Download Topic 2 Notes

Topic 2: Homeostasis in
Organisms
What is Homeostasis?

Maintain a stable internal environment
such as body temperature or pH

Biochemical processes- chemical reactions
that occur in living organisms
Plant Nutrition:
Photosynthesis
How do organisms obtain their
nutrition?
 Heterotrophs-
can’t make own
food- obtain from other
organisms
 Autotrophs- make food from
inorganic compounds
 Photoautotroph-
use light energy
 Chemoautotroph- use chemical
energy
Who does what kind of nutrition?

Heterotrophs- animals, fungi, some
bacteria

Autotrpohs- plants, many protists and
some bacteria
Plants are autotrophs

Photosynthesis: use light energy to
convert small inorganic compounds into
food (glucose- simple sugar)
How do plants get energy from light?
Sunlight contains radiation energy
 How do we know sun contains energy?
 Ex: a day at the beach…

Equation for Photosynthesis
Goal of photosynthesis: make GLUCOSE
 Starting products of photosynthesis:

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Sunlight
Carbon dioxide CO2
Water H2O
End products

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Glucose C6H12O6
Oxygen (O2)
Water H2O
Where does photosynthesis take place?
Chloroplasts-
contain the
photosynthetic pigments
Equation for Photosynthesis
The balanced equation for photosynthesis is:
6CO2 + 12H2O + light  C6H12O6 + 6O2 + 6 H2O
How do plants gather the sun’s energy?
Plants can absorb this energy using
pigments
 Other wavelengths of light not absorbed
are reflected
 The color we see is reflected light

Plant Pigments- Why are plants green?

Chlorophyll- absorb red and blue light and
reflect green light

Chlorphyll “a” is main photosynthetic pigment
Carotenes- orange
 Xanthophylls- yellow
 Why do plants have these accessory
pigments?


ANSWER: Allow plant to absorb more light
Fate of Glucose

Glucose can be used as a food resource
Glucose can make (synthesis) complex
molculeules

ATP, DNA, Carbohydrates, Lipids, proteins
Cellular Respiration
Obtaining energy from
food!
What is respiration?

Respiration- convert the energy in
glucose into usable energy for the cell by
breaking the bonds between atoms

What is formed from respiration?


Make energy molecules ATP!
Enzymes are needed in order for the
chemical reactions to take palce
Types of Respiration

Aerobic- respiration requiring oxygen



Get the maximum amount of energy from glucose
Takes place in MITOCHONDRIA
Anaerobic- respiration without oxygen



Get only a small amount of energy out of glucose
Many forms of bacteria
Yeast cells
Summary of Aerobic Respiration
C6H12O6 + 6O2  6CO2 + 6H2O + Energy (36 ATP)
Glucose + oxygen  carbon
dioxide, water, and ATP
Carbon Monoxide Poisoning
Toxicity primarily results from cellular
hypoxia caused by impedance of oxygen
delivery. CO reversibly binds hemoglobin,
resulting in relative anemia. Because it
binds hemoglobin 230-270 times more
avidly than oxygen, even small
concentrations can result in significant
levels of carboxyhemoglobin (HbCO).
 Interferes with electron transport chain

Enzymes
Enzymes
 Enzymes-
proteins that speed
up chemical reaction
 Usually end in –ase and rest of
name comes from substrate
acts on
 Involved in digestion,
respiration, reproduction,
movement etc.
Enzymes
 Enzymes
are catalysts- brings
about reaction without being
changed (get reused)
 Substrate- what the enzyme is
changing
Parts of an enzyme
 Active
site- part of the enzyme
at which the substrate attaches
 Enzyme-substrate complexwhen enzyme and substrate join
together
 Enzyme
activity is regulated-
WHY?
 Inhibition- slow down how fast
enzyme works or shut down
Lock and Key Model
Active site
Enzymesubstrate
complex
Induced-Fit Model
Factors that Affect Enzyme Action
 Temperature-
work best at
certain temperatures
 High
temp, molecules move
fasterenzymes work faster
 Too hot- proteins fall apart- denature
 pH-
varies depending on the
enzyme (amino acids made of)
Factors that Affect Enzyme Action
 Concentration
of enzyme Little enzyme, lots of
substrate- enzyme limits
reaction rate
 Add more enzyme, increase
until all substrates are in active
sites
Factors that Affect Enzyme Action
 Concentration
of substrate
 Little substrate, lots of
enzyme- substrate limits
reaction
 Add substrate- increase until
all enzymes being used
Temperature
Effects of pH
In
stomach
In intestine
Enzyme concentration constant
Substrate concentration constant
Enzyme Worksheet
Enzyme Worksheet page 2
Enzyme Worksheet
Y Axis =
dependent
variable =
_________
X- Axis = INDEPENDENT
VARIABLE = _____________
Amylase Enzyme Activity at Different Temperatures
1.1
1
Rate of starch conversion (grams/minute)
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
5
10
15
20
25
30
35
40
45
50
Temperature Celsius
Rate of starch conversion (grams/minute)
55
60
65
70
75
Feedback and
Homeostasis
Which graph of blood
sugar level over a
12-hour period best
illustrates the concept
of dynamic equilibrium
in the body?
(1) (2) (3)(4)
Feedback Mechanisms

Positive Feedback- early part of childbirth

Negative Feedback- like a thermostat
Negative Feedback
Viruses and Disease

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Pathogens- viruses/bacteria and other
organisms that cause disease
Antigens- molecules that trigger immune
response
Viruses damage or destroy cells

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AIDS- attacks immune system – helper T cells
 Weakened immune system cause of death
Linked to cancerous tumors
 Can
carry oncogenes- genes that cause
cancer
Viruses and immune defense
 Immune
system has three main
functions:
 Recognition
 Destruction
 Memory
Immune Defense

Initial protection comes from FIRST LINE
DEFENSES

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SKIN
Mucous- trap pathogens, wash them away
Cilia/Hair
Enzyme/Acids
Sweat, Tears, Saliva
Immune Defense

If get past first-line, second line
defense:
 Inflammatory response- swelling,
redness, warmth in area of infection
 Cells release chemical - get increased
blood flow
 Attract macrophages- giant white
blood cells- swallow up bacteria
 Interferon- causes cells to produce
enzyme that stop viral reproduction
Immune Response

Third line defense- IMMUNE SYSTEM
 Helper T cell
 Killer T cell
 B cell
 Suppressor T cell
 Memory T cell- help if get infected again
Immune Defense Summary
 white
blood cells engulf
pathogens
 B cells make antibodies
 Antibodies attach to antigen
 Leads
to destruction of antigen
Allergies
Immune response to environmental
substances such as pollen dust, insects,
etc
 Antihistamines used to combat
