MICROBIOLOGY - ALCAMO LECTURE: CRITERIA FOR PROKARYOTES & EUKARYOTES.
-
Upload
erika-berry -
Category
Documents
-
view
226 -
download
0
Transcript of MICROBIOLOGY - ALCAMO LECTURE: CRITERIA FOR PROKARYOTES & EUKARYOTES.
MICROBIOLOGY - ALCAMOLECTURE: CRITERIA FOR
PROKARYOTES & EUKARYOTES
Introduction - Cells
• All living organisms have cells
• Basic unit of structure
• Large organisms – many cells
• Cells are organized into:
– Tissues – stomach lining
– Organs – esophagus, stomach, intestines
– Systems – digestive system
MICROORGANISMS
One or a few cells take care of all functions
Prokaryotic Cell:
• No nuclear membrane
• No other internal membranes (no organelles)
• Only has a cell membrane
• Examples – bacteria, cyanobacteria
.
PROKARYOTES
- They are very small cells
- They have a very thin cell wall:- Shape - Protection
- They have a cell membrane:- Lines the cell wall
- Regulates molecular traffic
- They have a nucleoid or nuclear region where their one, looped molecule of DNA resides
PROKARYOTES- Their cytoplasm is a soup of chemicals
(including free ribosomes), where all cell activities take place
- They may contain a flagella – a long hair-like appendage made of protein and responsible for motion in MO’s- May have one or many- Made of protein flagellin- Movement is chemically driven - chemotaxis
Eukaryotic Cell:
•Has a nuclear membrane
•Has other membrane bound organelles:
mitochondria
Golgi bodies
endoplasmic reticulum
•Examples – animals, plants, fungi, protozoa, unicellular algae
EUKARYOTES
- They are larger cells than the prokaryotes
- They may have a 3 layer cell wall:- Shape- Protection
- They have a cell membrane: - Lines the cell wall - Regulates molecular traffic
- They have a nucleus with a nuclear membrane:
- Double stranded DNA (chromosomes)
- RNA
.
- They have a cytoplasm – Soup of chemicals containing membrane bound organelles for all cell activities
- They may have a flagella –
- cable-like
- Made of tubulin protein
- Arranged in a microtubule array of 9 doublets around 2 singlets
Prokaryotic vs. Eukaryotic CellsCharacteristic Prokaryotes Eukaryotes
Nucleus Absent Present with nuclear membrane
Organelles Absent Present in a variety of forms
DNA Structure Single closed loopNaked strand with no protein
Multiple chromosomesProtein associated with DNA
Chlorophyll When present – dissolved in cytoplasm
When present –contained in chloroplasts
Ribosomes Smaller and free in cytoplasm
Larger and often bound to membranes
Cell walls Present and complex Present /absent and simple
Reproduction Fission – no mitosis Mitosis
Examples Bacteria, Cyanobacteria Fungi, protozoa, plants, animals, humans
Classification of Organisms
-Eukaryotes - all multicellular organisms and unicellular organisms (except 2)
Examples: mammals, fish, plants, fungi, algae and protozoa
-Prokaryotes – (the other 2) only bacteria and cyanobacteria
Microorganism Size
• Micrometer – unit of length most commonly used (1/1,000,000 of a meter)
• MO’s range in size from almost visible protozoa (100um) down to incredibly small viruses (0.01 um)
• Most bacteria are 1 – 5 um in length
Bacteria
• Prokaryotes and one of the most abundant organisms on earth
• Can affect us positively (digest sewage, extract N from air for plants, break down dead and decaying matter)
• Can be harmful to us (produce toxins in our bodies, infect plants and animals, etc)
• Are able to live under almost any conditions (arctic ice, hot springs, ocean trenches, acidic conditions, no oxygen)
Small Bacteria
• Rickettsiae barely seen with light microscope
• Transmitted by arthropods such as ticks and lice
• Can cause Rocky Mountain spotted fever and typhus fever
Small Bacteria
• Chlamydiae – even smaller than rickettsiae and can’t be seen with light microscope– One species causes the gonorrhea-like disease
known as chlamydia
• Mycoplasmas – smallest known bacteria and do not have cell walls– Can cause one form of pneumonia and one type
of sexually transmitted disease
Cyanobacteria
• Used to be known as blue-green algae, but are more closely related to bacteria
• They are prokaryotes and have light trapping pigments for photosynthesis
• Many are blue, but some are black, green or red (Red Sea)
• Inhabit freshwater and marine environments (ponds turn green, need algicide in pools)
Protozoa
• Single celled microscopic eukaryotes
• Some cause diseases such as malaria and sleeping sickness
• Come in many shapes and sizes and some are capable of photosynthesis
• Classified according to how they move (flagella, cilia, cytoplasmic extensions called pseudopodia)
Cilliate Amoeba
Fungi• Primary decomposers of organic matter in
the world
• Can cause human diseases such as athlete’s foot
• Used to be classified as plants but:– Don’t do photosynthesis – must obtain
preformed food– Cells have different cell wall
Fungi
• Eukaryotic organisms – 2 groups:– Yeasts – unicellular, ~ size of large bacteria
• Play a vital role in fermentation of beer and wine and production of bread
– Molds – long chains of cells seen as fuzzy masses
Yeast Mold
Unicellular Algae
• The term algae refers to any plant-like organisms that practice photosynthesis and differ structurally from land plants
• Two important algae for microbiology:– Diatoms – Dinoflagellates
Diatoms
• Eukaryotic marine organisms• They are photosynthetic – make carbohydrates –
passed on to other marine organisms when they are eaten
• Cell walls are impregnated with silicon dioxide (glasslike)
• When they die their remains accumulate on the sea floor as diatomaceous earth (used to produce filters)
Dinoflagellates
• Photosynthetic eukaryotes
• Important in the world’s food chains
• They can also produce periodic red tides in the oceans
Viruses
• Neither prokaryotes nor eukaryotes
• They are non-cellular, do not grow, do not show any nutritional pattern
• Only observable activity is replication, which can only be done inside a living cell
• They are just a fragment of DNA or RNA inside of a protein sheath
• Cause many human diseases – flu, polio, hepatitis, chickenpox