Download Review: Scientific Method & Cells

Review:
Scientific Method and Cells
The Scientific Method
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•
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O = observe
P = problem
H = hypothesis
E = experiment and record data
A = analyze data
C = conclusions
R = repeat and continue research
“OPHEACR”
Hypothesis & Experiment
• Propose a hypothesis: an educated guess to predict possible
answer to problem based on research, previous knowledge,
observations, and information from studying a problem
• Test a hypothesis: design an experiment to test hypothesis
with repeated trial, large sample size* and collection of data
• Controlled experiment = tests only one* changing factor or variable and
other parts remain the same or controlled
– control group* = does not change during testing, compared to
experimental results
– experimental group = contains change being tested
– Manipulated or independent variable = what you change (becomes
experimental group)
– Responding or dependent variable = what you measure, depends on
other variable
Data Tables
• To record and organize observations
Line Graphs
• To show change
over time
Dependent
Variable
0
Independent
Variable
Analyze Data & Valid Conclusions
• Inference: your judgment based on an observation
• Interpret what the data means for example by
graphing or using calculations
• Review data from observations to determine if data
supports hypothesis and to develop additional
hypotheses, generalizations or explanations
• Hypothesis is either supported or rejected (not
proven!)
Repeat the experiment
• many scientists repeatedly test the
experiment to ensure conclusions are
supported and may become a scientific law
– a. Facts = based on experiments and careful observations
– b. Theories = scientific hypotheses that have been tested
many times and confirmed by many scientists
– c. Scientific law = result of many scientists repeatedly
reaching the same conclusions
Metric Conversions
Kilo-
Hecto-
Decadeci-
Kilo (K)
centi-
milli-
= Thousand, so 1km = 1000m
Centi (c) = Hundredth, so 1cm = 1/100m or 0.01m
Milli (m) = Thousandth, so 1mm = 1/1000m or 0.001m
Micro (µ) = 1µm = 1/1000000 or 0.000001m
pH
• The pH scale ranges from 0 to 14 and increases by a factor of 10
– pH of 7 = neutral because there’s an equal number of H+ &
OH- ions
– pH < 7 = acids because there’s more H+ ions than OH- ions
– pH > 7 = bases because there’s less H+ ions than OH- ions
Organic Compounds
• Contain carbon and hydrogen
• Ex: C6H12O6
CH4
Chemical Reactions
• A process that changes a set of chemicals into
another set of chemicals
• Reactants = the set of chemicals that enters
into a chemical reaction
• Products = the set of chemicals produced by a
chemical reaction
• Chemical reactions break bonds in the
reactants and form new bonds in the products
• When chemical bonds break or form, energy is
released or absorbed
• Organisms need to carry out reactions that
require energy
– Plant get energy from sunlight
– Animals get energy from plants or other
animals and release energy by breaking
down food
Catalysts
• A catalyst is a substance that
speeds up the rate of a chemical
reaction by lowering the
activation energy.
• Enzymes are proteins that act as
biological catalysts to speed up
chemical reactions in cells.
• Enzymes are very specific and
they are usually named after the
reaction they catalyze and end in
-ase
Enzyme Action
• Reactants must collide with enough energy to break bonds and form
new ones
• Enzymes provide a site for the substrates (reactants) to react, reducing
the energy needed for the reaction to occur
• Enzymes are specific having an active site that is complementary to the
shape of the substrates it catalyzes = “lock and key”
• This forms an enzyme-substrate complex
• Enzymes activity can be affected by any variable that influences a
chemical reaction
– pH
– Temperature
Unicellular vs. Multicellular Organisms
• One-celled organism is able • The cells in a multicellular organism
are interdependent (can not live on
to function despite lacking
their own)
the levels of organization
(they depend on each other like
present in more complex
players on a team)
organisms.
• Cell specialization = each type of
• The structures present in
specialized cell performs separate
some single-celled
roles or functions within the
organisms act in a manner
organism, has a different number
similar to the tissues and
of each organelle depending on
systems found in
function
multicellular organisms,
• Ex: red blood cells, nerve cells,
thus enabling them to
muscle cells, pancreatic cells – have
enormous amounts of organelles
perform all of the life
involved in their functions
processes needed to
maintain homeostasis.
• Ex: yeast
HOMEOSTASIS
• THE PROCESS OF MAINTAINING A CONSTANT
INTERNAL ENVIRONMENT DESPITE
CHANGING EXTERNAL CONDITIONS
Levels of Organization
• Cell: specialized to obtain food & oxygen, and carry out
specific functions
• Tissue: a group of similar cells that perform a particular
function
– Four types of tissue in living things: epithelial (skin), muscle,
nerve, & connective (bone, blood, cartilage & lymph)
• Organs: many tissues working together to perform a function
(ex. Muscle = muscle tissue, nerve tissue & connective tissue)
• Organ systems: group of organs working together to perform
a specific task (ex. Digestive system, nervous system, &
circulatory system)
The Cell Theory
• 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.
• Cells have particular structures that perform
specific jobs. These structures perform the actual
work of the cell. Just as systems are coordinated
and work together, cell parts must also be
coordinated and work together. These structures
are called organelles.
Section 7-2
Smooth endoplasmic
reticulum
Vacuole
Ribosome
(free)
Chloroplast
Ribosome
(attached)
Cell
Membrane
Nuclear
envelope
Cell wall
Nucleolus
Golgi apparatus
Nucleus
Mitochondrian
Rough endoplasmic reticulum
Plant Cell
Go to
Section:
Section 7-2
Nucleolus
Nucleus
Ribosome
(attached)
Nuclear
envelope
Mitochondrian
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Centrioles
Golgi apparatus
Animal Cell
Go to
Section:
Ribosome
(free)
Cell
Membrane
Cell Membrane
• Thin, flexible barrier around cells
(inside cell wall on plant cells)
• Provides protections and support
• Helps maintain homeostasis with
a chemical balance between
materials inside and outside the
cell by removing wastes from the
cell
• Selectively permeable = allows
only certain material in or out of
the cell
• Made up of a lipid bilayer with
some proteins scattered
throughout
PASSIVE TRANSPORT
• MOVEMENT OF MOLECULES FROM AN
AREA OF HIGHER CONCENTRATON TO AN
AREA OF LOWER CONCENTRATION
• KINDS:
– DIFFUSION
– OSMOSIS
– FACILITATED DIFFUSION
• DOES NOT REQUIRE THE USE OF ENERGY
Diffusion
• Movement from an area of higher concentration to an area of
lower concentration to reach equilibrium without using
energy to cross the cell membrane
• CONCENTRATION GRADIENT:
exists when particles are in higher concentration in one area
and lower in concentration in another. Causes movement of
the molecules
• EQUILIBRIUM:
when the rate of particle spreading is even throughout a
given area.
• http://www.northland.cc.mn.us/biology/BIOLOGY1111/anima
tions/active1.swf
Osmosis
• The diffusion of water through a selectively
permeable lipid bilayer membrane without
the use of energy
• FROM AN AREA OF HIGHER CONCENTRATION
TO AN AREA OF LOWER CONCENTRATION
• When the transfer of water molecules into
and out of the cell reaches the same rate, a
state of equilibrium is reached.
• Cell shrinks, because water moves out of cell,
because there’s more water in cell than in
solution.
Salt
water:
15%
salt,
85%
pure
water
Cell:
95%
water
start
end
• Cell swells (can burst), because water moves
into cell, because there’s more water outside
cell than in solution
Water:
100%
pure
water
Cell:
95%
water
start
end
Facilitated Diffusion
• movement across the membrane through
protein channels from an area of high
concentration to an area of low concentration
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Active Transport
Molecule to
be carried
• movement from an area of
lower concentration to an area
of higher concentration against
the concentration gradient
using energy
Low
Concentration
Cell
Membrane
High
Concentration
– Endocytosis – taking in materials
by forming pockets
Low
Concentration
• Phagocytosis – taking in large
particles
• Pinocytosis – taking in liquid/fluids
Cell
Membrane
– Exocytosis – removing materials
by fusing vacuoles
High
Concentration
Energy
Energy
Nucleus
•
•
Large structure that contains the
cell’s genetic material or hereditary
information (DNA - holds instructions
for making proteins)
Controls the cell’s activities
– Chromatin – granular material visible
with nucleus made up of DNA bound
to protein
– Chromosomes – formed by
chromatin during cellular
reproduction to be passed on to the
next generation
– Nucleolus – small, dense region
within the nucleus where ribosome
assembly begins
– Nuclear Envelope – double
membrane around the nucleus with
nuclear pores to allow material to
move through (including RNA)
Ribosomes
• Made of RNA and protein
• Build proteins on ribosome from proteins and
RNA (coded instructions from the nucleus)
Chloroplasts
• Use energy from sunlight
with carbon dioxide and
water to make food
(carbohydrates) and oxygen
through photosynthesis in
plant cells and some other
cells (not in animal/fungi
cells)
• Double envelop membrane
• contain the green pigment
chlorophyll
• Contain some of its own
genetic information (DNA)
Mitochondria
• Use food to make
energy (ATP) for
growth, development,
and movement
• Double envelop
membrane
• Contain some of its own
genetic information
(DNA)
Photosynthesis
• Photosynthesis is a process used by green plants
• The is a type of autotrophic nutrition.
• Photosynthesis is carried out by chloroplasts, which
contain chlorophyll
• In the chloroplasts, CO2 and H2O are used to form C6H12O6
and O2
• Stomata = pore-like opening on the bottom of plant leaf
that allows carbon dioxide to diffuse in or oxygen to
diffuse out only when the plant has enough water to open
the guard cells and perform photosynthesis
6CO2 + 6H2O
carbon
dioxide
water
light energy trapped in
the chloroplast makes
this process happen
C6H12O6 + 6O2
sugar
(glucose)
oxygen
Cellular Respiration
• Cellular respiration is the process of breaking down food
(glucose) in cells in the presence of oxygen to release energy.
• In the presence of oxygen, food is broken down through the
processes of glycolysis, the Krebs cycle and the electron
transport chain = cellular respiration
• It uses oxygen taken in as you breath = aerobic
• Carbon dioxide, water, energy, and some heat are given off as
waste products.
C6H12O6 + 6O2
sugar
(glucose)
oxygen
6CO2 + 6H2O + energy
carbon
dioxide
water
Energy Transfer & Food Chains
• All energy comes from the Sun!
• Energy Transfer:
Sunlight  Autotroph  Heterotroph  other heterotrophs
(herbivore)
(carnivore)
• Food Chain:
Autotroph  Heterotroph  other heterotrophs
(herbivore)
(carnivore)
Cellular Reproduction
• Reproduction – the life process by which living things produce
other living thing of the same species
• It is necessary for the survival for the species
• Two types of Reproduction through cell division:
– Sexually reproducing organisms go through mitosis and meiosis
– Asexually reproducing organisms only go through mitosis
Genetically
identical
to parent
Genetic
variability
in gametes
Uncontrolled Cell Growth
• Internal Regulators = Proteins that respond to events inside the cell.
• External Regulators = Proteins that respond to events outside the
cell and direct the cell to slow down or speed up the cell cycle.
• Cancer: cells lose the ability to control growth or don’t respond to
signals that regulate cell growth.
• Tumor: cancer results in masses of cells that damage surrounding
tissues.
• Cancer cells can break loose from tumors and spread throughout
the body, disrupting normal activities and causing serious medical
problems or even death.