Introduction to Cytology or Cell Biology How do we observe cells? Light microscope Visible light...

Introduction toCytology or Cell Biology

How do we observe cells?

Light microscope Visible light passes through object Lens magnify image

Electron microscope Scanning - surface of object Transmission - sees through objects 100,000 X to Millions magnification

power

How do we know what happens in each part of

the cell? Radioisotopes are used to "trace"

different chemical reactions through a cell.

Separate cellular structures with a blender

Centrifuge material and analyze each layer.

People who were important in early cell

discovery:

Zacharias Jannsen (1590)

Helped invent the First compound microscope

Robert Hooke (1665) Observed dead cork - called them

“cells“ Compound Microscope

Anton Von Leeuwenhoek (1674)

- living cells in pond water; one celled organisms -- animalcules

Robert Brown (1831) identifies the nucleus of a cell

Mattias Scleiden (1838)

stated that plants are made up of cells

Theodor Schwann (1839)

stated that animals are made up of cells

Rudolph Virchow (1858) Studied the pathology of cells. (ability to

cause disease)1. All cells arise from preexisting cells.  2. New cells can only arise from other

living cells by the process of cell division or reproduction

Cell Theory

1. All living things are composed of cells

2. Cells are the fundamental building block of life

3. All cells come from pre-existing cells (life begets life)

PROCESSES OF CELLS

All life processes involve energy changes.

1. Nutrition - food is needed for energy and building materials.

2. Digestion - breaking down reactions of food into usable parts.

3. Absorption - water, food, ions and other materials

4. Biosynthesis - cells organize many organic substances for cell activity.

5. Respiration - cell energy is released when certain organic molecules are split - energy is used for cell activity.

6. Excretion - waste materials passed from cell to environment

7. Secretion - synthesized molecules which are passed out of a cell and which affect the activities of other cells (vitamins, hormones)

8. Reproduction - cells divide; unicellular - more organisms, multicellular - more cells.

9. Movement - motion of all types; cellular contractions, flowing substances within the cell

10. Egestion - elimination of insoluble compounds and nondigestible particles

Eukaryotic cells – advanced cells

Have nucleus Plasma membrane Cytoplasm - everything between

plasma membrane and nucleus Organelles Fluid

Cytoskeleton – threads of microtubules and microfilaments in cytoplasm

Animal cells have unique structures Centrioles Lysosome Flagellum 1. 2.

3. Plant cells have unique structures

Large central vacuole Cell wall 1. 2. Chloroplasts

3.

Animal vs Plant Cell

Mitochondrion

Plasma Membrane

Cell Wall

Central Vacuole

Vesicle

Ribosomes

Envelope

DNA

Nucleolus

Cytoskeleton Fibres

Chloroplast

Pore

Golgi Body

Smooth ER

Rough sdfER

Mitochondrion

Centriole

Plasma Membrane

Protein MarkerSugar Chain

Lipid BilayerLipid Bilayer

Cholesterol Proteins

Embedded Protein

OUTSIDE OF CELL

INSIDE OF CELL

Cell Membrane Side Profile

Different membranes

All have similar functions & structures Plasma membrane separates inside of cell

from outside of cell Other membrane define organelles to form

compartments of eukaryotic cells

Forms a selectively permeable layer Lets some things in or out but not all Like a window screen

Nucleus

Envelope Double membrane Pores to get messages in and out

Chromatin DNA threads Protein balls called histones - wrapping

Nucleolus - site of ribosome production

Nucleus - Structures

Nucleolus – where rRNA or Ribosomes are made

Ribosomes

Consists of 2 parts, which are made in nucleus

Make protein in the Cytoplasm

Produce proteins from ‘recipes’ in the nucleus copied into mRNA Some (proteins) will remain in cytoplasm Some will be exported out of cell Some will attach to membranes in cell

Ribosomes are found on the endoplasmic reticulum and in the cytoplasm

Endoplasmic Reticulum

Rough ER

Smooth ER

Rough Endoplasmic Reticulum

Rough ER - attached to nucleus

Ribosomes stud surface

Produces Membrane proteins - stay in cell Secretory proteins - exported from cell

RER makin’ Proteins!

Smooth Endoplasmic Reticulum

No ribosomes, so not protein factories

More like transport system Makes steroids, lipids Liver cells have lots of smooth ER

Detoxify chemicals Supply and demand

Increases tolerance to drug So higher doses needed for same effect

Golgi apparatus – the Post Office of the Cell

Refines, stores and marks molecules for

shipment Looks like stack of hollow pancakes Products of ER arrive & leave via

transport vesicles Moving from one sac to the next

Molecules get modified Labeled and / or stored

Called the cell “Post office” because it marks and directs products in the cell

Golgi apparatus – what it does

Lysosome

Greek for breakdown body

Recylcer Sac of strong digestive enzymes

Compartmentalized for safety Can release to breakdown entire cell –

“suicide sack” Functions

Digest food vacuoles Digest invading bacteria Digest old organelles

Lysosome

Lysosome

Lysosomal diseases Genetic disorders ‘Recipe’ is messed up so protein doesn’t

work If recipe for lysosome enzyme

What should get broken down doesn’t Ex. Tay Sachs

Lipids aren’t broken down Build up occurs Eventually causes death

Usually in before age 5

Mitochondria

Site of cellular respiration Conversion of food into energy (ATP)

ATP is what cells use to make things happen (drive chemical reactions)

Double membrane Big bag stuffed in smaller bag Folds of inner bag called cristae

Space inside inner bag called matrix Also once free living bacteria Efficiency - gasoline engines converts 25% of

energy mitochondria converts 54% of energy

Mitochondria

contains some of its own DNA (amount varies within organisms)

believed to evolved from a primitive cell engulfing it and creating a symbiotic relationship

DNA in mitochondria obtained only from mother of organism.

Chloroplast1. chlorophyll is green chemical that releases electrons, working like a solar panel in sunlight

2. forms glucose

3. photosynthesis 6CO2 + 6H2 O ---> C6H12 O6 + 6O2

Plant Organelles Chloroplasts - in plants

Chloroplast

s

Structure of Chloroplast Double membrane Grana

Stack of thylakoids Hollow disk Where sunlight energy is captured and converted

to chemical energy

Stroma Thick fluid filling chloroplast

Contains some DNA Once free-living bacteria

Cytoskeleton

Actin filaments

Microtubules

Network of fibers

Give shape to cells Allow movement of cell Move organelles around Made of microtubules and

microfilaments

Role of the Cytoskeleton

Cilia

Flagella

9+2 Arrangment in Cilia or Flagella

Basal Body of a Flagella or Cilia

•Note the triplet rings of tubulin protein

•9+0 arrangement•Nine sets of rings, with no set in middle•Used to set up 9+2 arrangment in cilia or flagella

Centrioles

Cell reproduction; goes to poles of cell during cell division and helps cell divide

Centrioles at Work in Cell Division

Different kinds of cells suited for a different activity. 

Cell Specialization

Division of Labor Different cells divide their labor

each has a specific function and supports each other.

1. Cell 2. Tissue 3. Organ 4. Organ system 5. Organism

Levels of structure

Tissue Level  

A group of cells that are alike in structure and activity in an organism muscles

- Skeletal muscle cells – motion- Cardiac muscle cells – heartbeat- Bones - support- Nerve cells - coordination, perception and automatic body functions

Organ Level

several tissues working as a unit

heartAnimals brain

stomach 

roots Plants stem

leaf 

Organ Systemmany organs involved in carrying out a function

digestive nervous skeletal excretory respiratory endocrine – (hormones) circulatory muscular reproductive

Organism

complete living thingcell

tissueorganorgan systemorganismIN

CR

EA

SIN

G S

IZE