Honors BiologyUnit 1: The Life of the Cell

A: Characteristics of LifeCore Concept #1: All forms of life share common features

• Structural and functional unit of life• Two kinds of cells: 1) prokaryotic – no nucleus

- small, simple- quick, easy reproduction- fast exchange with environment

1. Made of one or more cells

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 codeDNA - Deoxyribonucleic Acida. Instructions for all life functionsb. “Gene” – one section on a DNA strand

- codes for one trait

b. Cells copy DNA and pass it to offspringc. “Universal” code – same for all organisms

- Shows unity of life A C T G

Shared genetic code makes gene engineering possible

Examples: • Human insulin• Drought-resistance• GM foods

Genetically Modified Corn

Bacteria – toxin kills wormGene 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 Energya. Food – for energy and raw materialsb. Autotrophs - Producers

b. Make their own foodc. Most use sunlight - photosyntheticd. Combine water and CO2 to make basic carbs

e. Some use chemical energy - chemosynthetic f. Base of all food chains

c. Heterotrophs - Consumers a. find food in environment

Interdependence in NatureCore concept #2: All forms of life

depend on each other and on physical parts of environment

a. Biotic and abioticb. 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 CYCLEEnvironment autotrophs heterotrophs saprobes back to environment

Light energy chemical energy in food energy used for life functions some lost as heat

Energy does NOT cycle

4. Grow and Develop

a. Grow – increase in size (add more cells)b. Develop – change while maturing

a. Multicelled begin as a single cellb. Cells copy and specialize (differentiate)c. Form many different kinds of cellsd. Organisms change as they

grow older

Bones grow longer with maturity

Stem Cellsa. Can become specific kinds of cellsb. Some genes are turned on, some offc. Depends on chemical signals from their

environment

With many complex chemicalsHave recognizable size and shapeCells and organisms – different parts perform different functions

5. ARE ORGANIZED

Core Concept #3: Life proceeds from simple to more complex

a. Cells differentiate specialized cellsb. Different kinds of cells form tissuesc. Different kinds of tissues form organsd. Organs work together to form organ

systemse. Body systems work together to keep an

organism alive.

Multicellular - Levels of Organization

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 divisionb. Make new cells or a new organismc. Asexual – one parent - identical offspringc. 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 reactionb. Response - reaction to a stimulusc. Internal or external stimulid. 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 evolved. Earliest life 3.5 billion years ago

Darwin’s Theory of Evolution

Darwin’s observations

Darwin’s inference

Competition for survival

Nature selects those best suited to survive- reproduce and pass on helpful traits

- species slowly change over time

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 make-

up and processes

Life is Diverse

Living things are diverse - special features for different environments

Diversity of Life

6 Kingdom System of Classification1. Archaebacteria – oldest kind of bacteria2. Eubacteria – most bacteria3. Protista – one-celled eukaryotes4. Fungi – mostly decomposers5. Plantae – multicelled photosynthetics6. Animalia – multicelled heterotrophs

6 Kingdoms

3 Domain SystemArchaea – ArchaebacteriaBacteria – EubacteriaEukarya – all eukaryotic organisms

Newest Tree of Life

Shares genes with Eukarya

Structure and Functiona. “Form follows function”b. Features evolve to perform a

function betterc. 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 Biology1. 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 ProcessesHow 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. Make their own food b. Photosynthesis c. Base for all food chains d. 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, vesselsPlants : transport tissue (veins)

4. ExcretionRemove 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 bloodLiver – detoxify wastesLungs – exhale CO2Skin - sweat

5. SynthesisCells 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. ReproductionMake 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. RegulationControl 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 ScienceEvidence: can be observed or measured1. Discovery science - tries to describe nature2. Experimental science - tries to explain nature - hypothesis – possible answer/ solution - can be testedQuestion 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 experimentPe

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t of t

otal

att

acks

on a

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nake

s

100

80

60

40

20

0

83%

17% 16%

84%Artificial king snakes

Artificial brown snakes

Coral snakesabsent

Coral snakespresent