Introduction to Cytology or Cell Biology. 5 Characteristics of Living Things ① Respond to the...

Introduction toCytology or Cell Biology

5 Characteristics of Living Things

① Respond to the environment② Require Energy③ Grow④ Reproduce⑤ Eliminate wastes

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

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Chapter 2Measurement and Microscopy

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Scale


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Discovery of Microorganisms

Antoine van Leeuwenhoek (1632-1723)

first to observe and describe microorganisms


The Compound – multiple lens microscope


Stereoscope


Microscope Resolution ability of a lens to separate or distinguish

small objects that are close together

wavelength of light used is major factor in resolutionshorter wavelength greater resolution

At what point are the dots separate? Can they be resolved or separated from each other??


Resolving Power


Resolving Power Resolving power is the ability to make out detail

Human Eye 0.1 mm

Compound Microscope 0.2 um

Electron Microscope 0.5 nm

Limitations of Microscopes

Light waves scattering causes distortion and unclear images Maximum magnification is about 1500X


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Electron Microscopy

beams of electrons are used to produce images

wavelength of electron beam is much shorter than light, resulting in much higher resolution


TEMS ---> Ebola Virus


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Scanning Electron Microscope3D Images


The Scanning Electron Microscope

uses electrons reflected from the surface of a specimen to create image

produces a 3-dimensional image of specimen’s surface features


Common Dog Flea – Magnified 350X


Bristle on Common Earthworm – Magnified

350X


Trypanosome (parasite) next to a red blood cell.


Fly head

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:

Robert Hooke (1665) Observed dead cork - called them

“cells“ Compound Microscope

Anton Von Leeuwenhoek (1674)

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

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)

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

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!

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

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

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

Prokaryotes

Cells that do not have a nucleus

Exist almost every where on earth

Grow in numbers so great you can see them with the unaided eye

Eukaryotic vs Prokaryotic Cells

What are Viruses

A virus is a non-cellular particle made up of genetic material and

protein that can invade living cells.

T4 Bacteriophage

Herpes Virus

E. Coli and the Bacteriophage

What it looks like in real life

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