Monthly Archives: November 2012


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8.1a Aerobic Respiration

Mitochondria are usually found in the cytoplasm of eukaryotic cells. They have a smooth outer membrane and there is a inner membrane. The inner membrane has folds and invaginations. In between the membranes is a narrow space, called the matrix. It consists of enzymes, ribosomes and naked DNA. This double layer membrane makes the mitochondria unique.
In oxidative phosphorylation, ADP is phosphorylated to produce ATP, using energy released by oxidation. The chain of electron carriers carries the releasing in small steps. This is better because more energy can be trapped in ATP. Chemiosmosis in mitochondria is when a chemical substance moves across the inner membrane, releasing energy from ATP.

Data-based questions

1) Pyruvate is a substrate for aerobic respiration, therefore the oxygen consumption couldn’t begin.
2) ADP could have needed to be added during I and II.
3) If ADP had not been added at III, the consumption would have stayed contant , instead of continuing with the consumption.
4) The consumption had hit a plateau. This could be because of the lack of energy.


3.7b Aerobic Respiration

When oxygen is available to a cell, pyruvate that was produced by glycolysis is oxidized to release more energy. In eukaryotic cells, this occurs in the mitochondria. The energy released to used to make ATP. Organisms used carbon dioxide as a waste product that is released.
Oxidation and reduction are chemical processes that occur together since it involves the loss and gain of electrons between each other. In oxidation, electrons are lost, while reduction is the gain of electrons.
Electron carries are substances that can accept and give up electrons when needed, linking oxidations and reductions in cells.
Oxidation and reduction can occur through the loss or gain of atoms of oxygen. Adding oxygen atoms to a molecule or ion is oxidation, while loosing oxygen atoms is reduction.
In the Krebs Cycle two molecules of pyruvate are produced in glycolysis per molecule of glucose. Contradicting glycolysis, this is not a single-step process. The oxidization  of pyruvate is gained by removing pairs of hydrogen atoms. Decarboxylations is the reaction where carbon & hydrogen are removed.


3.7a Anaerobic Respiration

Cell Respiration- is the controlled release of energy from organic compounds to form ATP
Energy is needed in the cells for:
– synthesizing large molecules (DNA,RNA,proteins)
– pumping molecules (ions) across membranes by active transport
– moving substances (chromosomes, vesicles) around in the cell
ATP = adenosine triphosphate     ADP = adenosine diphosphate
When ATP is split into ADP and phosphate, energy is released
ATP cannot be absorbed through the plasma membrane, so the cell has to make it’s own supply
Organic compounds containing energy are broken down by enzymes

Data-based Questions: production and consumption of ATP
1a) the volume units are dm3
1b) the mass units is g and kg
3) It is possible because large amount of ADP and phosphate aren’t needed



1) translation requires tRNA
2a) a
3) RNA
4) 360
6) Universal genes means that the genes are the same in almost every organism. Degenerate there is more than one codon for an amino acid.
7a) it is not possible to predict the sequence since the genetic code is generate
7b) the sequence is derived from the genetic code, and it nearly impossible to predict the sequence of the gene it is coded for
8) nucleotides are found in the DNA and in mRNA
the nucleotides are composed of the base, phosphate, and sugar
polypeptides are bonded by peptide bonds and made of amino acids
9) Transcription takes place in the nucleus whereas translation happens in the cytoplasm. Transcription requires mRNA, and RNA. Translation produces mRNA.
10) The genetic code is universal and degenerate. It is composed of 64 codons, which is composed of base triplets.

15a) The sequence replace thymine with uracil
b)Met (start), Tyr, Gly, Gly, Phe, Leu, Arg, Lys, Tyr, Pro, Lys, (stop)
c) The genetic code is degenerate which means that one codon can code for the same amino acid sequence
d) One amino acid is removed from the sequence from translation to transcription


Chapter 7 practice questions

Revenues-  income earned from a firm’s sale of its good or service to consumers in the products market
Profit- difference between a firm’s total revenues and it’s total costs
Explicit costs- monetary payments a firm makes to owners of the resources (wages, transport costs, raw material costs)
Implicit costs- opportunity costs faced by a business owner who chooses to use his skills and resources to operate his own enterprise rather than seek employment by someone else. (normal profit)
– Wages (explicit)
– Interest (explicit)
– Rent (explicit)
– Profit (implicit)
Law of diminishing returns- determines how a firm’s cost change as it varies it’s level of production in the short run

Practice Questions #3

3a) Companies are more efficient, and should produce more when their marginal revenue equals their marginal cost. MR=MC. When the marginal revenue is higher then the marginal cost, the company is profiting. Otherwise, when the marginal cost is higher than the marginal cost, then the company is inefficient and loosing money.

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The graph represents the profit maximization rule, which shows which point at which the company should, which is the place where MC & MR intersect.

3b) “Whatever the type of market structure, profit maximization will always be the only goal of firms.” This statement is true, since all firms in any kind of market wan to succeed and make the most amount of money as possible. Also, firms want make money in the short term, and the long run. Firms would want to last in the market for as long as possible, making a good profit.

3.5/7.4 Translation


– takes place on ribosomes
– ribosomes are placed in the cytoplasm, outside the nucleus
– a ribosome has a small and large subunit
– mRNA binds to small subunit
– tRNA molecules carry the specific amino acid, corresponding the anti-codon
– tRNA binds to ribosome at the place where it’s anti-codon matches the anti-codon on the mRNA
– two tRNAs bind at once and the first one in transfer the growing polypeptide chain to the second one
– the ribosome moves along the mRNA and the process continues until a stop codon is reached  when the completed polypeptide is released

Details of Translation 

– translation always begins in the cytoplasm
(when proteins are destined to be in lysosomes or export:
– ribosomes bind to endoplasmic reticulum and complete the process of translation)
– ribosomes are composed of ribosomal RNA (rRNA) and other proteins
– each ribosome is composed of two subunits – small and large
– each ribosome has three tRNA binding sites – the E (exit) or P (peptidyl) or A (aminoacyl) sites
– more than one ribosome can be actively translating the same mRNA molecule at the same time
– polyribosome/polysome: complex ribosomes along a single mRNA

Initiation, elongation & termination

I: mRNA molecule binds to the small ribosomal subunit at an mRNA binding site
– and initiator tRNA molecule carrying methionine then binds at the start of codon AUG
– the large subunit then binds to the small one
– initiator tRNA is in the P site
– codon signals another tRNA to bind
– occupies A site
– peptide bond is formed between amino acids in the P and A sites
E: ribosome translocated three bases along mRNA
– moves the tRNA in the P site into the E site
– this allows tRNA with the appropriate anticodon to bind to the next codon and occupy the vacant A site
T: process continues until a stop codon is reached
– direction of movement is along the mRNA 5′ to the 3′ end

Data-based questions: interpreting electron micrographs

1) Translation – polysomes are in the image
2) Replication – there is the loop in the image
3) Transcription – relation to translation