WEEK 2

Question 1

Mitochondria

Answer 1

• double lipid bilayer - proves that it came from outside the cell orginally (has double bilayer as it gained another during endocytosis into human cell)
• food into ATP
• outer membrane
• intermembrane space
• inner membrane
• cristae
• matrix
• dynamic branched tubular network

Question 2

Plastids

Answer 2

• share evolutionary origin with mitochondria
• chromoplasts - colour
• chloroplasts - green - photosynthesis
• Leucoplasts - amyloplasts (dense - gravitropism - auxin), proteinplasts (seeds), elaioplasts (lipid store and metabolism)

Question 3

Mitochondria and Plastids similarities

Answer 3

own dna
double lipid bilayer
came from outside the animal and plant cell orginally
both prokaryotes (prokaryotic traits)
divide via binary fission
ribosomes similar to bacterial ribosomes
mitochondria maternally inherited - ancestry

Question 4

what is the ECM

Answer 4

3D matrix of macromolecules

Question 5

ECM in animals

Answer 5

long rigid fibers - glycoproteins = collagen and elastin

embedding material = proteoglycans

Question 6

collagen?

Answer 6

• glycoprotein
• fibers of high strength (triple-helical Quaternary structure)
• found in bones, cartilage, tendons, ligaments and skin
• Two associated amino acids hydroxyproline and hydroxylysine
• made by fibroblasts

Question 7

Elastin?

Answer 7

a glycoprotein for elastic tissue

Question 8

Proteoglycans?

Answer 8

polysaccharides connected to small protein core

Main carb is glycosaminoglycans (GAGs)

Question 9

ECM production in animals

Answer 9

ER manufacturing then golgi sends out proteins to different parts of the cell
- vitamin C needed to make hydroxyproline –> no vitamin c = scurvy

Question 10

ECM in plants

Answer 10

more rigid and stationary
Holds cells together
Plant cell walls are porous and dynamic 
long rigid fibers = cellulose 
Embedding material - pectin, hemicellulose, proteins

Question 11

cellulose

Answer 11

Primary component of plant cell walls

Indigestible

Question 12

pectin

Answer 12

Set of polysaccharides
Help bind cells together
Part of the cell wall matrix

Question 13

production of ECM in plants

Answer 13

Lamella laid down (pectin)
Primary wall secreted by young plant cells
Wall strengthened by addition of secondary wall after cell growth complete
Cellulose synthesised directly at plasma membrane by cellulose synthase which resides in the plasma membrane
Other cell wall components made in the Golgi apparatus and secreted via exocytosis

Question 14

protist cell wall

Answer 14

made from silia

Question 15

bacteria cell wall

Answer 15

made of peptidoglycans –> mainly protein with small chains of carbs

proteins linked together by transpeptidase

penicillin inhibits cell wall growth by inhibiting transpeptidase

Question 16

summary on glycoproteins, proteoglycans and peptidoglycans

Answer 16

glycoproteins - mainly protein with short chains of carbs covalently bonded

proteoglycans - small protein core with many carb chains attached

peptidoglycans - carb chains crosslinked with short peptides

Question 17

cytoplasm

Answer 17

complex dynamic system of protein filaments

Question 18

function of cytoplasm

Answer 18

Cell division
Shape and mechanical support (skeleton)
Motility - movement of things within cells and cells within their environment

Question 19

2 components of the cytoplasm?

Answer 19

microtubules

micro-filaments

Question 20

microtubules structure?

Answer 20

2 subunits of alpha and beta tublin proteins forming heterodimers

grow from organising centre (centrosome)

plus end (elongation) and minus end (breakdown)

motor protein dynein - walks towards -ve end

motor protein kinesine - walks towards +ve end

Question 21

how do microtubles serve as motility

Answer 21

• flagella
• cilia
• mitotic spindle

Question 22

function of flagella

Answer 22

help move unicellular eukaryotes, sperm, algae and some plants and fungi

1 per cell

unrelated to prokaryote flagella

beat in wave like motion

Question 23

function of cilia

Answer 23

food collection and move locomotion in protists

coordinated with recovery stroke

move environment past cell (mucus)

Question 24

structure of flagella and cilia and how to do they move

Answer 24

9 microtubules around the perimeter

2 in the center

held together by dynein

coated in plasma membrane sheathe

ATP causes dynein to make the microtubules slide past each other making cilia beat

in flagella dynein causes the microtubules to bend causing a wave like motion

Question 25

What is the microfilament and what is its structure

Answer 25

Actin actin chain made of a double twisted chain of actin monomers dynamic - monomers add onto +ve end and are taken off the -ve end myosin binds to actin for muscle contractions myosin walks along actin towards the +ve end carrying cargo

Question 26

functions of actin microfilaments

Answer 26

Cell shape Cell motility Organelle motility Muscle motion

Question 27

explain muscle contractions using actin

Answer 27

myosin forms bundles and form thick filaments Ca2+ causes tropomyosin to reveal myosin binding site myosin binds on and with ATP can contract the muscle by pulling the thick and thin filaments closer together

Question 28

what filament helps with cytoplasmic streaming and what is it

Answer 28

microfilaments - flow of cytoplasm - myosin coated organelles move along microfilaments

Question 29

structure of bacterial flagella and how it operate

Answer 29

- basal apparatus - hook - filament (protein flagellin) - rotates like a propeller - driven by proton gradient