Review #3 Flashcards
What is the process of glycolysis?
Glycolysis breaks down glucose in the cytoplasm into ATP and 2 pyruvate molecules. A hexose (6-carbon) sugar (usually glucose) is PHOSPHORYLATED by 2 ATP molecules in the cytoplasm, forming hexose bisphosphate and making the molecule less stable. The hexose bisphosphate is split into 2, 3-carbon trioses called triphosphates (3GP). Each 3GP molecule is oxidized - each loses electrons and 2 hydrogen ions to NAD+, reducing it and producing 2 NADH and H+. Enzymes directly synthesize ATP from sugar intermediates, and the 2 remaining molecules become pyruvate.
Explain the process of aerobic respiration.
- Glycolysis breaks down glucose in the cytoplasm into ATP and 2 pyruvate molecules.
- Pyruvate is actively transported into the mitochondrial matrix where it is decarboxylated and combines with coenzyme A in the LINK REACTION to produce CO2, NADH + H+, and acetyl CoA.
- Acetyl CoA enters the Krebs cycle (in the matrix) - the Krebs Cycle decarboxylates substrates to produce CO2, substrates are oxidized to provide electrons to NAD+ and FADH (they become NADH and FADH2), and substrate-level phosphorylation produces 2 ATP.
- NADH and FADH2 donate electrons to the electron transport chain (in the cristae). Electrons pass down the chain to OXYGEN, the final electron acceptor. Oxygen, electrons, and hydrogen ions combine to form water.
- Proteins in the electron transport chain use the energy from electron movement to pump H+ ions from the matrix into the intermembrane space (creating a hydrogen ion concentration gradient).
- Chemiosmosis: H+ions flow DOWN their concentration gradient (from the intermembrane space to the matrix) through ATP synthase proteins (in the cristae). ATP synthase uses the energy from H+ movement to combine ADP + P, making 34 ATP.
Explain the process of photosynthesis (light-dependent).
- Light is absorbed by the pigment chlorophyll A (blue and red absorbed; green reflected).
- Photolysis: light-energy used to split water molecule to supply electrons to photosystem II (PSII).
- Light absorbed by PSII “excites” electrons and they “jump” to a higher energy level.
- Excited electrons from PSII are “caught” and delivered to electron transport chain #1.
- Electrons moved down the chain to photosystem I (PSI).
- Movement of electrons used to pump H+ ions from the stroma INTO the thylakoid.
- CHEMIOSMOSIS: H+ ions move DOWN their concentration gradient (back into the stroma) through ATP Synthase proteins, generating ATP (Photophosphorylation – LIGHT powers the electron transport chain which aids in ATP production).
- Light absorbed by PSI “excites” electrons and they “jump” to a higher energy level.
- Excited electrons from PSI are “caught” and delivered to electron transport chain #2.
- Electrons move down the chain to NADP reductase, which reduces NADP+ to NADPH+.
Explain the limiting factors in photosynthesis (with labelled graphs too).
Temperature:
- Temperature increases = Rate of photosynthesis increases (enzymes have more collisions with substrates). - Higher than optimum temperature = enzymes denature and rate of photosynthesis decreases.
Light Intensity:
- Light intensity increases = rate of photosynthesis increases. - Once all the pigments/photosystems have become saturated, the rate of photosynthesis plateaus.
CO2 Concentration:
- CO2 concentration increases = rate of photosynthesis increases. - Once Rubisco (enzyme in the Calvin Cycle) becomes saturated, the rate of photosynthesis plateaus.
Outline anaerobic respiration in humans and yeast.
- Glycolysis breaks down down glucose in the CYTOPLASM into ATP and pyruvate.
- Glucose is phosphorylated (using ATP), is split into 2 molecules (lysis), each molecule is oxidized by NAD+ (NAD+ becomes NADH), ATP is formed (net = 2). “Leftover” two molecules = pyruvate.
- To regenerate NAD+ and keep glycolysis running, pyruvate in the CYTOPLASM broken down into:
- Pyruvate –> Lactate (animal cell/humans) OR
- Pyruvate –> Ethanol (alcohol) + CO2 (in plants, yeast, fungi, and bacterial cells). This process is called FERMENTATION.
Outline the structure of the mitochondria and how it’s adapted to its function.
Inner membrane/cristae -
- FOLDED = increases SURFACE AREA for electron transport chains/ATP synthase/chemiosmosis/oxidative phosphorylation.
Intermembrane space -
- Small = allows for rapid build up of H+ ions (protons) to create a gradient.
Matrix -
- Fluid = Contains appropriate enzymes and pH for link reaction and Krebs Cycle.
Outer membrane -
- Separates mitochondria from the rest of the cell and contains appropriate proteins to shuttle pyruvate into matrix from cytoplasm.
Outline the action and absorption spectra of photosynthesis (and be able to diagram the graphs, with labels, for these as well).
The action spectrum shows the RATE of photosynthesis for each wavelength of light absorbed.
The absorption spectrum shows the amount of each wavelength absorbed by the each pigment in photosynthesis. It shows two “peaks” (at red and blue) with a valley in the middle at green.
There is a strong correlation between the action spectrum and (cumulative - all pigments) absorption spectrum for photosynthesis (more light absorbed = higher rate).
Outline the structure of a saturated fatty acid.
STRUCTURE:
- Has no double bonds in the hydrocarbon chain (they are saturated with carbon atoms being bonded to as many hydrogen atoms as possible). - Linear. - Generally solid at room temperature (e.g. animal fat).
Outline the use of carbohydrates and lipids in energy storage.
Carbohydrates are starches and sugars. Lipids are oils and fats. Both are used as energy storage molecules, however, they differ in key aspects.
CARBOHYDRATES:
- Short-term energy storage.
- Stored as glycogen (animals) and starch (plants) that are hydrolyzed when energy is needed.
- Smaller ATP yield.
- Soluble in water (easier to transport).
- Easier to digest.
LIPIDS:
- Long-term energy storage.
- Stored as triglycerides (in adipose cells in liver/muscle tissue).
- Triglycerides are hydrolyzed to glycerol and fatty acids when energy is needed.
- Larger ATP yield (-2x).
- Harder to digest.
- Insoluble in water (more difficult to transport).
Outline the 3 types of carbohydrates (know what these are, examples of each, and be able to identify them in diagrams).
Monosaccharides:
- “Single sugars”
- Can be linear or form singular rings.
- CnH2nOn
- Three forms: Triose (3-carbon = C3h6O3), Pentose (5-carbon = C5H10O5), and Hexose (6-carbon = C6H12O6).
- Ex: Glucose, fructose, galactose, ribose, deoxyribose, ribulose.
- Glucose is broken down to make ATP in animals, primary fuel for cell respiration; fructose is the source of sweetness in plants.
Disaccharides:
- Two monosaccharides joined together with a glycosidic linkage formed via a condensation reaction.
- Ex: Maltose (glucose + glucose), lactose (glucose + galactose), and sucrose (glucose + fructose)
- In animals, lactose serves as milk sugar
- In plants, sucrose is the form of sugar plants transport from their leaves to other locations via phloem transport.
Polysaccharides:
- Three or more monosaccharides joined together with glycosidic linkages formed via condensation reactions.
- Ex: starch, glycogen, and cellulose.
- In animal cells, glycogen (composed of glucose subunits) is how glucose is stored in liver and muscle cells.
- In plant cells, starch (composed of glucose subunits called amylopectin and amylose) is used to store glucose in plastids and chloroplasts.
- In plant cells, cellulose (composed of glucose subunits) is used to build cell walls.
- Even though starch, glycogen, and cellulose are made up of glucose subunits, they have different structures, giving them different biological functions.
Outline the structure of cellulose and starch and how the structure of each is related to its function (be able to describe the structure of amylose and amylopectin in starch and identify cellulose, amylose, and amylopectin in diagrams in too).
In plant cells, starch is composed of alpha-glucose subunits called amylose and amylopectin. It is used to store glucose in plastids and chloroplasts. Cellulose is composed of linear beta-glucose subunits that have high tensile strength. It is used to build plant cell walls. Even though both are composed of glucose subunits, they have different structures, which gives them different functions.
Outline redox reactions.
Redox reactions require BOTH electron donor molecules and electron acceptor molecules (electron acceptor molecules in cellular respiration = NAD+ and FAD).
OXIDATION (LEO):
- Loss of electrons.
- Loss of hydrogen atoms.
- Gain of oxygen.
- Many C - O bonds formed.
- Compound formed has lower potential energy.
REDUCTION (GER):
- Gain of electrons.
- Gain of hydrogen atoms.
- Loss of oxygen.
- Many C-H bonds formed.
- Compound formed has higher potential energy.
Outline how to measure rates of photosynthesis (directly and indirectly).
Direct:
- Oxygen production: from light-dependent reactions (count bubbles/ measure dissolved oxygen in water).
- CO2 uptake: Calvin cycle (measure pH of water; more CO2 taken into plant = increase in pH of water).
Indirect:
- Biomass Increase: more sugars = more tissues/ growth/ more stored carboyhydrate.
Outline the use of respirometers to measure oxygen consumption/ rates of respiration.
An alkali (like KOH) is used to absorb CO2, so reduced volume is due to oxygen use. A soap bubble must be used to block the end of the pipet; more O2 used = higher reduction in volume = soap bubbles move farther. Temperature must be kept constant, or volume changes will be due to temperature fluctuations.
Outline the use of chromatography to separate and identify plant pigments.
- A mixture is dissolved in a fluid (called the mobile phase) and passed through a static material (called the stationary phase).
- The different components (pigments) of the mixture travel at different speeds (due to variation in size/ polarity etc.), causing them to separate.
- A retardation factor can then be calculated (Rf value = distance pigment travels ÷ distance solvent travels) - different pigments have different Rf values (can be used to identify pigments).
The most common chromatography techniques are:
- Paper chromatography – uses paper (cellulose) as the stationary bed. - Thin layer chromatography – uses a thin layer of adsorbent (e.g. silica gel) which runs faster and has better separation.
