7A Muscles and Respiration Flashcards
skeletal muscle
muscle you use to move
contractions are voluntary
flexor
muscle bends at joint when contracting
extensor
muscle that straightens at joint when contracting
antagonistic pairs
muscle pulls in one direction at a joint and the other muscle pulls in the opposite direction
sarcomere
each repeated pattern of proteins
ligaments
join bone to bone
tendons
join muscle to bone
used to repair ligaments in keyhole surgery
NOT ELASTIC
A band
AMIABLE
has both myosin and actin
-> shows movement of actin fibres BETWEEN myosin fibres
myofibrils
bundles of actin and myosin filaments
-> slide past each other during muscle contraction
H zone
H ate
A ctin
only myosin present
-> shortens when contracts
I band
only actin
myosin
dark bands
actin
light bands
cartilage
protects bones within joints by
absorbing shock
synovial fluid
fluid that acts as lubricant as enables bones to move freely
why do muscle work in pairs?
they can only pull when they contract
how do cells get their energy?
during respiration -> glucose broken down
-> releases energy which is used to
make ATP (phosphorylation)
explain why glycolysis happens in the cytoplasm?
- cytoplasm has enzymes needed for glycolytic pathway
- only place where these enzymes are found!!!
state the coenzymes used in respiration and their function
-
NAD and FAD
-> transfer H⁺ from one molecule to another - so they can red / ox molecule
-> so NAD stops area where other** enzymes** are getting too acidic so enzymes don’t denature -
Coenzyme A
-> transfers acetate between molecules (link reaction)
substrate level phosphorylation
breaking of bonds in glucose gives energy needed to phosphorylate (add Pi group) ADP to ATP
why does the link reaction happen in the mitochondrial matrix?
- enzymes and coenzymes needed located here
- NADH made is in right place to be used by oxidative phosphorylation (in inner mitochondrial membrane)
why does the Kreb cycle happen in the mitochondrial matrix?
- each reaction in Krebs is controlled by specific intracellular enzyme
- which is found in mitochondrial matrix
describe how acetate in made from pyruvate in the link reaction
- pyruvate is decarboxylated (carbon removed) - 1C removed in form of CO₂
- NAD is reduced (NADH) by collecting H from pyruvate -> making acetate!!
for every 1 glucose molecule …
link reaction occurs x2
- 2 acetyl co. A go into Krebs
- 2 CO₂ molecules released as waste product of respiration
- 2 NADH made and are used in oxidative phosphorylation
chemiosmosis
movement of H⁺ ions across selectively permeable membrane down grad to generate ATP
e- lose energy down the E.T.C. what is this energy used for?
used by e- carriers to pump H⁺ ions into intermembranal space
suggest why acetyl co. A cannot be made in anaerobic respiration
check
pyruvate cannot be ox as NADH not recycled
describe how ATP is synthesised in oxidative phosphorylation
- H⁺ ions move down electrochemical gradient back into mitochondrial matrix via enzyme ATPsynthase
- this movement drives ADP + Pi -> ATP
- this is chemiosmosis
suggest why a cell may have more cristae (folds) in mitochondria
if cell is metabolically active
= more ATP made = more cristae
state why glycolysis is an anaerobic process itself
doesn’t need O₂ to take place
what is the final e- acceptor in oxidative phosphorylation?
O₂ (from blood)
1/2 O₂ + 2H⁺ + 2e⁻ -> H₂O
what happens to lactate (lactic acid) after a period of anaerobic respiration?
- ox. back into pyruvate
- pyruvate directly ox. into CO₂ and H₂O via Krebs
- some lactate converted to …
-> glycogen (stored form of glucose)
and stored in liver cells
-> OR glucose and respired
metabolic pathway
- many stepped process
- with each step controlled and catalysed by specific intracellular enzyme
state the adv. and disadv. of using a simple respirometer in finding the rate of respiration
adv.
- easy to set up
- not many connections so makes ‘good seal’ easier to obtain
disadv.
- cannot be reset
- needs control tube alongside it
- scale not as accurate = measurements not as accurate
state the adv. and disadv. of using a u-tube respirometer in finding the rate of respiration
adv.
- doesn’t need additional control
- syringe allows dye to be reset
disadv.
- tendency for connections to leak in old models
- more expensive
what is the use of soda lime / KOH sol in rate of respiration practical?
absorbs CO₂
why can’t filaments slide past each other when muscle is relaxed?
- actin-myosin sites blocked by tropomyosin held in place by troponin
- so myofilaments cannot slide past each other …
- as myosin heads cannot bind to actin-myosin binding sites on actin filaments
what happens to troponin during muscle contraction and what is the effect of this?
- Ca²⁺ bind to troponin …
- changing its shape so tropomyosin is moved …
- and actin-myosin binding sites exposed
describe what happens in the sarcomere when a muscle contracts
(6 marks)
- action potential stimulates muscle cell and depolarises sarcolemma
- depolarisation spreads down T-tubules to sarcoplasmic reticulum -> causes SR to release Ca²⁺ into sarcoplasm
- Ca²⁺ bind to troponin -> causing it to change shape and make tropomyosin move…
- … exposing actin-myosin binding site -> allows myosin heads to bind to them -> ACTIN-MYOSIN CROSSBRIDGE FORMED
- Ca²⁺ activate ATPase -> breaks down ATP->ADP + Pi to provide energy needed for muscle contraction
- energy moves myosin head -> pulls actin over myosin
- energy also used to break actin-myosin crossbridge -> myosin head detaches from actin
- myosin head reattaches to binding site further along actin -> new crossbridge formed and cycle repeats
- many crossbridges form and break v rapido = shortens sarcomere = muscle contracts
why is ATP required for muscle contraction?
- provides energy to move myosin head
- and break crossbridge to allow binding to next binding site
