 + H2O + Energy (36 ATP)
4. Excretion- the removal of wastes from cells + from an
organism which were produced during life
processes.
•lungs remove CO2 + H2O
•skin removes H2O, salts + urea
•kidneys remove H2O, salts + urea
•liver removes dead RBCs
5. Synthesis & Assimilationchemical reactions
where large molecules
are built from smaller
ones
The incorporation of these synthesized
molecules into the organism’s body
Ex) when proteins become part of a
body builder’s muscles from a proteinrich diet
“You are what you eat!!!”
6. Regulation- the control & coordination of all life
activities in an effort to maintain
homeostasis (stable internal environment)
2 systems involved:
•a. nervous- electrical: brain, spinal cord, nerves
•b. endocrine- chemical: hormones, glands
7. Growth- increase in size and/or number of cells
• you grow in # of cells from infant teen
• an ameba’s 1 cell can increase in size
• requires materials that were synthesized
from the nutrients ingested
• includes differentiation (cell specialization)
in multi-cellular organisms
8. Reproduction- creating a new organism/cell
~species survival is dependent on reproduction,
individual survival is not.
~asexual & sexual
•1 parent,
•identical offspring,
•no variety
•2 parents,
•offspring have a
combination of parents’
traits
Metabolism
the total of all life processes/chemical
reactions working together to sustain the organism
anabolism- synthesis of complex molecules from
simpler ones
requires energy
ex) photosynthesis, growth
catabolism- the breakdown of complex molecules into
simpler ones
releases energy
ex) digestion of carbohydrates
Homeostasis
The maintenance of a stable internal environment w/in
an organism
ex) maintaining a constant body temperature, blood
sugar level
End of notes for Life Function Quiz
Borderline cases of living things:
Seeds, flower bulbs, viruses, HIV
They display only some of the life functions some
of the time. At other times, they are said to be
dormant (“sleeping”)
More on viruses……..
•contain genetic material but lack other cell
structures to carry out metabolism
•the DNA/RNA is wrapped in a protein coat
•they are not cells and do not fit into any kingdom
•they cannot reproduce without a host cell
•survive by attacking a living cell, use the cell’s
machinery to reproduce which leads to death,
disease
…….disruption of homeostasis!!
http://phschool.com/
Enter code cbp-6192
How did we discover the cell?
The Cell
`the basic unit of all living things
Historical Background
A. 1600s
1. Robert Hooke- coined the word “cell” when
looking at cork w/a compound microscope
(he was seeing their cell walls)
2. Anton Von Leeuenhoek- used a simple
microscope (1 lens). He was the 1st to see
living cells (blood, pond water organisms)
B. 1800s
1. Dutrochet- (1824) stated that all living things are
made of cells
2. Brown- (1831) 1st to see a nucleus
3. Schleiden (1838)- said that all plants are made of cells
4. Schwann (1839)- said that all animals are made of
cells
5. Virchow (1855)- said that all cells arise from other
cells
These discoveries led to the development of the
Cell Theory
1. All living things are made of 1 or more cells.
2. Cells are the basic unit of structure and function
(can carry out life processes).
3. New cells arise from other cells.
Exceptions to the Cell Theory
~where did the 1st cell come from?
~viruses: not made of cells, contain DNA, can only
reproduce w/host cell
Laser clip “Intro to Cell Study”
Microscopes
1. Simple•1 lens
•magnifies 3-10 times
•AKA magnifying glass
2. Compound- (what we use at school)
•2 lenses
•magnifies 40-400 times
• See diagram
Nikon ppt linked
here
ocular/eyepiece
body tube
nosepiece
objective lens
arm
objective lens
objective lens
stage clips
stage
coarse adjustment
diaphragm
light
fine adjustment
base
3. dissecting/stereo microscope•2 eyepieces: binocular
•magnifies 6-60 times
•shows external features (ex. fly, ladybug)
•creates a 3-D image
4. Electron-
SEM video
•developed in 1930s
•bounces electrons off of specimen (instead of light)
•creates a 3-D image
•magnifies more than 250,000 times
•views specimens in a vacuum (kills live specimens)
Tips for microscope use:
•Start on low power
•Brighter
•Larger field of view
•When you switch from low to high:
•center your specimen, b/c you will only see a
fraction of the center of the specimen when you go
to high power
•the field of view gets smaller and darker
•only use fine adjustment on high power
•objects appear upside down and backwards in the
field
under the
becomes
scope
•when you move the slide to the left, the image moves
to the right & vice-versa
Preparing a wet mount slide:
•add a drop of water to a slide
•add specimen (cheek cell, onion cell, etc.)
•put coverslip on at a 45o angle (removes air bubbles)
Staining a specimen:
•Place 1 drop of stain at the edge of the coverslip
•Place a paper towel at the opposite edge so that the
water from under the coverslip is absorbed and stain
is drawn under coverslip
paper
towel
stain
Microscopic Measurement:
Units: in a meter, there are 1000mm (millimeters)
in 1 mm., there are 1000 um (micrometers/microns)
Determine the approximate
diameter of the cell in um.
The cell takes up approx
one quarter of the field
1.6 mm.
(diameter of the field of view)
1.6 / 4 = .4 mm.
= 400um
Other laboratory equipment:
Centrifuge/ultracentrifugemachine that spins specimens at high speeds which
separates the materials w/in the specimen according to
density
 heaviest materials settle to the bottom
 can be used to separate out cell parts
(nucleus from ribosomes…)
Micro-dissection Instrumentssurgical instruments that cut apart microscopic things
(ex. removing a nucleus from a cell)
Incubatorkeeps specimens warm (premature babies, cell samples)
Chromatography “chrom” = color
 process in which a substance (ink, chlorophyll) is
separated into its component parts/colors
 The rate at which the components move/separate
are unique to the substance being tested
 By comparing the separation of the unknown
substances to that of a known substance, an
identification may be made.
Misc Lab Tips….
 Always wear goggles when using chemicals.
 When heating a material in a test tube:
 point tube away from you
 never put a stopper in the tube
 glassware:
beaker
test tube
Graduated cylinderflasks
always read volume at
meniscus
Safety rap
 Science uses the metric system:
grams
liters
meters
with prefixes such as
millicentikilo-
Conducting an Experiment:
A valid experiment must have the following elements:
 A question you are trying to answer or problem
you want to investigate
 A control- the setup that remains the same
through the experiment; provides a
comparison
 A variable- the element/factor that changes in
the experiment (amount of sun,
water)
-a valid experiment tests only ONE
variable at a time
independent- variable that does not depend on a
factor in the experiment (ex. time,
days)
dependent- relies on the independent variable
ex) plant growth depends on time, time
does not depend on plant growth
 A hypothesis- possible answer to the question
you are asking
often posed as an “if…then…” statement
 An observation- what you see happening; provides
data for analysis
 A conclusion- Sums up the findings. Scientists
use the data to determine whether
the hypothesis was supported or
refuted
 Sample size- Refers to the # of organisms being
tested. The larger the sample size, the
more valid the results are.
The Cell
 Smallest unit of living things
 2 types of cells:
Prokaryotic Lack membrane-bound organelles
 No nucleus
 1 to 10 um. (smallest organisms)
 Include bacteria/Monerans
cell membrane
DNA
Slimy coating
ribosome
(only organelle)
Cell wall
(not the same as in plants)
Eukaryotic Present in all living things but bacteria
 Have many tiny “organs” called organelles
 These organelles carry out life functions
 Cells can be organized into more complex levels:
organelle
cell
tissue
organ
organ system
organism
 Cells are specialized to perform different functions
ex)nerve cells carry electrical messages
muscle cells move body parts
gland cells produce hormones

Cells are most often microscopic (10- 100 um)
exceptions:
chicken egg- 6 cm.
nerve cell- up to 1 meter!
 Importance of cell size:
cells are small so that they can get materials in &
out at rates that meet the cell’s needs (nutrients
in, wastes out)
Cell size & scale
animation
Surface Area to Volume Ratio
 The larger the ratio, the more materials that can
pass across the membrane
 Small cells have a bigger ratio
 Larger cells have smaller ratios (less efficient)
 Many structures outside large cells are farther from
the membrane than in a small cell
To calculate surface area/volume ratio:
For convenience in calcualtions, consider a cell to be shaped
like a cube
If the length of the side is 1 cm.,
surface area= l x w x # sides
1 x 1 x 6 = 6 cm.2
Volume = l x w x h
1
x
1
x
1 = 1 cm3
Surface area/volume ratio = 6/1 or 6:1
If the cell was bigger….
(sides were 2 cm.)
surface area= l x w x # sides
2 x 2 x 6 =24cm.2
Volume = l x w x h
2 x 2 x 2 = 8 cm3
Surface area/volume ratio = 24/8 or 3:1
Ratio is smaller than the cell w/1 cm. sides.
This is b/c volume more rapidly than surface area, causing the ratio to
This can cause serious problems for the cell.
therefore, larger ratios (found in smaller cells) are
more efficient in the transport of materials across cell
membranes
End quiz info
Cell Organelles
 subcellular structures
 suspended in cytoplasm (the watery material
inside the cell where chemical reactions occur)
 carry out life functions
1. Cell (plasma) membrane-
 surrounds the cell
 is selectively permeable (regulates the passage of
materials into and out of the cell) and therefore
maintains homeostasis (tries to)
 3 components:
a. cholesterol (soft, waxy substance)
b. double lipid layer:
Video clip:
membrane
hydrophillic
(H2O loving
head)
hydrophobic
(H2O fearing
tail)
c. proteins- float in lipid layer
~transport- helps move substances across membrane
~receptor- acquire info from extracellular area &
relays it into cell via cytoplasm
- posseses special shape that fits particular
molecules; helps regulation
- disruption of homeostasis…..HIV fools
receptors w/its shape!!
~markers- often have branching carbohydrates
- like “name tags” on cells that identify
them as your cell & not someone else’s
Fluid Mosaic Model
 cell membrane described as such by J.S. Singer
(1972) due to the fluid movement of the differently
shaped (“mosaic”) molecules of the membrane
*Life function: Transport, Regulation, Excretion
 endocytosis:
cell membrane forms a pocket to take in materials
pinocytosis- materials are small molecules/
liquids
phagocytosis- materials are large solids (ex.
when a WBC engulfs a virus)
2. nucleus- control center for the cell (brain)
 membrane contains pores to allow exchange of
materials btwn. nucleus & cytoplasm
 contains:
nucleolus- (directs ribosome production)
chromatin-(DNA in thread-like form)
chromosomes- (DNA in rod-like, coiled form)
*Life function: regulation, reproduction, metabolism, etc
3. nucleolus inside nucleus
 produce ribosomes & ribosomal RNA
*Life function: synthesis
4. ribosomes synthesize proteins
 may be free in cytoplasm or lining E.R.
*Life function: synthesis
5. Endoplasmic Reticulum- (“ER”)
 a network of fluid filled channels connected to
the nuclear membrane
 transport proteins w/in cell
 smooth ER- not lined w/
ribosomes
also responsible for lipid synthesis & detoxification
 rough ER- lined w/ribosomes
also responsible for protein synthesis
 small regions of ER bud off to produce vesicles
(pouches) containing the newly synthesized
proteins (then transported to golgi for packaging
*Life function: transport, synthesis
6. Golgi body/complex stack of membranes/enclosed sacs
 receives vesicles from ER, packages & ships them
to cell membrane for release (exocytosis)
 secretory vesicles that are produced in the golgi
also release their contents by exocytosis
*Life function: none
7. lysosomes- “stomach” of the cell
 small sacs that contain hydrolytic (digestive)
enzymes
 carry out intracellular digestion
 fuse w/vacuoles to break down ingested materials
 can break down cell’s own materials & release endproducts into cytoplasm for reuse
 has an acidic pH (5) as opposed to the cytoplasm (7)
*Life function: nutrition
8. vacuole membrane enclosed sacs
 formed after endocytosis (transporting material
into a cell via a vesicle)
~food: contain food & fuse w/lysosome
~ contractile: in freshwater protists, pumps out
excess water
 plant vacuoles are much larger than animal
*Life function: nutrition, excretion, homeostasis
9. mitochondria- (powerhouse)
 site of cellular respiration; releases energy, ATP
 Inner membrane (cristae) is highly folded. This
increases surface area for chemical reactions to
occur; very efficient
*Life function: respiration
10. centrioles found only in animal cells
 function in cell division
*Life function: reproduction, synthesis
11. plastids- found in photosynthetic eukaryotes
a. chloroplasts- contain chlorophyll
• site of photosynthesis
• contains its own DNA
• membranes arranged in stacks called grana
• the protein-containing material
that fills the rest of the chloroplast
is called stroma
b. leucoplasts- colorless, stores starch
c. chromoplasts- contain pigments that give color
to fruits, flowers & leaves.
*Life function: synthesis, nutrition
12. Cell wall non-living
 surrounds & supports plant cells
 composed of cellulose (complex carbohydrate)
13. cytoskeleton-structures that provide support & shape for
the cell
 microtubules~hollow rods made of a protein called tubulin
~make up centrioles, cilia & flagella
~give structures their shape
~also found in cytoplasm
 microfilaments~long, solid thread-like strands
~made of a protein called actin
~thought to have the ability to contract;
responsible for:

cyclosis- movement of cytoplasm in cell

muscle contraction
 intermediate fibers~size is “intermediate” btwn. microtubules &
filaments
~provide structure for the cell
~thought to form a basketlike structure to hold
Test your skills w/this activity:
“Name that organelle”
Protein Activity inside Cells:
nucleolus
makes
ribosomes
E.R.
ribosomes
make
proteins
E.R.
proteins
taken to
proteins
E.R. membrane
packaged
& released
in golgi
to body so
they can be used
body
synthesis &
assimilition
*reminder………
 A cell can be part of a multicellular organisn (dog,
tree)
OR
 A cell can be an entire organism (ameba,
paramecium)
HOW?!
• the organelles present in a single celled
organism act like the systems (resp.,
excretory, etc) in a multicellular organism
• these organisms perform all of the life
functions needed to stay alive
*reminder………
plant cells
Large vacuoles
Chloroplasts
No centrioles
Cell membrane & cell wall
“cyto” = prefix meaning cell
Laser clip: cell
*review life funct
animal cells
Small vacuoles
No chloroplasts
Centrioles
Cell membrane only