Exam 2
how can prokaryotes preform cell resp. if they do not have mitochondria?
prokaryotes can use respiration without mitochondria because they have etc and atp synthase in the cell membrane
why is an electron transport chain so important? what does it do? why?
the electron transport chain itself does not generate atp it just gradually releases energy and pumps h+ against their concentration gradiant -creating a proton motive force -q is reduced along the way and so is cytochrome c -o is reduced (use of o makes the aerobic) -oxidative for NADH anf FADH2 -then atp synthase completes phosphorylation by making atp through chemiosmosis final product 25 atp
Why do fatty acids have more free energy than carbohydrates?
they have more C-H bonds than carbohydrates
how can many of our cells function as facultative anaerobes? what is an obligated anaerobe?
Facilitated anaerobes can switch between fermentation and aerobic cell respiration obligated anaerobes- cant handle o2
What are the similarities and differences between RNA and DNA? What are Chargaff's rules?
-The primary structures of dna and rna differ because dna uses thymine and rna uses uracil *Dna contains deoxyribose and rna contain ribose- the -oh group on the 2' carbon of ribose makes it less stable and more reactant -Chargaff's rules- the total number of purines= the total number of pyrimidines *the number of adenines=the number of thymines and the number of guanines = the number of cytosines in dna
Why is it significant that proteins may be amphipathic? What does this have to do with amino acids?
-amphipathic proteins can be added into lipid bilayers. -amino acids vary in their affinity for water. nonpolar amino acids are stable in the membrane due to hydrophobic interactions with hydrocarbon tails and polar or charged amino acids are stable next to the polar heads and in the surrounding water. - these proteins come in many shapes and sizes - some form channels or pores across a lipid bilayer
what does delta g stand for? what are endergonic and exergonic reactions and how do they relate to delta g? how can cells use the energy given off by one to help one that needs energy to occur?
-biologist try to figure out which reaction occur spontaneously and which require energy so the look at free energy change (delta g) -delta g is a measure of how the total energy of a biological system changes due to entropy and temperature -only processes with negative delta g are spontaneous: they release energy =exergonic -processes with a positive delta g are never spontaneous they require energy input=endergonic
What happens in the primary structure of a person with HbS and how does it affect their red blood cells?
-in the primary structure of a protein in a person with sickle cell the amino acid glutamate is replaced with the amino acid valine. This causes the protein to go from being polar to nonpolar and causes it to stick to other HbS molecules -this causes the red blood cell to have half moon shape instead of a round shape this means that the red blood cell cannot carry as much oxygen and clots more easily
What are the different types of carbohydrates? What are some of their distinguishing features? What is the general chemical formula for a carbohydrate? How might you recognize the name of one?
-oligosaccharides(few sugars- small polymer) and polysaccharides (complex, many sugars) -the chemical formula for most carbohydrates is a multitude of CH2O (CHO in a 1:2:1 ratio) -aldose- carbonyl group at the end of the chain -ketose - carbonyl group in the middle of the chain
what does it mean when a cell membrane is selectively permeable? how does this relate to unsaturated and saturated fats? which has more chemical energy? what is a trans fat?
-small nonpolar molecules cross the bilayers more easily than charged substances and large molecules -lipid bilayers with short and unsaturated hydrocarbon tails have a higher permeability and fluidity -lipid bilayers w long saturated hydrocarbon tails have a lower permeability /fluidity.
what does a phospholipid bilayer look like and how does this work as a cell membrane?
-the polar head of the phospholipid faces outward toward the water and the hydrophobic tails face inward toward other tails -
what is a reducing agent? what is a oxidizing agent?
-when something is oxidized the reducing agent is the electron donor -when something is reduced the oxidizing agent is the electron acceptor
what happens in the citric acid cycle? how many times does this happen per glucose? why is it a cycle? where does it take place? what is the starting material that is regenerated?
1 Acetyl CoA-CoA=Acetyl 2Acetyl+oxaloacetate=citrate 3 the next 7 steps decompose the citrate back to oxaloacetate making the process a cycle - this happens 2 times per glucose -it alos occurs in the mitochondrial matrix - it regenerates oxaloacetate
what are the 4 stages of cellular respiration? What is happening during each? where do they occur?
1 glyvolysis- breaks down a glucose (6C) into 2 molecules of pyruvate (3C each); NAD+ is reduced to NADH+ (cytosol) 2pyruvate processing- each 3c pyruvate is oxidized into a 2c acetyl -CoA; more NAD+ is reduced to NADH+ (matrix of the mitochondria) 3 citric acid cycle- oxidizes acetyl -CoA to CO2 NAD+ becomes NADH+ and FAD+ becomes FADH2 4 electron transport chain and oxidative phosphorylation- most of the NADH+ and the FADH2 drop off their electrons at the ETC after lots of redox reaction lots of ATP is made
how does phosphofructokinase exemplify the concept of an enzyme having an allosteric inhibitor?
ATP is the allosteric inhibitor-if there is to much ATP then the ATP binding changes the enzymes shape to decrease activity. if the ATP is at low concentration than the it goes to the active site where ATP is hydrolyzed
what is the basic formula of cellular respiration? what is being oxidized and reduced? what do each of those terms mean?
C6H1206 +6O2->6CO2+6H20+ENERGY glucose is being oxidized which means it is losing electrons oxygen is being reduced which means it is gaining electrons
What roles do RNA and DNA play?
DNA -information storage for genetic material -chromosomes and genetics -sequence determines the primary structure of proteins RNA - used in protein synthesis
what are the differences between the two types of muscle fibers? under which circumstances would you want to have each? how does substrate level phosphorylation factor into all of this?
Dark muscle- stores oxygen for anaerobic respiration and has lots of mitochondria -slow twitch used for endurance light muscle-only uses lactic acid fermentation to make ATP -fast twitch -speed substrate level phosphorylation is a metabolic reaction that results in the formation of atp or gtp by the direct transfer of a phosphoryl group to adp or gdp from another phosphorlayted compound
how are fats, steroids, and phospholipids constructed? Why is it significant that phospholipids are ampipathic?
Fats-glycerol and three fatty acids using ester linkages- they do not have monomers or polymers because they cannot keep going. - fats= triglycerol/ triglycerides Steriods- distinguished by it 4 carbon rings -no monomer or polymer -an example is cholesterol - nessecary in animal cell membranes and needed to make hormones (amphipathic) Phospholipids- glycerol and phosphate group and 2 tails -joined by ester linkages -polar head and nonpolar tail - they are amphipathic -so they are perfect for cell membranes
what role does feedback inhibition play in the citric acid cycle?
Low atp causes high reaction rates whereas high atp concentration inhibits the citric acid cycle -- atp inhibits the enzyme that converts acetyl CoA to citrate also occurs at 2 other points --in one case NADH binds to the enzymes active site as a competitive inhibitor in the other case atp binds to an allosteric site
What is an N-terminus and what is a C-terminus? How would you be able to recognize them?
N-terminus- amino acid C-terminus-carbohydrate
how do NAD+ and NADH+ relate to each other? what are the net results of glycolysis?
NAD+ is reduced it gains 2 electrons, it also gains an H+ and then becomes NADH+ net results 2 ATP
What are the monomers for proteins, nucleic acids, and carbohydrates?
NUCLEIC ACIDS- m: nucleotides- made of a phosphate group bonded to a five-carbon sugar p:can either be DNA or RNA CARBOHYDRATES- m: monosaccharides p: oligosaccharides(few sugars small polymer)- they are part of glycoproteins- they are the identification badge for cells. ex. how sperm recognize a fertilized egg. Polysaccharides(Complex carbohydrate- many sugars- large polymers) they usually contain 100s-1000s of monomers PROTEINS- m: amino acids p: peptide chains- oligopeptide (small or short chain) and polypeptide (longer- over 50 amino acids joined)
What chemical reaction links each monomer?
NUCLEIC ACIDS-condensation reactions create phosphodiester linkages between the phosphate group of one nucleotide and the - OH group on another nucleotide CARBOHYDRATES-condensation reactions create glycosidic linkages between monosaccharides PROTEINS- condensation reactions create peptide bonds between amino acids LIPIDS-fatty acids are link by ester bonds through a condensation reaction
How do you recognize a nucleotide monomer? What are all of the parts? What is the difference between a ribose and a deoxyribose?
Nucleotide has 3 parts: 1. phosphate group 2. nitrogenous base -2 types- pyrimadines- single six member rings cytosine, uracil, thymine and purines guanine and adenine 3. 5 carbon (pentose) sugar- ribose- contains an extra oxygen and deoxyribose- has an H instead of an OH
What are the four levels of the protein structure?
Primary Structure- unique sequence of amino acids- side chains (R groups do not interact yet) Secondary structure- hydrogen bonds can form in the same polypeptide chain creating secondary coils and folds - hydrogen bonds are not between R groups just from C=O to N-H - alpha helix and beta pleated sheet -ribbon diagrams of secondary structure -secondary structure is responsible for making spider silk as strong as it is. Tertiary Structure- structure is determined by interaction between the R group and the side chain Quaternary Structure- when 2 or more polypeptide chains form one macromolecule.
What make pyrimidines different from purines? Be sure to know examples of each. How do they pair with each other?
Pyrimidines - single six member rings- cytosine, uracil, thymine Purines- six member ring and five member ring-guanine and adenine -adenine with thymine -guanine with cytosine
What are the three types of lipids and what are their characteristics?
Saturated lipids -butter - most animal fats solid at room temperature -single bonds -they lead to health problems because they are layered tightly unsaturated lipids -sunflower oil -liquid at room temp -have double bonds -they are better for because there is space between the bonds. -you can turn unsaturated fats into transfats by partially hydrogenating them
What are the types of storage polysaccharides in plants and animals and how does their structure relate to their function? How about with structural polysaccharides in plants, animals, fungi, and bacteria? How does this affect how bacteria react to antibiotics? What are some special things about cellulose in particular?
Storage polysaccharides: strong bonds but they are fairly easy to hydrolize -animals- glycogen -plants-starch structural polysaccharides: Animals/fungi-chitin bacteria-peptidoglycan plants- cellulose * different glycosidic linkages hard to hydrolyze *stronger bonds, harder to hydrolyze *many herbavors can digest cellulose only with the help of microbes- a type of symbiotic relationship called mutualistic -cellulose is the roughage that we can't digest
What are glycoproteins and does it do?
The identification badge for cells- help with cell to cell signaling most important thing for sperm to recognize a fertilized egg
what is so important about the last stage of cellular respiration? what is meant by oxidative phosphorylation?
The last step of respiration is the big payoff- this is where most of the atp comes from.
what happens to each pyruvate before it heads into the citric acid cycle? how many times does this happen per glucose?
each pyruvate is then converted into acetyl CoA with a C that is converted into a CO2
what are the two major phases of glycolysis? what does this mean? why is the third enzyme phosphofructokinase so important? what happens if the cell already has plenty of atp? what happens if it needs more?
energy investment phase- uses 2 ATP to phosphorylate intermediate compounds -phosphfrukokinase is an important regulatory enzyme of no return. -atp acts like the allosteric inhibitor of this enzyme -if there is too much atp then the enzyme cannot bind with the substrate but if there is not to much the glycolysis continues (has 2 binding sites active and regulatory) energy payoff phase -enzymes are involved - each NAD+ is reduced and so it gains 2 electrons to be used later abd H+ follows - only gets 2 net ATP
what is energy? what is the relationship between potential and kinetic energy?
energy is the ability to do work or supply heat kinetic energy is active motion and potential is stored in chemical bonds
how does feedback inhibition work? what is substrate level inhibition?
feedback inhibition is used to maintain cell homeostasis. cells with lots of atp do not need to make more and can save their glucose substrate level inhibition means that their are 2 binding sites an active and a regulatory
What are the net yields of each step of respiration?
glycolysis -2 pyruvate -2 net atp -2 nadh pyruvate processing -Acetyl CoA (2c each) and Co2 citric acid cycle 2 co2 1 atp 3 nadh 1 fadh2 per turn (double each) electron transport chain 25 atp total 29 atp
why do we say that glycolysis is evolutionarily significant?
glycolysis occurs in nearly all organisms it probably evolved in ancients prokaryotes before there was co2 in the in the atmosphere it happens in the cytosol no organelles or or o2 needed
what are the major differences between the processes and products of the two types of fermentation?
lactic acid fermentation- when muscles metabolize glucose faster then oxygen can be supplied this type of fermentation produces lactate in addition to regenerating NAD+ yeast deprived of oxygen uses alcohol fermentation in which the pyruvate loses co2 and is converted to acetylaldehyde, which accepts an electron from NADH to produce nad+
why is fermentation good for meeting all of small organisms energy needs but not for big organisms
organisms on produce 2 atp during fermentation unlike the 29 atp during respirtation. consequently organisms that usually use oxygen as a electron acceptor only use fermentation when oxygen is not available
what is q and how is it important? what is it similar to in photosynthesis?
q is a ubiquinone it is lipid soluble and easily moves and easily moves throughout the inner mitochondrial membrane q and pq are both hydrophobic, both move thru the membrane,both carry electrons, h+ follows both and get kicked out the build up of h+ leads to making atp they differ in how they make atp
what type of organism is yeast?
single cell fungi saccharomyces arevisiace bakers yeast co2 makes bread dough rise also used to make beer and wine
How do cells communicate over long distances? What are the different sequences of events depending on whether the communicating molecule is hydrophilic or hydrophobic?
they communicate long distance through hormones. hydrophilic- need a membrane receptor and a signal transduction pathway -extracellular signal 1. signal receptions 2 signal transduction often assisted by G proteins 3 signal amplification 4 signal response hydrophobic- can get to receptor inside cell because lipid is soluble -steroid hormone 1 signal arrives and diffuses into cell 2signal reception with conformational change 3 direct signal response by changing dna expression
