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Carbohydrates- different types
- monosaccharides (glucose and company)
- disaccharides (maltose and sucrose, etc.)
- polysaccharide (starch and multiple monosaccharides bonded together)
These carbohydrates as used to make ATP via cellular respiration. It's basically a place for energy storage. It can also be used in cells as cell walls (chitin and cellulose are both carbohydrates). Their structure is appropriate, because it's purpose is an energy bank and thus getting the energy when it is needed would be helpful. All you have to do to get energy from polysaccharides is just add H2O and it'll become a simpler monosaccharide, easily able to be formed into ATP.
Lipids- Includes triglycerides, steroids, phospholipids, and fats.
Fats: fatty acids and glycerol, has a carboxyl group at the end. Fats help to protect organs, provide insulation, and to store energy.
Saturated and Unsaturated Fats: Saturated has kinks, Unsaturated has no kinks.
Phospholipids: Has a hydrophobic and hydrophilic part. Vital to the fluid mosaic membrane model. It's structure keeps it so there are hydrophilic parts facing the water while the hydrophobic parts do not in the cell membrane.
Steroids: Hormones and stuff are included in this.
Triglycerols: make up body fat, good for storage of energy.
Proteins- Many different types and functions of proteins, including but not limited to:
- Structural proteins
- Storage proteins
- Transport proteins
- Enzymes
Primary structure is composed of amino acids; secondary structure are alpha helixes and beta sheets; Tertiary structure are folds of a-helixes and b-sheets, R group interactions make them fold; Quaternary structure have complex folds and twists, interaction between proteins with subunits.
Nucleic acids- Usually found in DNA/RNA, have genetic info stored in chains of nucleotides. Nucleotides: Adenine, Guanine, Cytosine, Thymine If the cell cycle doesn't function properly, tumors may form. Some cell cycle inhibitors may mutate and cause cells to multiply uncontrollably, which forms a tumor. The cell cycle in these tumor cells is equal or longer than that of a normal cell, but the number of cells undergoing cell division is much higher.
Each point of transition in the cell cycle from one phase to another is governed by multiple proteins which serve as either "accelerators" or "brakes" for the cell cycle. These proteins are coded by DNA,. The mutation in the protein-specific DNA creates either no protein, overactive protein, or under active protein. In any case, it creates a disruption to the cycle, which disturbs orderly cell growth and division. This problem can lead to cancer.
Cancers are diseases in which there is a defect in the regulation of the cell cycle. Cancer cells are rapidly dividing cells that no longer are controlled. Cancer cells can form tumors due to this unchecked growth.
Normal cells have a characteristic called "contact inhibition" which limits the division of cells when the space is very crowded. Normal cells also are limited by the number of times that they may divide, therefore limiting their lifespan. Unlike normal cells, cancer cells lack the contact inhibition that limit their growth. They also are immortal cells and are not limited by the number of times they can divide. During meiosis, the genome of a diploid germ cell, which is composed of long segments of DNA packaged into chromosomes, undergoes DNA replication followed by two rounds of division, resulting in haploid cells called gametes. Each gamete contains one complete set of chromosomes, or half of the genetic content of the original cell. These resultant haploid cells can fuse with other haploid cells of the opposite sex or mating type during fertilization to create a new diploid cell, or zygote. Thus, the division mechanism of meiosis is a reciprocal process to the joining of two genomes that occurs at fertilization. Because the chromosomes of each parent undergo genetic recombination during meiosis, each gamete, and thus each zygote, will have a unique genetic blueprint encoded in its DNA. In other words, meiosis and sexual reproduction produce genetic variation.
Also in meiosis crossing over occurs- this increases genetic variation. Crossover produces recombinant chromosomes that combine genes inherited from both parents. Ensures greater variation among gametes. The C4 photosynthetic adaptation has allowed plants living in conditions with low CO2 to keep their stomata open less often since PEP Carboxylase fixes the CO2 immediately into OAA (oxaloacetate) once it enters the plant cell and transfers it into mesophyll cells. The OAA is then converted into malate with the help of NADPH, which is then taken to the chloroplasts in specialized bundle sheath cells. The four carbon malate then breaks into a CO2, three carbon pyruvate, and NADPH. The CO2 then enters the calvin cycle, producing the sugars like normal. The pyruvate re-enters the mesophyll cells, reacts with ATP, and is converted back to PEP so the whole cycle can start over again.
CAM plants open their stomata to fix CO2 only at night, using PEP carboxylase to form the CO2 into OAA, just like in C4 plants. THe OAA is converted to malate, which is then stored in vacuoles. When the stomata are closed during the day, CO2 is removed from the malate to enter the Calvin cycle. Prokaryotes regulate gene expression through the operon. There are two different models: the inducible (ex: the Lac Operon) and the repressible (ex: The Tryptophan Operon).
The lac operon: This only gets turned on when no other sugar is available to the bacteria, so they HAVE to use lactose.Allolactose binds to the repressor and changes its shape. Because its shape is changed, there is no longer anything stopping RNA polymerase from binding to the promoter, and transcription occurs.
The tryptophan operon: If Tryptophan levels are high, then the bacterium doesn't need anymore, so it doesn't need to make anymore. A repressor binds to the corepressor, tryptophan, it changes its shape and binds to the operator, which prevents RNA polymerase from binding to the promoter. And, because of this transcription cannot happen, and no more are made!!
Eukaryotes regulate gene expression through Hormones. There are two different types of hormones: steroids and nonsteroidal. Steroids are lipids that just diffuse through the cell membrane and bind to a receptor, causing a cell response. Non Steroids are proteins that bind to a receptor outside of the cell. This triggers a secondary messenger inside the cell, and triggers the cell response. 
