cells, organelles, stem cells

Question 1

What are the roles of the cell membrane?

Answer 1

• regulate transport of solutes
• mediate cell to cell communication

Question 2

What are the roles of mitochondria?

Answer 2

• site of ATP generation
• clustered in cells that have high energy

Question 3

Describe the structure of mitochondria?

Answer 3

• permeable outer membrane
• less preamble inner membrane, folded into cristae
• inside is the matrix

Question 4

What is the role of the golgi apparatus?

Answer 4

modify, package, sort, proteins and lipids

Question 5

What are lysosomes and their role?

Answer 5

• small irregular cytoplasmic vesicles
• packed with degradation enzymes
• principal sites of intracellular digestion

Question 6

What is the main function of peroxisomes?

Answer 6

• oxidation reactions for the breakdown of fatty acids
• detoxify toxic substances such as ethanol (via catalase)

Question 7

What are peroxisomes?

Answer 7

• small cytoplasmic vesicles
• contained environment for reactive H202 generation

Question 8

What is the main function of cytosol?

Answer 8

• contains meany metabolic pathways
• protein synthesis

Question 9

What is the main function of the nucleus?

Answer 9

• contains main genome
• DNA and RNA synthesis (nucleolus)

Question 10

What are the main functions of the endoplasmic reticulum?

Answer 10

• synthesis of most lipids
• synthesis of proteins for distribution to many organelles and to the plasma membrane

Question 11

What is the main function of endosomes?

Answer 11

sorting of endocytosed material

Question 12

What are the functions of the cytoskeleton?

Answer 12

• pulls chromosomes apart during mitosis
• guides the intracellular traffic of organelles, proteins and RNA
• supports plasma membrane
• enables some cells to move

Question 13

What are the 3 major components of the cytoskeleton?

Answer 13

• intermediate filaments
• microtubules
• actin filaments

Question 14

Describe the intermediate filaments in the cytoskeleton

Answer 14

• twisted into ropes and provide tensile strength
• needed to maintain cell shape

Question 15

Identify the fibrous proteins used in the intermediate filaments in various cells

Answer 15

• KERATIN: epithelial cells
• VIMENTIN: many other cells
• NEUROFILAMENT: neurones
• IAMINS: nucleus

Question 16

Describe the microtubules in the cytoskeleton

Answer 16

• polymers of tubulin dimers
• form the spindle fibre in mitosis
• important in cell shape and movement

Question 17

What are haemopoietic stem cells?

Answer 17

stem cells that can differentiate into all type of blood cells

Question 18

What are the advantages of Induced pluripotent stem cells (IPS)?

Answer 18

• cells taken from patient should not elicit immune response
• fewer ethical issues
• any cell type could be replaced (theoretically)

Question 19

What are the disadvantages of IPS?

Answer 19

• more basic research needs to be done on developmental pathways
• transplanted stem cells could develop into cancer cells

Question 20

What are the two ways a cell can die?

Answer 20

• apoptosis
• necrosis

Question 21

What is apoptosis?

Answer 21

• programmed cell death
• normal pathway for cell death
• triggered as signalling processes within the cell activate intracellular suicide proteases

Question 22

How do intracellular suicide proteases carry out apoptosis?

Answer 22

• degrade intracellular structures and organelles
• collapse the cytoskeleton
• fragment the cell into mini-cells, which are then engulfed by phagocytes

Question 23

Why is apoptosis the normal pathway for cell death?

Answer 23

the apoptosic cell dies neatly without damaging its neighbours

Question 24

What is necrosis?

Answer 24

where cells simply lyse and burst

Question 25

How is necrosis carried out?

Answer 25

• cell membrane integrity is destroyed
• cell soluble contents are released into the tissue fluids
• cell components are degraded by the action of extracellular enzymes
• phagocytic cells enfold fragment remains