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chapter 1 Flashcards

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1
Q

 Explain how the various characteristics of life differentiate between ‘life’ and ‘not life’

A

RREOREG reproduction,response,evolution,order,regulation,energy processing,growth

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2
Q

 Clarify the various levels of organization of life

A

AMOCOPCEB atom,molecule,organelle,cell,organism,population,community,ecosystem,biosphere

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3
Q

 Describe what it means to be an organic molecule and explain the properties of carbon that are important in biological molecules

A

organic molecules contain carbon and it is the most versatile element when it come to covalent bonds because of its 4 valence electrons

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4
Q

 Explain what is meant by the terms monomer and polymer and be able to describe the chemical reactions leading to polymer synthesis (dehydration reactions) and breakdown (hydrolysis)

A

monomer is two carbon molecules sharing a double bond which can be broken and connected together with other monomers to create a polymer. hydrolysis is when hydrogen breaks off to create water and to join two molecules together to create a polymer. dehydration’s the opposite

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5
Q

 List the four major types of macromolecules and understand which are polymers

A

lipids not polymers,amino acids ,nucleotides and carbohydrates are all polymers

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6
Q

 Identify the monomers for each of the polymers

A

carbonyl,carboxyl,hydroxyl,phosphate,amino,methyl

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7
Q

 Explain the functions of the various macromolecules

A

lipids energy storage and membrane makeup. proteins transport, communication,energy storage, nucleic acid holds genetic info. carbohydrates every storage and structural

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8
Q

 Outline the tenets of cell theory

A

smallest unit of life can self sutain all life is made up of cells and all cells arise from pre-existing cells

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9
Q

 Differentiate between the various functional groups found on biological molecules and recognize the structures of each

A

carboxyl,carbonyl,methyl,hydroxyl,phosphate,amino

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10
Q

 Describe the similarities and differences between prokaryotic cells, eukaryotic animal cells and eukaryotic plant cells

A

prokaryotic contain unbound organelles, dna is in the nuclide and is circular, eucaryotic cells have a nucleus and bound organelles dna is linear and housed in the nucleus, plant eucaryotic have a cell wall

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11
Q

 Describe the structures and functions of the eukaryotic cell organelles (only those discussed in class)

A

Ribosomes- made up of ribosomal RNA and protein and use DNA info to synthesis proteins
RER- bound by ribosomes, membrane factory and distributes vehicles
SER- synthesyses lipids ,metabolises carbohydrates, filters poisons
golgi apparatus- sorts and packages materials into transport vesicles, modifies RER and SER products
Lysosomes- bag or hydrolytic enzymes, digests macromolecules
mitochondria-Smooth outer membrane
Inner membrane folded into cristae
Provide a large surface area for enzymes to synthesis ATP,Cell powerhouse,where most of ATPis made

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12
Q

 Explain the differences between metabolism, anabolism and catabolism

A 
Metabolism is the totality of an organism’s chemical reactions
Metabolism is an emergent property of life that arises from interactions between molecules within the cell
Catabolic pathways (Gk katabole ‘throwing down’): release energy by breaking down complex molecules into simpler compounds

Anabolic pathways (Gk anabole = ‘ascent’): consume energy to build complex molecules from simpler ones

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13
Q

Describe the major difference(s) between positive and negative feedback and be able to explain examples of each (see Chapter 1. P10-11 for more info)

A

1

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14
Q

 Explain the concept of free energy as it is applied to metabolism

A

A living system’s free energy is energy that can do work when temperature and pressure are uniform, as in a living cell
Assume temperature and pressure are uniform (This is true living cells of a particular organism)

G = Gfinal – Ginitial

Only processes with negative ∆G are spontaneous
Spontaneous processes (i.e. negative G) can be harnessed to perform work
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15
Q

 Know the difference between catabolic and anabolic reactions in terms of free energy release

A

4catabolic releases energy through the break down of molecules. starts with a larger free eery and has less at the end
anabolic takes energy to create larger molecules and has a larger free energy in the end

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16
Q

xplain the differences between endergonic and exergonic reactions

A

An exergonic reaction
proceeds with a net release of free energy
Spontaneous (G decreases)
An endergonic reaction
absorbs free energy from its surroundings
Nonspontaneous (G increases)

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17
Q

 Describe the three main kinds of work performed by the cell and provide examples

A

Chemical-pushing of endergonic reactions
Transport-pumping of substances across a membrane
Mechanical- e.g. beating of cilia

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18
Q

 Know which molecule is a renewable source of cellular energy currency and that energy from hydrolysis (exergonic) of this molecule can be coupled to drive endergonic reactions

A

Energy for cellular functions comes from ATP
Think of ATP as the ‘energy currency’ of all cells:
Store ATP (anabolism) when able to make currency
Spend ATP (hydrolysis, catabolism) when want to do something that needs currency (e.g. cellular workBonds between phosphate groups of ATP’s tail can be broken by hydrolysis
Energy is released from ATP when the terminal phosphate bond is broken (releasing inorganic Pi)
Energy release comes from change to a state of lower free energy, not from phosphate bonds themselves

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19
Q

 Explain the concept of an enzyme as a catalyst and explain precisely the different ways that enzymes can lower activation energy

A

Enzymes catalyze reactions by lowering the EA barrier
Enzymes do not affect the change in free energy (∆G); instead, they hasten reactions that would occur eventuallyActive site is enzyme region where substrate binds
Substrate fitting in active site brings chemical groups of the active site into positions that enhance their ability to catalyze the reactionIn an enzymatic reaction, the substrate binds to the active site of the enzyme
The active site can lower an EA barrier by
Orienting substrates correctly
Straining substrate bonds
Providing a favorable microenvironment (e.g change in pH)
Covalently bonding to the substrate (direct participation on the active site)

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20
Q

 Explain what is meant by the term ‘enzyme-substrate complex’ and explain the mechanisms through which catalysis occurs in the enzyme’s active site

A

The chemical reactant that an enzyme acts upon is referred to as the enzyme’s substrate
The enzyme binds toits substrate, formingan enzyme-substratecomplex
Active site is enzyme region where substrate binds
Substrate fitting in active site brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction

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21
Q

 Describe the effects of pH and temperature on enzyme activity

A

Each enzyme has an optimal temperature in which it can function
Each enzyme has an optimal pH in which it can function
Optimal conditions favor the most active shape for the enzyme molecule

Each enzyme has an optimal temperature in which it can function:
Below optimum, molecular motion insufficient
Above optimum, heat interferes with protein structure

22
Q

 Explain the difference between competitive and non-competitive enzyme inhibitors

A

competative-Bind to the active site of an enzyme:
Competes with the substrate for binding:
No substrate binding  no catalysis
non-competativeBind to another part of an enzyme:
Non-competitive- inhibitor causes a change in enzyme shape
Active site of enzyme becomes less effective

23
Q

 Understand the different mechanisms (allosteric regulation, cooperativity and feedback inhibition) whereby enzyme activity can be regulated

A

Allosteric regulation may either inhibit or stimulate an enzyme’s activity
Allosteric regulation occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another siteMost allosterically regulated enzymes are made from polypeptide subunits
Each enzyme has active and inactive forms
The binding of an activator stabilizes the active form of the enzyme
The binding of an inhibitor stabilizes the inactive form of the enzymeCooperativity is a form of allosteric regulation that can amplify enzyme activity
One substrate molecule primes an enzyme to act on additional substrate molecules more readily
Cooperativity is allosteric because binding by a substrate to one active site affects catalysis in a different active siteOften production of a biological molecule involves a complex series of reactions known as a metabolic pathway

In feedback inhibition, the metabolic pathway is active or inactive depending upon the presence of the end product of the pathway

Without feedback inhibition, a cell might waste chemical resources by synthesizing more product than is needed

24
Q

 Be prepared to describe to a lay person the big picture in cellular metabolism

A

4

25
Q

 Understand the differences between oxidation and reduction reactions

A

In oxidation, a substance loses electrons, or is oxidized
The electron donor is called the reducing agent
In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced

26
Q

 Explain the concepts of oxidation and reduction (redox) reactions and electron carriers as they apply to cellular respiration

A

During cellular respiration, the fuel (such as glucose) is oxidized, and O2 is reducedElectrons are at higher energy level in glucose than in oxygen, so transferring electrons from glucose to oxygen releases energy (like rolling downhill)

27
Q

 List the three stages of cellular respiration and know the location in the cell where each takes place and which do and do not require oxygen

A

Glycolysis - in cytoplasm
breaks down glucose into two molecules of pyruvate
The Citric Acid Cycle (aka Krebs cycle or TCA cycle)- in mitochondria
completes the breakdown of glucose
Oxidative Phosphorylation (ETC and chemiosmosis) -inner membrane
accounts for most of the ATP synthesisImportance of glycolysis:
Pyruvate ( Krebs cycle)
2 NADH ( ETC) (not much )
2 ATP (not much )
Importance of Krebs cycle:
2 ATP (not much )
6 NADH + 2 FADH2 (also 2 NADH from pyruvate metabolism) (lots! )
Importance of oxidative phosphorylation:
32-34 ATP (buckets and buckets!  )

28
Q

 Explain the terms aerobic and anaerobic

A

Aerobic respiration uses oxygenAerobic respiration occurs in most cells.Does not produce lactic acid
Carbon dioxide, water, ATP
Anaerobic respiration is respiration without oxygen; the process uses a respiratory electron transport chain but does not use oxygen as the electron acceptors.

29
Q

 Describe the importance of each stage of cellular respiration in terms of:
• The input(s) to the stage (e.g. organic molecules, NADH, etc.)
• What product(s) is/are produced (e.g. organic molecules, NADH, ATP, etc.)
• The relative amounts of the different products
• Where the products go from one stage to another
• Note: it is NOT necessary to know each step of the pathways in detail)

A

Glycolysis -
energy investment stage- glucose and 2ATP
energy pay off phase- form 4ATP and H2O and pyruvate
pyruvate oxidation- enzyme breaks a CO2 off of pyruvate and NAD+ forms NADH and coenzyme A attaches to pyruvate creating acetyl CoA
Citiric acid Cycle- breakdown of pyruvate to CO2
generates 1ATP,3NADH and1FADH2—outputs CO2,NADH

30
Q

 Explain the concept of ‘electron carrier’ and be able to identify at least two different electron carriers operating in cellular respiration

A

The carriers alternate reduced and oxidized states as they accept and donate electrons
Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O
NADH passes the electrons toelectron transport chain (ETC)
Unlike an uncontrolled reaction,the ETC passes electrons instepwise series instead of oneexplosive reaction
Oxygen pulls electrons downthe chain in an energy-yieldingtumble
The energy yielded is used toregenerate ATP

31
Q

 Explain the difference between substrate-level phosphorylation and oxidative phosphorylation

A

substrate phosphorylation-Enzymatic transfer of a PO43 from a phosphorylated substrate (e.g. glucose metabolite) to ADP
Oxidative phosphorylation-Adds inorganic PO43 (Pi) to ADP (powered by redox reactions

32
Q

 Explain how the electron transport chain, chemiosmosis, proton-motive force and oxidative phosphorylation operate in cellular respiration

A

The electron transport chain is in the inner membrane (cristae) of the mitochondrion
Most of the chain’s components are proteins, which exist in multiprotein complexes (I-IV)The carriers alternate reduced and oxidized states as they accept and donate electrons
Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O
Electrons are transferred from NADH or FADH2 to the electron transport chain
The electron transport chain generates no ATP directly
It breaks the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
Energy flow in the ETC is used for one purpose: to set up a proton gradient (used in chemiosmosis)
High H+ in intermembrane space
Low H+ in matrix

Chemiosmosis is the mechanism for coupling the energy flow in the ETC with production of ATP

Energy in a H+ gradient is harnessed to do cellular work (making ATP)Electron transfer in the ETC causes proteins to pump H+ from the mitochondrial matrix into the intermembrane space
H+ then moves back across the membrane through channels in ATP synthaseATP synthase uses the exergonic flow of H+ to drive phosphorylation of ADP
Energy stored in H+ gradient across the membrane couples redox reactions of electron transport chain to ATP synthesis
H+ gradient is referred to as a proton-motive force (which emphasizes its capacity to do work)

33
Q

 Explain the role of ATP synthase in cellular respiration

A

ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ADP

34
Q

 Describe the biological significance of fermentation in terms of electron carriers

A

Fermentation enables some cells to produce ATP without the use of oxygen
Cellular respiration requires O2 to produce ATP
Without O2, the electron transport chain will cease to operate
Glycolysis ( does not require O2) couples with fermentation or anaerobic respiration to produce ATP

35
Q

 Outline the different types of fermentation in terms of starting substrate and finishing product

A

In alcohol fermentation, pyruvate is reduced to ethanol in two steps, with the first releasing CO2
Alcohol fermentation by yeast is used in:
Brewing beer
Winemaking
Baking
In lactic acid fermentation, pyruvate is reduced to lactate, with the electrons coming from NADH
Lactate (lactic acid) is released as an end product
No release of CO2
Lactic acid fermentation is used by some fungi and bacteria to make cheese and yogurt
Lactic acid fermentation is used by human muscle cells to generate ATP when O2 is scarce

36
Q

 Outline the similarities and differences between cellular respiration and fermentation

A

Both processes use glycolysis to oxidize glucose and other organic fuels to pyruvate
Cellular respiration occurs in the mitochondrion
Fermentation occurs in the cytoplasm
The processes differ in final electron acceptors:
Fermentation uses an organic molecule (lactate/ethanol)
Cellular respiration uses O2
Cellular respiration produces much more ATP than fermentation
Fermentation yields total of 2 ATP per glucose
Cellular respiration yields total of 38 ATP per glucose

37
Q

 Explain the concept of terminal electron acceptor and identify the different terminal electron acceptors in cellular respiration, alcoholic fermentation and lactic acid fermentation

A

4

38
Q

 Understand how other catabolic and anabolic pathways or products feed into, or are derived from, the cellular respiration pathways

A

Catabolic pathways funnel electrons from many kinds of organic molecules into cellular respiration
Glycolysis accepts a wide range of carbohydrates
Proteins must be digested to amino acids; amino groups can feed glycolysis or the citric acid cycle
Fats are digested to glycerol (used in glycolysis) and fatty acids (used in generating acetyl CoA)
An oxidized gram of fat produces more than twice as much ATP as an oxidized gram of carbohydrate

39
Q

 Describe in general terms how cellular respiration is regulated

A

Feedback inhibition is the most common mechanism for control
If ATP concentration begins to drop….respiration speeds up
When there is plenty of ATP….respiration slows down
Control of catabolism is based mainly on regulating the activity of enzymes at strategic points in the catabolic pathway

40
Q

 Describe the difference between autotrophs and heterotrophs

A

Autotrophs sustain themselves without eating anything derived from other organisms
Autotrophs are the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules
Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecule

Heterotrophs obtain their organic material from other organisms
Heterotrophs are the consumers of the biosphere
Almost all heterotrophs, including humans, depend on photoautotrophs for food and O2

41
Q

 Explain the concepts of oxidation and reduction (redox) reactions and electron carriers as they apply to photosynthesis and the photosystems

A

Photosynthesis reverses the direction of electron flow compared to respiration
Photosynthesis is a redox process in which H2O is oxidized and CO2 is reduced
Photosynthesis is an endergonic process; the energy boost is provided by light

42
Q

 Outline the two stages of photosynthesis and know the locations in the plant cell where each takes place and which do and do not require light

A 
Photosynthesis consists of the two stages:
light reactions (the photo part) 
Calvin cycle (the synthesis part)
The light reactions (in the thylakoids)
Split H2O
Release O2
Reduce NADP+ to NADPH
Generate ATP from ADP by photophosphorylation

Stage 2: Calvin cycle
Begins with carbon fixation (process of incorporating CO2 into organic molecules)
Uses ATP and NADPH (from light reactions)
Forms sugar from CO2
Calvin cycle occurs in the chloroplast stroma

43
Q

 Describe the importance of each stage of photosynthesis in terms of what enters the stage (e.g. light, organic molecules, NADPH, etc), what products are produced (e.g. organic molecules, NADPH, ATP, etc) and where the products go from one stage to another (it is NOT necessary to know each step of the pathways in detail)

A

4

44
Q

 Explain the role of the photosynthetic pigments in photosynthesis and be able to name and describe the functions of the major pigments

A

Pigments are substances that absorb visible light
Different pigments absorb different wavelengths
Wavelengths that are not absorbed are reflected or transmitted
Leaves appear green because chlorophyll reflects and transmits green light
An absorption spectrum is a graph plotting a pigment’s light absorption versus wavelength
Absorption spectrum of chlorophyll a suggests that violet-blue and red light work best in PS
Purely chemical relationship

45
Q

 Explain what is meant by the term absorption spectrum as it applies to photosynthetic pigments

A

An absorption spectrum is a graph plotting a pigment’s light absorption versus wavelength
Absorption spectrum of chlorophyll a suggests that violet-blue and red light work best in PS
Purely chemical relationship

46
Q

 Describe the similarities and differences between an absorption spectrum and an action spectrum for a photosynthetic pigment

A

Biological relationship
Profiles relative effectiveness of different radiation wavelengths in driving a process (e.g. photosynthesis)
Areas receiving wavelengths favourable to photosynthesis produced excess O2
He used aerobic bacteria clustered along the alga to detect O2 production

47
Q

 Describe how photosystems generate high-energy electrons and the different pathways electrons take in photosynthesis to generate ATP and NADPH

A

A primary electron acceptor in the reaction centre accepts an excited electron from chlorophyll a

Solar-powered transfer of an electron from a chlorophyll a molecule to the primary electron acceptor is the first step of the light reactions

Photosystems are located in thylakoid membrane
Photosystem II (PS II)
Functions first (the numbers reflect order of discovery)
Best at absorbing wavelength of 680 nm (red)
Reaction centre chlorophyll a termed P680
Photosystem I (PS I)
Best at absorbing a wavelength of 700 nm (far red)
Reaction centre chlorophyll a termed P700
The two photosystems work together to use light energy to generate ATP and NADPHA photon hits a pigment and its energy is passed among pigment molecules until it excites P680
An excited electron from P680 is transferred to the primary electron acceptor (we now call it P680+)P680+ is a very strong oxidizing agent
H2O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680+, thus reducing it to P680
O2 is released as a by-product of this reaction

48
Q

 Explain how the electron transport chain, chemiosmosis and oxidative phosphorylation operate in photosynthesis (it is NOT necessary to know each step of the electron transport chain in detail)

A

Each electron “falls” down an electron transport chain from the primary electron acceptor of PS II to PS I

Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane

Diffusion of H+ (protons) across the membrane drives ATP synthesis

49
Q

 Understand the importance of ATP synthase and the RUBISCO enzyme in photosynthesis

A

1

50
Q

 Explain what is meant by carbon fixation and understand the arithmetical relationship between carbon fixation and sugar production

A

1

51
Q

 Explain the concept of photorespiration and outline why it is a problem in C3 plants and

A

Most plants are C3 plants:
CO2 fixation forms 3C compound
CO2 starvation reduces sugar production:
Calvin cycle is starved for input
However, rubisco enzyme can also bind O2:
O2 competes with CO2 for the enzyme, so at low CO2 or high O2 levels, O2 wins

52
Q

 Explain the different ways that the photorespiration problem is overcome in C4 and CAM plants

A

C4 plants minimize the cost of photorespiration by incorporating CO2 into four-carbon compounds in mesophyll cells
This step requires the enzyme PEP carboxylase
PEP carboxylase has a higher affinity for CO2 than rubisco does; it can fix CO2 even when CO2 concentrations are low
These four-carbon compounds are exported to bundle-sheath cells, where they release CO2 that is then used in the Calvin cycle

Some plants, including succulents, use crassulacean acid metabolism (CAM) to fix carbon
CAM plants open their stomata at night, incorporating CO2 into organic acids
Stomata close during the day, and CO2 is released from organic acids and used in the Calvin cycle

biology 126 (1 decks)

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