02. Chemical and Cellular Basis of Life [DEFINITIONS] Flashcards
Polarity
polarity is an uneven charge distribution within a molecule.
Hydrogen Bonds
Weak attractions between the slightly polar hydrogen atom of one water molecule and the slightly polar oxygen atom of the adjacent water molecule are known as hydrogen bonds.
Cohesion
Attraction between water molecules due to hydrogen bonding is known as cohesion
Adhesion
Attraction between water molecules and other substances
Carbohydrates
Carbohydrates are the most abundant group of organic compounds on earth with a major elemental composition of C, H, and O.
Hydrates of carbon contain the same proportion of H:O which equals to 2:1 as in water.
The general formula of carbohydrates is Cx(H20)y
Monosaccharides
The simplest form of carbohydrates having the general molecular formula of (CH2O)n are monosaccharides.
Disaccharides
They are the sugars formed by joining two monosaccharides by a glycosidic bond
Glycosidic Bond
A glycosidic bond is formed by the removal of a water molecule from two adjacent monosaccharides by a condensation reaction.
Polysaccharides
They are macromolecules and biopolymers made up of a few hundred to a few thousand monosaccharide subunits.
Lipids
Lipids are a diverse group of large hydrophobic molecules which are biological molecules but not considered as polymers or macromolecules.
They consist of C,H,O and H:O ratio is not 2:1. Comparatively more H is present.
Saturated Fats
Fats are made up of saturated fatty acids (fatty acids with hydrocarbons having no double bonds)
Unsaturated Fats
Fats are made up of unsaturated fatty acids (fatty acids with hydrocarbons having one more more double bonds)
Phospholipids
Phospholipids are major components of cells membranes composed of two fatty acids and one phosphate group attached to one glycerol molecule.
Proteins
Proteins
Proteins are made up of amino acids and has an elemental composition of C, H, O, N and S
Primary Structure of Proteins
The unique sequence of linearly arranged amino acids linked by peptide bonds is the primary structure of proteins.
Secondary Structure of Proteins
When the primary structure of a single polypeptide chain coils and folds, as a result of intra molecular hydrogen bonds between the oxygen atoms and hydrogen atoms attached to the nitrogen atoms of the same poly peptide chain backbone to form the secondary structure.
Tertiary Structure of Proteins
Usually the secondary polypeptide chain bends and golds extensively forming a precise compact unique, functional and three-dimensional shape resulting from the interactions between the side chain/R-group of amino acids.
Quaternary Structure of Proteins
The aggregation of two or more polypeptide chains involve in the formation of one functional protein. Separate chains are called sub units which were held together by inter and intra-molecular bonds.
Denaturation of Proteins
Denaturation of proteins is the loss of its specific chemical three dimensional shape due to the alteration of weak chemical bonds and interactions.
Nucleic Acids
Nucleic acids are polymers that exist as polynucleotides made up of monomers called nucleotides containing C,H,O,N and P
Base Pair Rule
Always a purine base, pairs with a specific pyrimidine base
RNA
This is normally a single stranded nucleic acid composed of ribonucleotides containing the bases Uracil (U), Cytosine (C), Guanine (G), Adenine (A)
Messenger RNA
Messenger RNA is a linear molecule and is the least abundant type of RNA in a cells comparatively.
Transfer RNA (tRNA)
This is the smallest RNA molecule which is linear, but forms a three-looped structure.
Ribosomal RNA (rRNA)
It is the most abundant type of RNA. rRNA has a complex irregular structure and provides a site where polypeptide chains are assembled.
Magnification
Magnification is the ration of an object’s image size to its actual size.
Resolution
Resolution power is the minimum distance between two points that can be distinguished as separate points. It is a measure of the clarity of the image.
Total Magnification
Total magnification is the product of the magnification of each lens.
Transmission Electron Microscope
It’s used to study the internal structures of cells. In this microscope, a beam of electrons is passed through a thin, especially prepared slice of material.
Scanning electron microscopes
In this instrument, a fine beam of electrons is reflected from the surface of specimen.
Scanning electron microscopes
In this instrument, a fine beam of electrons is reflected from the surface of specimen.
Cell Theory
- All organisms are composed of one or more cells
- The basic structural and functional unit of organisms is the cells.
- All cells arise from pre-existing cells.
Plasma Membrane
The plasma membrane is the outer limit of the cytoplasm.
It is mainly composed of 1. phospholipids (the most abundant type of lipid in plasma membrane)
2. protein
Peripheral Proteins
Some proteins are not embedded in the lipid bilayer at all, and are loosely bound to the inner surface of the membrane, called peripheral proteins.
Subcellular Components
There are many subcellular components in the cell. Some of them are organelles, which are bound by membranes and suspended in the cytosol of eukaryotic cell to perform specialized functions.
Nucleus
The nucleus is the most prominent organelle, which consists of most of the genes, having an average diameter of 4um and enclosed by a double membrane cover called nuclear envelope
Ribosomes
These are subcellular components which carry out protein synthesis. They consist of two subunits; the larger subunit and smaller subunit. They are composed rRNA and protein.
Endoplasmic Reticulum
It is a network of internal membranes forming flattened or tubular sacs separating cytosol from ER lumen. It is continuous with the outer membrane of nuclear envelope.
Rough ER
Rough ER consists of flattened sacs, and ribosomes bound to surface. Proteins synthesized by ribosomes move into lumen of ER.
Smooth ER
Smooth ER is a network of tubular sacs without ribosomes. Membrane bound enzymes are present.
Lysosomes
They are single membrane bounded vesicles contributing to digestive activity. They contain hydrolytic enzymes which catalyze breakdown of carbohydrates, proteins, lipids and nucleic acids.
Peroxisome
They are single membrane bounded vesicles with oxidizing enzymes present in both plants and animals. Enzymes in peroxisome catalyze the breakdown of H202.
Mitrochondria
It is one of the most common organelles in eukaryotic cells. It is an elongated organelle with two enclosing membranes.
Chloroplast
It is a biconvex lens shaped organelle with 2 membranes which is found in plants and some protists.
Cytoskeleton
The cytoskeleton is the supporting structure of the cell and maintains its shape. It’s more important for animal cells which lack cell walls.
The three components in the cytoskeleton are microtubules, actin filaments/ microfilaments and intermediate filaments.
Flagella
Flagella are long elongates structures
Cilia
cilia are short cellular projections that are often organized in rows.
Centrioles
A centriole is made up of cylindrically arranged microtubules which are non membrane bounded subcellular component present only in animal cells.
Central Vacuole
A central vacuole is a large structure bound by tonoplast filled with a liquid called cell sap found in plant cells.
Cell Wall
A cell wall is an extracellular structure in plant cells. Animal cells do not have cell walls.
Cell Junctions
Cell junctions are structures at which neighboring plasma membranes are joined. They interact and communicate via sites of direct physical contacts.
Plasmodesmata
Microscopic channels which runs through plant cell walls. They are cytoplasmic living connections between cytoplasm of adjourning cells. They are membrane lined channels filled with cytoplasm.
Extracellular Matrix of Animal Cells (ECM)
Main components of ECM are glycoproteins and other carbohydrates containing molecules secreted by the cells. Although animal cells lack cell walls they have an elaborate extracellular matrix.
Cell Cycle
The sequence of events that takes place in the cell from the end of one cell division to the end of the next cell division is referred to as cell cycle.
Mitosis
Mitosis is the nuclear division which gives rise to two genetically identical daughter nuclei from a mother nucleus.
Cytokinesis
The division of the cytoplasm starts at the end of the telophase. Therefore, at the end of the mitosis two genetically identical daughter cells are produced.
In animal cells, a cleavage furrow forms. This produces two genetically identical daughter cells.
Meiosis
Meiosis is a type of nuclear division which gives rise to four haploid, genetically non-identical daughter nuclei, from a diploid mother nucleus.
Galls in Plants
Galls are the bumps and growths that develop on different parts of plants after being invaded by some very unique organisms.
Catabolism
Catabolism is the breaking down of complex molecules into simple molecules by releasing energy.
Anabolism
Anabolism is making complex molecules from the simple molecules by absorbing free energy.
Photophosphorylation
This is the synthesis of ATP using solar energy in photosynthesis
Substrate Phosphorylation
This is the synthesis of ATP using energy released by the breaking down of complex molecules into simple ones.
Oxidative Phosphorylation
This is the synthesis of ATP using energy released as a result of oxidation of molecules.
Enzyme
An enzyme is a macromolecule which acts as a biological catalyst produced in living cells.
Substrate
The reactant the enzyme acts on is referred to as the substrate
Active Site
The active site is formed by only a few amino acids. The other amino acids are needed to maintain the shape of the enzyme molecule.
Induced Fit Mechanism
As enzymes are not rigid structures, the interactions between substrate and active site may slightly change the shape of the active site, so that the substrate and the active site become complementary to each other.
Cofactors
Non-proteinuos components which are essential for the catalytic activities of certain enzymes are called cofactors.
Enzyme Inhibitors
Certain molecules or ions selectively bind permanently or temporarily to the enzyme molecules and prevent them from forming enzyme-substrate complex. These substances are called inhibitors.
Competitive Inhibitors
Most of these are reversible inhibitors that resemble the shape and nature of the substrate and compete selectively with the substrate for the active site of certain enzymes.
Cooperativity
This is another type of allosteric activity in which the binding of one substrate molecule can stimulate binding or activity at other active site, thereby increasing the catalytic activity.
Feedback Inhibition
In feedback inhibition, a metabolic pathway is stopped by the inhibitory binding of its end product of a process to an enzyme. Thereby the production of more end products than required and wasting chemical resources is limited.
Feedback Inhibition
In feedback inhibition, a metabolic pathway is stopped by the inhibitory binding of its end product of a process to an enzyme. Thereby the production of more end products than required and wasting chemical resources is limited.
Photosynthesis
Photosynthesis is a metabolic process by which light energy is trapped and converted to chemical energy.
Absorption Spectrum
An absorption spectrum is a graph of the relative amounts of light absorbed at different wavelengths by a pigment.
Action Spectrum
An action spectrum is a graph showing the effectiveness of different wave lengths of light in stimulating the photosynthesis.
Linear Electron Flow
Light is absorbed by the photosynthetic pigments and synthesize ATP and NADPH due to the excitation of photosystem I and photosystem II which are embedded in the thylakoid membrane of chloroplast.
Cyclic Electron Flow
This occurs in photosystem I but not in photosystem II. Here, some photoexcited electrons uses alternative cyclic pathway. This produces ATP but not NADPH and oxygen are released
The Calvin Cycle
The Calvin cycle takes place in the stroma of the chloroplast. Energy from ATP and NADPH produced by the light reaction are used to reduce CO2
Photorespiration
Kranz Anatomy
The bundle sheath cells enclose the vascular bundles and are themselves surrounded by the mesophyll cells and this type of leaf anatomy was termed kranz anatomy.
Factors affecting Photosynthesis
Cellular Respiration
Cellular respiration is the process by which chemical energy in organic molecules such as carbohydrates is released in a stepwise oxidative process, catalyzed by enzymes and made available in living cells in the form of ATP.
Aerobic Respiration
The process of synthesizing ATP from respiratory substrates such as glucose in the presence of molecular oxygen (o2) is known as aerobic respiration.
Glycolysis
Glycolysis takes place in the cytosol of the cell, because all enzymes that catalyze reactions of the glycolysis are find in the cytosol of the cell.
Oxidation of Pyruvate / Link Reaction
Two pyruvate molecules enter mitochondrion by active transport through the membrane. In the matrix of mitochondria, pyruvate is converted to acetyl group by releasing two CO2 molecules.
Citric Acid Cycle
This takes place in the matrix of mitochondria using specific enzymes where citric acid undergoes a series of reactions to regenerate OAA by releasing two CO2 molecules by a decarboxylation reaction.
Electron Transport Chain
This step is taken place across the inner membrane (cristae) of mitochondria where NADH and FADH2, which are products of the early stages of aerobic respiration are oxidized by transferring electrons.
Anerobic Respiration
Anerobic respiration is breaking down of glucose in the absence of molecular oxygen which is regulated by enzymes of cells occurring in cytosol.
Respiratory Quotient
It is the ratio of CO2 evolved and the volume of O2 consumed in a given time for the respiratory substrate.
