cellular biology quiz
Why does carbon work so well in organic molecules?
Carbon has 4 valence electrons, giving it 4 opportunities to bond with other atoms, making it very stable. Because of its stability large proteins or molecules like titin can be formed
Macromolecules
made of polymers (repeating units of monomers) Carbohydrates, lipids, proteins and nucleic acids are all examples
monomer
the smallest repeating unit of a polymer
Carbohydrates
Consist of Carbon, Hydrogen and Oxygen. They are made of one or more simple sugars, their monomers often being ring shaped. Their main function is short-term energy storage. Carbon-hydrogen-oxygen follow a 1:2:1 ratio and appear as CH2O in their basic form
Monosaccharides
A simple carbohydrate containing 3-7 carbon atoms. Hexosugars C6H12O6 and Pentosugars C5H10O5
Glucose
Hexosugar, it's the base unit for many polymers, Oxygen takes the 6th corner while the rest are carbon (counter-clockwise), another carbon appears at the top of the first corner. The form of sugar that fuels respiration
Properties of Glucose
Glucose is a polar molecule because of the covalent bond in its 5 hydroxl groups (-OH), making it stable, highly soluble in water, easily transportable within fluids, and creates lots of chemical energy when covalent bonds are broken. Alpha glucose: Hydrogen on top of 5th corner, Beta glucose: Hydrogen on bottom of 5th corner
Galactose
Hexose sugar, same formula as the others but is less sweet, commonly found in milk
Fructose
hexose-sugar. Looks like a pentose-sugar, but the other two carbons branch off the 5th and 1st corners. Commonly found in fruits and honey, is the sweetest natural carbohydrate
Ribose
Pentose-sugar, forms the backbone of RNA
Deoxyribose
form of ribose, differs because it has no hydroxyl group on carbon 2, and only a hydrogen, forms the backbone of DNA
disaccharides
a carbohydrate composed of two monosaccharides joined by a covalent bond, this bond is called a glycosidic linkeage and forms between the hydroxyl groups, only occurs between the hoxose-sugars. Formed through a condensatiion reaction, H2O is always left behind
Maltose
A dimer (two of) glucose
Lactose
made up of galactose and glucose, most commonly found in milk
Sucrose
made up of glucose and fructose, also known as table sugar
polysaccharides
many monosaccharides bond together via glycosidic linkages to form them. Starch, glycogen and cellulose are the most common. Most common links occur between hydroxyl groups on carbons 1 and 4 (1-4) and between the hydroxyl groups on carbons 1 and 6 (1-6)
cellulose
Found in the cell walls of plants, 1-4 bond between beta glucose. They are unbranched and each subunit alternate between upwards and downwards, causing a straight chain and high tensile strength. Prevents plants from bursting.
Starch
1-4 link between alpha glucose. Each subunit is orientated in the same way, causing the chain to be curved. Amylose and Amylopectin are two forms of starch. Amylose is unbranched and forms a helix. Amylopectin has more glucose units, is more globular in shape and branched. Starch is only found in plants, both types are hydrophilic but too large to be soluble in water
Glycogen
Links happen between 1-4 on a-glucose, and branches occur where 1-6 links happen (branches many times). Glycogen is made by animals and some fungi, stored in the liver and some muscles. When blood glucose is high, the pancreas will release insulin, causing glucose in the blood to merge in the liver and create glycogen which can be stored for later. Later on Glucogon will break down glycogen again to send it back to the blood.
glycoproteins
proteins with an oligosaccharide attached (covalently). There are two types that show up on the membrane of red blood cells, A and B (both antigens) these determine your ABO blood type. Important for cell recognition by the immune system and hormone receptors.
Lipids
Used for long term energy storage, coating and cushioning organs, hormones, etc. Insoluble in water, but soluble in non-polar substances (hydrophobic). Lipids are made of glycerol and fatty acids which contain oxygen, hydrogen, and carbon
Phospholipids
a glycerol and 2 fatty acids bonded together with an r group. IN water, phospholipids form a lipid bilayer. They arange themselves so that the non-polar tail is tucked away from the water, and the polar head are directed toward the water
Hydrolysis reactions
The reverse of condensation reactions, e.g polysaccharide + water --> monosaccharides
Steroids
composed of four fused carbon rings with functional groups attached to them. makes hormones like cholesterol and testosterone. They are produced in the gonadal tissue and are involved in the development of secondary and primary sex characteristics from puberty. Hydrophobic and can pass through the lipid bilayer of cells
Waxes
Composed of long carbon-based chains, solids at room temperature, can be found on skin, hair, feathers, etc. Function as waterproof coatings
Triglycerides
used for energy storage, composed of one glycerol molecule and three fatty acids (ester bonds). Carboxyl from fatty acid and hydroxyl from glycerol (ester linkage)
Saturated fatty acids
No double bonds, contain maximum amount of hydrogen bonds, mostly solid, straight
Monounsaturated fatty acids
have one double bond between carbon atoms, tail kinks so molecules arent too close, liquid at room temperature
polyunsaturated fatty acids
two or more double bonds between carbon atoms, low melting points
Discovery of DNA
Friedrich Miescher isolated the nuclei of white blood cells, from there he extracted a slightly acidic substance containing phosphorus and nitrogen, which was later named nucleic acid (DNA). Phoebus Levene was able to isolate DNA and RNA in the 1900s, he also proposed that they were both made up of subunits called nucleotides
Nucleic Acids
Information from DNA is passed from cell to cell through generations, it also codes for proteins (one gene --> one protein)
What experiment determined DNA's hereditary purpose?
Hershey-chase
Viruses
viruses can have either DNA or RNA as their genetic information, not considered to be alive since they cannot survive without a host cell, only purpose is to reproduce
Nucleotides
They are monomers that make up nucleic acids (polymers). Composed of a nitrogenous base: Adentine, Thymine, Cytosine, Guanine, Uracil, pentose sugar, and a negatively charged phosphate group
Nitrogen bases
Both RNA and DNA use cytosine, adenine, and guanine. DNA uses thymine and uracil
connection of Nucleotides
bonds are formed between the phosphate of one nucleotide and the pentose sugar of the next. Results in a phosphodiester bond and the formation of a water molecule. This runs throughout the whole strand, creating a phosphate-sugar backbone
DNA structure
phosphate sugar backbone is on the outside, hydrogen bonds within the nitrogenous bases hold the two strands together, strands run in opposite directions (anti-parallel),
Complementary base pairing
Adenine only pairs with Thymine, and Guanine only pairs with cytosine, however in RNA Adenine is replaced by Uracil
Differences between DNA and RNA
DNA is double stranded, codes for making RNA during transcription, found in the nucleus. RNA is single stranded, codes for making proteins during transcription, found in the nucleus and the cytoplasm
DNA sequence
every three nitrogenous bases from nucleotides make a triplet codon, one each coding for an amino acid, all living things use the same genetic code, and it is theorized that this code came from Last Universally Common Ancestor
Polypeptides
a polymer composed of amino acid monomers, one or more of them together creates a protein,
Amino Acids
Composed of a central carbon atom bonded to a hydrogen atom, an amino group, a carboxyl group, and a variable R group (r is what determines which out of 20 amino acids), Linked by peptide bonds (between amine group and carboxyl group) to form polypeptides, 9 are considered essential (body doesnt make them, need to be consumed) children and vegans need to eat more
Anabolism by condensation
Ribosomes condense two amino acids to form a peptide bond, taking the hydrogen from one and hydroxyl group from the other = dipeptide and h2o,
Oligopeptides and peptide bonds
Two amino acids are linked via the carboxyl group of one and the amine group of the other. Long chains of peptide bonds are called oligopeptides. The four atoms surrounding a peptide bond should consist of hydrogen linked to nitrogen, nitrogen to carbon, and carbon double bonded to oxygen, only remaining amine and carboxyl groups are the terminals at the end.
Central Dogma of genetics
Most genes in a cell store the polypeptide chains. DNA --(transcription)--> messenger RNA --(translation)--> Polypeptide
Primary Structure
The order amino acids are in that compose the protein, formed by peptide bonds between adjacent amino acids, controls all subsequent levels of structure, funky squigly line
Secondary structure
chains of amino acids fold/turn in on themselves, held together by hydrogen bonds via the (non-adjacent) charged amine and carboxyl groups. Shaped like helixes or pleated sheets, very stable
tertiary structure
polypeptide folds and coils to form a complex 3d shape, caused by reactions between the r groups. Structure depends on the function, some are long chains (fibrous proteins) and others are sphere shaped (globular proteins)
Quaternary structure
interaction between multiple polypeptides or prosthetic groups - inorganic compound involved in the protein, fibrous and globular proteins
Polarity on protein structure
Lipase (enzyme that breaks down lipids in small intestine, non-polar amino acids go in the middle, polar ones go on the outside to make it soluble in the small intestine) and glycoproteins (portion within the membrane is hydrophobic to interact with lipid tails, outer portion is hydrophilic to interact with plasma and sugars)
fibrous proteins
long and narrow, provide strength and support, insoluble in water, repetitive amino acid sequence, much more stable, e.g collagen and keratin
globular proteins
round shape, used for transport and functional purposes, soluble in water, irregular amino acid sequence, less stable, e.g insulin
non-conjugated vs conjugated proteins
non-conjugated only contain amino acid residues but no other chemical components, conjugated contain amino acid residues and other chemical components like a prosthetic group
insulin
non-conjugated, globular, affected cells have a protein on their surface causing a signal pathway (reactions) to occur, channels open in the liver, muscles etc to allow glucose in, secreted by the pancreas. Insulin can be inactive because it forms dimers or hexamers, only active when theyre seperate
collagen
fibrous polypeptides wound together to form a helix shape, takes up a quarter of all protein in the human body, repeating sequences, forms a mesh of fibres to help prevent tearing and create strength (blood vessels, muscles) prevents teeth from cracking
hemoglobin
conjugated protein in red blood cells, transports oxygen and other stuff throughout the body, made of 4 subunits (prosthetic group: Heme) oxygen and carbon dioxide are non-polar so they bind to the heme to be transported
denaturation of proteins
Bonds between r groups in amino acids are weak and can be broken easily, denaturation happens when proteins completely unfold, can't perform its usual function, exposure to chemicals and extreme temperatures can cause it. exceptions: Volcanic spring microrganisms (hot temperatures), and pepsin enzyme (acids)
Water is essential
there is evidence that water on earth first originated 4.5 billion years ago, in order to maintain itself the molecular ingredients of life must react together in a liquid solvent (there is also debate on what form the water originally came in). The first cells formed and developed in oceans
water purpose
Water is the solvent that makes up the cytoplasm, makes up the fluid inside organelles, permits transport in and out of cells, essential to blood, etc
Water molecules and their bonds
The covalent bonds between hydrogen and oxygen are not shared equally, oxygen has 8 electrons vs hydrogen with one, making the oxygen end slightly negative and hydrogen end slightly positive. This makes it polar, and it can attract other polar molecules
Cohesion: Water
this is caused by hydrogen bonds within water molecules, hydrogen bonds are weak alone, but together they are very strong. Each hydrogen molecule sticks to four others.
Surface tension
Causes droplet formation because the molecules above the water establish hydrogen bonds with the molecules in the water. These molecules have no other molecules to bond with, so they are automatically attracted to their nearest neighbor on and below the surface making it contract, allowing bugs to live on it, evaporation forces can also make water stick and move upwards on a plant
Adhesion: Water
Happens because of polarity and hydrogen bonds, It is attracted to polar/charged materials, allowing it to be drawn through narrow tubes
Capillary action
Helps water be drawn into a plant from soil, soil has many thin tube like channels through which water molecules stick to soil molecules and are drawn up into the plant. Capillary action also allows for water to be drawn up plant stems as they are made of polar cellulose fibre wicks
Solvation: Water
Solvation is the combination of a solvent and the molecules/ions of a solute. A hydration shell is formed when solvent molecules form a solvent shell around solute molecules (as water does this to dissociated ions water molecules shell around each individual ion, charged ends of water interact with oppositely charged ions) Ions get separated and stabilized, less attracted to eachother and more to the water
Water: solvent properties
The polar attraction of large amounts of water molecules can interrupt bonds and other forces between molecules (positive atoms are surrounded by -oxygen, negative atoms are surrounded by +hydrogen). E.g Metabolic reactions happen often in water such as oxygen in alveoli turning into the moist layer around it befoe diffusing into the blood
Transport of molecules in the blood
In plants, the xylem carries nutrients throughout, in animals it's the blood. Glucose (hydrophilic) placed in water forms hydrogen bonds with its hydroxyl groups. Amino acids (The r group can be charged) soluble enough to be carried in blood plasma. Oxygen, hydrogen + carbon dioxide (non-polar) must be bound to the heme to travel in water. Fats (non-polar) goes into lipoprotein complex which has phophate layer (hydrophilic). Cholestoral (hydrophobic) in lipid protein complex, and steroids which bind to proteins to travel through blood
Buoyancy: Water
fluid will exert an upward force on objects placed in it - force is equal to weight of the fluid displaced by object. Object (lower density = float, higher density = sink) Ice is less dense than water, baring/protecting liquid water for animals in winter months. Bony fish have air in them so they float (bones are denser than water), birds have lighter bones to stay buoyant in air
viscosity: Water
consequence of the type of bonding within a fluid, in liquids water has relatively weak forces of attraction so its viscosity is low, solutes increase viscosity
Water: thermal conductivity
The rate at which heat passes through animals, water has a high thermal conductivity. Warm blooded animals lose energy fast by transfering their heat energy to water. High water content of blood allows it to transfer heat around the body easily
specific heat capacity
The heat required to raise temperature of 1g of materical by 1 C. Water has a high heat capacity due to the hydrogen bonds that limit molecular motion, hydrogen bonds must be broken to change temperature a lot of energy is required to do so. Water's stability makes it a perfect habitat for animals
Ringed seal
floating is difficult because seals are heavy but the fat storage under the skin makes the seal more buoyant, obese so not much effort needed when penetrating viscosity of water, flippers, heat from the seal is easily conducted to water, blubber provides insulation, nests in ice caves
Arctic Loon
Airy feathers make wings buoyant, in water buoyancy is aided by air sacs which can be inflated or compressed, powerful muscles in legs to help with diving, torpedo bodyshape, thick dense feathers are waterproof
Goldilocks Zone
the habitable zone, the region around a star where conditions are just right for the prescence of liquid water and therefore life