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Unit 1
1a. Scientific Method
1b.Life Characteristics
1c. Microscopes
1d. Cell Structure
1e. Osmosis
1f. Cell Energy
Unit 1a
Scientific Method
I.
The Scientific Method
a.
PHEOC
1.
Problem -What is wrong, or what you are interested in
understanding
2.
Hypothesizing (An “If . . . then . . .because. . . ” statement)
i.
ii.
3.
.
explanation for a question
educated guess
Experimenting – The physical steps you take (The
Requirements)
i.
ii.
Control = The condition(s) that is kept the same
Independent Variable = Condition that is changed – The
different/new thing you are testing.
iii. Dependent Variable = The condition that results from changes
in the independent variable – What you want the
Independent variable to do
4.
5.
Observing – Data
Conclusion – If your hypothesis is correct or not and why.
1. Talk about your data and how you can improve the experiment
II.
How Do We Write a Hypothesis?
a.
Three Requirements
1. If…,then… because statement
2. Can be tested
3. Be Specific!
How to write Hypotheses Examples:
1.
Incorrect: Chocolate may cause pimples
Correct: If chocolate causes pimples, then people who eat lots of
chocolate will get pimples, because chocolate leaves toxins in the
intestinal tract.
2.
Incorrect : Salt in soil may affect plant growth.
Correct: If salt affects plant growth, then plants with exposure to
excessive amounts of salt will not grow, because the salt sucks
the water out of the soil.
3.
Incorrect: Plant growth may be affected by the color of light
Correct: If light color affects plant growth, then plants will grow the
tallest in white light, because the light is a mixture of all colors.
4. Incorrect: Bacteria growth may be affected by
temperature
Correct: If temperature affects bacterial growth, then
bacteria will not grow if the temperature gets to 0 C
because the temperature is too cold for bacteria to
reproduce.
5. Incorrect: Ultra violet light may cause skin cancer
Correct: If skin cancer is caused by ultraviolet light , then
people with a high exposure to uv light will have a higher
frequency of skin cancer, because ultra violet light will
mutate skin cells.
6. Incorrect: Temperature may cause leaves to change color
Correct: If leaf color change is related to temperature , then
exposing plants to low temperatures will result in
changes in leaf color, because the low temperatures
cause the chlorophyll to break down.
Ex. Scientific Method
• Problem/Observation:
– The flashlight doesn’t work
• Hypothesis #1:
– If the batteries are dead, then
replacing them will cause the flashlight to work
• Test Hypothesis #1 in Experiment #1:
– Replace batteries
• Results observed in Experiment #1:
– After replacing batteries: flashlight still doesn’t work
• Conclusion:
– The batteries were not the problem
• New Hypothesis:
– If the bulb is damaged then replacing the bulb will
cause the flashlight to work.
• Test New Hypothesis in Experiment #2:
– Replace bulb
• Results observed in Experiment #2:
– After replacing bulb, flashlight now works
• Conclusion:
– The bulb was burnt out and the flashlight needed
a new one to function properly.
III. What is the difference between hypothesis,
theory & law?
1.
2.
3.
Hypothesis - “an educated guess”; a tentative
explanation of phenomena.
Theory - a widely accepted explanation of natural
phenomena; has stood up to testing.
Law - a statement of what always occurs under
certain conditions.
IV. Kinds of Information
a. Quantitative = numerical data
i. There were 7 blue birds after 3 months.
b. Qualitative = observational data (no
numbers)
i. A Red and Yellow bird couple gave birth to all
blue birds.
c. SI = International System of
Measurements
i. Base Units
1.
2.
3.
4.
Length = meter
Mass = gram
Volume = liter
Time = second
Unit 1b.
Life Characteristics
I.
Characteristics of Life
a. What makes something living?
i.
ii.
iii.
iv.
v.
vi.
Has an orderly structure
Produce offspring
Grow and develop
Requires energy
Expels waste / Respiration
Made of at least one cell
i.
A cell in and of itself is considered a living thing
because it performs all of these functions.
vii. Adjust to change in the environment involves. . .
1. Responding to Stimuli
a. Ex. Getting a shot (the stimulus) makes you flinch
2. Homeostasis = Regulation of organism’s internal
environment to maintain conditions suitable for survival.
a. Ex: humans sweating and shivering
3. Adaptation = Inherited from generations (over time) that
enables an organism to survive & reproduce
Living or NonMule? Living? Liger?
• Characteristics of life are subjective to human
reasoning.
II. All living things share common chemical
compounds that help them to survive
– Carbohydrates
• are sugars and starches that provide energy for humans and
animals
• Carbohydrates are made up of simple sugars known as mono(one) saccharides:
– Ex. Glucose
• di- (two) saccharides = two monosaccharide joined together
– Ex. Sucrose
• poly- (many), saccharides, = many monosaccharides linked
– Ex. Glycogen (in animals), Cellulose (in plants)
– Lipids
• These are fats, oils, and waxes
• The three major purposes of lipids are
1.
2.
3.
energy storage
cell membrane development
serving as a component of hormones and vitamins in the
body.
• Lipids don’t dissolve (non-soluble) in water.
–
–
One part is hydrophobic = fear of water
Other part is hydrophilic = loves water
– Proteins
• Required for the structure, function, and regulation of
the body’s tissues (hair, nails, etc.) and organs.
• They do most of the work inside and outside cells
– Ex. Enzymes are proteins that do jobs for the cell and they
regulate the body’s tissues and organs.
– Ex. Antibodies are used to target viruses and bacteria for
destruction.
– Without certain proteins we wouldn’t be able to move
around.
• Proteins are made up of hundreds or thousands of
smaller units called amino acids.
– Nucleic acids
•
Is the genetic information that can be passed from
parent to offspring.
Composed of Nucleotides that are made up of three
parts
•
–
–
–
•
Nitrogenous Base
Monosaccharide
Phosphate group
Ex. are DNA and RNA
Unit 1c.
Microscopes
I.
Microscopes
a.
Compound Light Microscopes
i.
Magnify objects 1500 times
b. Electron Microscopes
i.
Uses electrons instead of light to magnify
structure up to 500,000 times
1. SEM= Scanning Electron Microscope
a. Scans the surface of cells to learn 3-D shapes
Electron Microscope Images
Anatomy of a Microscope
Unit 1d.
Cell Structure and Function
II. Two Types of Cells
1. Prokaryotes
i.
ii.
iii.
iv.
NO NUCLEUS- DNA is floating freely inside cell!
Smallest cells / unicellular – made of one cell
No cellular organs (organelles)
Ex: bacteria
2. Eukaryotes
i. DNA is held in the nucleus
ii. Contains organelles
iii. Eukaryotic cells are MUCH BIGGER then
Prokaryotic cells.
iv. Can be multicellular or unicellular
v. Ex: animals, plants, fungi, protist
III. Discovery of Cells
1. Robert Hooke
i. British scientist who first
observed and named cells
ii. studied bark of trees in 1665
2. Virchow
i. Russian Scientist came up with
the Cell Theory:
1. All organisms are composed of one
or more cells
2. The cell is the basic unit of
organization
3. All cells come from preexisting
cells
IV. What are Organelles?
I.
II.
Tiny organs of a Eukaryotic cell
Most organelles have an outer membrane layer.
i.
ii.
Membranes are made of lipids
The lipid membranes keep the inside of the organelle
separate from the outside. (like a wall)
III. Each Organelle has a job to do.
IV. There are a lot of different organelles.
1. Plasma membrane
i. Structure and Security
ii. Surrounds the entire cell
iii. Made of Phospholipids and Proteins
2. *Cell Wall- (Plants Only)
i. Used for structure (Helps plants stand up)
ii. Surrounds the entire cell (even the plasma
membrane)
iii. Like a solid wall
3.
Cytoplasm- Work Area (Not really an organelle)
i.
ii.
The fluid that makes up the inside of the
cell.
Organelles and proteins work in this
space.
4. Nucleus- main office
i. Where the DNA is kept.
a. DNA is the blueprint for making proteins
ii. Ribosomes are made in the nucleolus.
5. Ribosomes- worker-bees
i. They help make proteins
6. Endoplasmic Reticulum (ER)
i.
Two Types
a. Rough ER- Finishes protein- Specialized proteins are
completed here and shipped off to other parts of the cell.
i. Located next to the nucleus.
ii. Where ribosomes are located.
b. Smooth ER- Makes Lipids / Breakdown toxins
7. Golgi Complex
i.
Package & ships proteins to other parts
of the cell.
a.
Golgi receives and sends proteins in objects
called Vesicles.
8. Lysosomes
i.
recycling & waste removal
a.
b.
Can break up food particles into smaller
parts for cell to use.
Can break down old useless organelles
9. *Chloroplast (Plants Only)
i.
Converts light into Carbohydrates.
a.
Carbohydrates are used by the cell for
energy!
10. Mitochondria
i.
Provides cell with energy!
a.
Does this by breaking down Carbohydrates.
11. Vacuole
i.
ii.
Stores water and waste/toxins
In plants, puts pressure against the cell
wall to keep cell rigid.
12. Cilia & Flagella
i.
ii.
Cillia - catches particles
Flagella - used for movement.
Comparison of Animal and Plant cells
Lysosome
Vesicle
Fungus-like
Plant-like
Animal-like
Unit 1e.
Osmosis
V. How stuff gets into and out of the cell
1. Passive Transport
i.
Particles can enter and exit the cell without the use
of energy.
1. Carrier Proteins move small particles into the cell.
2. Diffusion moves very small particles from an area of high
concentration to an area of lower concentration.
2. Active Transport
i.
Particles can enter and exit the cell with the use of energy
3. Endocytosis (“in to” the cytoplasm)
a. The process where a cell will take in foreign substances.
1. This is done by the cell wrapping its cell membrane around a
substance and literally “taking it in.”
4. Exocytosis (“exit” the cytoplasm)
a. The process where a cell will release substances from
itself.
1. This is done by vesicles fusing with the cell’s cell membrane.
VI. How water moves in and out of a cell.
a.
There must first be a Concentration gradient!
i.
ii.
b.
Difference in concentration of stuff across a space
Diffusion will continue until there is no concentration
gradient - - equilibrium has occurred.
Osmosis
i.
ii.
The diffusion of water.
Water molecules moving from an area of high concentration
to an area of low concentration
VII. Three types solutions
1. Isotonic =
a. Concentration of non-water molecules outside the
cell is the same as the concentration of non-water
molecules inside the cell. (i.e. equal water inside
and outside of cell)
b. Water will move in and out of cell at same speed.
c. Cell keeps its shape
2. Hypotonic =
a. High concentration of non-water molecules inside
the cell (i.e. less water inside)
b. Low concentration of non-water molecules outside
of the cell (i.e. more water outside)
c. Osmosis will cause water to move into the cell
d. Cells will get bigger . . . and explode!!!
3. Hypertonic
a. High concentration of non-water molecules
outside of the cell (i.e. Less water outside)
b. Low concentration of non-water molecules
inside the cell (i.e. More water inside)
c. Osmosis will move the water out of the cell
d. Cell will shrink
VIII. Osmosis in Plant cells
1. Turgor Pressure
a. Pressure that builds inside of a cell as the result of
osmosis
b. Helps plant cells to keep the plant “standing up.”
2. Plasmolysis
a. Loss of water resulting in a drop in turgor pressure
b. Causes plant cells to wilt
Unit 1f.
Energy in a cell
IX. Cell Energy – ATP
–
ATP is the energy source used by cells
•
•
Ex.: Powers the creation of proteins and used to maintain
homeostasis.
In order to get ATP cells need carbohydrates
Photosynthesis – Creates Carbohydrates
–
–
Plant cells use sun’s energy to split water into
separate Hydrogen and Oxygen atoms.
Freed Hydrogen combines with CO2 to make
carbohydrates and oxygen is released
Cellular Respiration – Breaks down Carbohydrates
–
the process by which mitochondria use oxygen to
break down food molecules (carbohydrates) to
produce ATP, CO2, and water