Cell Respiration Flashcards
Unit 3: Photosynthesis and Respiration
What are our major biomolecules?
Carbohydrates, Lipids, Proteins and Nucleic acids (DNA/RNA)
What is the characteristics of nucleotides
They are composed of 3 parts: a nitrogen containing base, a 5 carbon sugar and one or more phosphate groups
What make ATP useful as the distributor of energy in cells
- Soluble in water (Moves freely)
- Stable at neutral pH
- Does not freely pass through plasma membrane, movement can be controlled by the cell
- 3rd phosphate can be easily removed and reattached (hydrolysis and condensation)
- The removal of the 3rd phosphate releases a small amount of energy
What do cells in ATP for?
- Making macromolescules
- Active Transport
- Movement
Characteristics of ATP?
They are energy rich molecules need to be converted into a useable form in cells
The molecule ATP is the cells energy currency or usable form
What is ATP made of?
They are a nucleotide that consists of the base adenine, a 5 carbonsugar (ribose) and three phosphate groups
How is ATP used by cells in making macromolecules?
Through anabolic reactions (BUILD), by linking monomers together (uses one or more ATP for each link).
Which has more potential energy ATP or ADP
ATP has more potential energy than ADP, so conversion to ADP releases some energy
Example of the use of ATP in cells when making macromolecules?
Building DNA during S phase (DNA replication) and building proteins (called protein synthesis)
How is ATP used by the cells in active transport?
ATP causes reversible shape changes to pump proteins in membranes. The shape change caused by ATP allows a specific molecule to enter the pump. Becuase it is unstable compared to the original shape, it is able to revert back to its original shape without the use of ATP.
Example of the use of ATP in cells when they are needed for movement?
They are needed for moving chromosomes around during mitosis/meiosis, vesicles to move as they transport stuff, pinching in during cytokinesis, changing shpes of some cells for movement sliding muscle fibers to cause contration.
What happens when P group is released from ATP to form ADP?
It cause either a conformational change or chemical change (hydrolysis reaction)
How can ADP be revert back to ATP?
Energy is required to reform the bond of the 3rd phosphate.
Where does energy to revert back to ATP come from?
This energy comes from repiration, photosynthesis or chemosynthesis
What happens when ATP supplies are low?
When they are too low, the cell functions stop.
What happens to cells without ATP being present?
The cells breakdown within minutes
Define cell respiration?
It is a step by step controlled release of energy from carbon compounds. The energy released is used to convert ADP back to ATP
What are the most common compounds used in cell respiration?
Many carbon compounds but the most common are carbohydrate (glucose) and lipids (fatty acids)
How do humans obtain carbs and lipids?
The course of carbs and lipids for human and animals are from the food we eat
How do plants obtain carbs and lipids
They make it through photosynthesis
What do most cells use for respiration?
Oxygen
What wastes are produced by many cells during respiration
Carbon dioxide
What is a gas exchange
O2 will have to enter the cells and CO2 will need to leave the cells during respiration
Where does cell respiration occur?
in the mitochondria
Where does gas exchange occur
They occur through the cell membrane of cells
What does respiration create for gas exchange?
They create the concentration gradient needed for gas exchange
What does gas exchange provide for respirations?
They provide a mechanism to move one of respirations reactants and remove a waste product
Difference between aerobic and anaerobic respiration?
Aerobic respiration require oxygen while anaerobic respiration do not require oxygen
Two different fermentations of anaerobic respirations
Alcoholic fermentation
Lactic acid fermentation
Where does alcoholic fermentation usually occur?
Yeast and other fungi
Where does lactic acid fermentation usually occur?
Humans, other animals and some bacteria
Difference bewteen aerobic respiration and anaerobic respiration in terms of substrates used
Aerobic respiration uses glucose, lipids and amino acids as substrate while anaerobic respiration only uses carbs
Difference between aerobic respiration and anaerobic respiration in terms of wastes produced
In aerobic respiration only CO2 and water are a waste while in anaerobic respiration, CO2, lactate or ethanol are produced as a waste (no water produced)
Difference between aerobic respiration and anaerobic respiration in terms of ATP yield
In aerobic respiration high yield of ATP (more than 30, max 38) while in anaerobic respiration low ATP yield (2)
Difference between aerobic and anaerobic respiration in terms of where they occur
Step 1 of aerobic respiration (glycosis) occurs in cytoplasm, then remainder of process is occurs in the mitochondria (use of CO2), while in anaerobic respiration, it all occurs in the cytoplasm
Why do human muscles sometimes conver to anaerobic
When oxygen demand is greater than the supply (oxygen debt), provides quick burst of ATP (maximizes power)
What restricts how much anaerobic respiration our muscles can do
Lactate waste is produced and our body can only tolerate so much (toxic)
Why does “the burn” occur in our muscles
It is lactic acid needing oxygen to be broken down and this taking some time.
DIfferent ways to measure rate of respiration
Oxygen uptake (commonly used)
Carbon dioxide production
Consumption of glucose (or other substrate)
Fomula to calculate respiration rates?
Amount/time, volume of CO2 consumed/tme
What are the controlled variables whne calculating rate of respiration?
Temperature, air pressure should be controlled
What is a redox reaction?
Redox reactions involves the reduction of one chemical species and the oxidation of another
What do most redox reaction typically involve
Typically involve transfer of electrons, loss and gain of hydrogen/oxygen
What is cell respiration?
It is the controlled release of energy from organic compounds to produce ATP
What happens during the break down of organic molecules
Hydrogen atoms/electrons are transferred to carrier molecules
What is an electron carrier
It is a substrate that can accept and loose electrons reversibly.
When do we say that it is oxydized
In respiration when hydrogen (with an electron) is removed from a substrate
What od hydrogen carriers function like?
They function like taxis, transporting the electrons (and hydrogen ions) to the mitochondria
Example of two electron carriers
NAD+ (main one) and FAD+
What is the first step in aerobic respiration?
Glycosis
What happens during the first step of aerobic respiration (glycosis)
Glucose is converted to pyruvate
What is a pyruvate
A chain reaction, each step catalyzed by a different enzyme
Define phosphorylation
Adding of a phosphate (PO4) molecule to an organic molecule,
What is caused by phosphorylation
This tends to make the molecule less stable and therefore more likely to react
Summary of glycosis
1 glucose converted to 2 pyruvate
2 NAD+ are converted to 2NADH+ + H+
Yield of 2ATP
What is required for a glycosis to continue?
Supllies of glucose, NAD and ADP must not run out.
When will we run out of ADP
When it has all been converted into ATP (No need for glycosis since cell does not need to make anymore ATP)
How is NAD generated?
2H atoms are transferred to another molecule, in some human/animal cells the H from NADH is transferred to pyrubate turning it into lactate (lactic acid)
Where does generation of NAD occur
In the cytoplasm
How does the regeneration process of NAD work?
2NADH are generated by glycosis so at the end of glycosis both NADH can be converted back to NAD
A way NAD is regenerated in terms of converting pyruvate
Pyruvate can be converted to ethanol and CO2 in a process called alcoholic fermentation, producting 2ATP of glycosis indefinitely
What is the type of anaerobic respiration that regenerate NAD with only glycosis called?
Lactic acid fermentation
Define decarboxylation
Is a chemical reaction that removes a carboxyl group and releases carbon dioxide
What happens in the link reaction
Pyruvate enters the matrix of the mitochondria via active trasnport (by a transporter protein). Pyruvic acid is then converted into a usable form acetyl Co-A
what is the characteristics of a Krebs cycle
They begin adn end with the same substance
When happens when a cell’s level of ATP are low?
Acetyl coA enters the Krebs cycle
Where does the oxidation and decarboxylation of acetyl groups in the krebs cycle with yield of ATP and reduced NAD occur?
In the matrix of the mitochondria
How much ATP per tun does the Krebs cycle generate
1 ATP per turn of acetyl coA by phosphorlyation is generated
What happens to most of the chemical energy during the Krebs cycle
Most of the chemical energy is transferred ruing the redox reactions
What does NADH and FADH2’s role in the oxidation and decarboxylation of acetyl groups in the krebs cycle?
They transport their load of high energy electrons to the ETC (Electron transport chain)
What is produced as a waste product during the oxidtaion and decarboxylation of acetyl groups in the Krebs cycle
CO2 is produced as a waste product
What is the substrate during the oxidation and decarboxylation of acetly groups in the krebs cycle?
Substrate is usually glucose but can be fat.
How many carbons do oxaloacetate have?
4 carbon
How many carbon do citric acid have?
6
What does the kreb cycle convert citiric acid back to?
Kreb cycle converts citric acicd back to oxalocetate each time acetly Co-A is added
What happens during each turn around the cycle in terms of molecules formed?
- 2 decarboxylations (2 CO2 produced)
- 3 NADH molecules formed
- 1 FADH2 molecules formed
- 1 ATP produced
What are the totals after the kerbs cycle
- 6 NADH
- 2 FADH2
- 2 ATP
What happens in the 3rd and fianl step of electron transport chain
- Groups of proteins in the inner mitochondrial memberane act as electron carriers, passing on pairs of electrons (forms ETC)
- ADP will be converted into ATp using substances released by oxidation
What happens to the NADH, the substances oxidized
The NADH made in glycolysis, link and Kerbs will provide the electrons to the ETC proteins
How does the first protein in teh ETC oxidize NADH?
It oxidize NADH by removing 2 electrons ,converting it back to NAD and gaining energy as it does
What happens to the FADH2 made in Krebs?
FADH2 made in krebs is also transferred to the ETC, providing 2 electrons/H’s
Characteristics of Intermembrane space
Small space to quickly accumulate proteins
Characteristics of inner memberane of the mitochondria
Contains ETC and ATp snthase for oxidative phosphorylation
Characteristics of matrix of the mitochondria
Has appropriate enzymes and a suitable pH for the Krebs cycle
Characteristics of the outer membrane of the mitochondria
Contains transport proteins for shuffling pyruvate into mitochondrion
Characteristics of cristae of the mitochondria
Highly folded so as to increase SA Vol ratio
What happens after the electrons from NADH are accepted by the first protein in the ETC
The electrons are passed from carrier to carrier, releasing energy at each step
What is the energy released (from the 3 proteins) used for?
It is used to transfer protons across the inner membrane (from the matrix) into the intermembrane space.
How are proteins therefore acting as proton pumps
Because they have to move against the concentration gradient
What is the high H+ gradient created in the inner membrane space
This space is stored energy that will be used to generate ATP
How many H+ do each proteins pump?
First to proteins (I and II) each pump 4H+, the third (III) pumps 2H+ for a total of 10H+ for each pair of electrons reduced from one NAD
How many protons do FADH2 pump?
They only pump 6 protons for every 2 electrons
Why do FADH2 only pump 6 protons
It is due to its location further down the chain
