Lysosomes, vacuoles and peroxisomes

Question 1

What are lysosomes?

Answer 1

Membrane bound sacs containing hydrolytic enzymes for intracellular digestion

Question 2

How are lysosomes produced?

Answer 2

Addition of hydrolytic enzymes to early endosomes from the golgi

Question 3

What is the function of lysosomes?

Answer 3

-Digestion
-Fuse with and dispense enzymes into vacuoles to digest contents

Question 4

What do lysosomes digest?

Answer 4

-Worn out organelles
-Food particles
-Engulfed viruses

Question 5

Why are lysosomes nicknamed ‘suicide-bags’?

Answer 5

Their role in autolysis leading to cell death

Question 6

How do lysosomes heal the cell membrane?

Answer 6

Serving as a membrane patch

Question 7

What does the membrane surrounding the lysosome allow the digestive enzymes to do?

Answer 7

Work at an acidic pH

Question 8

What occurs if digestive enzymes leak into the cytosol?

Answer 8

Potential for cell damage is reduced as their not at optimum pH

Question 9

What are peroxisomes?

Answer 9

Ubiquitous membrane-bound organelles

Question 10

What are the functions of peroxisomes?

Answer 10

-Metabolism of fatty acids
-Enzymes that rid cells of toxic peroxides
-Part of secretory pathway

Question 11

What is the process of fatty acid metabolism?

Answer 11

Beta-oxidation

Question 12

In what cells is beta-oxidation exclusive to the peroxisomes?

Answer 12

yeast and plant cells

Question 13

How do peroxisomes have specificity?

Answer 13

Contain different oxidases with different substrate specificity

Question 14

How is toxic H2O2 produced in organic substances?

Answer 14

Hydrogen removed using O2 in an oxidative reaction

Question 15

What is the role of catalase in peroxisome enzymes?

Answer 15

Uses toxic H2O2 to oxidise other substances

Question 16

What substrates are oxidised using H2O2?

Answer 16

-Phenols
-Formic acid
-Formaldehyde
-Alcohol

Question 17

Where is detoxification important?

Answer 17

Liver and kidneys

Question 18

Why do peroxisomes detoxify substances in the liver and kidneys?

Answer 18

Prevents toxic substances entering the blood

Question 19

What does catalase convert excess H2O2 to?

Answer 19

H2O

Question 20

What is the difference between lysosomes and peroxisomes?

Answer 20

-Lysosomes contain a full range of hydrolytic enzymes
-Peroxisomes tend to specialise and contain enzymes specific for particular substrates

Question 21

What is Zellweger’s syndrome?

Answer 21

Born with empty peroxisomes as enzymes fail to be imported

Question 22

What is the result of zellweger’s syndrome?

Answer 22

Children die shortly after birth as peroxisomes are essential for cell function

Question 23

What is the role of the peroxisomes in regards to O2 tension?

Answer 23

Regulates O2 tension in the cell, especially when pressure rises

Question 24

What form of peroxisome is contained in germinating seeds?

Answer 24

Glyoxysome, carries out the glyoxylate cycle

Question 25

What is the role of peroxisomes in plamalogens?

Answer 25

Synthesises plasmalogens

Question 26

What is the role of plasmalogens?

Answer 26

provides 80-90% of the lipid in the myelin sheath on the axons of nerve cells

Question 27

What results from a deficiency of plasmalogens?

Answer 27

Neurological disease

Question 28

What are vacuoles?

Answer 28

Membrane bound compartments that serve a secretory, excretory and storage function

Question 29

What is the membrane of a vacuole called?

Answer 29

tonoplast

Question 30

What is the arrangment of vacuoles in animal cells?

Answer 30

Have many small ones or do not have them at all

Question 31

What is the arrangement of vacuoles in plant cells?

Answer 31

Have on large vacuole

Question 32

What are the functions of the vacuole?

Answer 32

-Remove unwanted debris -Isolate materials that are harmful -Contains waste -Maintains internal acidic pH -Maintains hydrostatic pressure -Exports unwanted substances -Stores food -Aids destruction of bacteria

Question 33

What are food vacuoles?

Answer 33

Used by protists and macrophages in phagocytosis

Question 34

What are contractile vacuoles?

Answer 34

Pump excess H2O out of the cell to reduce osmotic pressure to prevent bursting

Question 35

What is the role of cell sap in plant cells?

Answer 35

Contains enzymes, inorganic ions, salts, toxic byproducts

Question 36

How is the vacuole in plant cells kept acidic?

Answer 36

Transport of H+ from cytosol to vacuole

Question 37

How does the vacuole aid in keeping chloroplasts close to light?

Answer 37

By pushing the cell contents against the cell wall

Question 38

How is water controlled in and out of the vacuole to maintain turgor?

Answer 38

Proteins in the tonoplast control the flow of water through active transport

Question 39

What is the role of vacuoles in animal cells?

Answer 39

Exocytosis and endocytosis