Diseases & immunity, Enzymes, Biological molecules

What is a pathogen?

A pathogen is a disease causing organism

What type of diseases do pathogens cause?

Transmissible diseases

How can pathogens be transmitted?

Direct contact and indirect contact

Give an example of direct transmission

HIV transmitted through body fluids

Give an example of indirect transmission

Cholera through contaminated water

Name three mechanical barriers to disease

Skin nasal hairs scabs

How does skin prevent disease?

It forms a physical barrier to pathogens

How do nasal hairs protect the body?

They trap pathogens in the nose

Name two chemical barriers

Mucus and stomach acid

How does mucus protect the body?

It traps pathogens so they can be removed

How does stomach acid protect the body?

It kills pathogens using hydrochloric acid

What type of cells destroy pathogens?

White blood cells

What is phagocytosis?

Engulfing and digesting pathogens

What are antibodies?

Proteins that bind to antigens on pathogens

What is agglutination?

Clumping of pathogens by antibodies

Why is agglutination useful?

It makes pathogens easier to destroy

Name two ways to control disease spread

Clean water and hygiene

Why is clean water important?

It prevents waterborne diseases

How does waste disposal prevent disease?

It reduces vectors like flies

Define active immunity

Immunity produced by making antibodies and memory cells

Is active immunity fast or slow?

Slow

Is active immunity long lasting?

Yes

How can active immunity be gained?

Infection or vaccination

What are antigens?

Molecules on cell surfaces that trigger immune response

Where are antigens found?

On the surface of cells

What produces antibodies?

Lymphocytes

How are antibodies specific?

They are complementary to antigens

What do antibodies do?

Cause agglutination and signal phagocytes

What are memory cells?

Cells that remember how to make antibodies

Why do memory cells give immunity?

They produce antibodies quickly

Why do some diseases not give immunity?

They mutate their antigens

Define vaccination

Introduction of weakened or dead pathogens

What does a vaccine contain?

Antigens

Why do vaccines not cause disease?

Pathogens are weakened or dead

What is herd immunity?

Protection when most of population is vaccinated

Why is herd immunity important?

It protects unvaccinated individuals

What happens if vaccination rates drop?

Disease can spread rapidly

Give an example of an eradicated disease

Smallpox

Define passive immunity

Immunity from antibodies from another individual

Is passive immunity long lasting?

No

Does passive immunity produce memory cells?

No

How do babies gain passive immunity?

Through breast milk

What causes cholera?

Vibrio cholerae bacteria

What symptom does cholera cause?

Severe diarrhoea

Why is diarrhoea dangerous?

Loss of water and ions

How is cholera treated?

Oral rehydration therapy

How does cholera cause diarrhoea?

Toxin causes chloride ions to enter intestine

How does water move into intestine in cholera?

By osmosis

What are enzymes?

Biological catalysts

What type of molecule are enzymes?

Proteins

What do enzymes do?

Speed up chemical reactions

Are enzymes used up?

No

Why are enzymes needed?

To maintain metabolic reactions

What is a substrate?

The molecule an enzyme acts on

What is enzyme specificity?

Each enzyme works on one substrate

What model explains enzyme action?

Lock and key model

What is the active site?

Region where substrate binds

What is an enzyme substrate complex?

Enzyme with substrate bound

What happens to enzyme after reaction?

It is unchanged

What happens to starch in amylase experiments?

It is broken down

What colour shows starch is present?

Blue black with iodine

What does iodine test for?

Starch

What does Benedict’s test for?

Reducing sugars

What colour change shows glucose?

Blue to brick red

What does Biuret test for?

Protein

What colour change shows protein?

Blue to purple

What does the emulsion test detect?

Lipids

What result shows lipids?

Cloudy emulsion

What does DCPIP test for?

Vitamin C

What result shows vitamin C?

Blue dye disappears

What is optimum temperature?

Temperature enzyme works fastest

What is human enzyme optimum temperature?

37 degrees Celsius

Why does enzyme activity increase with temperature?

More kinetic energy

What happens at high temperatures?

Enzymes denature

What does denature mean?

Enzyme loses shape

Is denaturation reversible?

No

Do low temperatures denature enzymes?

No

What is optimum pH?

pH enzyme works best at

What is most enzyme optimum pH?

pH 7

What enzyme works at pH 2?

Pepsin

Why does extreme pH denature enzymes?

Bonds break changing active site

What are carbohydrates?

Organic molecules made of sugars

What is glucose?

A monosaccharide

What is maltose?

A disaccharide

Name three polysaccharides

Starch glycogen cellulose

What are lipids?

Fats and oils

What is a triglyceride?

Glycerol plus three fatty acids

Difference between fats and oils?

Fats are solid oils are liquid

What are proteins made of?

Amino acids

How many amino acids are there?

About 20

What determines protein structure?

Order of amino acids

What is DNA?

Molecule containing genetic instructions

What shape is DNA?

Double helix

What is a nucleotide?

Basic unit of DNA

What are the four DNA bases?

A T C G

Which bases pair together?

A with T and C with G

What holds DNA strands together?

Hydrogen bonds

What forms the DNA backbone?

Sugar and phosphate

What does DNA code for?

Proteins