biology test #2 material

what are the two types of cells?

• prokaryotic

• eukaryotic

what are the characteristics of a prokaryotic cell?

• they are 1/10th the size of a eukaryotic cell

• DNA is located in the nucleoid

• no organelles are present

• ribosomes are smaller than eukaryotic

• ex: bacteria, archaea

a prokaryotic cell is before what?

“before the nucleus”

what are the characteristics of a eukaryotic cell?

• the cytoskeleton permits a larger size than the prokaryotic cell

• DNA is locates in the nucleus

• has various types & numbers of organelles

• ribosomes are larger than prokaryotic cell

• ex: animals, plants, fungi, protozoa, & algae

a eukaryotic cell is a true what?

“true nucleus”

why is the size of the cell limited by its surface area-to-volume ratio?

everything that enters or leaves a cell (nutrients & waste) must pass through its plasma membrane so cells try to maintain a limited surface area

what is the primary function of the plasma membrane?

the physical barrier that encloses cytoplasm

what is the primary function of microvilli?

a “brush border” that absorbs nutrients, water, & etc

what is the primary function of the cell wall?

the structural support for plant, fungi, & bacteria cells

what is the primary function of the cytoplasm?

fluid that fills the inside of the cell

what is the primary function of nucleoplasm?

fluid that fills the inside of the nucleus

what is the primary function of the nucleus?

manage’s the cell’s genetic material (DNA)

what is the primary function of the ribosomes?

synthesizes proteins by translating DNA

what is the primary function of the smooth ER?

makes lipids & fats w/ no ribosomes attached

what is the primary function of the rough ER?

makes & folds proteins covered w/ ribosomes

what is the primary function of the golgi apparatus?

processes & packages proteins (cell’s post office)

what is the primary function of the vesicles?

stores & transports hormones & enzymes to be released outside of the cell

what is the primary function of the vacuoles?

stores water, waste, & nutrients to maintain the cell’s balance

what is the primary function of of lysosomes?

uses enzymes to break down waste & worn-out cell parts (cell’s garbage/recycling)

what is the primary function of the mitochondria?

produces the chemical energy needed in the cell (the powerhouse of the cell)

what is the primary function of the chloroplasts?

converts sunlight into energy through photosynthesis

what is metabolism?

all the chemical reactions taking place in an organism

what is anabolism?

pathways where complex molecules are synthesized from simpler substances (requires energy)

what is catabolism?

pathways where larger molecules break down into smaller ones (releases energy)

what is potential energy?

the capacity to do work as a result of the position or state (ex: a drawn bow)

what is kinetic energy?

the energy of motion used to perform work

what is chemical energy?

the potential energy stored in chemical bonds

what is entropy?

measures the randomness of energy

• disorganized = high entropy

• organized = low entropy

what is enthalpy?

the total potential energy/ total chemical energy of a system

what is free energy?

the energy available to do work under conditions of a biochemical reaction

how does change in free energy for a reaction predict whether the reaction will release energy as it occurs/requires an input of energy to occur?

a change in free energy of a system (△G is more convenient to measure than the total free energy of a system (G) + an equation (△G=△H-T△S)

what is an exergonic reaction?

(catabolism) - a reaction that releases energy in a “downhill” reaction, going from a higher to lower free energy (△G is negative)

what is an endergonic reaction?

(anabolism) - a reaction where there is a gain of free energy (△G is positive & requires energy input from the environment

what is a coupled reaction?

occurs when a thermodynamic favorable exergonic reaction provides energy required to drive a thermodynamic unfavorable endergonic reaction

what is the role of coupled reactions in metabolism?

the conversion of energy

what is the role of a common intermediate in coupled reactions?

acts as a physical & thermodynamic bridge that transfers free energy from a spontaneous to a non-spontaneous reaction

what is the general structure of ATP?

a nitrogenous base + a five-carbon sugar + a chain of 3 phosphate groups

what is the role of ATP as a storehouse of energy?

acts as a energy currency for cells by storing & releasing chemical power to drive body processes

how does ATP serve as a common intermediate in coupled reactions

by linking exergonic & endergonic reactions to process through direct transfer of a phosphate group

what is a redox reaction?

energy transferred when electrons move from one substance to another oxidation-reduction reaction (involves a series of electron transfers)

what is an electron carrier?

molecules that commonly accept an electron along w/ its energy, during a redox reaction

what are electron carriers role in aerobic respiration & photosynthesis?

• they carry electrons & transfer them to another molecule

• transfers a carrier molecule which is reduced to NADH

what are the roles of enzymes as biological catalysts?

• increases the speed of a chemical reaction w/o being consumed by the reaction

• regulates the rate of chemical reactions

• speeds reaction rates up by lowering activation energy (EA)

what is activation energy (EA)?

the minimum amount of energy required to start a chemical reaction

what is a substrate?

a molecule that bind’s to an enzymes’s active site

what is an enzyme-substrate complex?

an unstable intermediate complex w/ the substance(s) which acts as substrate(s)

what is a product (according to enzymes)?

a molecule formed when enzymes-substrate complex undergoes a chemical reaction

what is a cofactor?

the additional chemical component that may be a specific metal ion (iron, copper, etc.)

what is a coenzyme?

an organic, nonpolypeptide compound that binds to apoenzyme & serves as a cofactor

what are the factors that influence the activity of an enzyme?

• pH

• temperature

• the concentration of enzyme or substrate

what is the role of feedback inhibition in controlling activity of enzymes involved in metabolic pathways?

the enzyme regulation in which the formation of a product inhibits an earlier reaction in sequence (negative feedback)

what is irreversible inhibition?

an inhibitor that permanently inactivates or destroys an enzyme (combines w/ one of enzyme’s functional groups, either active site or elsewhere)

what is a reversible inhibition?

an inhibitor forms weak chemical bonds w/ the enzymes

what is a competitive enzyme inhibition?

an inhibitor competes w/ normal substrate for binding to the active site of the enzyme

what is a noncompetitive enzyme inhibition?

an inhibitor binds at a site other than the active site

what are the four steps of aerobic respiration?

1. glycolysis

2. formation of acetyl coenzyme A

3. citric acid cycle (krebs)

4. oxidative phosphorylation (electron transport & chemiosmosis

what is glycolysis?

the breakdown of glucose into 2 molecules of pyruvate

• takes place within the cytosol

what is the equation for glycolysis?

C₆H₁₂O₆ + 2NAD⁺+2ADP → 2C₃H₄O₃ + 2NADH + 2ATP + 2H₂O

what is the preparatory & energy payoff stage in glycolysis?

• preparatory stage - uses 2ATP to split glucose into 2 molecules of G3P

• energy payoff stage - 4 ATP & 2NADH produced through G3P & pyruvate

  • ATP is generated by substrate-level phosphorylation

  • released hydrogen atoms are harnessed by electron carrier NAD⁺

what is the net yield per glucose in glycolysis?

2 ATP & 2 NADH (2 pyruvate molecules)

what is the formation of acetyl coenzyme A (CoA)

the transition step that takes place between glycolysis & the citric acid cycle

• occurs in the mitochondria

what is the equation for the formation of acetyl coenzyme A (CoA)?

2C₃H₄O₃ + 2NAD⁺ + 2CoA → 2C₂H₃O-CoA + 2NADH + 2CO₂

what happens during the formation of acetyl coenzyme A (CoA)?

• pyruvate molecules combine w/ CoA to form acetyl CoA

• hydrogen atoms are harnessed by electron carrier NADH (ATP synthesize takes place)

what is the net yield per glucose in the formation of acetyl coenzyme A (CoA)?

2 acetyl CoA & 2 NADH (no ATP generated)

what is the citric acid cycle?

the degradation of acetyl CoA that result in the release of CO₂, transfer of hydrogen atoms to the electron carriers NAD⁺ & FAD, & the generation of a small amount of ATP

• occurs in the mitochondrial matrix

what is the equation for the citric acid cycle?

2C₂H₃O-CoA + 6NAD⁺ + 2FAD + 2ADP → 4CO₂ + 6NADH + 2FADH₂ + 2ATP

what happens in the citric acid cycle?

• acetyl CoA passes carbon acetyl group to carbon compound oxaloacetate to form citrate (citric acid)

• hydrogen atoms harness electron carriers (NAD⁺ & FAD)

• ATP is generated by substrate-level phosphorylation

what is the net yield per glucose in the citric acid cycle?

6NADH, 2FADH₂, & 2ATP

what is oxidative phosphorylation (OxPhos)?

the harnessing of energy from NADH & FADH₂ in the form of ATP

• occurs in mitochondrial matrix, inner membrane, & inter-membrane space

what happens during oxidative phosphorylation (OxPhos)?

• the electron support chain - a series of electron carriers embedded in the inner mitochondrial membrane

• the protons (H⁺) move across the inner mitochondrial into inter-membrane space to establish an electrochemical gradient

  • higher (H⁺) intermembrane space, lower (H⁺)

  • oxygen in ETC results in the formation of H₂O

what is aerobic respiration?

the harnessing of energy from an organic molecule like glucose in a manner that requires oxygen

what is anaerobic respiration?

the harnessing of energy from an organic molecule like glucose in a manner that doesn’t require oxygen

• uses glycolysis, citric acid cycle, & OxPhos

• inorganic molecules bedsides O₂ (nitrate, sulfate) is terminal electron acceptor

what is fermentation?

the harnessing of a small amount of energy from molecules like glucose

• uses glycolysis only, 2 ATPs are formed per, & only used for short periods of time due to inefficiencies