Cell Organelles

Question 1

What are the 2 main regions of the cell?

Answer 1

cytoplasm + nucleus = protoplasm

Question 2

What is cytoplasm?

Answer 2

jelly like substance that constitutents float in

Question 3

What are the contents of cytoplasm?

Answer 3

organnelles and inclusions

Question 4

Cytoplasmic ground substance is known as?

Answer 4

cytoplasmic matrix

Question 5

What is an organelle?

Answer 5

little organ - memmbrane systems + membrane bound compartments + nonmembranous structural components

Question 6

What are inclusions?

Answer 6

materials that may of may not have a membrane

Question 7

What are microcompartments and what happens in them?

Answer 7

spaces enclosed by membranes in which substrates & products of chemical reactions are segregated or concentrated

Question 8

What are the membrane bound organelles?

Answer 8

plasma membrane, RER, SER, golgi apparatus, mitochondria, lysomes, endosomes, perioxisomes

Question 9

The roles of the intramembrane system?

Answer 9

provide surface area for chemical reactions

Question 10

What is the cell membrane made of?

Answer 10

phospholipid bilayer + glycoproteins + cholesterols

Question 11

How are phospholipids amphiphatic?

Answer 11

they have both hydrophilic (phosphate head) and hydrophobic components (fatty acid tail)

Question 12

What is the cell coat made of?

Answer 12

glycocalyx - glycolipids + glycoproteins

Question 13

What is a cell membrane?

Answer 13

mosaic of protein molecules in a fluid bilayer of phospholipids - it is not static

Question 14

Function of cholesterol?

Answer 14

maintaining fluidity in high and low temps.

Question 15

Cholesterol function at high temperatures?

Answer 15

at high temps. phospholipids move away from each other making the membrane leaky so cholesterol keeps the phospholipids together

Question 16

Cholesterol function at low temperatures?

Answer 16

at low temps. phospholipids pack so closely together making the membrane brittle so cholesterol packs in bettween the phospholipids enhancing fluididty

Question 17

What enhances fluidity?

Answer 17

unsaturated hydrcarbon tails prevent molecules from packing closely together enhancing fluidity

Question 18

What are functions of membrane proteins? TESCA

Answer 18

1. transportaion of substances - ions channels, carriers 2. enzymatic activity 3. signal transduction 4. cell to cell recognition - receptors 5. adhesion - attachment to the cytoskeleton and extracellular matrix

Question 19

How do substances pass through the cell membrane?

Answer 19

1. diffusion 2. active transport 3. vesicular transport

Question 20

What is vesicular transportation?

Answer 20

formation of vesicles from membrane or fusion of vesicles with membrane

Question 21

What is endocytosis?

Answer 21

vesicular transport of substances entering the cell

Question 22

What is exocytosis?

Answer 22

vesicular transport of substances leaving the cell

Question 23

What are the forms of endocytosis?

Answer 23

phagocytosis, pinocytosis and facilitated endocytosis

Question 24

What is the function of the cell membrane?

Answer 24

organization and localization of function - compartmentization

Question 25

What is the endoplasmic reticulum?

Answer 25

a series of interconnected membrane bound flattened sacs called cisternae - has large flattened sheets

Question 26

What is cisternae?

Answer 26

flattened sacs that are interconnected and membrane bound

Question 27

What is present in the RER?

Answer 27

ribosomes - for protein synthesis

Question 28

What is the RER continuous with?

Answer 28

nuclear envelope

Question 29

What are polysomes/polyribosomes?

Answer 29

groups of ribosomes attached to mRNA

Question 30

What is the function of polysomes?

Answer 30

protein synthesis - 1. integral membrane proteins 2. cell proteins 3. proteins for export

Question 31

Free ribosomes synthesize proteins to be used?

Answer 31

within the cell

Question 32

What are the 3 functions of RER?

Answer 32

1. protein biosynthesis 2. initial protein processing 3. quality control 4. form transition vesicles

Question 33

Explain RER initial protein processing?

Answer 33

1. initial glycosylation 2. polypeptide folding 3. assembly of multi-subunit proteins

Question 34

What do transition vesicles do?

Answer 34

shuttle lipids and proteins to golgi apparatus

Question 35

What is the smooth endoplasmic reticulum?

Answer 35

network of membranous sacs, vesicles and tubules continuous with the RER but lacking ribosomes

Question 36

Cells with a lot of SER show what under a light microscope?

Answer 36

acidophilia - may look empty

Question 37

Sacroplasmic reticulum stores what in muscles?

Answer 37

calcium ions

Question 38

What is hydroxylation?

Answer 38

addition of hydroxyl groups to organic acceptor molecules - increases solubility of hydrophobic drugs in water

Question 39

What are the functions of the smooth ER?

Answer 39

1. lipid absorption 2. glycogen metabolism 3. membrane formation & recycling - phospholipids 4. detoxify drugs and other noxious substances (hydroxylation)

Question 40

Where is SER found abundantly?

Answer 40

liver cells - sight of detoxification of drugs and other substances

Question 41

What is the golgi apparatus?

Answer 41

enveloped, disc shaped, slightly curved vesicle system with two sides - system of membranes parallel to each other

Question 42

Does the golgi apparatus stain with H & E?

Answer 42

No

Question 43

What are the faces of the golgi apparatus?

Answer 43

1. forming face/ cis-Golgi 2. maturing face/ trans-Golgi

Question 44

Which side receives transport vesicles from the RER?

Answer 44

forming face/Golgi A

Question 45

What are 3 kinds of proteins that coat vesicles?

Answer 45

1. clathrin 2. COPI 3. COPII

Question 46

What are 7 functions of the Golgi Apparatus?

Answer 46

handles distribution of newly synthesized membranes and their proteins - 1. packaging and shipping 2. modifying glycoproteins and hormone precursors received from the RER 3. sorting of proteins according to their target sequence or attached oligosaccharides 4. recycling of plasma membrane proteins via endocytosis 5. ER-specific protein retrieval through tags e.g. KDEL (Lys-Asp-Glu-Leu) 6. synthesis of lysosomes and their loading of enzymes 7. synthesize polysaccharide and emulsify lipid

Question 47

Explain the SNARE hypothesis?

Answer 47

hypothesis connects coated vesicles and target membranes : SNARE protein - SNAP receptor

Question 48

What are SNARE proteins?

Answer 48

the molecular componnts that facilitate sorting and targeting of vesicles - v-SNARES and t-SNARES

Question 49

Discuss vesicular trafficking proteins?

Answer 49

SNARE proteins - v-SNARES and t-SNARES allow a vesicle to recognize a target organelle

Question 50

What are mitochondria?

Answer 50

powerhouse of the cell

Question 51

What is the structure of mitochondria?

Answer 51

1. outer membrane 2. folded inner membrane - folds are known as cristae 3. matrix

Question 52

Mitochondria is present in all cells but?

Answer 52

red blood cells

Question 53

What are the TEM configurations of mitochondria?

Answer 53

1. orthodox 2. condensed

Question 54

Describe the orthodox configuration?

Answer 54

the cristae is prominent, matrix compartment large and has a low level of oxidative phosphorylation

Question 55

Describe the condensed configuration?

Answer 55

cristae not easily recognizable, matrix concentrated and reduced and has a high level of oxidative phosphorylation

Question 56

Mitochondria is crucial in?

Answer 56

apoptosis - cytoskeletal disintegration, metabolic derangement, genomic fragmentation

Question 57

What are lysomes?

Answer 57

suicide bags with hydrolytic enzymes - isolate digestive enzymes from the rest of the cell

Question 58

What are the functions of the lysosomes?

Answer 58

intracellular digestion

Question 59

What are primary lysosomes?

Answer 59

newly formed lysosomes - not yet acquired the materials to be digested

Question 60

What are secondary lysosomes?

Answer 60

formed by the fusion of the primary lysosome with the substrate to be degraded and have contents in the various stages of degradation 1. phagosomes/heterophagic - substances are of extracellular origin 2. autophagic - with materials of intracellular origin

Question 61

What are tertairy lysosomes?

Answer 61

debris filled vacuole or broken down contents of sec. lysome

Question 62

What are endosomes?

Answer 62

vesicles formed as a result of phagocytosis - receive lysosomal enzymes from clathrin coated transported vesicles

Question 63

Endosomes are subclassified into?

Answer 63

early and late endosomes depending on their stage of maturation

Question 64

Pathway followed by endosomes?

Answer 64

1. it may fuse with lysosome to form phagosome 2. it may fuse with another domain or region of cell membrane to release its product from cell (transcytosis)

Question 65

Late endosomes mature to form?

Answer 65

lysosomes - have inactive enzymes

Question 66

Function of endosomes?

Answer 66

intracellular sorting and transport systems

Question 67

Function of early endosomes?

Answer 67

1. internalize materials from outside the cell via plasma membrane invagination 2. recycle receptors and transport them back to the cell surface membrane 3. can receive vesicles from the golgi apparatus and send them back

Question 68

Function of late endosomes?

Answer 68

fuse with lysosomes and thereby allows for lysosomal degradation of endosomal content

Question 69

What are peroxisomes?

Answer 69

spherical organelles surrounded by a single membrane

Question 70

Function of peroxisomes?

Answer 70

1. degradation of hydrogen peroxide 2. beta oxidation of very long chain fatty acids - starts in the peroxisome and proceeds until carbon chain has been reduced to a length 10 carbons 3. phospholipid exchange 4. bile acid and cholesterol synthesis

Question 71

Name the oxidative enzyme in peroxisomes?

Answer 71

catalase

Question 72

Where are peroxisomes found?

Answer 72

liver and kidney cells