1-1.5 cell biology

Question 1

why are stem cells used for therapeutic use? (3)

Answer 1

• stem cells are undifferentiated cells from embryos/bone marrow/umbilical cord blood
• they can replicate and differentiate into specialised cells
• and can form a variety of diff tissues
• thus can repair damaged tissues in an indiv

Question 2

how is leukemia treated with stem cells

Answer 2

• leukemia is excessive production of abnormal and ineffective WBC
• patient undergoes chemotherapy to remove blood stem cells in bone marrow
• compatible donor’s bone marrow stem cells is transplanted

Question 3

how is stargardt’s disease treated with stem cells

Answer 3

• stargardt’s disease is a recessive disease that results in macular degeneration
• embryonic cells are induced to differentiate into retina cells
• injected into patient’s eyes for attachment onto retina
• transplanted functional retinal cells improve central vision

Question 4

draw a prokaryotic cell

Answer 4

• pilus
• flagellum
• plasmid
• 70S ribosomes
• cell wall
• nuclear DNA
• cytoplasm
• plasma membrane

Question 5

draw an eukaryotic animal cell

Answer 5

• Nucleus
• RER
• SER
• Golgi
• 80s Ribosomes
• Mitochondria
• plasma membrane
• cytoplasm

Question 6

draw an eukaryotic plant cell

Answer 6

• Nucleus
• RER
• SER
• Golgi
• 80s Ribosomes
• Mitochondria
• plasma membrane
• cytoplasm
• cell wall
• vacuole
• chloroplast

Question 7

function of nucleus

Answer 7

• contains the genetic material of the cell
• provides a suitable environment for the synthesis of RNA

Question 8

function of RER

Answer 8

• site of protein synthesis
• bound ribosomes synthesise proteins for secretion out of the cell

Question 9

function of ribosomes

Answer 9

• free ribosomes synthesise proteins for the cell
• translate mRNA to synthesise polypeptides

Question 10

function of SER

Answer 10

• site of lipid synthesis
• detox of drugs + alcohol

Question 11

function of golgi

Answer 11

• modify + package the proteins from ER for cell secretion or use within the cell
• vesicles bud off from golgi and transport proteins to plasma membrane

Question 12

diff btw prokaryotes and eukaryotes

Answer 12

-

Question 13

draw the fluid mosaic model of plasma membrane

Answer 13

-

Question 14

function of cholesterol in plasma membrane +how?

Answer 14

• regulates fluidity of the membrane, especially at the extremes of temperature
• at high temperatures, cholesterol restrains movement of phospholipids –> less fluid, maintain membrane integrity
• at cool temperatures, it hinders tight packing of phospholipids and –> maintains the fluidity

Question 15

what are the types of membrane transport (6)

Answer 15

1. osmosis
2. diffusion
3. facilitated diffusion
4. active transport
5. endocytosis
6. exocytosis

Question 16

what is endocytosis +eg.

Answer 16

• infolding/extension of the cell membrane to form a vesicle
• phagocytosis: pseudopodia formed forms a vacuole

Question 17

what is exocytosis +eg.

Answer 17

• release of materials out of the cell by fusion of vesicles with the cell membrane
• secretion of enzymes: from pancreas

Question 18

what are the passive processes of membrane transport

Answer 18

1. osmosis
2. diffusion
3. facilitated diffusion

Question 19

what are the processes of membrane transport that require energy

Answer 19

1. active transport
2. endocytosis
3. exocytosis

Question 20

what property of the plasma membrane allows endo/exocytosis

Answer 20

fluidity of membranes allows vesicles to bud off membranes

Question 21

functions of membrane proteins (4/6)

Answer 21

• binding site for hormones
• cell recognition
• channels for facilitated diff
• pumps for AT
• enzymes imbedded in membrane (ATP synthase)
• electron transport chain

Question 22

hypertonic means

Answer 22

conc of solute is higher than cell

Question 23

hypotonic means

Answer 23

conc of solute is lower than cell

Question 24

how does the sodium potassium pump work (mechanism)

Answer 24

1. 3 Na+ in the cytoplasm bind to the pump, stimulating its phosphorylation by ATP
2. phosphorylation of the pump results in a conformation change such that the Na+ ions now face the exterior of the cell
3. Na+ ions are released while 2 extracellular K+ bind to the pump
4. binding of 2 K+ ions will trigger the release of the phosphate group on the pump
5. loss of phosphate group leads to a conformation change, back to its original conformation
6. K+ ions are released into the cytoplasm and the cycle repeats

Question 25

what was pasteur's experiment?

Answer 25

- used **swan neck flasks** which allows air movement but not microorganisms - **nutrient broth** was added to the flask and **boiled to sterilise** - 1st flask had the **neck broken off** --> nutrient broth **exposed to air** - 1st flask broth was cloudy, while 2nd remained clear - indicates how **microbe growth only occured in 1**, debunking spontaneous generation

Question 26

what is the endosymbiotic theory

Answer 26

- states the eukaryotic cells evolved from prokaryotes - eg. mitochondria - aerobic prokaryote **enters larger anaerobic prokaryote** by endocytosis - **survives digestion** - **symbiotic rship** --> enables anaerobic prokaryote to **outcompete other anaerobic prokaryotes** - aerobic prokaryote **evolves** and is **assimilated to become mitochondrion**

Question 27

evid for endosymbiotic theory

Answer 27

- mitochondria and chloroplasts - have their own naked + circular DNA - 70S ribosomes - double membrane