Cellular physiology

Question 1

why do organelles have membranes

Answer 1

to keep things contained eg. especially those things that might be damaging to the cell such as free radicals

Question 2

membranous organelles examples

Answer 2

○ Nucleus, mitochondria, lysosomes, peroxisomes, endoplasmic reticulum, and Golgi apparatus, vesicles

Question 3

non-membranous organelles examples

Answer 3

○ Ribosomes, centrioles, flagella

Question 4

largest organelle is

Answer 4

nucleus (5 micrometer diameter)

Question 5

example of nuclear cell

Answer 5

red blood cell

Question 6

example of multinucleate cell

Answer 6

skeletal muscle cell

Question 7

chromatin composed of

Answer 7

DNA and protein (that hold it together)

Question 8

ribosome biogenesis occurs at

Answer 8

nucleoli

Question 9

nucleoli are

Answer 9

protein/DNA/RNA masses

Question 10

nuclear envelope made of

Answer 10

double phospholipid bilayer

Question 11

nuclear envelope has

Answer 11

○ Perforated by nuclear pores formed by rings of proteins

§ Regulate molecular traffic through envelope

Question 12

ribosomes are

Answer 12

• Protein-making machines

○ Very small molecular machines

Question 13

ribosomes are found

Answer 13

○ Found free in the cytoplasm’s, or on membranes (RER, nuclear envelope) or in other organelles (nucleus, mitochondria)

Question 14

ribosomes do

Answer 14

○ They read coded genetic messages (messenger RNA) and assemble amino acids into proteins specified by the code (called translation)

Question 15

endoplasmic reticulum

Answer 15

• System of channels (cisternae: flat sacks) enclosed by a membrane
  ○ Continuous with outer membrane of nuclear envelope

Question 16

name of channels of the endoplasmic reticulum

Answer 16

cisternae

Question 17

smooth ER

Answer 17

no ribosomes
□ Synthesises fats and lipids
□ Synthesised steroid hormones
□ Detoxifies alcohol and other drugs
□ Calcium storage (esp. in muscle = sarcoplasmic reticulum)

Question 18

rough ER

Answer 18

is covered with ribosomes
□ Produces phospholipids and proteins of the plasma membrane
□ Synthesises proteins that are packaged in other organelles or secreted from the cell
□ Ribosomes make proteins

Question 19

space between the two nuclear membranes

Answer 19

fluid filled gap called the intermambrane space

Question 20

outer membrane of the nucleus becomes

Answer 20

endoplasmic reticulum

Question 21

nuclear pores

Answer 21

create a gap between the nuclear envelope to allow things to get in and out

Question 22

Golgi apparatus

Answer 22

• System of cisternae; synthesizes carbohydrates and puts finishing touches on proteins (post-translational mod)

Question 23

function of the Golgi apparatus

Answer 23

○ Receives newly synthesized proteins from rough ER (cis)
○ Adds carbohydrates/sulphates to come (glycosylation/sulfation)
○ Packages them into membrane bound vesicles (trans)
○ Sorts and targets proteins to their correct destinations
§ Some -> lysosomes
§ Some -> plasma membrane
§ Some -> secretes

Question 24

post translational protein modifications by the golgi apparatus

Answer 24

glycosylation - adding sugars

sulfonation - adding sulphates

Question 25

something leaving a cell

Answer 25

exocytosis

Question 26

something entering the cell

Answer 26

endocytosis

Question 27

types of endocytosis

Answer 27

big things - phagocytosis | small things - pinocytosis

Question 28

the cytoskeleton

Answer 28

- Network of protein filaments and cylinders ○ Grow and shrink to determine cell shape, structure, organizes cell contents, move materials within cell and contribute to cell movement (yes, many cells are mobile)

Question 29

3 constituents of cytoskeleton

Answer 29

microfilaments, interveniate filaments, microtubules

Question 30

Microfilaments

Answer 30

6nm actin | § Cell shape and movement

Question 31

Intermediate filaments

Answer 31

8-10nm | § Provide mechanical strength

Question 32

Microtubules

Answer 32

tubulin § Intracellular transport § Position of organelles § Cell shape and division

Question 33

motor proteins

Answer 33

attaches vesicle onto a microtubule and moves it along the microtubule

Question 34

lysosomes

Answer 34

○ Membrane bound package of enzymes | ○ Digestion of proteins, nucleic acids, complex carbohydrates, phospholipids, and other substances

Question 35

peroxisomes

Answer 35

○ Use hydrogen peroxide (H2O2 -> H2O and O2) ○ Neutralise free radicals, detoxify alcohol, other drugs, and a variety of blood borne toxin ○ Break down fatty acids into acetyl groups for mitochondrial use in ATP synthesis

Question 36

difference between lysosomes and peroxisomes

Answer 36

lysosomes use enzymes, whereas peroxisomes use oxidation via (H2O2 -> H2O and O2) peroxisomes are less selective

Question 37

proteosomes and autophagosomes

Answer 37

- Clear old/damaged proteins and organelles to provide the cell with building blocks for renewal - Non-membrane bound

Question 38

proteosomes

Answer 38

digest proteins | ○ Contain enzymes that break down targeted tagges (with ubiquitin) proteins into short peptides and amino acids

Question 39

Autophagosomes

Answer 39

digest organelles ○ They form, then engulf cellular contents, such as damaged proteins and organelles ○ Fuses with the lysosome, where the contents are degraded into smaller constituents

Question 40

main differences between proteosomes and autophagosomes

Answer 40

proteosomes digest proteins and autophagosomes digest organelles

Question 41

autophagosomes fuse with

Answer 41

lysosomes

Question 42

membrane of the mitochondria

Answer 42

double membrane

Question 43

inner membrane of the mitochondria

Answer 43

has folds called cristae

Question 44

spaces between the cristae are called

Answer 44

matrix

Question 45

matrix of the mitochondria contains

Answer 45

ribosomes, enxymes used for ATP synthesis, small circular DNA molecule mtDNA

Question 46

how is ATP generated

Answer 46

- burn feuls in the mitochondria forcing protons into the inter membrane space - protons fall back into the centre and are driven through ATP synthase which mechanically adds a phosphate group onto ADP

Question 47

enzyme responsible for making ATP

Answer 47

ATP synthase

Question 48

ATP synthase works by

Answer 48

having protons driven through it

Question 49

3 types of junctions between cells

Answer 49

tight, desmosomes, gap

Question 50

tight junctions

Answer 50

(occluding) ○ Cell adhesion proteins (claudins) attached to plasma membranes ○ Seals gap between cells (prevent leakage in or out)

Question 51

desmosomes

Answer 51

○ Adheaerans junction ○ Cadherins attach to the cytoskeleton ○ Super strong - holds cells together

Question 52

gap junctions

Answer 52

(connexons) ○ Pores connecting cytoplasms ○ Allows direct communication between cells (shared cytoplasm)