what are differences between human and bacteria cells?

Question

about cell membrane and cytoplasm

Answer 1

The bacteria have prokaryotic cells. The prokaryotic cells are most primitive and simple type of cells. They have a single coiled chromosome(DNA) lying free in the cytoplasm, and ,therefore, no well developed nucleus. Further, the membrane bound organelles like mitochondria, golgi, ER, lysosomes etc are absent. Ribosomes of 70s type. All bacteria have a rigid cell wall of murein.
On the other hand, humans have eukaryotic cells. They have well developed nucleus with nuclear membrane. They possess membrane bound organelles like mitochondia, golgi, ER, lysosomes etc. Ribosomes are of 80s type. no cell wall, only cell membrane is present.
Human cells divide by mitosis while as bacterial cells divide by binary fission.

Answer 2

one million. Human chromosomes are plenty greater complicated than bacterial chromosomes as they are linked with histones and are enclosed in a nucleus. 2. because human chromosomes are interior a nucleus, they do no longer work together with the plasma membrane 3. Human chromosomes are related to a minimum of one yet another throughout the time of replication yet no longer afterwords. comparable with a bacterial genome. 4. genuine, this is a difference. All our somatic cells have 23 pairs of chromosomes. micro organism have one chromosome. 5. genuine, micro organism are plenty smaller than maximum human cells and absence complicated organelles. 6. selection 3 is a similarity.

Answer 3

The number of cells

Answer 4

1)Bacteria Cell Structure

They are as unrelated to human beings as living things can be, but bacteria are essential to human life and life on planet Earth. Although they are notorious for their role in causing human diseases, from tooth decay to the Black Plague, there are beneficial species that are essential to good health.
Prokaryotic Cell Structure

For example, one species that lives symbiotically in the large intestine manufactures vitamin K, an essential blood clotting factor. Other species are beneficial indirectly. Bacteria give yogurt its tangy flavor and sourdough bread its sour taste. They make it possible for ruminant animals (cows, sheep, goats) to digest plant cellulose and for some plants, (soybean, peas, alfalfa) to convert nitrogen to a more usable form.

Bacteria are prokaryotes, lacking well-defined nuclei and membrane-bound organelles, and with chromosomes composed of a single closed DNA circle. They come in many shapes and sizes, from minute spheres, cylinders and spiral threads, to flagellated rods, and filamentous chains. They are found practically everywhere on Earth and live in some of the most unusual and seemingly inhospitable places.

Evidence shows that bacteria were in existence as long as 3.5 billion years ago, making them one of the oldest living organisms on the Earth. Even older than the bacteria are the archeans (also called archaebacteria) tiny prokaryotic organisms that live only in extreme environments: boiling water, super-salty pools, sulfur-spewing volcanic vents, acidic water, and deep in the Antarctic ice. Many scientists now believe that the archaea and bacteria developed separately from a common ancestor nearly four billion years ago. Millions of years later, the ancestors of today's eukaryotes split off from the archaea. Despite the superficial resemblance to bacteria, biochemically and genetically, the archea are as different from bacteria as bacteria are from humans.

In the late 1600s, Antoni van Leeuwenhoek became the first to study bacteria under the microscope. During the nineteenth century, the French scientist Louis Pasteur and the German physician Robert Koch demonstrated the role of bacteria as pathogens (causing disease). The twentieth century saw numerous advances in bacteriology, indicating their diversity, ancient lineage, and general importance. Most notably, a number of scientists around the world made contributions to the field of microbial ecology, showing that bacteria were essential to food webs and for the overall health of the Earth's ecosystems. The discovery that some bacteria produced compounds lethal to other bacteria led to the development of antibiotics, which revolutionized the field of medicine.

There are two different ways of grouping bacteria. They can be divided into three types based on their response to gaseous oxygen. Aerobic bacteria require oxygen for their health and existence and will die without it. Anerobic bacteria can't tolerate gaseous oxygen at all and die when exposed to it. Facultative aneraobes prefer oxygen, but can live without it.

The second way of grouping them is by how they obtain their energy. Bacteria that have to consume and break down complex organic compounds are heterotrophs. This includes species that are found in decaying material as well as those that utilize fermentation or respiration. Bacteria that create their own energy, fueled by light or through chemical reactions, are autotrophs.

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Capsule - Some species of bacteria have a third protective covering, a capsule made up of polysaccharides (complex carbohydrates). Capsules play a number of roles, but the most important are to keep the bacterium from drying out and to protect it from phagocytosis (engulfing) by larger microorganisms. The capsule is a major virulence factor in the major disease-causing bacteria, such as Escherichia coli and Streptococcus pneumoniae. Nonencapsulated mutants of these organisms are avirulent, i.e. they don't cause disease.
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Cell Envelope - The cell envelope is made up of two to three layers: the interior cytoplasmic membrane, the cell wall, and -- in some species of bacteria -- an outer capsule.
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Cell Wall - Each bacterium is enclosed by a rigid cell wall composed of peptidoglycan, a protein-sugar (polysaccharide) molecule. The wall gives the cell its shape and surrounds the cytoplasmic membrane, protecting it from the environment. It also helps to anchor appendages like the pili and flagella, which originate in the cytoplasm membrane and protrude through the wall to the outside. The strength of the wall is responsible for keeping the cell from bursting when there are large differences in osmotic pressure between the cytoplasm and the environment.

Cell wall composition varies widely amongst bacteria and is one of the most important factors in bacterial species analysis and differentiation. For example, a relatively thick, meshlike structure that makes it possible to distinguish two basic types of bacteria. A technique devised by Danish physician Hans Christian Gram in 1884, uses a staining and washing technique to differentiate between the two forms. When exposed to a gram stain, gram-positive bacteria retain the purple color of the stain because the structure of their cell walls traps the dye. In gram-negative bacteria, the cell wall is thin and releases the dye readily when washed with an alcohol or acetone solution.
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Cytoplasm - The cytoplasm, or protoplasm, of bacterial cells is where the functions for cell growth, metabolism, and replication are carried out. It is a gel-like matrix composed of water, enzymes, nutrients, wastes, and gases and contains cell structures such as ribosomes, a chromosome, and plasmids. The cell envelope encases the cytoplasm and all its components. Unlike the eukaryotic (true) cells, bacteria do not have a membrane enclosed nucleus. The chromosome, a single, continuous strand of DNA, is localized, but not contained, in a region of the cell called the nucleoid. All the other cellular components are scattered throughout the cytoplasm.
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Cytoplasmic Membrane - A layer of phospholipids and proteins, called the cytoplasmic membrane, encloses the interior of the bacterium, regulating the flow of materials in and out of the cell. This is a structural trait bacteria share with all other living cells; a barrier that allows them to selectively interact with their environment. Membranes are highly organized and asymmetric having two sides, each side with a different surface and different functions. Membranes are also dynamic, constantly adapting to different conditions.

One of those components, plasmids, are small, extrachromosomal genetic structures carried by many strains of bacteria. Like the chromosome, plasmids are made of a circular piece of DNA. Unlike the chromosome, they are not involved in reproduction. Only the chromosome has the genetic instructions for initiating and carrying out cell division, or binary fission, the primary means of reproduction in bacteria. Plasmids replicate independently of the chromosome and, while not essential for survival, appear to give bacteria a selective advantage.

Plasmids are passed on to other bacteria through two means. For most plasmid types, copies in the cytoplasm are passed on to daughter cells during binary fission. Other types of plasmids, however, form a tubelike structure at the surface called a pilus that passes copies of the plasmid to other bacteria during conjugation, a process by which bacteria exchange genetic information. Plasmids have been shown to be instrumental in the transmission of special properties, such as antibiotic drug resistance, resistance to heavy metals, and virulence factors necessary for infection of animal or plant hosts. The ability to insert specific genes into plasmids have made them extremely useful tools in the fields of molecular biology and genetics, specifically in the area of genetic engineering.
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Flagella - Flagella (singular, flagellum) are hairlike structures that provide a means of locomotion for those bacteria that have them. They can be found at either or both ends of a bacterium or all over its surface. The flagella beat in a propeller-like motion to help the bacterium move toward nutrients; away from toxic chemicals; or, in the case of the photosynthetic cyanobacteria; toward the light.
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Nucleoid - The nucleoid is a region of cytoplasm where the chromosomal DNA is located. It is not a membrane bound nucleus, but simply an area of the cytoplasm where the strands of DNA are found. Most bacteria have a single, circular chromosome that is responsible for replication, although a few species do have two or more. Smaller circular auxiliary DNA strands, called plasmids, are also found in the cytoplasm.
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Pili - Many species of bacteria have pili (singular, pilus), small hairlike projections emerging from the outside cell surface. These outgrowths assist the bacteria in attaching to other cells and surfaces, such as teeth, intestines, and rocks. Without pili, many disease-causing bacteria lose their ability to infect because they're unable to attach to host tissue. Specialized pili are used for conjugation, during which two bacteria exchange fragments of plasmid DNA.
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Ribosomes - Ribosomes are microscopic "factories" found in all cells, including bacteria. They translate the genetic code from the molecular language of nucleic acid to that of amino acids—the building blocks of proteins. Proteins are the molecules that perform all the functions of cells and living organisms. Bacterial ribosomes are similar to those of eukaryotes, but are smaller and have a slightly different composition and molecular structure. Bacterial ribosomes are never bound to other organelles as they sometimes are (bound to the endoplasmic reticulum) in eukaryotes, but are free-standing structures distributed throughout the cytoplasm. There are sufficient differences between bacterial ribosomes and eukaryotic ribosomes that some antibiotics will inhibit the functioning of bacterial ribosomes, but not a eukaryote's, thus killing bacteria but not the eukaryotic organisms they are infecting.
2)human cells
CHEMICAL LEVEL - includes all chemical substances necessary for life (see, for example, a small portion - a heme group - of a hemoglobin molecule); together form the next higher level


Source: http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH25/FG25_07.JPG

CELLULAR LEVEL - cells are the basic structural and functional units of the human body & there are many different types of cells (e.g., muscle, nerve, blood, and so on)


Source: http://www.nigms.nih.gov/news/science_ed/whatart1.html

TISSUE LEVEL - a tissue is a group of cells that perform a specific function and the basic types of tissues in the human body include epithelial, muscle, nervous, and connective tissues

ORGAN LEVEL - an organ consists of 2 or more tissues that perform a particular function (e.g., heart, liver, stomach, and so on)

SYSTEM LEVEL - an association of organs that have a common function; the major systems in the human body include digestive, nervous, endocrine, circulatory, respiratory, urinary, and reproductive.

There are two types of cells that make up all living things on earth: prokaryotic and eukaryotic. Prokaryotic cells, like bacteria, have no 'nucleus', while eukaryotic cells, like those of the human body, do. So, a human cell is enclosed by a cell, or plasma, membrane. Enclosed by that membrane is the cytoplasm (with associated organelles) plus a nucleus.

Cell, or Plasma, membrane - encloses every human cell

o Structure - 2 primary building blocks include protein (about 60% of the membrane) and lipid, or fat (about 40% of the membrane). The primary lipid is called phospholipid, and molecules of phospholipid form a 'phospholipid bilayer' (two layers of phospholipid molecules). This bilayer forms because the two 'ends' of phospholipid molecules have very different characteristics: one end is polar (or hydrophilic) and one (the hydrocarbon tails below) is non-polar (or hydrophobic):

o Functions include:
+ supporting and retaining the cytoplasm
+ being a selective barrier
# The cell is separated from its environment and needs to get nutrients in and waste products out. Some molecules can cross the membrane without assistance, most cannot. Water, non-polar molecules and some small polar molecules can cross. Non-polar molecules penetrate by actually dissolving into the lipid bilayer. Most polar compounds such as amino acids, organic acids and inorganic salts are not allowed entry, but instead must be specifically transported across the membrane by proteins.
+ transport
# Many of the proteins in the membrane function to help carry out selective transport. These proteins typically span the whole membrane, making contact with the outside environment and the cytoplasm. They often require the expenditure of energy to help compounds move across the membrane
+ communication (via receptors)


Source: http://bio.winona.msus.edu/berg/ANIMTNS/Recep.htm

+ recognition


Source: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html

Cells, cytoplasm, and organelles:

* Cytoplasm consists of a gelatinous solution and contains microtubules (which serve as a cell's cytoskeleton) and organelles (literally 'little organs')

* Cells also contain a nucleus within which is found DNA (deoxyribonucleic acid) in the form of chromosomes plus nucleoli (within which ribosomes are formed)

* Organelles include:
o Endoplasmic reticulum -
+ comes in 2 forms: smooth and rough; the surface of rough ER is coated with ribosomes; the surface of smooth ER is not
+ functions include: mechanical support, synthesis (especially proteins by rough ER), and transport
o Golgi complex -
+ consists of a series of flattened sacs (or cisternae)
+ functions include: synthesis (of substances likes phospholipids), packaging of materials for transport (in vesicles), and production of lysosomes
o Lysosomes -
+ membrane-enclosed spheres that contain powerful digestive enzymes
+ functions include destruction of damaged cells (which is why they are sometimes called 'suicide bags') & digestion of phagocytosed materials (such as bacteria)

o Mitochondria -
+ have a double-membrane: outer membrane & highly convoluted inner membrane

+ inner membrane has folds or shelf-like structures called cristae that contain elementary particles; these particles contain enzymes important in ATP production
+ primary function is production of adenosine triphosphate (ATP)
o Ribosomes-
+ composed of rRNA (ribosomal RNA) & protein
+ may be dispersed randomly throughout the cytoplasm or attached to surface of rough endoplasmic reticulum
+ often linked together in chains called polyribosomes or polysomes
+ primary function is to produce proteins
o Centrioles -
+ paired cylindrical structures located near the nucleas
+ play an important role in cell division
o Flagella & cilia - hair-like projections from some human cells
+ cilia are relatively short & numerous (e.g., those lining trachea)
+ a flagellum is relatively long and there's typically just one (e.g., sperm)

o Villi - projections of cell membrane that serve to increase surface area of a cell (which is important, for example, for cells that line the intestine)

DNA (Deoxyribonucleic acid) - controls cell function via transcription and translation (in other words, by controlling protein synthesis in a cell)


Source: www.ornl.gov/hgmis/publicat/primer/fig5.html

Transcription - DNA is used to produce mRNA


Source: http://www.nytimes.com/2003/01/21/science/21RNA.html

Translation - mRNA then moves from the nucleus into the cytoplasm & is used to produce a protein

o requires mRNA, tRNA (transfer RNA), amino acids, & a ribosome


tRNA molecule

Used with permission of John Kimball

o sequence of amino acids in a protein is determined by sequence of codons (mRNA). Codons are 'read' by anticodons of tRNAs & tRNAs then 'deliver' their amino acid.
o Amino acids are linked together by peptide bonds (see diagram to the right)
o As mRNA slides through ribosome, codons are exposed in sequence & appropriate amino acids are delivered by tRNAs. The protein (or polypeptide) thus grows in length as more amino acids are delivered.
o The polypeptide chain then 'folds' in various ways to form a complex three-dimensional protein molecule that will serve either as a structural protein or an enzyme.



Used with permission of John Kimball




Source: http://www.acsu.buffalo.edu/~jbarnard/GtRNA.html

COMPONENTS OF THE CELLULAR ENVIRONMENT

Water:

* comprises 60 - 90% of most living organisms (and cells)
* important because it serves as an excellent solvent & enters into many metabolic reactions

Ions = atoms or molecules with unequal numbers of electrons and protons:

* found in both intra- & extracellular fluid
* examples of important ions include sodium, potassium, calcium, and chloride

Carbohydrates:

* about 3% of the dry mass of a typical cell
* composed of carbon, hydrogen, & oxygen atoms (e.g., glucose is C6H12O6)
* an important source of energy for cells
* types include:
o monosaccharides (e.g., glucose) - most contain 5 or 6 carbon atoms
o disaccharides
+ 2 monosaccharides linked together
+ Examples include sucrose (a common plant disaccharide is composed of the monosaccharides glucose and fructose) & lactose (or milk sugar; a disaccharide composed of glucose and the monosaccharide galactose)
o polysaccharides
+ several monosaccharides linked together
+ Examples include starch (a common plant polysaccharide made up of many glucose molecules) and glycogen (commonly stored in the liver)

Lipids:

* about 40% of the dry mass of a typical cell
* composed largely of carbon & hydrogen
* generally insoluble in water
* involved mainly with long-term energy storage; other functions are as structural components (as in the case of phospholipids that are the major building block in cell membranes) and as "messengers" (hormones) that play roles in communications within and between cells
* Subclasses include:
o triglycerides - consist of one glycerol molecule + 3 fatty acids (e.g., stearic acid in the diagram below). Fatty acids typically consist of chains of 16 or 18 carbons (plus lots of hydrogens).

o phospholipids - a phosphate group (-PO4) substitutes for one fatty acid & these lipids are an important component of cell membranes
o steroids - include testosterone, estrogen, & cholesterol

Proteins:

* about 50 - 60% of the dry mass of a typical cell
* subunit is the amino acid & amino acids are linked by peptide bonds
* 2 functional categories = structural (proteins part of the structure of a cell like those in the cell membrane) & enzymes
o Enzymes are catalysts. Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze. In doing so, they lower the amount of activation energy needed and thus speed up the reaction.


Used by permission of John W. Kimball

Nucleic Acids:

* DNA
* RNA (including mRNA, tRNA, & rRNA)

Movement Across Membranes

1 - Passive processes - require no expenditure of energy by a cell:

* Simple diffusion = net movement of a substance from an area of high concentration to an area of low concentration. The rate of diffusion is influenced by:
o concentration gradient
o cross-sectional area through which diffusion occurs
o temperature
o molecular weight of a substance
o distance through which diffusion occurs
* Osmosis = diffusion of water across a semipermeable membrane (like a cell membrane) from an area of low solute concentration to an area of high solute concentration (check rbl.cvmbs.colostate.edu/hbooks/cmb/cells/pmemb/osmosis.html for more information about osmosis)

* Facilitated diffusion = movement of a substance across a cell membrane from an area of high concentration to an area of low concentration. This process requires the use of 'carriers' (membrane proteins). In the example below, a ligand molecule (e.g., acetylcholine) binds to the membrane protein. This causes a conformational change or, in other words, an 'opening' in the protein through which a substance (e.g., sodium ions) can pass.

2 - Active processes - require the expenditure of energy by cells:

o Active transport = movement of a substance across a cell membrane from an area of low concentration to an area of high concentration using a carrier molecule


Active Transport: The Sodium-Potassium Pump
Used with permission of Gary Kaiser

o Endo- & exocytosis - moving material into (endo-) or out of (exo-) cell in bulk form


Used with permission of Gary Kaiser

Shown here is one way that active transport can occur. Initially, the membrane transport protein (also called a carrier) is in its closed configuration which does not allow substrates or other molecules to enter or leave the cell. Next, the substance being transported (small red spots) binds to the carrier at the active site (or binding site). Then, on the inside of the cell, ATP (Adenosine TriPhosphate) binds to another site on the carrier and phosphorylates (adds one of its phospate groups, or -PO4, to) one of the amino acids that is part of the carrier molecule. This attachment of a phosphate group to the carrier molecule causes a conformational change in (or a change in the shape of ) the protein so that a channel opens between the inside and outside of the cell membrane. Then, the substrate can enter the cell. As one molecule of substrate enters, the phosphate group comes off the carrier and the carrier again 'closes' so that no other molecules can pass through the channel. Now the transport protein, or carrier, is ready to start the cycle again. Note that as materials are transported into the cell, ATP is used up and ADP and -PO4 accumulate. More ATP must be made by glycolysis and the Kreb's cycle.

Characteristics of Facilitated Diffusion & Active Transport - both require the use of carriers that are specific to particular substances (that is, each type of carrier can 'carry' one type of substance) and both can exhibit saturation (movement across a membrane is limited by number of carriers & the speed with which they move materials; see graph below).

CELLULAR METABOLISM:

Cells require energy for active transport, synthesis, impulse conduction (nerve cells), contraction (muscle cells), and so on. Cells must be able to 'capture' and store energy & release that energy in appropriate amounts when needed. An important source of energy for cells is glucose (C6 H12O6):

C6H12O6 + O2 ----------> CO2 + H2O + ENERGY

However, this reaction releases huge amounts of energy (for a cell). So, cells gradually break down glucose in a whole series of reactions & use the smaller amounts of energy released in these reactions to produce ATP (Adenosine Triphosphate) from ADP (Adenosine Diphosphate). Then, cells can break down ATP (as in this reaction):

A----P++P++P <-----> A----P+++P + P + 7700 calories*

(*Those of you who know about food Calories may be surprised by this number. After all, an entire candy bar may contain only 200 food Calories. The explanation lies in the capital C. One food Calorie, spelled with a capital C, is 1000 times larger than one physiologist's calorie, spelled with a small c.)

The energy released in this reaction is used by cells for active transport, synthesis, contraction, and so on. Cells need large amounts of ATP &, of course, must constantly make more. But, making ATP requires energy. The breakdown of glucose does release energy. But, how, specifically, is the energy released in the breakdown of glucose used to make ATP.

A primary source of ENERGY is OXIDATION. Specifically, cells use a type of oxidation called HYDROGEN TRANSFER to generate energy:

XH2 + Y ------> X + YH2 + ENERGY

These hydrogen transfer reactions are so-named because pairs of hydrogens are 'transferred' from one substance (XH2 in the above reaction) to another (YH2 in the above reaction). Because the reactants (XH2 + Y) represent more energy than the products (X + YH2), this reaction releases energy.

In a cell, hydrogen transfer reactions occur in MITOCHONDRIA. Pairs of hydrogens are successively passed from one substance to another, and these substances are called HYDROGEN CARRIERS.

XH2 + NAD ----> NADH2 + FAD ----> FADH2 + Q ----> QH2 + C-1 ----> C-2 ---->

C-3 ----> C-4 ----> H2O + X

These hydrogen transfer reactions release energy that is used to make ATP from ADP (in other words, to add a third phosphate to adenosine diphosphate in a reaction called phosphorylation). So, what occurs in mitochondria involves hydrogen transfer (a type of oxidation) + phosphorylation, or, in other words, OXIDATIVE PHOSPHORYLATION. Oxidative phosphorylation produces lots of energy but requires hydrogen. Where do the hydrogens come from?

Sources of hydrogen include GLYCOLYSIS and the KREB'S CYCLE.

Glycolysis involves the breakdown of glucose. Cells obtain glucose from the blood. Blood glucose levels are maintained by the interaction of two processes: glycogenesis and glycogenolysis. Glycogenesis is the production of glycogen from glucose and occurs (primarily in the liver and skeletal muscles) when blood glucose levels are too high (for example, after a meal).

Glycogenolysis is the reverse process - the breakdown of glycogen to release individual molecules of glucose. This occurs when blood glucose levels begin to decline (for example, several hours after a meal). The interaction of these two processes tends to keep blood glucose levels relatively constant.

Glucose taken up by cells from the blood is used to generate energy in a process called glycolysis.

In the first few steps of glycolysis, glucose is converted into fructose-1,6-diphosphate. These reactions, like all chemical reactions, involve making and breaking bonds between atoms, and this sometimes requires energy. Even though glycolysis, overall, releases energy, some energy must be added initially to break the necessary bonds and get the energy-producing reactions started. This energy is called activation energy. In the above diagram, energy (i.e., a molecule of ATP) is needed at steps 1 & 3. So, before the energy-producing reactions of glycolysis begin, a cell must actually use two molecules of ATP.

Overall, glycolysis can be summarized as:

Glucose ----> 2 Pyruvic Acid (or pyruvate) + 2 net ATP + 4 hydrogens (2 NADH2)

So, glycolysis produces 2 direct ATP (ATP produced directly from the reactions that occur during glycolysis) and 6 indirect ATP (the 4 hydrogens produced in glycolysis will subsequently go through oxidative phosphorylation and produce 3 ATP per pair, i.e., 4 hydrogens equals 2 pair and 2 pair times 3 ATP equals 6 ATP). Thus, glycolysis produces a total of 8 ATP.

Next comes an intermediate step (called oxidative decarboxylation):


Used with permission of Gary Kaiser

the 2 Pyruvic Acid are converted into 2 Acetyl CoA & this reaction produces 4 hydrogens (2 NADH2). Those hydrogens (i.e., 2 pair of hydrogens) go through oxidative phosphorylation and produce 6 more ATP (2 pair @ 3 ATP per pair).

Finally, comes the Kreb's Cycle:

2 Acetyl CoA go through this cycle of reactions and produce 2 ATP (= GTP in the above diagram) + 16 hydrogens (6 NADH2 + 2 FADH2) plus the waste products carbon dioxide + water. The 16 hydrogens go through oxidative phosphorylation and produce 22 ATP [22 because 12 of these hydrogens (6 NADH2) go completely through the reactions of oxidative phosphorylation and produce 18 ATP (6 pair @ 3 ATP per pair), while 4 of these hydrogens (2 FADH2) go through only some of the reactions and produce 4 ATP (2 pair @ 2 ATP per pair).

Overall, therefore, the Kreb's cycle produces 24 ATP (2 direct & 22 indirect).

OVERALL ATP PRODUCTION from glucose = 8 (from glycolysis) + 6 (from the hydrogens produced when the 2 pyruvic acid are converted into 2 acetyl CoA) + 24 (from the Kreb's cycle) for a GRAND TOTAL OF 38:


Direct

Indirect (O.P.)

TOTAL
Glucose ----> 2 Pyruvic Acid

2

6

8
2 Pyruvic Acid ----> 2 Acetyl CoA

0

6

6
2 Acetyl CoA ----> CO2 + H2O

2

22

24

Overall Total = 38 ATP

Glucose (carbohydrates) are not the only source of energy for cells. Fats (or lipids), like triglycerides, are also metabolized to produce energy.

Triglycerides ----> Glycerol + Fatty Acids:

* Glycerol ----> Glyceraldehyde ----> Pyruvic Acid ----> Acetyl CoA ----> Kreb's Cycle
* Fatty Acids are converted into molecules of Acetyl CoA in a process called BETA OXIDATION.

This reaction not only produces lots of Acetyl CoA (or acetate) but lots of hydrogens. The Acetyl CoA goes through the Kreb's Cycle, while the hydrogens go through Oxidative Phosphorylation.

Proteins are first broken down into amino acids. The nitrogen component of amino acids is then removed (in a reaction called DEAMINATION), and these deaminated amino acids are then converted into Acetyl CoA which passes through the Kreb's Cycle to make more ATP.


Proteins are also used as a source of energy.