Ch13 Flashcards
Define osmosis
Passive net movement of water molecules from an area of high WP to an area of low WP across partially permeable membrane down conc gradient
Features of bacteria
Single celled
No nucleus
No mitochondria
Produce toxins
Pilli
For horizontal gene transfer
Attachment to other surfaces
Cholera
Cause by bacterium vibrio cholera
Transmitted by ingestion of contaminated water and food
Facultative anaerobes : can respire aerobically and anaerobically
How cholera causes disease
Vibrio cholera reach small intestine and use flagellum to propel through mucus lining of intestinal wall & produce toxin protein
Toxin protein 2 parts one binds to carbs receptor
Other part enter’s epithelial cells
Causes ion channels of cell membrane to open
Chloride ions move into lumen of intestine
Chloride ions accumulate in lumen and lower WP
Water from surrounding cells move in lumen by osmosis
Causing watery stools
Diarrhea
Intestinal disorder
Damages the epithelial cells lining the intestine
Loss of microvilli due to toxins
Excessive secretion of water
Oral rehydration therapy
Water : rehydrate cells
Sodium
Glucose : provide energy and stimulate uptake of sodium ions from intestine
Potassium : to replace lost potassium and stimulate appetite
How sodium ions help
Epithelial cells have Another type of carrier protein in its cell membrane that absorbs sodium ions
This reduces the WP
Water will diffuse into cells by osmosis
Rehydration therapy limitations
Excess sodium : increases secretion of water
Excess glucose : lowers WP in lumen so more dehydration
Less glucose : less energy released during respiration
Starch
Large insoluble so no osmotic effect
Provides other nutrients like amino acids
Viruses
Microorganisms Damage host tissues
Can have RNA or DNA
Reproduce inside living hosts
HIV
Human immunodeficiency virus
Attacks immune system
Protein antigen on nuclear envelope help HIV virus to attach to hosts cell surface membrane
AIDS when immune system too weak
Structure of HIV
Viral/lipid envelope that has surface proteins embedded
Protein antigens/surface proteins : help viruses attach to hose membran/receptor
Capsid : protein layer that encloses RNA/DNA and enzymes
Why HIV classified as retrovirus
Uses enzymes reverse transcriptase
It’s RNA used to synthesize DNA
HIV replication
Uses genetic material to instruct host cells biochemical mechanisms to produce required components
1.enters blood stream and circulates body
2.protein attachment binds to protein CD4 found on surface of T-helper cells
3.protein capsid fuses with the cell membrane of T-helper cell and releases content into cell (RNA and enzyme reverse transcriptase)
4.enzymes converts HIV viral RNA into double stranded DNA
5.newly made DNA moved into T-Helpers nucleus and inserted into cells own DNA = destruction of T-helper
How HIV replicates after it enters human cell
Reverse transcriptase uses viral RNA to make a DNA
DNA polymerase used to make double strand viral DNA
integrase enables viral DNA to integrate into just cells DNA
Viral DNA transcribed & used to make new HIV proteins at ribosomes
Lipid envelope acquired from membrane of infected cell
How viral proteins produced inside a T helper cell
Viral RNAused to make cDNA using reverse transcriptase
HIV dna used to make mRNA
Translated into HIV proteins
In the ribosomes
Inhibitors for HIV
Similar shape
Competes with
Viral DNA strand can’t form
Viral replication prevented
Reducing number of HIV particles in blood
