Characteristics of Living Things

Krogh Ch 1,4

Characteristics of Life

1. Reproduce 2. Obtain and use Energy 3. Made of cells 4. Contain DNA 5. Evolves 6. Levels of Organization 7. Respond to stimuli 8. Grow and Develop

Levels of Life

Abiotic………… Biotic………..........................................BOTH……..

1. MADE OF CELL(S)Cell theory

1. All organisms are made of one or more cells.

2. All cells come from pre-existing cells.

1. MADE OF CELL(S) Smallest living unit; has DNA

Prokaryotes: – Small, unicellular, loose DNA, hard outer walls– Ex. bacteria, archeans

Eukaryotes:– Larger, DNA in nucleus, specialized organelles,

often multicellular w/ tissues & organs– Ex. plants, fungi, animals, protists

Prokaryote

Eukaryotes

circular but loose

absent

.1-10um 30-100umpg 64

All cells have…

a plasma membrane DNA (cell coordination) Ribosomes (to make proteins) Cytoplasm

Main categories of cells

Prokaryotes Eukaryotes“Before kernels” = before there were nuclei.

“True kernels” = when nuclei were a reality.

No nucleus Membrane enclosed nucleus

Few different parts scattered throughout

Many compartmentalized (isolated) regions with specialized functions.

All are single celled organisms Single celled or multicellular.

Divide by binary fission Divide by mitosis

Bacteria Protists, fungi, plants, animals

The Three Domains

The Three Domains Prokaryotes – no nucleus

– Archaea– Bacteria

Eukaryotes – have nucleus– Eukarya

Protists– Algae – plant-like– Protozoa – animal-like

Plantae Fungi Animalia

– Vertebrate Birds Mammals Reptiles Amphibians Fish

– Invertebrate

The six kingdoms

Endosymbiosis Some parts of complex

(eukaryotic) cells may actually be engulfed prokaryotes many years ago.

If so, they continued to evolve this way because it is mutually beneficial.

Root words:Endo- (inside)-symbiosis (to live together)

Question…

Is the entire mass of an organism made entirely of cells?

NO!! Many cells secrete chemicals that form an extracellular matrix.

i.e. they “build” the house that they live in, just like we do.

Also consider blood cells that move around in plasma, which is mostly water.

CELL ORGANELLESCells have specialized structures that perform various tasks.

Phelan: Sections 3.4 & 3.13 – 3.21

NucleusPhelan: Figure 3-26

Control center of the cell

Contains the DNA (genetic information), which never leaves the nucleus!

Cell membrane

Phelan: Figure 3-9

Main gatekeeper

Selectively allows certain things in and out.

Cell wall Provide

strength and rigid shape

Water resistance

Only found in plants and some prokaryotes.

Phelan: Figure 3-36

Cytoskeleton Internal scaffolding to

provide shape to the cell.

“Roadways” for transport of materials within the cell.

Enables movement

Cytoplasm is the fluid in between the fibers.

Phelan: Figure 3-27

Cytoskeleton (cont.) Cilia are projections of fibers out of the cell

that can sweep fluid past the cell. A flagellum (pl, flagella) is a long “tail”

that whips back and forth to propel the cell.

ChloroplastsPhelan: Figure 3-38

Packages unusable energy into usable “boxes”

Turns “unusable” sunlight energy into “usable” glucose

Plants and algae

Mitochondria sing,

mitochondrion

Powerhouse of a cell

Converts stored energy to functional energy for usage to do just about anything.

EndoplasmicReticulum & ribosomes Smooth ER (top) &

rough ER (bottom)

Make and modify important molecules for the organism

Detoxification

Ribosomes (the small dots) make proteins.

Golgi apparatus Packages and

ships important molecules out of the cell to other parts of the organism.

Endomembrane system at work

LysosomesGarbage

disposals

Break down and recycle cellular waste productsWorn-out

organellesPathogensMetabolic wasteEtc.

Vacuoles Mainly storage of

various materials

Found in many eukaryotes, mostly prominent in plant cells.

Review Phelan: Figure 3-39

THE SIZE OF CELLSThe size of cells illustrates a very important concept in all of Biology.

Notes on cell size lab:

Surface areaMore SA = more transport possible.“doors” or contact to the outside world.

VolumeMore Volume = more that must be transportedMore volume = more that must be taken care ofSize or amount of people in a building

RatiosMore SA by itself isn’t necessarily betterHigher SA / Volume ratio = most efficient transportNote card vs. large ball

Review!

The term that means internal stability within an organism.Homeostasis

The type of cell that is organized into specialized regions on the inside.Eukaryote

The name of the cell division process for the simplest cells.Binary fission

2. OBTAIN / USE ENERGY METABOLISM combination of all

chemical reactions in cell Autotrophs: use sun’s energy to build

food like sugar or fats Heterotrophs: eat/absorb food, then

digest into less complex molecules

3. RESPOND TO STIMULI

Ex.?

Homeostasis = regulating internal environment– Ex. pH, temp, fluids, salts, gases,

cell division, toxin removal– How? Feedback loops

4. REPRODUCE w/ DNA

Asexual Sexual Genetic clones 1 cell 2 cells

Ex.– Bacteria or

paramecium fission– Sponges or hydra

budding– Spider plants, tulip

bulbs, crabgrass

Joining of DNA from 2 gametes (sperm & egg)

Not necessarily two parents!!!

Ex.HumansHermaphrodite

worms

Cell divisionProkaryotes divide by binary fission – simple duplication and “pinching off”

Eukaryotes divide by mitosis (complex series of steps)

5. LIFE CYCLE Grow = size Develop = changing physical or

mental characteristics

One twin mouse is going through normal aging, while the other’s is halted.

What about…– Fire?– Crystals?

6. GENERATIONS EVOLVE

Human heights Bacteria war Darwin’s finches