SBI4U1 EXAM REVIEW Flashcards
UNIT 1: BIOCHEMISTRY
what is monosacc and dissacc
- Monosaccharides and Disaccharides
They are both types of carbohydrates (macromolecules)
A monosaccharide has ONE sugar.
Glucose: primary energy supply for the body
Galactose: called milk sugar
Fructose: in fruits, and honey.
Glucose, fructose and galactose are their isomers. (isomer is the
same chemical formula but different structure)
A disaccharide is two monosaccharides joined together by a glycosidic linkage.
Sucrose – glucose + fructose
Maltose – glucose + glucose
Lactose – glucose + galactose
- triglyc and fatty acids?
- Triglycerides and Fatty Acids
They are both types of lipids (macromolecule)
A simple fat (triglyceride) forms when a reaction occurs between a molecule of glycerol and 3 fatty acids
Energy storage
Fatty acids can be either saturated or unsaturated.
Saturated fats contain only single bonds between carbons
Unsaturated fats contain at least one double bond between
carbons (causes “kinks” in their tails)
The more unsaturated, the more liquid the fat
hydrolysis?
- Hydrolysis reactions (big → small)
Occur when WATER molecules are ADDED (water is a reactant)
A chemical reaction that results in the DISASSEMBLY of larger molecules into smaller molecules
Examples:
Dipeptide + water → amino acid + amino acid
Disaccharide + water → monosaccharide + monosaccharide
Triglyceride + 3 water → glycerol + 3 fatty acids
They are CATABOLIC reactions: reactions that break macromolecules into individual subunits
They are EXERGONIC reactions: reactions that will occur
spontaneously and produce ENERGY when they occur
Therefore, an organism will break down macromolecules
when they require energy.
condensation?
- Condensation of a triglyceride (small → big)
Occur when WATER molecules are REMOVED (water is a product)
A chemical reaction that results in the ASSEMBLY of smaller molecules into larger molecules
Example: Glycerol + 3 fatty acids → triglyceride + 3 water
They are ANABOLIC reactions: reactions that produce large molecules from smaller subunits
They are ENDERGONIC reactions: reactions that will not occur spontaneously and require ENERGY to make occur
Therefore, it is costly to an organism to make macromolecules because they require energy.
factors affecting enzyme activity?
PH:
Most human enzymes work best within the range of pH 6 to 8.
Some enzymes function best in very acidic conditions.
Changes in the enzyme’s optimal pH may cause the enzyme to denature and lose function
Substrate Concentration:
The formation of an enzyme substrate complex will take longer if there are few substrates present, since they will encounter each other less frequently.
Enzyme activity generally increases as substrate concentration increases.
However, there are a limited number of enzyme molecules in a cell at any one
time
Therefore, enzymes can become saturated with substrates and the
speed of the reaction can no longer increase
Inhibitors:
Molecules that interact with an enzyme and reduce the activity of the enzyme.
Competitive inhibition:
Inhibitor that interacts with the active site directly and prevents enzyme-substrate interaction.
Non-competitive inhibition:
Inhibitor that binds to an allosteric site on an enzyme
causing an alteration of the enzyme’s 3D shape.
Allosteric Site:
A site on the enzyme that is not the active site.
Location where other molecules can interact with
and regulate the activity of the enzyme.
Activators:
Molecules that bind to the allosteric site and keep the enzyme active or cause an increase in the activity of the enzyme.
6. Components of the Cell Membrane
Structure - Phospholipids, carbohydrate chains, and proteins
HYDROPHILIC heads - (water-liking)
Because of phosphate group
Attracted to the water
NEGATIVELY CHARGED heads
HYDROPHOBIC tails - (water-fearing)
Because of fatty acid chains
Not attracted to the water
NON-POLAR tails
Bilayer:
If you put phospholipids in a beaker of water
they will automatically form a cell membrane
structure because the head are polar so they
will face the water and the tails are non-polar
so they will face each other and form a bilayer
types of active and passive transport?
- Types of Passive and Active Transport
Passive Transport cell doesn’t use energy
Diffusion: random movement of ions or molecules from an area of high
concentration to an area of low concentration.
Facilitated Diffusion: occurs when molecules or ions that cannot pass through
the cell membrane unassisted are helped through by channel or carrier proteins embedded in the cell membrane – These particles move through the proteins
along the concentration gradient.
Osmosis: diffusion of water through a selectively
permeable membrane (Water moves from high to
low concentrations)
Active Transport cell does use energy
Transport of a solute across a membrane AGAINST its concentration
gradient.
Low → High
Actively moves molecules to where they are needed
Cell uses energy in the form of ATP
The hydrolysis of the end phosphate group from an ATP molecule releases energy.
Direct use of ATP energy is called primary active transport.
Indirect use of ATP energy is called secondary active transport.
Primary Active Transport (sodium potassium pump) (one protein chanel)
Secondary Active Transport
Example: Hydrogen-Sucrose Pump (two protein channels)
Hydrogen ions are first pumped out of the cell AGAINST their concentration gradient by a hydrogen ion pump. This pump requires ATP.
The H+ pump creates an electrochemical gradient (an area of higher concentration and greater positive charge) outside the cell.
Sucrose molecules outside the cell bind to a hydrogen-sucrose pump. This pump binds sucrose and allows H+ to move into the cell.
As the H+ move back into the cell, they release the energy needed to transport the sucrose AGAINST its concentration gradient.
Membrane-assisted transport cell does use energy
Endocytosis: taking bulky material into a cell
Uses energy
Cell membrane extends outward, around material
Exocytosis: forces material out of cell in bulk
membrane surrounding the material fuses with cell membrane
Cell changes shape – requires energy
UNIT 2- METABOLIC PROCESSES
1. Oxidation vs. Reduction
LEO the lion says GER
When a molecule loses electrons it becomes oxidized and has undergone a process called oxidation.
When a molecule gains electrons from an oxidized molecule, it becomes reduced and has undergone a process called reduction.
- Overall reaction of glycolysis
- Overall reaction of glycolysis
Glucose + 2NAD+ + 2ADP + 2Pi → 2 Pyruvate + 2H2O + 2NADH + 2ATP
- The Location of Each Stage of Respiration
- The Location of Each Stage of Respiration
Glycolysis → cytoplam
Pyruvate oxidation → Matrix of mitochondria
Krebs cycle → Matrix of mitochondria
- Light-dependent reactions vs. light-independent reactions
- Light-dependent reactions vs. light-independent reactions
The light-dependent reactions are broken down into two categories: noncyclic and cyclic. Both cycles need a photon of light to strike a pigment in the antenna complex.
The Calvin cycle is a light-independent reaction. This means the Calvin cycle can occur at any time of the day with or without light. However, it is not totally light-independent because it needs the ATP produced in the light-dependent reactions to work.
- Main events of non-cyclic electron flow
- Main events of non-cyclic electron flow
Step 1- A photon strikes a pigment in the antenna complex of photosystem II. The light energy is transferred from pigment to pigmen until it reaches the reaction centre P680 (chlorophyll a).
Step 2- The P680 molecule absorbs the energy, which excites it to leave the molecule. The excited electron jumps from P680 to a primary acceptor molecule. (P680 has been oxidized and the primary acceptor molecule has been reduced.)
Step 3- A water molecule splits two hydrogen ions and an oxygen atom which combines with another to form O2 and is released into the environment. The hydrogen fills the missing spot in P680.
Step 4- From the primary electron acceptor, the energized electrons originating from P680 are transferred, one by one, along a series of electron-carrying molecules. Together, these molecules are referred to as the ETC
Step 5- With each transfer of electrons along the system, a small amount of energy is released. The released energy is used to pump H+ from the stroma, across the thylakoid membrane and into the thylakoid membrane.
Step 6- While events of Steps 1-5 are taking place, light E is absorbed by photosystem I. This energy is transferred to the reaction centre P700, where an electron becomes excited. Once again, the excited electron is passed to a primary electron acceptor. In photosystem I, the lost electron is replaced by the electron that has reached the end of the ETC from photosystem II.
Step 7- The electrons that were received by the electron acceptor from photosystem I are used to reduce NADP+ to NADPH. The reducing power of NADPH will be used in the light-independent reactions.
- Relationship Between Respiration and Photosynthesis
Both aerobic respiration and photosynthesis occur in plants and are closely related. Together they represent a plant cell’s energy cycle.
UNIT 3- MOLECULAR GENETICS
1. Hershey and Chase experiment
Hershey and Chase ruled out protein as the hereditary material.
Their experiments used viruses, which consist of nucleic material surrounded by a protein coat.
A bacteriophage infects a bacterial cell by attaching to the outer surface of the cell, injecting its hereditary info into the cell and producing thousands of new viruses.
DNA contains phosphorus but not sulfur
Proteins contain sulfur but not phosphorus
Hershey and Chase used two different radioactive isotopes to track each molecule (35S for proteins and 32P for DNA).
In their first experiment:
a virus with DNA radioactively labelled with 32P was allowed to infect bacteria. After agitation and separation, radioactivity was found in the bacteria pellet but not in the liquid medium.
In their second experiment:
a virus with its protein coat radioactively labelled with 35S was allowed to infect bacteria. After agitation and separation, radioactivity was found in the liquid medium but not in the bacteria pellet.
The Hershey-Chase experiments settled the matter of which molecule is the genetic material.
The results provided conclusive evidence that viral DNA was transferred to the bacterial cells and that viral DNA held the genetic information needed for viruses to reproduce
- Complementary Base Pairing
Chargaff had reached two conclusions:
DNA is composed of repeating units of nucleotides in fixed proportions that vary with different species
Regardless of the species, DNA maintains certain nucleotide proportions:
A = T and G = C, in RNA T=U
This constant relationship is known as Chargaff’s rule.
3. Bonding Within DNA Molecule
Nuclienc acids are long strands of DNA molecules made up of covalent bonds
Nitrogen bases are attached to the 1’ carbon by a glycosidic bonds
The phosphate groups are attached to the 5’ carbon by a phosphodiester bond
Intermolecular forces hold the different srands together. Intramolecular forces hold the individual strands together
Hydrogen bonds hold the DNA strands together
- Bonding Within DNA Molecule
Nuclienc acids are long strands of DNA molecules made up of covalent bonds
Nitrogen bases are attached to the 1’ carbon by a glycosidic bonds
The phosphate groups are attached to the 5’ carbon by a phosphodiester bond
Intermolecular forces hold the different srands together. Intramolecular forces hold the individual strands together
Hydrogen bonds hold the DNA strands together
