Carbohydrates, Lipids, Cellular Respiration, and Photosynthesis (Review #3)

Question 1

Monosaccharides Overview

Answer 1

-(“single sugars”) – General formula = CnH2nOn
-3 types (based on number of carbon atoms)
–Trioses (3 carbons) = C3H6O3
–Pentoses (5 carbons) = C5H10O5
–Hexoses (6 carbons) = C6H12O6

Question 2

Disaccharides

Answer 2

Maltose, lactose, sucrose
Lactose: Milk sugars for feeding young
Sucrose: form of sugar transported from leaves to other locations

Question 3

Polysaccharides

Answer 3

Starch, glycogen, cellulose (all made of glucose, but put together differently = different structure = different functions)
Glycogen: Stores glucose in liver/ muscle cells
Cellulose: makes up plant cell walls (𝛽-glucose subunits; are linear and have high tensile strength)
Starch: stores glucose; made of α-glucose subunits (2 forms: amylose and amylopectin)

Question 4

Structure of Amylose and Amylopectin in Starch:

Answer 4

Amylose is linear/ helical and subunits are bound in a 1-4 arrangement
Amylopectin is branched and subunits are bound in 1-4 AND 1-6 arrangements

Question 5

Monosaccharide Specific Details

Answer 5

Glucose, galactose, fructose
Glucose: Chemical fuel for cellular respiration (ATP)
Fructose: Fruit sugar (makes them sweet)

Question 6

Condensation reactions create…. and hydrolysis reactions break…. (glycosidic linkages)

Answer 6

glycosidic linkages between sugars, and hydrolysis reactions break glycosidic linkages between sugars

Question 7

Condensation reactions create….. Hydrolysis reactions break…. (Esther linkages)

Answer 7

ester linkages between glycerol and fatty acids. Hydrolysis reactions break ester linkages between glycerol and fatty acids.

Question 8

Fatty Acids Overview

Answer 8

Fatty acids in lipids are hydrocarbon chains that vary in length (number of carbons, usually 11-23) and in the number and locations of double bonds
ALL fatty acids have a carboxyl group at one end (COOH) and a methyl group (CH3) at the other end (called the “omega” end)

Question 9

Unsaturated Fatty Acids

Answer 9

have one or more C=C double bonds between carbon atoms (forming bends or “kinks” in the fatty acid chains)
Bent/ kinked
Monounsaturated fatty acids have one C=C
double bond
Polyunsaturated fatty acids have two
or more C=C double bonds
Omega-3 fatty acids (1st C=C double
bond is on 3rd carbon from omega/ methyl end)
Omega-6 fatty acids (1st C=C double bond is on
6th carbon from omega/ methyl end)
Note: C=C bonds with hydrogen atoms on SAME side = CIS
C=C bonds with hydrogen atoms on OPPOSITE sides = TRANS

Question 10

Saturated Fatty Acids

Answer 10

have no C=C double bonds (they are “saturated,” or “maxed out” with the carbon atoms being bonded to as many hydrogen atoms as possible – they form linear fatty acid chains)
Linear/ straight (no C=C double bonds)
Animal fats are saturated fats
Diets rich in contribute to CHD, high LDL cholesterol, atherosclerosis, hypertension, obesity, clots/ thrombosis

Question 11

Hydrogenated Fatty Acids

Answer 11

olyunsaturated fats are often hydrogenated (or partially hydrogenated) in food processing
Hydrogen atoms are added to the molecules, eliminating some (or all) of the C=C double bonds/ kinks and bends in the fatty acid chain (straightens, or partially straightens fatty acid molecule)
WHY? Higher melting temperatures (crispier french fries from hydrogenated oils due to higher oil temp, chocolate coatings/ baked goods etc. do not melt on shelves/ have longer shelf lives, “butters” are more spreadable etc.)

Question 12

Cis Fatty Acids

Answer 12

Naturally occurring polyunsaturated fatty acids are curved (called cis fatty acids). Hydrogenated fatty acids are straightened/ linear double bonds (called trans fatty acids).

Question 13

Trans Fats

Answer 13

Trans double bonds are not fully recognized by enzymes that break down fats in the body (not the right shape!), causing them to remain in the bloodstream for extended amounts of time.
Trans fats in the diet ARE eventually incorporated into living tissues (as best as they can be), but because they are unnatural fats, they do not properly bind to natural enzymes etc. in the body, contributing to:
High cholesterol, heart disease, liver dysfunction, cardiovascular disease

Question 14

Fats and Dietary Suggestions

Answer 14

Living organisms NEED fats (cell membranes, energy storage, cushioning, heat retention, immune system etc.)
Low-fat diets aren’t necessarily the “key” to better health (although counting calories based on lipid content is important for the health of many people) – it’s the TYPE of fats in the diet that are important!
All fats contribute the SAME relative amount of calories (per gram of lipid) to a food (9 calories per gram)
Polyunsaturated (best), monounsaturated (good), saturated (ok, but should be limited), trans (HORRIBLE!)

Question 15

BMI=

Answer 15

weight (kg)/ height (m)^2
or
(weight (lbs)/ height (in)^2) x 703

Question 16

Carbohydrate Energy Storage

Answer 16

Stored as glycogen (animals) and starch (plants)
Glycogen and starch are hydrolyzed to glucose when energy needed
Short-term energy storage (disrupt osmotic balance of tissues in large quantities)

Question 17

Lipid Energy Storage

Answer 17

Stored as triglycerides (in adipose cells in liver/ muscle tissue)
Triglycerides are hydrolyzed to glycerol and fatty acids when energy needed
Long-term energy storage (hydrophobic, so do not disrupt osmotic balance and can be stored for long periods of time)
Twice the energy content (per unit mass/ per gram) of carbohydrates
(-Lipids = 9 calories per gram
-Carbohydrates = 4 calories per gram)

Note: Proteins also contain 4 cal/ gram

Question 18

ATP Structure and
Function

Answer 18

Adenosine
triphosphate (ATP =
3 phosphates)
*One phosphate group
broken off releases
energy for cells and
creates ADP

Adenosine diphosphate (ADP = 2 phosphates)
*Can be “recharged” (like a battery) by adding a phosphate
group back onto it, using energy from the breakdown of food
molecules (like glucose) – cellular respiration!

Question 19

Redox reactions require BOTH…

Answer 19

electron donor molecules and electron acceptor molecules (electron acceptor molecules in cellular respiration = NAD+ and FAD)

Question 20

Oxidation (Leo or Oil)

Answer 20

Loss of electrons, gain of oxygen, loss of hydrogen atoms

Question 21

Reduction (ger or rig)

Answer 21

gain of electrons, gain of hydrogen atoms, loss of oxygen

Question 22

Aerobic Cellular Respiration

Answer 22

1. Glycolysis breaks down glucose in the cytoplasm into ATP and pyruvate (PLOP)
   Glucose is phosphorylated (using ATP), Lysis (splits into 2 molecules), each molecule is oxidized by NAD+ (NAD+ becomes NADH), ATP is formed (net gain = 2). “Leftover” two molecules = pyruvate
2. 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 can also be produced using fatty acids or amino acids if little to no sugars)
3. 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 ATP (2)
4. NADH and FADH2 donate electrons to the electron transport chain (in the cristae/ inner mitochondrial membrane). Electrons pass down the chain to oxygen, the final electron acceptor. Oxygen, electrons, and hydrogen ions combine to form water.
5. 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).
6. In chemiosmosis, H+ ions flow DOWN their concentration gradient (from the intermembrane space to the matrix) through ATP synthase proteins (in the cristae/ inner mitochondrial membrane). ATP synthase uses the energy from H+ movement to combine ADP + Pi, making ATP (34 ATP).
   Note: Because oxidation of food molecules “powers” the electron transport chain, which creates the H+ gradient, the phosphorylation of ADP at this step (ADP + Pi) is called OXIDATIVE PHOSPHORY

Question 23

Anaerobic Cell Respiration

Answer 23

1. Glycolysis breaks down glucose in the cytoplasm into ATP and pyruvate
   Glucose is phosphorylated (using ATP), Lysis (splits into 2 molecules), each molecule is oxidized by NAD+ (NAD+ becomes NADH), ATP is formed (net = 2). “Leftover” two molecules = pyruvate
2. To regenerate NAD+ and keep glycolysis running, pyruvate in the cytoplasm broken down into:
   A. Pyruvate Lactate (animal cells/ humans) OR
   B. Pyruvate Ethanol (alcohol) + CO2 (in plants, yeast, fungi, and bacteria cells) – this process is called FERMENTATION

Question 24

Mitochondrial Structure: Inter membrane (cristae)

Answer 24

Folded – increases SURFACE AREA for electron transport chains/ ATP Synthase/ chemiosmosis/ oxidative phosphorylation

Question 25

Mitochondrial Structure: Intermembrane Space

Answer 25

Small – allows for rapid build up of H+ ions (protons) to create a gradient

Question 26

Mitochondrial Structure: Matrix

Answer 26

Fluid = Contains appropriate enzymes and pH for link reaction and Krebs Cycle

Question 27

Outer membrane

Answer 27

Separates mitochondria from rest of cell and contains appropriate proteins to shuttle pyruvate into matrix from cytoplasm

Question 28

Absorption Spectrum

Answer 28

for photosynthesis shows the amount of each wavelength absorbed by each pigment in photosynthesis. In general, it shows two “peaks” (at red and blue) with a “valley” in between at green

Question 29

Action Spectrum

Answer 29

for photosynthesis shows the RATE of photosynthesis for each wavelength of light absorbe

Question 30

The Light Dependent Reactions (THYLAKOID)

Answer 30

1. Light is absorbed by pigment chlorophyll a (blue and red absorbed; green reflected) 2. Photolysis: light energy used to split water molecule to supply electrons to photosystem II (PSII) Oxygen gas is given off as a byproduct 3. Light absorbed by PSII “excites” electrons (and they “jump” to a higher energy level) 4. Excited electrons from PSII “caught” and delivered to an electron transport chain (#1) 5. Electrons move 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) 6. Light absorbed by PSI “excites” electrons (and they “jump” to a higher energy level) 7. Excited electrons from PSI “caught” and delivered to an electron transport chain (#2) 8. Electrons move down the chain to NADP reductase, which reduces NADP+ to NADPH+

Question 31

Light Independent Reactions (STROMA)

Answer 31

1. Carbon Fixation Enzyme Rubisco adds CO2 (inorganic) to RuBP (5C compound) – “fixing” it (making it part of an organic compound) 6C compound is unstable and splits into two 3C compounds (G3P = glycerate-3-phosphate = first identifiable/ measurable product of carbon fixation/ light-independent reactions) 2. Reduction G3P reduced to triose phosphate sugar by NADPH from light-dependent reactions (NADPH back to NADP+ again) Requires ATP (from light-dependent reactions) 3. Regeneration of RuBP (Most) Triose phosphate and ATP used to regenerate RuBP (Some) Triose phosphate used to make/ store glucose (starch)

Question 32

Direct Ways of Measuring Photosynthesis

Answer 32

-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/ more basic)

Question 33

Indirect Way of Measuring Photosynthesis

Answer 33

Biomass Increase: more sugars = more tissues/ growth/ more stored carbohydrate

Question 34

Effect of Temperature on Photosynthesis

Answer 34

-as temperature increases, so does photosynthesis -at a certain point, too hot of temperature will denature proteins and rate will decrease

Question 35

Effect of Light Intensity on Photosynthesis

Answer 35

-light intensity increases rate of photosynthesis -at certain point, pigments become saturated and rate plateaus

Question 36

Effect of CO2 Concentration on Photosynthesis

Answer 36

-As CO2 concentration increases, so does rate of photosynthesis until Rubisco is saturated and rate plateaus

Question 37

ATP as a limiting factor for photosynthesis

Answer 37

(more of it required for light-independent reactions than CO2 or NADPH): Cyclic photophosphorylation turns off 2nd electron transport chain in light-dependent reactions and electrons CYCLE from PSI BACK to 1st electron transport chain over and over to make more ATP (no excess NADPH). Reversible when enough ATP is produced.

Question 38

Chloroplast Structure: Thylakoids (disc-shaped structures)

Answer 38

Small lumen/ space inside – allows for rapid accumulation of protons (H+)

Question 39

Chloroplast Structure: Grana

Answer 39

Thylakoids in stacks – increases surface area for light absorption (more photosystems with chlorophyll)

Question 40

Chloroplast Structure: Stroma (fluid within the chloroplast/ OUTSIDE of thylakoids)

Answer 40

Contains appropriate enzymes and pH for light-independent reactions

Question 41

Chloroplast Structure: Double Membrane

Answer 41

Isolates enzymes etc. from other parts of plant cell

Question 42

Respiration/ Respirometer Experiments

Answer 42

1. In respiration/ respirometer experiments, know that an alkali (like KOH) is used to absorb CO2, so reduced volume is due to oxygen use Note: a soap bubble is usually used to block the end of the pipet; more O2 used = higher reduction in volume = soap bubble moves farther. Temperature MUST be kept constant to avoid volume changes due to temperature fluctuations. 2. In photosynthesis experiments, if water needs to have CO2 removed you can BOIL it and then COOL it to do this.

Question 43

Chromatography Overview

Answer 43

-used to separate mixtures (plant pigments - chlorophyll a, chlorophyll b, xanthophyll, and carotenes) -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)

Question 44

Techniques for Separating Pigments for Chromatography

Answer 44

-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

Question 45

Calvin's Lollipop Experiment

Answer 45

Calvin’s experiments with chlorella and radioactive carbon-14 allowed him to map the entire process of the light-independent reactions (aka, the CALVIN cycle) Note: these experiments are called the lollipop experiments, as the apparatus Calvin used to carry them out looked like an upside-down lollipop Green algae placed in “lollipop” container Algae provided with radioactive carbon-14 and light (to carry out photosynthesis and incorporate radioactive C-14 into organic substances) Note: Using and tracing radioactive C-14 was a new, technological advance at the time! Chlorella samples were taken at different time periods after beginning experiment and “killed” (using heat/ alcohol to STOP metabolic reactions) Carbon compounds (containing C-14) in each sample were separated by chromatography and then identified using autoradiography By taking samples at different time periods, Calvin could identify the order in which the events of the light-independent reactions occurred. Results showed: RuBP was initially phosphorylated At the very beginning (within first 5 seconds of exposure), MORE G3P was radioactively labelled than any other compound (showing it was the first carboxylated/ stable product of the light-independent reactions) After more time, triose phosphate was the NEXT compound to be radioactively labelled Overall, specific carbon compounds are made in a specific sequence and this cycle of reactions regenerates RuBP to begin the process again