Midterm 1 Flashcards
What are the properties of life?
Homeostasis, energy utilization, reproduction, order, growth & development, response to environment and evolutionary adaptation.
Are all 7 properties of life required for something to be considered living?
Yes. Viruses have only a few of the properties of life and therefore are not considered to be living.
Does all life stem from a common ancestor?
Yes, all forms of life come from a common ancestor.
What are the levels of biological organization, from biggest to smallest?
Biosphere, ecosystem, community, population, organism, organ system, organ, tissue, cell, organelles, molecules, atoms.
Define “energy flow”.
Energy flow refers to the transfer and transformation of energy that is performed by all living things. Recall that energy utilization is a property of life. It is the flow of energy through an ecosystem.
What is the primary source of energy for all life on earth?
The sun.
What are autotrophs?
Autotrophs are organisms that do not consume other organisms. They produce their own organic molecules (food) by means of photosynthesis, hence the name “producers”.
What are heterotrophs?
Heterotrophs are organisms that cannot produce their own food. They are “consumers” in that they must consume other organisms and/or organic molecules produced by other organisms.
Is the classic food chain model actually found in nature?
No, to model the actual behaviour of each organism in relation to each other organism, we’d have to draw up a complex food web.
What is trophic structure?
Also referred to as an energy pyramid, it is the system of organization of organisms into different trophic levels based on the amount of energy it consumes.
How much energy is transferred from one trophic level to the next? What happens to the rest of it?
Only about 10% of the energy consumed from one trophic level is passed on the next, the other 90% is lost to the environment in the form of heat.
What is photosynthesis?
Photosynthesis is the transformation of solar energy to chemical energy (glucose). This chemical reaction occurs in the CHLOROPLAST of plants, algae and some bacteria.
What is the chemical equation of photosynthesis?
CO2 + H2O + Solar E –> C6H12O6 (glucose) + O2
What is cellular respiration?
Cellular respiration is the process of breaking down food (such as glucose) transforming it into chemical energy in the form of ATP. This chemical reaction occurs in all organisms in the MITOCHONDRIA.
What is the chemical equation of cellular respiration?
C6H12O6 (glucose) + O2 –> CO2 + H2O + ATP
What is ATP?
Adenosine triphosphate is the energy currency of the cell. It is not energy itself, but rather an organic compound that stores energy for cellular work.
What does ATP consist of?
A nitrogenous base, a 5-carbon sugar (ribose) and 3 negatively charged phosphate groups.
What is hydrolysis?
A chemical process wherein the introduction a water molecule can break down complex molecules.
ATP is said to be a renewable source of energy in the cell. What does this mean?
When an ATP molecule is broken down by hydrolysis and energy is released, you are left with an inorganic phosphate and an adenosine diphosphate molecule (ADP). When the cell carries out an unrelated catabolic reaction, the energy released can be used to rebuild the “broken” ATP molecule from its components. This new energy is therefore being stored in the bonds of our newly built ATP molecule. In that sense, ATP is a renewable resource.
What is catabolism?
Catabolism refers to the catabolic processes that involve a series of degrative chemical reactions that break down complex molecules into smaller units, releasing the energy stored in that molecule’s bonds. These processes are exergonic.
What is anabolism?
Anabolism refers to the anabolic processes that involve a sequence of chemical reactions that synthesis molecules from smaller units, requiring an input of energy (ATP). These processes are endergonic.
An exergonic reaction _____ energy.
An exergonic reaction releases energy.
An endergonic reaction _____ energy.
An endergonic reaction absorbs energy.
Using ATP as a medium, describe the cycle formed by catabolic and anabolic processes.
The energy released by catabolic processes is stored in the form of ATP. This energy is eventually released and used by anabolic processes to build a complex molecule from smaller units. This complex molecule is eventually broken down again by another catabolic process in which more energy is released.
Are Hydrogen bonds a type of covalent bond?
No, hydrogen bonds are attractive forces between two molecules resulting from the polarity of each molecule.
Is water polar? If so, why?
Water molecules are polar due to the unequal charge distribution of its atoms. Since the electrons spend more time around the oxygen atom than they do the hydrogen atoms, oxygen is more electronegative than hydrogen.
Do hydrogen bonds form between different water molecules?
Yes, the slightly H+ atoms of one water molecule is attracted to the slightly O- atom of another molecule. Each water molecule can form a maximum of 4 hydrogen bonds.
What is cohesion?
Cohesion is water’s ability to link together by forming hydrogen bonds between its molecules. This makes water more structured than other liquids and gives it a higher surface tension.
What is adhesion?
Adhesion is water’s ability to form hydrogen bonds with a substance other than water (such as vessel walls in plants).
Both _____ and _____ allow for the upward transport of water in plants.
Both cohesion and adhesion allow for the upward transport of water in plants.
What is a hydrophilic substance?
A hydrophilic substance is a substance that can dissolve in water, such as ionic compounds and polar covalent compounds.
What is a hydrophobic substance?
A hydrophobic substance is a substance that cannot dissolve in water, such as non-polar covalent compounds.
Polymers are formed from _____.
Polymers are formed from monomers.
What are monomers?
The term monomer is used to define small molecules that can bind with similar molecules to former a larger, more complex molecule (a polymer). These are the building blocks for biological macromolecules such as DNA, RNA, proteins and carbohydrates.
How are polymers formed?
Polymers are formed by a dehydration / condensation reaction, wherein a water molecule is removed to form a new bond. More specifically, an H+ atom is removed from the end of a short polymer and combines with a hydroxide molecule (HO-) that is removed from an unlinked monomer, forming an H2O molecule. The monomer can join add itself to the end of the short polymer, forming a longer polymer.
How are polymers broken down?
Polymers are broken down by a hydrolysis reaction, wherein the insertion of a water molecule between a polymer and one of its monomers causes them to separate.
What is a carbohydrate?
A carbohydrate is a biomolecule consisting of carbon, hydrogen and oxygen atoms. The term refers to simple sugars (monomers) and their polymers. Carbohydrates serve as fuel for cells and as a carbon source to build other molecules.
What is the general formula for monosaccharides? What is its most common variant?
The general formula is (CH2O)n, where n is a whole number other than 0. The most common variant is (CH2O)6 = C6H12O6 (glucose).
What two forms can sugars be found in?
Either in linear form or in ring form.
What is the most common form a sugar can be found in? Why?
In nature, sugars are most commonly found in ring forms since this is the form they naturally take when in an aqueous solution.
What is a disaccharide?
A disaccharide is the name given to two sugar monomers (two monosaccharides) joined together by a glycosidic linkage.
What is a polysaccharide?
Polysaccharides range from a few hundred to tens of thousands of sugar monomers (monosaccharides) joined together by glycosidic linkages.
What is cellulose?
Cellulose is a polysaccharide consisting of beta-glucose subunits. It reinforces plant cell walls (structural support) and cannot be digested by most animals due to the fact that we do not have the enzyme that can break down beta-glycosidic bonds (the type of linkage found between joined beta-glucose molecules).
What is starch?
Starch is a polysaccharide consisting of alpha-glucose subunits. It is slightly branched (new branch about every 20 subunits) and acts as energy storage for plants when an excess of glucose is produced.
What is glycogen?
Glycogen is a polysaccharide consisting of alpha-glucose subunits. It is found in animals and is more branched than starch (new branch about every 10 subunits). Like starch, it also functions as energy storage.
What is chitin?
Chitin is type of polysaccharide found in the cell walls of some fungi and in the exoskeletons of animals such as lobsters, crabs and beetles (structural support).
Are lipids polymers?
Lipid molecules cannot link to one another to form polymers. They are the only biological macromolecules that behave this way.
Are lipids hydrophilic?
No, lipids are hydrophobic, meaning that they are insoluble in water.
What are fats / triglycerides / triacylglycerols made up of?
Fats are made up of a glycerol molecule (a 3 carbon alcohol) and 3 fatty acids (long hydrocarbons with a carboxyl group at one end).
How are fats / triglycerides / triacylglycerols formed?
Each fatty acid is linked to the glycerol molecule by a dehydration/condensation reaction. The linkage between them is known as an ESTER LINKAGE.
What is an Ester linkage?
An ester linkage is the name given to the bonds between a fat’s glycerol and its three fatty acids.
Why part of a fat / triglyceride / triacylglycerol makes it hydrophobic?
Fats are hydrophobic due to the hydrocarbon chains within each fatty acid.
What is a saturated fat / triglyceride / triacylglycerol?
A saturated fat means that the fat’s fatty acids are are saturated with hydrogen atoms (they contain as many H atoms as they can). This means there isn’t a single C=C double bond, which in turn means that there isn’t a bend in any of the chains either causing them to be solid at room temperature. Saturated fats are found in animal sources.
What is an unsaturated fat / triglyceride / triacylglycerol?
An unsaturated fat means that there is at least one C=C double bond in one of its fatty acids. This means there is a bend in at least one of the fatty acids, causing the sample to be liquid at room temperature. Unsaturated fats are found in plant and fish sources.
What are the 3 primary functions of fats / triglycerides / triacylglycerols?
Energy storage, fats contain twice as much energy per gram as polysaccharides; fats protect internal organs; fats prevent heat loss.
What are phospholipids made up of?
Phospholipids consist of a glycerol molecule, 2 fatty acids, a negatively charged phosphate group and a small hydrophilic group attached to the phosphate.
How are phospholipids amphipathic?
Phospholipids are amphipathic because they have both hydrophilic (phosphate group) and hydrophobic (fatty acid chains) regions.
What are micelles?
When phospholipids are submerged in water, they form aggregates called micelles wherein the hydrophilic heads are pointing outwards while the hydrophobic tails are sequestered. This is due to the amphipathic nature of phospholipids.
What is the primary function of phospholipids?
Phospholipids are the primary component of the cell membrane. Cell membranes are primarily comprised of a phospholipid bilayer, wherein the hydrophilic heads form the outer and inner edges while the hydrophobic tails form the core.
What do all steroids have in common in their composition.
All types of steroids consist of 4 fused Carbon rings.
Why is cholesterol significant as a steroid? (not to do with its role in the cell membrane).
Cholesterol is the starting compound for other steroids, such as estradiol, testosterone, progesterone and cortisol.
What does a hormonal protein do?
Hormonal proteins coordinate an organisms cellular activity.
What does a receptor protein do?
Receptor proteins react to chemical stimuli.
What does a contractile/motor protein do?
Contractile and motor proteins are responsible for movement.
What do structural proteins do?
Structural proteins act as support for things such as our hair.
What does an enzymatic protein do?
Enzymatic proteins (enzymes) selectively accelerate chemical reactions.
What does a defensive protein do?
Defensive proteins offer protection against disease (antibodies).
What does a storage protein do?
Storage proteins store amino acids.
What does a transport protein do?
Transport proteins aid in the transport of substances.
Proteins are polymers, the monomers of which are _____ _____.
Proteins are polymers, the monomers of which are amino acids.
How many different amino acids are there for all known living things?
There are 20 different amino acids for all known living things.
What do all amino acids have in common?
They all have a common sequence of atoms called a backbone. The variable side chain is what gives each amino acid its uniqueness.
Is a polymer of amino acids a protein?
Not necessarily. A polymer of amino acids is called a polypeptide. Under specific conditions, that polypeptide assumes a function and becomes a protein.
Can a protein consist of one of more polypeptides?
Yes, a protein can consist of one of more polypeptides.
In a protein / polypeptide, what are the bonds between amino acids called?
The bonds between amino acids are called peptide bonds.
When amino acids form a polypeptide, their common sequences of atoms become the _____ _____.
When amino acids form a polypeptide, their backbones link to become the polypeptide backbone,
How many amino acids are there in a polypeptide?
Polypeptides can range from only a few amino acids in length to thousands of amino acids in length.
What aspect of a protein determines its function?
The 3D structure (shape) of a protein is what determines its function.
What is protein denaturation?
When heated, a protein will collapse, losing its 3D shape and as a result, it will no longer be able to perform its function. Chemicals such as alcohol can also denature proteins.
What are the two types of nucleic acids?
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
What does DNA do?
Deoxyribonucleic Acid stores heritable information.
How is DNA organized?
DNA is organized into chromosomes which are made up of 100s to 1000s of genes.
What are genes?
A gene is the basic physical and functional unit of heredity. Each of these segments of DNA act as instructions to build a specific protein.
DNA directs its own synthesis through the process of _____.
DNA directs its own synthesis through the process of replication.
DNA directs the synthesis of RNA through the process of _____.
DNA directs the synthesis of RNA through the process of transcription.
What are the 3 types of RNA?
Messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA).
What does mRNA do?
Messenger RNA directs the synthesis of a protein through the process of translation.
What does tRNA do?
Transfer RNA acts as a amino acid delivery vehicle during the process of protein synthesis.
What does rRNA do?
Ribosomal RNA makes up the structure of the Ribosome.
Nucleic acids are polymers, the monomers of which are _____.
Nucleic acids are polymers, the monomers of which are nucleotides. In other words, nucleic acids are polynucleotides.
What are nucleotides comprised of?
A nitrogenous base, a pentose sugar and a phosphate attached to carbon 5 of sugar (5’).
What are the two types of nitrogenous bases?
Purines and pyrimidines.
What are the pyrimidines?
Cytosine, Thymine and Uracil (U replaces T in RNA).
What are the purines?
Guanine and adenine.
What’s different in the structure between DNA and RNA.
DNA’s pentose sugar has one less oxygen atom (deoxyribose) than RNA’s pentose sugar (ribose).
Describe the synthesis of a nucleic acid.
The pentose sugar of one nucleotide connects to the phosphate group of another nucleotide. This leads to the formation of a SUGAR PHOSPHATE BACKBONE.
What is the linkage between the pentose sugar of one nucleotide and the phosphate of another nucleotide called?
A phosphodiester bond.
DNA consists of two strands wrapped into a _____ _____.
DNA consists of two strands wrapped into a double helix.
How are DNA’s two strands held together?
DNA’s two strands are held together by hydrogen bonds between their nitrogenous bases.
