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32 Cards in this Set

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Normal Flora
There are various microorganisms that are found at any anatomical sites in the body and is referred to as the body's normal flora.

Normal flora in a healthy individual is found predominantly on the body's surface tissues, i.e., skin and mucous membranes as these surfaces are in constant contact with organisms in the environment. The body's surfaces can become readily colonised by various species of microorganisms however the internal tissues such as the blood, brain, muscle, etc., are normally free of microorganisms in a healthy individual.

The normal flora of humans is made up of Bacteria (most abundant) and eucaryotic fungi and protists
Bacteria, Bacterium
KINGDOM: Monera

have a sole purpose to replicate.

Greek for "rod, stick"

Bacteria are Prokaryotes

The favourable conditions that allow bacteria ot flourish include

Adequate supply of food and water
Carbon dioxide
Temperature
pH (most prefer alkaline environment)
Some like oxygen:

Aerobic bacteria – thrive in the presence of oxygen
Anaerobic bacteria –thrive in the absence of oxygen

Some bacteria have the ability to adapt and these are termed Facultative aerobes or anaerobes
Most Bacteria have three basic shapes
1. Rod shaped – Bacilli
2. Round – Cocci
3. Spiral shaped – spirilla, vibrios, spirochetes
Gram Positive Bacteria
these organisms stain purple due to thick peptydoglycan in the cell wall retaining the chrystal violet used in decolouring process
Gram Negative Bacteria
These organisms stain red due to not being able to retain the chrystal violet in the declouring process as it has a thinner peptydoglycan cell wall
gram -ve are considered a more virulent strain of bacteria
Has an added outer layer of lipids
Produces an endotoxin that can cause serious health issues: diarrhoea, and hemorrhagic shock
Viruses
Viruses are the smallest living things and can only be seen with an electron microscope.

Virus: latin for poison, venom

are the most abundent of all the microorganisms.

Viruses are not cells and cannot carry out any metablolic processes unless they are supported by a living cell.
Virus
They lack a rigid cell wall, have no nuclei, mitochondria, or ribosomes and some do not have cytoplasm
Unlike bacteria they cannot replicate unless they invade or infect a host: considered an intracellular parasite
Once inside the host the virus replicates by making multiple copies of itself, with the assistance of the host
Viruses have the capabilites to infect any type of organism including plants, animals, bacteria, achaea
Viruses will not respond to an attack in any way. They will either keep doing what they do or they will be killed
They cannot be cultured on dead or artificial material making it very hard to develop treatments to destroy the virus
All viruses have a few basic components:
DNA or RNA: (never both) genes are made from the DNA or RNA and is a small peice of nucleic acid which is considered the core of the virus
Capsid: a protein coat which protects the genes. It also helps the virus infect new cells.
Envelope: only some viruses have this extra envelope. It is made of lipids and proteins like other cells however the envelope assists the virus in getting into the host unnoticed and to also invade new host cells.
Viruses have three shapes
1. Helical Virons (cylindrical)
2. Polyhedral Virons (3D Hexagon like)
3. Complex Viron (robot like)
Life cycle of a virus
1 Attachment: the capsid adheres to the host cell wall and fusion occurs
2 Penetration: the virus enters the cell
3 Uncoating: the capsid of the virus degrades due to viral enzymes or host enzymes allowing release of the viruses genes into the cell
4 Replication: and assembly of the viruses protein genes occurs
5 Maturation: proteins are modified
6 Release: the cell breaks down and the membrane bursts releasing viruses from the host ready to infect new cells or be transferred to a new host.
Fungi
Mycology: the study of fungi

Mycologist: person who studies fungi

Heterotophs: fungi are heterotrophs as they require organic matter for growth

Hypae: a branched filament of a fungi

Structure:

Fungi are made up of filaments (hypae)
Fungi are all eukaryotic cells.

Fungi are either:

Saprophytic: secrete an enzyme which assists in the breakdown of dead organic materials
Parasitic: live on a host and obtain their nutrients from them

Fungi are different to plants as they do not carry out the process of photosynthesis
Two types of Fungi:
Moulds: Multicellular or acellular, reproduce by spores mainly asexually

Yeasts: unicellular (single), reproduce by budding, mainly asexually
Fungi are classified into four groups/phylum
Chytridiomycetes - Chytrids, as members of this group are known - produce motile spores called zoospores

Zygomycetes

Ascomycetes

Basidomycetes
Fungi
a hypha-bearing sporangium
sporangiophore
Fungi
the hyphae that anchors to the substrate
rhizoid
Fungi
two haploid nuclei combine to form a diploid nucleus
karyogamy
Fungi
asexual spore case
sporangium
Fungi
haploid nuclei share the cytoplasm
plasmogamy
Fungi
dormant sexual structure
zygospore
Ascomycetes
Commonly called 'sac fungi' or 'cup fungi'
This group contains many of the delicious edible fungi
30,000 known - 500 of which are yeasts
Basidomycetes
Most mushrooms
The most familiar
Also called 'Club fungi'
count for about 1/3rd of all known/identified fungi
25,000 species have been identified
Protozoa
KINGDOM: Protista
Unicellular - one cell
Single or multiple nuclei
Some are microscopic as they are the smallest organism in the animal kingdom and others can be seen be the unaided eye

differentiated from Algae (which is in the same Kingdom) as they do not contain chlorophyll.

Surrounded by a cell membrane (not a cell wall)

Able to mobilise by flagella (tail), cilia (fine hairs on its surface which act like a rudder), and pseudopodia ( arching and strecthing to move forward; like a worm)

Protozoa are parasitic and most live in water habitats but are found also in soil. A number of them do exist as parasites in humans, animals, insects and plants
Protozoa Classification: classified according to how they move
1. Sarcodina - Called an Amoeba, Moves by extending it's cytoplasm forward and the rest follows behind

2. Mastigophora - flagalettes - Move by a whip like tail propelling it though the water

3. Ciliated - The cilia move in a sychronised wave like motion to assist with motility

4. Sporozoa - Cause disease in a variety of species, fish, humans, rats, earthworms etc
many thousands of species of sporozoa
All are parasytic
This group of protozoa make up some of the pathogens that are infectious to humans such as; malaria, pnuemonia toxoplasmosis,
Protozoa - Helminths
KINGDOM: Protista
Another name for Helminths is worms:
Divided into

Platyhelminths: flat worms

Trematodes: flukes
Cestodes: tapeworms

Aschelminths:

Nematodes: round worms
Platyhelminths:

Cestodes: Flat Worms
are intestinal parasites
has a head (scolex) and a segmented body (proglottids)
the head has hooks or suction caps on it to enable it to attach to the intestinal wall of the host.
absorbs nutrients directly from the host through the pores in it's body
the segmented portion of the flat worms body contains the sexual organs of both the male and female allowing it to produce eggs

Dwarf Tapeworm: Some flat worms do not need an intermediate host and can infect the definative host with the eggs developing into mature worms in the human intestine:
Platyhelminths:

Trematodes: Flukes
flat leaf shaped body
have a mouth, an intestine but no anus
the body has muscular suckers to atach to the hosts tissue
the whole body is composed of a complex reproductive system
commonly infect birds, fish, mammals
requires an intermediate or a final host

Two types

Tissue flukes: invade lung tissue
Blood Flukes: lives in the body's blood vessels
Aschelminths:

Nematodes: Round Worms
long cyclindrical worms
found in all countries
have a mouth, intestine and an anus
are either a male (smaller) or a female (larger)
infect humans, plants, animals and insects

Pinworm: also known as the thread worm

the female emerges from the hosts anus at night to lay her eggs around the anus
this itches the hosts anus and they then scratch
the eggs are then transferred to another host or the initial host can be re-infected
eggs can also be spread on bed linen or clothing

Hookworm:

1cm in length
has a mouth with hooks or suckers on them which allow attachement to the intestinal wall
they suck the blood of the host
eggs are shed in faeces
develop into larvae in the soil
the larvae can burrow into the skin and enters the blood stream travelling to the lungs
the larvae are coughed up and swallowed
only to arrive at the intestine to start the cycle all over again
Algae
KINGDOM: Protista

Algae are plant like but do not have leaves, flowers or roots, that are common to plants. However they do use photosynthesis to gain their energy source for metabolism.

Algae are one of the most important organisms on earth absorbing more sunlight and producing the most oxygen than any other plant life combined

They are found mainly in both fresh and sea water and also grow in the soil, on animals and trees. Algae can grow in the extremes of weather from hot areas to sub zero temperatures. They also live in partnership with other organisms

The most common algae is found in the lakes and oceans is the Phytoplankton (1000 can fit on one pin head) forming seaweed
Types of Algae
Brown Algae
Desmid
Stonewart
Brown Algae
There are 1500 species of brown alga
forming seaweed
contains a pigment which masks the green of the chlorophyll making the algae look brown
Desmid
singled celled organism
cresent shaped
found in fresh water
two semetrical halves divided by a isthmus which contains the nucleus
can grow in colonies
able to get around by gliding and usually in the direction of sunlight
capable of sexual and asexual reproduction
Asexually: the algae divide at the ischmus
Sexually when pairs unite the cell contents fuse and then two new desmids are formed
Stonewart
This group of Algae belong to the KINGDOM PLANTS
Approx 200 species
covered with a thick, brittle, limy crust of calcium carbonate
grow in alkaline water
submerged under water forming blankets on the bottom of ponds
They have rootlike rhizoids, leaflike branches, and upright cylindrical axes surrounded by a sheath of cells.
Reproduce by sexual or asexual reproduction:
Asexual from the shedding of it's reproductive branches
Sexual reproduction: leaf like structures make up the female organ and large eggs are produced the male sexual organ produce sperm from filaments