Exam 2 Flashcards
Endocytosis
A form of active transport in which a cell transports molecules (such as proteins) into the cell (endo- + cytosis) by engulfing them in an energy-using process.
…the uptake by a cell of material from the environment by invagination of its plasma membrane; it includes both phagocytosis and pinocytosis.
Phagocytosis
A form of endocytosis in which the cell membrane actively engulfs large particles or cells into vesicles. A phagocyte is a cell specialized for doing this.
Pinocytosis
The engulfment, or endocytosis, of liquids by extensions of the cell membrane.
Receptor-mediated endocytosis
a process by which cells absorb metabolites, hormones, other proteins - and in some cases viruses - (endocytosis) by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being absorbed.
Metabolism
the sum of the chemical reactions in an organism
Catabolism
the breakdown of complex molecules in living organisms to form simpler ones - energy releasing process.
Anabolism
the synthesis of complex molecules in living organisms from simpler ones - energy using process
Catabolic reactions
breakdown of a molecule - release energy
Ex. Glycolysis -> Glucose
Anabolic reactions
synthesis of molecules - use up energy
Ex. Gluconeogenesis
What catalyzes chemical reactions in organisms and are important in metabolism?
Enzymes (proteins)
Are enzymes used up in chemical reactions?
no
Chemoheterotrophs
organisms that obtain energy by the oxidation of electron donors in their environments. (take organic matter and process it)
Enzymes
biological catalysts - represent the “workhorses” of the cell - speed up reactions
List 4 important enzymes.
NAD+ NADP FAD Coenzyme A (all capture electrons)
What factors influence enzyme activity?
temperature
pH
substrate concentration
enzyme concentration
Coenzymes
a nonprotein compound that is necessary for the functioning of an enzyme (NAD+; carriers of electrons)
Oxidation
the removal of electrons
Reduction
the gain of electrons
Redox reaction
an oxidation reaction paired with a reduction reaction
Glycolysis
(The oxidation of glucose to pyruvic acid; produces ATP and NADH.) An aerobic and anaerobic pathway which breaks down one molecule of glucose into two molecules of pyruvate. (overall generates little ATP!)
- Oxidation of glucose
- Cytosolic (occurs in the cytosol)
- Can occur with or without O2
in biological systems, the electrons are often associated with what?
hydrogen atoms
Biological oxidations are often what?
dehydrogenations
What are the possible fates of glucose through glycolysis?
Glucose -> pyruvate
Pyruvate -> ethanol or lactate (fermentation - low O2)
Pyruvate -> CO2 + H2O (complete oxidation - with O2)
What is the chemical formula for glucose? How many carbons does it have?
C6H12O6 (6 Carbons)
What happens during the preparatory stage of Glycolysis?
- 2 ATP are used
- Glucose is split to form 2 Glucose-3-phosphate
What happens during the energy-conserving stage of Glycolysis?
- 2 Glucose-3-phosphate oxidized to 2 Pyruvic acid
- 4 ATP produced
- 2 NADH produced
What is produced after the preparatory stage and energy-conserving stage of Glycolysis?
- 2 Pyruvate
- 2 ATP
- 2 NADH
What are the general functions of Glycolysis?
- Provides ATP energy
- Generates intermediates for other pathways including Pyruvate dehydrogenase which leads to the Krebs Cycleo
What tissues are associated with glycolysis (sources of ATP)?
- RBC’s - energy
- Skeletal muscle - energy during exercise
- Adipose tissue - source of glycerol-P and acetyl-CoA
- Liver - source of glycerol-P and acetyl-CoA
How can you slow down a pathway?
- Competitive inhibition - blocks the substrate from binding to the active site of the enzyme (a form of enzyme inhibition where binding of the inhibitor to the active site on the enzyme prevents binding of the substrate and vice versa. Most competitive inhibitors function by binding reversibly to the active site of the enzyme.)
- Feedback inhibition - A cellular control mechanism in which an enzyme that catalyzes the production of a particular substance in the cell is inhibited when that substance has accumulated to a certain level, thereby balancing the amount provided with the amount needed.
- Allosteric regulation - the regulation of a protein by binding an effector molecule at a site other than the enzyme’s active site. The site to which the effector binds is termed the allosteric site.
Name three processes that breakdown carbohydrates to release energy.
- Glycolysis
- Krebs cycle
- Electron transport chain
Molecules of ATP produced by glycolysis (low O2) are produced through what?
substrate-level phosphorylation (simple fermentations)
What is Glycolysis called when O2 is present? What is the final acceptor? Does it produce more or less ATP than substrate-level phosphorylation?
Cellular respiration
O2 is the final acceptor
Produces LOTS of ATP - more
What are the four stages of metabolism?
- Glycolysis
- Intermediate step
- Kebs cycle (TCA)
- Electron Transport Chain
What happens during the Intermediate step?
conversion of of pyruvate into acetyl CoA by the pyruvate dehydrogenase complex (3 enzymes); Pyruvic acid (from glycolysis) is oxidized and decarboyxlated.
What is the net result of the intermediate step?
- generates Acetyl CoA
- lose CO2
- adds thioester group
- NADH
How much ATP and NADH is produced per glucose molecule after the intermediate step? How much ATP and NADH is produced net after this step?
2 ATP and 4 NADH per glucose molecule produced by this step
Net (2 glucose molecules): 4 ATP and 8 NADH (4 from the intermediate step + 1 from each of the 4 pyruvates - 2 pyruvates from each molecule of glucose)
What happens during the Krebs cycle?
Acetyl CoA condenses with oxaloacetate to generate a six carbon intermediate (citric acid) that is acted upon by the enzymes which comprise this pathway. (oxidation of acetyl CoA produces NADH and FADH2 and little ATP)
Krebs Cycle is also known as what?
Citric Acid Cycle - a metabolic pathway that forms part of the break down of carbs, fats, and proteins into CO2 and H2O in order to generate energy.
Where does the Krebs Cycle take place?
in the mitochondria
How many carbons does acetyl CoA have?
2 carbons
How many carbons does oxaloacetate have?
4 carbons
How many carbons does citric acid have?
6 carbons
What is produced per each acetyl CoA (turn of the Krebs cycle)?
3 NADH
1 FADH2
1 ATP
About how much ATP is 1 NADH equivalent to?
About how much ATP is 1 FADH2 equivalent to?
1 NADH = 3 ATP
1 FADH2 = 2 ATP
How much ATP, NADH, FADH2, and CO2 will you have total after glycolysis?
ATP - 2
NADH - 2
FADH2 - 0
CO2 - 0
How much ATP, NADH, FADH2, and CO2 will you have total after the intermediate step?
ATP - 0
NADH - 2
FADH2 - 0
CO2 - 2
How much ATP, NADH, FADH2, and CO2 will you have total after the Krebs cycle?
ATP - 2
NADH - 6
FADH2 - 2
CO2 - 4
How many turns of the Krebs Cycle are made per glucose molecule?
2
What is the Electron Transport Chain?
A series of membrane complexes act as oxidation/reduction centers and pass on the electrons donated by coenzymes NADH and FADH2. The energy released can be used to produce ATP by chemiosmosis by a process called oxidative phosphorylation.
How much ATP, NADH, FADH2, and CO2 will you have total after glycolysis, the intermediate step, and the Krebs cycle combined?
ATP - 4
NADH - 10 (each NADH = 3 ATP - +30ATP)
FADH2 - 2 (each FADH2 = 2 ATP - +4ATP)
CO2 - 6
How much ATP is produced from complete oxidation of 1 glucose molecule in eukaryotes?
36 ATP’s
Aerobic respiration
the final electron acceptor in the Electron Transport Chain is molecular oxygen.
A small amount of ATP is produced by what? A large amount of ATP (90%) is produced by what?
small amount - substrate level phosphorylation
large amount - oxidative phosphorylation “ATP synthase”
where does Glycolysis take place in Eukaryotes? in Prokaryotes?
Eukaryotes - cytoplasm
Prokaryotes - cytoplams
where does the Intermediate Step take place in Eukaryotes? in Prokaryotes?
Eukaryotes - cytoplasm
Prokaryotes - cytoplams