Honors Biology
Unit 1: The Life of the Cell
A: Characteristics of Life
Core Concept #1: All
forms of life share
common features
1. Made of one or more cells
• Structural and functional unit of life
• Two kinds of cells:
1) prokaryotic – no nucleus
- small, simple
- quick, easy reproduction
- fast exchange with environment
Eukaryotic Cells
• Larger, complex, have nucleus
• Many organelles, compartmentalized
• Parts for specific cell functions
• Cells can specialize – form tissues
Can form
multicellular
organisms
Two Kinds of Cells
All cells share some features
• Enclosed by selective membrane
• Contain cytoplasm, DNA, complex molecules
• Make any needed substances from raw
materials from environment
2. Common genetic code
DNA - Deoxyribonucleic Acid
a. Instructions for all life functions
b. “Gene” – one section on a DNA strand
- codes for one trait
b. Cells copy DNA and pass it to offspring
c. “Universal” code – same for all organisms
- Shows unity of life
ACTG
Shared genetic code makes gene
engineering possible
Examples:
• Human insulin
• Drought-resistance
• GM foods
Genetically Modified Corn
Bacteria – toxin kills worm
Gene for toxin put into corn
Worm eats corn gene makes toxin  toxin kills worm
Why not hurt humans? Concentration too small
DNA is unique to an individual
DNA “fingerprint”
- a pattern of stripes/bands
- different for everyone
- depends on order of ACTG
3. Obtain and Use Energy
a. Food – for energy and raw materials
b. Autotrophs - Producers
b.
c.
d.
e.
f.
Make their own food
Most use sunlight - photosynthetic
Combine water and CO2 to make basic carbs
Some use chemical energy - chemosynthetic
Base of all food chains
c. Heterotrophs - Consumers
a. find food in environment
Interdependence in Nature
Core concept #2: All forms of life
depend on each other and on physical
parts of environment
a. Biotic and abiotic
b. Take in light, food, water, air
- For energy, material for growth and repair
c. Send out wastes, die
d. Decomposers (saprobes/saprophytes)
- break down waste, recycle chemicals
Web of Life
Chemicals CYCLE
Environment
 autotrophs
 heterotrophs
 saprobes
 back to environment
Energy does NOT cycle
Light energy  chemical energy in food 
energy used for life functions  some lost as heat
4. Grow and Develop
a. Grow – increase in size (add more cells)
b. Develop – change while maturing
a.
b.
c.
d.
Multicelled begin as a single cell
Cells copy and specialize (differentiate)
Form many different kinds of cells
Organisms change as they
grow older
Bones grow longer with maturity
Stem Cells
a. Can become specific kinds of cells
b. Some genes are turned on, some off
c. Depends on chemical signals from their
environment
5. ARE ORGANIZED
With many complex chemicals
Have recognizable size and shape
Cells and organisms – different parts
perform different functions
Core Concept #3: Life proceeds from
simple to more complex
Multicellular - Levels of Organization
Cells differentiate  specialized cells
Different kinds of cells form tissues
Different kinds of tissues form organs
Organs work together to form organ
systems
e. Body systems work together to keep an
organism alive.
a.
b.
c.
d.
Skin Tissue
• Many kinds of cells work together
Coating/lining cells
“Skin” cells
Muscle cells
Fat cells
Blood/nerve cells
Gland cells
Cells  tissues  organs
 organ systems  organism
Environment – Levels of Organization
• Organism – individual living thing
• Population – members of one species living in
same area
• Community – all living things living in the
same area
• Ecosystem – biotic and abiotic in one area
• Biosphere – layer on earth that supports life
6. Reproduce
a. New cells form by cell division
b. Make new cells or a new organism
c. Asexual – one parent
- identical offspring
c. Sexual – two parents
- offspring gets genes
from both parents
- must be same species
Is mule a species?
Parents – horse and donkey
Hybrid - offspring from two
closely-related species
- cannot reproduce
 NOT a species
(species - fertile young)
7. Respond to environment
a. Stimulus - causes a reaction
b. Response - reaction to a stimulus
c. Internal or external stimuli
d. Must keep homeostasis
(constant internal conditions)
8. Evolve – Biology’s Central
Unifying Theme
a. Species can slowly change over time to
better fit an environment
b. Traits fit environment  survive and
reproduce  pass on traits
c. Individual organisms DO NOT evolve
d. Earliest life 3.5 billion years ago
Darwin’s Theory of Evolution
Nature selects those best suited to survive
- reproduce and pass on helpful traits
- species slowly change over time
Darwin’s observations
Darwin’s inference
Competition
for survival
Core Concept #4: Evolution
explains Unity and Diversity
Life is unified  shared
ancestry
• all living things have
same life traits
• do same life functions
• same chemical makeup and processes
Life is Diverse
Living things are diverse
- special features for different environments
Diversity of Life
6 Kingdom System of Classification
1. Archaebacteria – oldest kind of bacteria
2. Eubacteria – most bacteria
3. Protista – one-celled eukaryotes
4. Fungi – mostly decomposers
5. Plantae – multicelled photosynthetics
6. Animalia – multicelled heterotrophs
6 Kingdoms
3 Domain System
Archaea – Archaebacteria
Bacteria – Eubacteria
Eukarya – all eukaryotic organisms
Newest Tree of Life
Shares genes
with Eukarya
Structure and Function
a. “Form follows function”
b. Features evolve to perform a
function better
c. Different environments need
different kinds of adaptations
Are viruses alive?
• NOT part of living kingdoms
• LACK MOST traits of life, have only 3:
– Have DNA and protein
– Organized, recognizable size and shape
– Can evolve
• BETWEEN living and nonliving
Core Concepts in Biology
1. All life forms share common features
– DNA, life traits, cell basic unit of life
2. Living things interact with each other and with
the environment (food chain, cycling)
3. Life proceeds from simple to complex
- levels of organization in organism, in environment
4. Evolution explains unity and diversity
a. Unity - All life forms share common traits
- cells, DNA, life functions
b. Diversity - Life evolves to suit its environment
– form and function
Life Processes
How do living things stay alive?
All life processes work to maintain
homeostasis
(stable internal conditions)
Metabolism – all the chemical processes an
organism performs
Includes: Anabolic – build a molecule
Catabolic – break a molecule down
1. Cellular Respiration
•
•
•
•
•
Make energy for all life processes
Release energy in food molecules
NOT digestion, NOT “breathing”
Aerobic – gets max energy
Anaerobic
2. Nutrition
• Get or make food; process it for cells to use
• Nutrients – for energy, raw materials
1. Autotrophs (producers)
a.
b.
c.
d.
Make their own food
Photosynthesis
Base for all food chains
Plants, algae, some bacteria
2. Heterotrophs (consumers)
a. Ingest – take in food from environment
b. Digest – break large molecules down
c. animals, fungi, many bacteria
3. Saprobes (decomposers)
a. Break down wastes, dead organisms
b. Recycle nutrient molecules
c. Fungi, many bacteria
Digestive System
• Breaks down food
into molecules small
enough to enter cells
• Nutrients and water
absorbed by cells
• Liver, pancreas, and
others make enzymes
3. Transport
Circulate materials in a cell or organism
• Cross cell membranes
• Spread throughout cell
• Deliver needed materials, remove
wastes
• Multicellular – need way to transport
throughout organism
Animals:
circulatory system
- heart, blood, vessels
Plants : transport
tissue (veins)
4. Excretion
Remove metabolic wastes
• Out of cell or organism  environment
• Wastes are toxic
• Animals have excretory system
• Kidneys, skin, liver, lungs
• Plants have pores in leaves
Excretory System in Humans
Kidneys – filter blood
Liver – detoxify wastes
Lungs – exhale CO2
Skin - sweat
5. Synthesis
Cells make any needed substance
• Use molecules from food or raw materials in
environment
• Use energy from cellular respiration
• Example: make muscle tissue from protein
6. Reproduction
Make new cells or new organism
• New cells – for growth, repair
• New organism – continues the species
7. Grow and Develop
Increase in size and mature
• One cell  multicellular
• Develop: cells differentiate
• Egg  embryo  young  adult
8. Regulation
Control rate and kinds of
chemical reactions
• Respond to stimuli
• Keep homeostasis
• Unicellular and Plants – chemical
messages
• Animals – nerves and chemicals
Nervous system
• Electric signals along nerves
• Fast but short-lived
Endocrine system
•
•
•
•
Hormones sent into blood stream
Cause response only in specific tissue
Slower, but last longer
Example: adrenaline, growth hormone
Plants have hormones, but not nerves
Endocrine System
Hormones made
in different
endocrine organs
control specific
life functions.
The Process of Science
Evidence: can be observed or
measured
1. Discovery science
- tries to describe nature
2. Experimental science
- tries to explain nature
- hypothesis – possible answer/ solution
- can be tested
Question  hypothesis  test it  confirmation
Independent or Dependent?
• Variables – affect outcome
• Controlled Experiment – change ONE variable
• Independent variable – the one you change
“Manipulated”
• Dependent variable – depends on the
independent variable
“Responding”
Eastern coral snake (poisonous)
Scarlet king snake (nonpoisonous)
Artificial snakes:
king snake (left); brown snake (right)
Results of mimicry experiment
100
84%
83%
Artificial king snakes
80
Percent of total attacks
on artificial snakes
Artificial brown snakes
60
40
20
17%
16%
0
Coral snakes
absent
Coral snakes
present