BIOLOGY, TOPIC SIX,6. Flashcards
WHAT IS A PATHOGEN?
A PATHOGEN IS ANY ORGANISM WHICH CAUSES DISEASE.
INFECTIOUS DISEASES.
INFECTIOUS DISEASES ARE ALWAYS CAUSED BY PATHOGEBNS, WHICH CAN SPREAD FROM PERSON TO PERSON TO INFECT OTHERS.
NON-INFECTIOUS DISEASES.
NON-INFECTIOUS DISEASES, SUCH AS LUNG CANCER OR DIABETES, ARE NOT CAUSED BY PATHOGENS AND TEND TO BE MORE INGLUENCED BY GENETIC OR LIFESTYLE FACTORS.
PATHOGEN EXAMPLES.
PATHOGENS INCLUDE, BACTERIA, VIRUSES, PROTOCISTS AND FUNGI.
PATHOGENIC ORGANISMS.
BACTERIA,
MYOBACTERIUM TUBERCULOSIS CAUSES, TB.
VIRUS,
HIV CAUSES AIDS.
COVID-19 CAUSES CORONAVIRUS.
THE INFLUENZA VIRUS CAUSES SEASONAL FLU.
PROTOCIST,
PLASMODIUM CAUSES MALARIA.
FUNGI,
TRICHOPHYTON CAUSES ALTHLETE’S FOOT.
BACTERIAL CELL STRUCTURE.
BACTERIA ARE SINGLE-CELLED PROKARYOTIC ORGANISMS WHICH CONTAIN THE FOLLOWING STRUCTURES:
CIRCULAR CHROMOSOMAL DNA.
RIBOSOMES.
CELL WALL.
PILI.
MESOSOMES.
PLASMIDS.
SLIME CAPSULE.
FLAGELLUM.
CIRCULAR CHROMOSOMAL DNA.
FLOATS FREE IN THE CYTOPLASM.
RIBOSOMES.
THESE ARE SMALLER THAN THOSE FOUND IN EUKARYOTIC CELLS.
70S RIBOSOMES.
PILI.
PILI ARE HAIR-LIKE STRUCTURES WHICH STICK OUT FROM THE PLASMA MEMBRANE.
THEY ARE USED TO COMMUNICATE WITH OTHER CELLS, INCLUDING THE TRANSFER OF PLASMIDS BETWEEN BACTERIA.
MESOSOMES.
THE MESOSOMES IS A FOLDED PORTION OF THE INNFER MEMBRANE.
WHILE SOME SCIENTISTS BELIVE THAT IT PLAYS A ROLE IN CHEMICAL REACTIONS, SUCH AS RESPIRATION, OTHER SCIENTISTS DOUBT WHETHER IT EVEN EXISTS AND THINK THAT IT MAY JUST BE AN ARTEFACT PRODUCED DURING THE PREPARATION OF BACTERIAL SAMPLES FOR MICROSCOPY.
PLASMIDS.
PLASMIDS ARE SMALL, CIRCULAR RINGS OF DNA WHICH ARE SEPARATE FROM THE MAIN CHROMOSOME.
THEY HOUSE GENES WHICH ARE NOT CRUCIAL FOR SURVIVAL BUT MIGHT PROVE USEEFUL, SUCH AS ANTIBIOTIC-RESISTANCE GENES, FOR EXAMPLE.
PLASMIDS CAN REPLICATE INDEPENDENTLY FROM THE MAIN CHROMOSOMAL DNA.
SLIME CAPSULE.
IN ADDITION TO A CELL WALL, SOME BACTERIA ALSO HAVE A CAPSULE WHICH IS MADE OF SLIME.
THE MAIN FUNCTION OF THE CAPSULE IS TO PROTCT THE BACTERIUM AGAINST AN IMMUNE SYSTEM ATTACK.
FLAGELLUM.
ROTATES TO MOVE THE BACTERIUM.
HIV.
HUMAN IMMUNODEFICENCY VIRUS, HIV.
WHAT IS HIV?
HIV, IS A DEADLY VIRUS, WHICH CAN WEAKEN A PERSON’S IMMUNE SYSTEM.
HOW DOES HIV WEAKEN AN INDIVIDUALS IMMUNE SYSTEM?
IT CAN WEAKEN A PERSONS’S IMMUNE SYSTEM BY DESTROYING A TYPE OF IMMUNE CELL CALLED T HELPER CELLS.
HIV, SPREAD.
IT IS SPREAD THROUGH THE TRANSMISSION OF INFECTED BODILY FLUIDS. FOR EXAMPLE, DURING SEXUAL INTERCOURSE, SHARING OF NEEDLES OR BLOOD TRANSFUSION.
OPPORTUNISTIC INFECTIONS.
HIV DOOES NOT KILL THE PATIENT DIRECTLY, BUT WEAKENS THE IMMUNE SYSTEM TO AN EXTENT THAT THE PATIENT IS UNABLE TO FIGHT OFF OTHER INFECTIONS WHICH NOMRALLY WOULD NOT A POSE A THREAT.
THESE ARE KNOWN AS OPPORTUNISTIC INFECTIONS.
AIDS, STAND FOR.
ACQUIRED IMMUNODEFICENCY SYNDROME, AIDS.
ZTHE DEVELOPMENT OF AIDS.
WHEN THE PATIENT’S IMMUNE SYSTEM HAS WEAKEND TO A PARTICULARLY LOW LEVEL, THIS IS SEEN BY A LOW T HELPER CELL COUNT IN HOSPITAL BLOOD TESTS, THE PATIENT HAS DEVELOPED A DISEASE CALLED AIDS.
WHAT IS AIDS?
AIDS IS A DISEASE.
THE LATENCY PERIOD.
THE TIME BETWEEN INITIAL INFECTION AND THE ONSET OF AIDS SYMPTOMS, THE LATENCY PERIOD, VARIES GREATLY BETWEEN INDIVIDUALS BUT IT IS USUALLY AROUND TEN,10, YEARS.
THE LENGTH OF THE LATENCY PERIOD, DEPENDANT ON.
THE LENGTH OF THE LATENCY PERIOD DEPENDS ON THE INDIVIDUAL’S AGE, STRENGTH OF THEIR IMMUNE SYSTEM AND ACCESS TO HEALTHCARE.
THE STAGES OF THE SYMPTOMS OF AIDS.
THE PERSON WILL FIRST DEVELOP LESS SERIOUS, MINOR INFECTIONS WHICH WILL GRADUALLY BECOME MORE AND MORE SEVERE.
AS THE PATIENT’S BODY TRIES TO FIGHT OFF MORE INFECTIONS, THE LOWER THEIR T CELL LEVELS DROP.
EVENTUALLY THEIR IMMUNE SYSTEM WILL BE SO WEAK THAT THEY WILL DIE OF AN OPPORTUNISTIC INFECTION BECAUSE THEY DO NOT HAVE ENOUGH IMMUNE CELLS TO DEFEND THEMSELVES.
HIV STRUCTURE.
THE HIV VIRUS CONSISTS OF A CORE OF RNA AND ENZYMES, REVERSE TRANSCRIPTASE AND INTERASE, WHICH ARE ENCLOSED IN A PROTIEN COAT CALLED A CAPSID.
SURROUNDING THE CAPSID IS AN OUTER LAYER CALLED THE ENVELOPE WHICH CONTAINS ATTACHMENT PROIENS, THESE PROTIENS ARE CRUCAL FOR THE VIRUS TO ENTER THE HOST CELL.
THE ACT LIKE LITTLE KEYS TO ACCESS OUR CELLS.
HIV REPLICATION.
IF A PERSON WITH HIV EXCHANES BODILY FLUIDS WITH ANOTHER PERSONS, HIV CAN INFECT THE SECON INDIVIDUAL AND WILL BE PRESENT IN THEIR BLOODSTREAM.
THE HIV VIRUD USES ITS ATTACHMENT PROTIENS TO ENTER HUMAN IMMUNE CELLS, SPECIFICALLY THE HELPER T CELL, BY BINDING TO RECEPTORS ON THE T CELL.
THE CAPSID IS RELEASED INTO THE CELL, WHERE IS BREALS APART TO RELEASE RNA AND ENZYMES.
THE ENZYME REVERSE TRANSCRIPTASE CONVERTS THE RNA INTO DNA.
THE SIGLE-STRANDED DNA IN CONVERTED TO DOUBLE-STRANDED DNA WHICH THE ENZYME INTEGRASE CAN INSERT THE DNA OF THE T CELL.
THE T CELL NOW HAS ‘INSTRUCTIONS”, GENES, TO PRODUCE VIRAL PROTIENS.
THE VIRAL DNA IS TRANSCRIBED AND TRANSLATED AND THE VIRAL PROTIENS ARE USED TO BUILD NEW VIRUS PARTICLES, WHICH MOVE OUT OF THE T CELL AND INFECT OTHER CELLS.
TB, STAND FOR.
TUBERCULOSIS, TB.
TUBERCULOSIS, CAUSES.
TUBERCULOSIS, TB, IS CAUSED BY BACTERIUM CALLED MYOBACTERIUM TUBERCULOSIS.
TUBERCULOSIS, SPREAD.
IT IS SPREAD THROUGH LIPID DROPLETS. FOR EXAMPLE WHEN AN INFECTED PERSON SNEEZES OR COUGHS.
THE LIPIS DROPLETS ARE INHALED BY ANOTHER PERSON, CAUSING THE BACTERIA TO MOVE INTO THE LUNGS.
TUBERCULOSIS, ONCE THE BACTERIA IS IN THE LUNGS.
ONCE THEY ARE IN THE LUNGS, THE BACTERIA ARE ENGULFED BY A TYPE OF WHIT BLOOD CELL CALLKED A PHAGOCYTE.
PHAGOCYTES USUALLY WORK BY DIGESTING AND KILLING THE PATHOGEN, BUT MYOBACTERIUM TUBERCULOSIS IS ABLE TO DISRUPT THIS PROCESS.
THE BACTERIA ARE ABLE TO SURVIVE AND REPLICATE FROM INSIDE PHAGOCYTES.
TUBERCULOSIS SYMPTOMS AND INFECTION.
THE TIME BETWEEN INFECTION WITH MYOBACTERIUM TUBERCULOSIS AND THE ONSET OF SYMPTOMS CAN VARY BETWEEN INDIVIDUALS, THE LATENCY PERIOD BETWEEN A FEW WEEKS AND MANY YEARS.
TUBERCULOSIS SYMTPTOMS.
INITIAL SYMPTOMS INCLUDE A COUGH AND FEVER WHICH IS CAUSED BY INFLIMATION OF THE LUNGS.
THE LUNGS BECOME PROGRESSIVELY MORE DAMAGED, LEADING TO RESPITORY FAILURE AND SOMETIMES DEATH. IT CAN ALSO SPREAS TO OTHER PARTS OF THE BODY, SUCH AS THE KIDNEYS AND THE BRAIN.
TUBERCULOSIS SYMPTOMS, NOT APPEARING IMMEDIATELY.
OFTEN THE SYMPTOMS OF TUBERCULOSIS DO NOT APPEAR IMMEDIATELY.
OUR BODY IS ABLE TO SEAL OFF INFECTED PHAGOCYTES INSIDE STRUCTURES WITHIN OUR LUNGS CALLED TUBERCLES.
THE BACTERIA WITHIN THE TUBERCLES LIE DORMANT FOR A PERIOD OF TIME UP TO A FEW YEARS.
THE BACTERIA THEN BECOME REACTIVATED, REACTIVATION CAN BE STIMULATED BY A WEAKENED IMMUNE SYSTEM, FOR EXAMPLE DUE TO AIDS.
DEFENSIVE BARRIERS.
OUR BODIES HAVE SEVERAL DEFENSIVE BARRIERS TO PREVENT US BECOMING INFECTED BY PATHOGENS.
BODY CAVITIES.
OUR BODY CAVITIES, SUCH AS EYES, NOSE, MOUTH, GENITALS, ARE LINED WIT A MUCUS MEMBRANE, WHICH CONTAINS AN ENZYME CALLED LYSOZYME.
LYSOZYME KILLS BACTERIA BY DAMAGING THEIR CELL WALLS, CAUSING THEM TO BURST OPEN.
SKIN.
OUR SKIN ACTS AS A PHYSICAL BARRIER TO STOP PATHOGENS FROM GETTIGN INSIDE OF US.
IF OUR SKIN IS CUT OR WOUNDED, OUR BLOOD QUICKLY CLOTS TO MINIMISE THE ENTRY OF PATHOGENS.
TRACHEA.
THE TRACHEA, WINDPIPE, CONTAINS GOBLET CELLS WHICH SECRETE MUCUS.
PATHOGENS THAT WE INHALE BECOME TRAPPED IN THE MUCUIS, WHICH IS SWEPT TOWARDS THE STOMACH BY THE ACTION OF CILIATED EPITHELIAL CELLS.
STOMACH.
OUR STOMACH CONTAISN GASTRIC JUICES WHICH ARE HIGHLY ACIDIC, THEESE WILL DENATURE PROTIENS AND KILL ANY PATHOGENS THAT HAVE BEEN INGESTED IN OUR FOOD AND DRINKS.
