Carbs + lipids + fermentation and metabolism Flashcards

Question

The functions of carbohydrates

Answer 1

▪ Energy storage and generation (starch, glycogen) ▪ Biological structural materials (cellulose, chitin, etc) ▪ Polysaccharide on cell surface or attached to proteins aid in molecular recognition

Answer 2

Positive = red colour Control = blue Siemens urine test slip used to test for issues detected from urine

Answer 3

Gram-positive organisms have a thicker peptidoglycan cell wall compared with gramnegative bacteria. It is a 20 to 80 nm thick polymer while the peptidoglycan layer of the gram-negative cell wall is 2 to 3 nm thick and covered with an outer lipid bilayer membrane.

Answer 4

Monosaccharides: Glucose fructose Disaccharides: Lactose Sucrose Function: Fuel : carbon sources that can be converted to other molecules or combined into polymers

Answer 5

Polysaccharides: Cellulose (plants) Starch (plants) Glycogen (animals) Chitin (animals + fungi) Function: Strengthen plant cell walls, Stores glucose for energy, Strengthens exoskeleton and fungal cell walls

Answer 6

* No simple definition, do not have common structural features * Not polymers as not built from a simple monomer * Are large molecules * The unifying feature of lipids is having little or no affinity for water, hydrophobic * Are varied in forms and functions

Answer 7

* Neutral lipids: fats and oils (simple lipids) * Phospholipids, glycolipids (complex lipids) * Steroids (isoprene lipids) * Waxes

Answer 8

* Often called a triacylglycerol * Made from two components, glycerol ( a simple alcohol) and fatty acids * The fatty acid joins to the alcohol by an ester link * Are the main storage form of fat in cells (adipose cells)

Answer 9

Blood test: triglyceride - normal level: <150 mg/dL - border line: 150-199 mg/dL - high: >200mg/dL

Answer 10

* May be saturated (no double bonds) or unsaturated (1-4 double bonds) * Double bonds are in cis conformation increasing area of lipid * Have an even number of carbon atoms (commonly 12-24) * Have a single carboxyl (acid) group (-COOH) * Become more hydrophobic with increasing carbon number

Answer 11

Saturated fats have no double bonds between carbon atoms in their structure where as unsaturated do * Unsaturated fatty acids have lower melting points than saturated fatty acids. * Unsaturated fatty acids maintain fluidity of cell membranes.

Answer 12

* Certain unsaturated fatty acids are not synthesized in the human and animal body * must be supplied in the diet * required for normal growth, and thought to provide protection against cardiovascular disease e.g. ω-6 fatty acids (linoleic acid), ω-3 fatty acids (linolenic acid)

Answer 13

* Present in the cell membrane * A key inflammatory intermediate

Answer 14

* Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature * Most animal fats are saturated * Fats made from unsaturated fatty acids are called unsaturated fats or oils, and are liquid at room temperature * Plant fats and fish fats are usually unsaturated

Answer 15

* In a phospholipid, two fatty acids and a phosphate group are attached to glycerol * The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head * Phospholipids make up cell membranes

Answer 16

* A genetically-inherited disese. * Type A and B: Sphingomyelinase deficiency * Type C: Defective cholesterol transport NPC-1 gene * Characterized by ✓ progressive neurologic damage ✓ enlarged live and spleen ✓ jaundice

Answer 17

* Cerebroside: contain sugar residues

Answer 18

* Steroids are lipids characterized by a carbon skeleton consisting of four fused rings * Cholesterol, an important steroid, is a component in animal cell membranes * Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease

Answer 19

Blood test- total cholesterol 5 mmol/L or less for healthy adults

Answer 20

* Structural components of cell membranes * Energy storage * Adipose tissue also cushions vital organs and insulates the body * Regulate cellular activities as hormones

Answer 21

Example: Triacylglycerols (fats or oils): Glycerol + 3 fatty acids Functions: Important energy source

Answer 22

Phospholipids: Glycerol + phosphate group + 2 fatty acids Function: Lipid bilayer of membranes (Hydrophilic heads, Hydrophobic tail)

Answer 23

Steroids: 4 fused rings with attached chemical groups Function: Component of cell membranes (cholesterol), Signalling molecules that travel through the body (hormones)

Answer 24

* Catabolic pathways (mostly exergonic) release energy by breaking down complex molecules into simpler compounds - Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism

Answer 25

* Anabolic pathways (endergonic) consume energy to build complex molecules from simpler ones - For example, the synthesis of protein from amino acids is an anabolic pathway

Answer 26

▪ By coupling exergonic to endergonic reactions ▪ Types of work in a cells: * Chemical: e.g. synthesis of polymers from monomers * Active transport * Mechanical Most energy coupling in cells is mediated by ATP

Answer 27

* The “energy currency” used by cells to carry out work is adenosine-3-phosphate (ATP) and ATP-like molecules * ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups

Answer 28

▪ The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis ▪ Energy is released when the terminal ATP phosphate bond is hydrolysed ▪ In the cell ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to another molecule to form a phosphorylated intermediate with a higher potential energy.

Answer 29

ATP hydrolysis leads to a change in protein shape and binding ability

Answer 30

* ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP) * The energy to phosphorylate ADP comes from catabolic reactions in the cell (cellular respiration)

Answer 31

Stage 1: Conversion of glucose, fatty acids and some amino acids to acetyl groups (in acetyl-coenzyme A) ➢ Glycolysis (Greek: glykys (sweet/sugar) & lysis (splitting)) conversion of 1 glucose to 2 pyruvate and ATP Stage 2: Citric acid cycle (Krebs cycle): oxidation of the acetyl groups to CO2 and electrons (in NADH and FADH2) Stage 3: Electron transfer and oxidative phosphorylation

Answer 32

Glycolysis occurs in the cytosol and involves substrate level phosphorylation

Answer 33

* Electrons from organic compounds are usually first transferred to NAD+ , a coenzyme. Another electron transporters is FAD (Flavin adenine dinucleotide) * As an electron acceptor, NAD+ acts as an oxidizing agent during cellular respiration. * Each NADH (the reduced form of NAD+ ) represents stored energy that is tapped to synthesize ATP via the electron transport chain.

Answer 34

* Glycolysis (“sugar splitting”) breaks down glucose into two molecules of pyruvate * Glycolysis occurs in the cytoplasm and has two major phases * Energy investment phase * Energy payoff phase * Glycolysis occurs whether or not oxygen is present * Glycolysis involves substrate level phosphorylation.

Answer 35

Pyruvate oxidation to Acetyl CoA and CO2 is catalysed by pyruvate dehydrogenase complex (E1, E2, E3): irreversible reaction ▪ Krebs cycle: Breakdown of pyruvate to CO2 in 8 steps, each catalyzed by a specific enzyme 1953: Nobel Prize in Physiology/Medicine ▪ The NADH and FADH2 produced by the cycle relay electrons and protons to the electron transport chain

Answer 36

Mitochondria

Answer 37

Metabolic pathway in which respiratory enzymes in the mitochondria (electron transport chain) synthesize ATP from ADP and inorganic phosphate during the oxidation of NADH and FADH2 by molecular oxygen Oxidation: the loss of electron(s) or proton(s) Reduction: the gain of electron(s) or proton(s) ▪ Electrons from electron donors (NADH or FADH2 ) create H+ gradient by passing through electron-transport complexes ▪ Oxygen is the final electron acceptor in aerobic organisms ▪ FADH2 provides 1/3 less energy for ATP synthesis than NADH ▪ The electron transport chain does not synthesise ATP directly – it creates a proton gradient

Answer 38

Chemiosmosis: the use of energy in a H+ gradient to synthesise ATP * Electron transfer in the electron transport chain causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space * H+ move back across the membrane through the ATP synthase * ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP

Answer 39

About 34% of the energy in a glucose molecule is converted into ATP during cellular respiration, making about 32 ATP molecules

Answer 40

* The process that generates almost 90% of the ATP is called oxidative phosphorylation because it is powered by redox reactions. * A smaller amount of ATP is formed in glycolysis and the citric acid cycle by substrate-level phosphorylation. * For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to 32 molecules of ATP

Answer 41

Enzymes can catalyse both anabolic and catabolic reactionsi.e., if an anabolic reaction is suppressed, this will suppress the catabolic too Points of regulation: Some reactions in a pathway (often highly exergonic) are catalysed by different enzyme(s) Mechanisms of regulation: * Expression of enzymes (transcription/translation) * Inhibition/activation of enzymes

Answer 42

* Anaerobic respiration uses an electron transport chains with a final electron acceptor other than O2 (e.g. sulphate in some bacteria) * Anaerobic respiration and fermentation can produce ATP without O2 * Fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP

Answer 43

Alcohol fermentation: in yeast Lactate fermentation: in fungi and bacteria, and in the muscles when O2 is scarce

Answer 44

* All oxidise glucose (net ATP = 2) * In all three, NAD+ is the oxidizing agent that accepts electrons during glycolysis * Different final electron acceptors: ➢ Organic molecule (e.g. pyruvate or acetaldehyde) in fermentation ➢ O2 in aerobic respiration * Cellular respiration produces 32 ATP per glucose molecule * Fermentation produces 2 ATP per glucose molecule

Carbs + lipids + fermentation and metabolism Flashcards

(71 cards)