unit 2: the unity and diversity of living things what determines if something is living?

Unit 2: The Unity and Diversity of Living Things

What determines if something is living?

In order to be considered “living”, you need to display the potential for all of the following life functions:

1. Nutrition-obtaining materials from the environment and processing them for use within the organism.

a. heterotrophs-organisms that consume food

ingestion-

digestion-

egestion-

taking in food

breaking down food

removal of undigested or indigestible food ex) corn, fiber, throwing up

What must an oak tree do to stay alive that both a fly and a human must also do?

b. Autotrophs-

*Photosynthesis:

“auto”= self, “trophic”= nutrition

Some types of bacteria carry out the process of making food by using energy

chlorophyll

light

enzymes

CO2 + H2O C6H12O6 + O2 + H2O

*Chemosynthesis:

2. Transport- the absorption and circulation of materials within an organism

•a. single-celled organisms (or any cell w/in an organism…

materials are diffused/absorbed directly across the cell membrane •b. multi-celled organisms- most cells aren’t in contact w/the environment so a circulatory system is needed

•a. anaerobic-

3. Respiration-The exchange of O2 and CO2 AND the release of energy that is stored in food molecules.

does not use oxygen, produces little energy•b. aerobic- does use oxygen, produces lots of energy, more efficient C6H12O6 + O2 CO2 + H2O + Energy (36 ATP) (glucose)

4. Excretion-

The incorporation of these synthesized molecules into the organism’s bodyEx) when proteins become part of a body builder’s muscles from a protein-rich diet

•skin removes H2O, salts + urea

•lungs remove CO2 + H2O

•kidneys remove H2O, salts + urea•liver removes dead RBCs

5. Synthesis & Assimilation-

chemical reactions where large molecules are built from smaller ones

the removal of wastes from cells + from an organism which were produced during life processes.

“You are what you eat!!!”

6. Regulation-the control & coordination of all life activities in an effort to maintain homeostasis(stable internal

environment)•a. nervous- •b. endocrine-

2 systems involved:electrical: brain, spinal cord, nerves chemical: hormones, glands

7. Growth-increase in size and/or number of cells• you grow in # of cells from infant teen• an ameba’s 1 cell can increase in size• requires materials that were synthesized from the nutrients ingested• includes differentiation (cell specialization) in multi-cellular organisms

8. Reproduction-creating a new organism/cell

~species survival is dependent on reproduction, individual survival is not.

•2 parents,•offspring have a combination of parents’ traits

•1 parent,•identical offspring,•no variety

~asexual & sexual

Metabolismthe total of all life processes/chemical

reactions working together to sustain the organism

anabolism-

catabolism-

requires energy

synthesis of complex molecules from simpler ones

ex) photosynthesis, growth

releases energy

the breakdown of complex molecules into simpler ones

ex) digestion of carbohydrates

Homeostasis

The maintenance of a stable internal environment w/in an organism

ex) maintaining a constant body temperature, blood sugar level

Borderline cases of living things:

Seeds, flower bulbs, viruses, HIV

They display only some of the life functions some of the time. At other times, they are said to be dormant (“sleeping”)

The Cell`the basic unit of all living things

Historical Background

2. Anton Von Leeuenhoek- used a simple microscope (1 lens). He was the

1st to see living cells (blood, pond water

organisms)

1. Robert Hooke- coined the word “cell” when

looking at cork w/a compound microscope (he was seeing their cell walls)

A. 1600s

1. Schleiden (1838)- said that all plants are made of cells

B. 1800s

These discoveries led to the development of the Cell Theory

3. Virchow (1855)- said that all cells arise from other

cells

2. Schwann (1839)- said that all animals are made of cells

3. New cells arise from other cells.

2. Cells are the basic unit of structure and function

(can carry out life processes).

1. All living things are made of 1 or more cells.

~where did the 1st cell come from?

Exceptions to the Cell Theory

~viruses: not made of cells, contain DNA, can only reproduce w/host cell

Cell Theory

Chicken egg= cell

Microscopes

•magnifies 40-400 times

•2 lenses

Compound- (what we use at school)

•See diagram

..\biomovies\intro to microscopes.mov

body tube

nosepiece

objective lens

objective lensobjective lensstage clips

diaphragm

light

ocular/eyepiece

arm

stage

coarse adjustmentfine adjustment

base

Dissecting/stereo microscope-•2 eyepieces: binocular

•magnifies 6-60 times•shows external features (ex. fly, ladybug)•creates a 3-D image

Tips for microscope use:

•Start on low power •Brighter•Larger field of view

•When you switch from low to high:•center your specimen, b/c you will only see a fraction of the center of the specimen when you go to high power •the field of view gets smaller and darker•only use fine adjustment on high power•objects appear upside down and backwards in the field becom

es

under the scope

•when you move the slide to the left, the image moves to the right & vice-versa

Preparing a wet mount slide:•add a drop of water to a slide

•add specimen (cheek cell, onion cell, etc.)•put coverslip on at a 45o angle (removes air bubbles)

•Place 1 drop of stain at the edge of the coverslip•Place a paper towel at the opposite edge so that the water from under the coverslip is absorbed and stain is drawn under coverslip

Staining a specimen:

paper towel

stain

Microscopic Measurement:

in a meter, there are 1000mm (millimeters) in 1 mm., there are 1000 um (micrometers/microns)

Determine the approximate

diameter of the cell in um.

1.6 mm. (diameter of the field of view)

The cell takes up approx

one quarter of the field

1.6 / 4 = .4 mm. = 400um

Units:

The Cell Smallest unit of living things 2 types of cells:

Prokaryotic- Lack membrane-bound organelles

No nucleus Include bacteria

DNA

Slimy coating

Cell wall

(not the same as in plants)

ribosome

(only organelle)

cell membrane

organelle

Eukaryotic- Present in all living things but bacteria

Have many tiny “organs” called organelles These organelles carry out life functions

Cells can be organized into more complex levels:

cell

tissue

organ

organ system

organism

Cells are specialized to perform different functions ex)nerve cells carry electrical messages muscle cells move body parts

gland cells produce hormones

Cell Organelles “tiny organs” suspended in cytoplasm (the watery

material inside the cell where chemical reactions

occur) carry out life functions

1. Cell (plasma) membrane-

surrounds the cell is selectively permeable (regulates

the passage of materials into and out of the cell) and

therefore maintains homeostasis

..\biomovies\cell organelles.mov

..\biomovies\fluidmosaicmodel.mp4

hydrophillic (H2O loving head)

hydrophobic (H2O fearing tail)

~transport- helps move substances across membrane ~receptor- receives info from extracellular area & relays it into cell

Video clip:membrane

cell membrane described as such by J.S. Singer (1972) due to the fluid movement of the differently shaped (“mosaic”) molecules of the membrane

endocytosis: cell membrane forms a pocket to take in materials

Fluid Mosaic Model

*Life function: Transport, Regulation, Excretion

pinocytosis- materials are small molecules/

liquids materials are large solids (ex. when a WBC engulfs a virus)

phagocytosis-

control center for the cell (brain)

membrane contains pores to allow exchange of materials btwn. nucleus & cytoplasm contains: nucleolus-

produce ribosomes & ribosomal RNA

(directs ribosome production)

2. nucleus-

chromatin- (DNA in thread-like form) chromosomes-(DNA in rod-like, coiled form)

*Life function: regulation, reproduction, metabolism, etc

3. nucleolus- inside nucleus

*Life function: synthesis

synthesize proteins may be free in cytoplasm or lining E.R.

a network of fluid filled channels connected to the nuclear membrane

transport proteins w/in cell

*Life function: synthesis

4. ribosomes-

5. Endoplasmic Reticulum- (“ER”)

smooth ER- not lined w/ ribosomes

rough ER- lined w/ribosomes

small regions of ER bud off to produce vesicles

(pouches) containing the newly synthesized

proteins (then transported to golgi for packaging

*Life function: transport, synthesis

6. Golgi body/complex- “UPS”

7. lysosomes-

stack of membranes/enclosed sacs receives vesicles from ER, packages &

ships them to cell membrane for release (exocytosis) secretory vesicles that are produced in the golgi also release their contents by exocytosis

carry out intracellular digestion

“stomach” of the cell small sacs that contain hydrolytic

(digestive) enzymes

*Life function: none

*Life function: nutrition

8. vacuole- membrane enclosed sacs Stores water food and waste

plant vacuoles are much larger than animal

*Life function: nutrition, excretion, homeostasis

Inner membrane (cristae) is highly folded. This increases surface area for chemical reactions to occur; very efficient

*Life function: respiration

9. mitochondria- (powerhouse)

site of cellular respiration; releases energy, ATP

10. centrioles- found only in animal cells function in cell division

*Life function: reproduction, synthesis

11. plastids-found in photosynthetic organisms

a. chloroplasts- contain chlorophyll• site of photosynthesis

*Life function: synthesis, nutrition

12. Cell wall- non-living

composed of cellulose (complex carbohydrate)13. cytoskeleton- structures that provide support &

shape forthe cell

surrounds & supports plant cells

~give structures their shape

Protein Activity inside Cells:

nucleolusmakes ribosomes

E.R. ribosomesmake proteins

E.R. proteins packaged in golgi body

E.R.

proteins taken to membrane & released to body so they can be used insynthesis & assimilition

*reminder………

A cell can be part of a multicellular organisn (dog, tree)

OR

A cell can be an entire organism (ameba, paramecium)

HOW?!• the organelles present in a single celled organism act like the systems (resp., excretory, etc) in a multicellular organism

• these organisms perform all of the life functions needed to stay alive

“cyto” =

Large vacuolesChloroplastsNo centriolesCell membrane & cell wall

Small vacuolesNo chloroplastsCentriolesCell membrane only

*reminder………

prefix meaning cell

plant cells animal cells

-Is the absorption and circulation of materials throughout an organism

Transport

-Diffusion- materials move from HIGH to LOW concentrations

randomly until an equilibrium is reached

-Osmosis- diffusion of water

1. Passive Transport- does NOT require energy

• another name for passive transport is: diffusion

• Materials move from a high to low concentration

2 Types of Transport

• Small molecules can pass through a selectively permeable membrane

Active Transport•Requires ENERGY•Materials move from low to high concentration•When materials are too big to move through the membrane- cell has to use energy

..\biomovies\activetransport.mp4

Solution around the cell has a lowerconcentration of dissolved particles (salt,sugar) than the cell. (therefore water will be higher). This causes water to move into the cell making it swell or burst.

animal cell:The cell will eventually burst; cytolysis

Hypotonic-

HypotonicRed Blood Cells placed in distilled

water

Isotonic-

Solution around the cell has the same concentration of dissolved particles as the cell. Water will be in equilibrium. This will have no effect on the cell.

Hypertonic-

plant cell:

vacuole swells and pressesagainst cell wall to create turgor pressure that is used to open stomates and flowers

H2O

Solution around the cell has a higherconcentration of dissolved particles than the cell. (therefore water will be lower). This causes water to move out of the cell making it shrink.

animal cell:

The cell will shrink; plasmolysis

plant cell:

The cytoplasm will shrink; vacuoles close, plant wilts

..\biomovies\OnionCells Plasmolysis.mp4

Hypertonic

Phagocytosis ..\biomovies\ameba eating para.mov

Also when cells use energy to engulf things: phagocytosis- ex: when a paramecium eats amoeba or when WBC engulfs/eats bacteria or viruses