ribosomes, peroxisomes and lysosomes

Question 1

prokaryotic ribosomes

Answer 1

70s ribosomes

50s large subunit + 30s small subunit

Question 2

eukaryotic ribosomes

Answer 2

80s ribosomes

60s large subunit + 40s small subunit

Question 3

s

Answer 3

Svedberg unit - arbitrary unit

Question 4

what s is base on

Answer 4

rate of sedimentation = size of ribosome

Question 5

rRNA

Answer 5

ribosomal RNA

Question 6

what ribosomes comprise of

Answer 6

rRNA and ribosomal proteins

Question 7

prokaryotes 50s large subunit

Answer 7

23s + 5s rRNA

34 ribosomal proteins

Question 8

prokaryotes 30s small subunit

Answer 8

16s rRNA

21 ribosomal proteins

Question 9

eukaryotes 60s large subunit

Answer 9

28s + 5.8s + 5s rRNA

around 45 ribosomal proteins

Question 10

eukaryotes 40s small subunit

Answer 10

18s rRNA

around 30 ribosomal proteins

Question 11

function of ribosomes

Answer 11

facilitate polypeptide synthesis

Question 12

how polypeptide is synthesised

Answer 12

• starts at A-site
• P-site - amino acid is added onto peptide chain
• leaves via E-site

Question 13

ribosome inactivating proteins - RIP

Answer 13

ricin - protein/toxin
target GAGA Tetraloop 23s rRNA
2 types

Question 14

Type 1 RIPs

Answer 14

has catalytic A domain
cant cross cell membrane - not cytotoxic
e.g wheat

Question 15

Type 2 RIPs

Answer 15

binding domain = entry of toxin in cell
crosses plasma membrane
N-catalytic A domain-S S-B domain-C

Question 16

A means in RIPs

Answer 16

Active

Question 17

B means in RIPs

Answer 17

Binding

Question 18

Peroxisomes structure

Answer 18

single membrane surrounding

no DNA/ribosomes - encoded by nucleus

Question 19

function of peroxisomes

Answer 19

contain oxidative enzymes - e.g. catalase and urate oxidase

import protein from cytosol via ER

Question 20

general equation for peroxisomes

Answer 20

• oxygen remove H atom from organic substrate = H2O2

- catalase - H2O2 oxidise range of compound

Question 21

Importance of H2O2

Answer 21

• In detoxification (phenol) and breakdown of FA to acetyl CoA

Question 22

equation for peroxidation

Answer 22

H2O2 + R’H2 –> R’ + 2H2O

Question 23

equation for forming H2O2

Answer 23

RH2 + O2 –> R + H2O2

Question 24

Peroxisome Biogenesis and maturation

Answer 24

• budding of vesicles from ER
• import proteins which recruit peroxisome proteins
• C-terminal Ser-Lys-Leu signal sequence

Question 25

how peroxisomes replicate

Answer 25

They undergo fission to replicate

Question 26

endosomes

Answer 26

intracellular sorting organelles | responsible for engulf and maintaining

Question 27

early endosomes

Answer 27

molecules internalised from extracellular space that have fused able to mature into late endosomes

Question 28

function of endosome

Answer 28

able to fuse with vesicles from Golgi to deliver material to lysosomes

Question 29

lysosomes environment

Answer 29

acidic - pH 4-5 | allow enzymes to be active

Question 30

enzymes in lysosomes

Answer 30

different enzymes for different function

Question 31

phagocytosis and endocytosis

Answer 31

enclose extracellular entities

Question 32

during phagocytosis

Answer 32

phagosome fuses with lysosomes causing bacteria in phagosome to be broken down

Question 33

Autophagy

Answer 33

digestion of self content

Question 34

does lysosomes digest themselves??

Answer 34

no, as adapted membrane has glycosylated proteins

Question 35

membrane transporters function

Answer 35

remove and recycle/excrete product

Question 36

function of vacuolar H+ ATPase

Answer 36

hydrolyses ATP and pumps H+ into lysosomes

Question 37

vacuole

Answer 37

fluid filled - regulate pressure containing hydrolytic enzyme - recycling function similar to lysosomes

Question 38

function of vacuole

Answer 38

regulate pH in cell - pump H+ in and out provide turgor pressure regulation stores nutrient and waste

Question 39

vacuole in plant and fungal cell

Answer 39

contain one or more vacuoles

Question 40

protease

Answer 40

digest protein

Question 41

nuclease

Answer 41

digest nucleic acid

Question 42

phospholipase

Answer 42

digests lipids

Question 43

phosphatase

Answer 43

digest phosphate groups

Question 44

sulfatase

Answer 44

catalyses hydrolysis of sulfate esters of complex macromolecules e.g. glycosaminoglycans