Studied by 5 people
Valency
The property of an element that dictates how many bonds it can form
Why are water molecules polar?
They have a 'bent' shape and therefore positive and negative poles
Catabolism
Breakdown in living organisms of more complex substances into simpler ones together with release of energy
Anabolism
The synthesis in living organisms of more complex substances from simpler ones together with the storage of energy
Metabolism
the sum of organic processes/ reactions that are necessary for life
What is the charge on a hydrogen atom within water?
Slightly positive/ delta positive
What is the charge on an oxygen atom within water?
Slightly negative/ delta negative
Cohesion
The property of water that means individual water molecules 'stick' to each other
Adhesion
The property of water that means water molecules 'stick' to other surfaces such as the side of a glass
Monosaccharide
A single-unit sugar (includes glucose, fructose and galactose)
All monosaccharides are reducing agents
Disaccharide
A two-unit sugar
Includes sucrose, lactose and maltose
Polysaccharide
A many-unit sugar
Includes starch, cellulose and glycogen
Reducing agent
A substance that causes another substance to be reduced by removing oxygen OR donating hydrogen and/or electrons
What does the acronym SHIPS represent in terms of the roles of fatty substances (ie. lipids)?
Storage of energy for long-term use (e.g. triglycerides) Hormonal roles (e.g. steroids such as oestrogen and testosterone) Insulation – both thermal (triglycerides) and electrical (sphingolipids) Protection of internal organs (e.g. triglycerides and waxes) Structural components of cells (e.g. phospholipids and cholesterol)
What do "saturated" and "unsaturated" mean in the context of fatty acids?
Saturated- no double bond
Unsaturated- contains a double covalent bond between two of the carbon molecules (can be monounsaturated or polyunsaturated)
Are saturated or unsaturated fats more likely to be solid at room temperature?
Saturated
What is a trans isomer of a fatty acid?
When the hydrogens either side of the C=C double bond are on opposite sides of the molecule
What is a cis isomer of a fatty acid?
When both the hydrogens either side of the C=C double bond are on the same side of the molecule
Which two functional groups do fatty acid chains contain?
Methyl/ CH3 group and Carboxyl/Carboxylic acid/ COOH group(=acid 'head')
What is an ester bond?
-An ester bond forms when a hydroxyl (-OH) group from the glycerol bonds with the carboxyl (-COOH) group of the fatty acid. -It is the joining of two carbons via one oxygen (-O-) -A molecule of water is produced alongside every ester bond
Describe the structure of cellulose
-A polysaccharide
-A linear molecule made of beta-glucose subunits bound in a 1-4 arrangement
What are the two forms of starch?
-Amylose and amylopectin
-Amylose is harder to digest and less soluble, however, as it takes up less space, is the preferred storage form in plants
Describe the structure of amylose
-Amylose is a linear (helical) polysaccharide molecule
-It is made up of α-glucose subunits (bound in a 1-4 arrangement)
Describe the structure of amylopectin
-It is made up of α-glucose subunits (bound in a 1-4 arrangement)
-Contains additional branching (1-6 linkages)
Structure of glycogen
-Energy storage polysaccharide formed in the liver in animals -Composed of α-glucose subunits linked together by both 1-4 linkages and 1-6 linkages (branching)
The function of starch
-Energy storage in plants -Preferred store as it is compact/takes up lace space
Function of glycogen
-Energy storage in animals
Function of cellulose
-Gives plant cell walls their structure
What is meant by "amphoteric" in reference to amino acids?
-They are both acidic and basic simultaneously
Which four elements do amino acids always contain?
C, H, O and N
Which two groups do amino acids contain?
COOH (/carboxyl) and NH2(/amino)
In amino acids, which group can gain an H+ ion in acidic solution?
NH2 can gain an additional H+ (nb. that Nitrogen can sometimes have a valency of 4)
In amino acids, which group can lose an H+ ion in alkaline solution?
COOH can lose an H+ (H+ is lost from the OH)
What is the name of the covalent bond between amino acids?
Peptide bond
What does a condensation reaction between two amino acids form?
A dipeptide and water
What are the two common secondary structures that amino acids can form?
Alpha helices and beta- pleated sheets (when no secondary structure exists, the polypeptide chain will form a random coil)
What type of bond is responsible for the secondary structure of a polypeptide chain?
Hydrogen bonds
What are prosthetic groups?
The non-amino acid component that is part of the quaternary structure of conjugated proteins
What types of bonds are responsible for the primary structure of amino acids?
The tertiary structure of a polypeptide chain will be determined by the interactions between the variable side chains These interactions may include hydrogen bonds, disulphide bridges, ionic interactions, polar associations, etc.
Give an example of a protein with a quaternary structure
Haemoglobin is composed of four polypeptide chains (two alpha chains and two beta chains) It is also composed of iron-containing haeme groups (prosthetic groups responsible for binding oxygen)
Amino acids are zwitterions. What are zwitterions?
Neutral molecules possessing both negatively (COO–) and positively (NH3+) charged regions
What are the differences between fibrous and globular proteins?
Fibrous: long/narrow shape, usually structural proteins, repetitive amino acid sequence (eg. keratin)
Globular: round shape, usually functional proteins, irregular amino acid sequence (eg. amino acids)
What is meant by the proteome?
The totality of proteins expressed within a cell/organism/etc at a given time
What are the main roles of proteins in an organism (SHITS ME)
Structure – e.g. collagen, spider silk Hormones – e.g. insulin, glucagon Immunity – e.g. immunoglobulins Transport – e.g. haemoglobin Sensation – e.g. rhodopsin Movement – e.g. actin, myosin Enzymes – e.g. Rubisco, catalase
Give three examples of enzymes used in industry
Proteases and lipases (used in biological detergents), pectinase (fruit juice production) and lactase (lactose-free milk for lactose intolerant humans and cats)
What is the allosteric site?
Any site on an enzyme that isn't the active site
What characterises a competitive enzyme inhibitor?
-Enzyme inhibitors are substances that interfere with the normal functioning of an enzyme -Competitive inhibitors must bind TO THE ACTIVE SITE of an enzyme on a TEMPORARY basis
Give an example of a practical use of enzyme inhibition.
-Competitive inhibition of alcohol dehydrogenase (the enzyme that converts ethylene into oxalic acid) by ethanol -Used to treat alcoholics who have consumed antifreeze
How is urea synthesised artificially?
Exothermic reaction of ammonia and carbon dioxide
What is the structure of urea?
CO(NH2)2
Structure of urea
CO(NH2)2
What are amylose and amylopectin?
-They are both forms of starch -Amylose is a linear (helical) molecule while amylopectin is branched (contains additional 1-6 linkages) -Amylose is harder to digest and less soluble, however, as it takes up less space, is the preferred storage form in plants
What is the supernatant?
The liquid component lying above a solid residue when a substance has been centrifuged etc.
What are the three components of a DNA molecule and how are they represented?
5-carbon pentose sugar (pentagon)
Phosphate group (circle)
Nitrogenous base (rectangle)
What are the two structural differences between DNA and RNA?
-The pentose sugar in DNA is deoxyribose, in RNA it is ribose
-The nitrogenous bases in DNA can be A,C,G,T; in RNA they are A,C,G,U
What name is given to the individual DNA units?
-The monomer units are called nucleotides
How many hydrogen bonds form between C and G in DNA?
3
How many hydrogen bonds form between A and T in DNA?
2
Describe the bonds between the DNA monomers
-Called phosphodiester bonds
-Form between carbon 3 of one nucleotide and carbon 5 of the next
What are the full names of A, C, G and T in DNA?
Adenine, Guanine, Thymine and Cytosine
Which two DNA bases are purines and which two are pyrimidines?
-A and G are purines, C and T are pyrimidines (nb. Uracil is also a pyrimidine in RNA)
-Only a purine can bond with a pyrimidine!
What is the difference in structure between a purine and a pyrimidine?
Pyrimidines are made up of a single ring of six members while purines are made up of a six-member ring and a five-member ring
What are the three main types of RNA?
Messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA)
What is the role of messenger RNA?
A transcript copy of the gene which can encode a specific polypeptide?
What is the role of transfer RNA?
Carries the polypeptide subunits (amino acids) to the organelle responsible for synthesis (ribosome)
What is the role of ribosomal RNA?
A primary component of the ribosome responsible for its catalytic activity
What is the name of the enzyme responsible for ‘unzipping‘ DNA?
Helicase
What is the name of the enzyme responsible for DNA replication?
DNA polymerase
How does DNA replicate (conservative, semi-conservative or dispersive)?
Semi-conservative (ie. each new DNA molecule contains one strand from the parent molecule and one is totally new)
Who experimented in 1958 to find out how DNA replicates?
Meselsohn and Stahl
What are the stages of aerobic respiration in order?
Glycolysis, the link reaction, the krebs cycle and the electron transport chain
How many molecules of ATP are produced per glucose in anaerobic respiration?
2
How many molecules of ATP are produced per glucose in aerobic respiration?
30-40
ATP
A nucleotide triphosphate that is a common source of energy in cells
Cristae
Invaginations of the inner mitochondrial membrane
Glycolysis
A metabolic pathway that breaks down glucose to pyruvate
Krebs cycle
Link reaction
A decarboxylic reaction that occurs in the mitochondria between glycolysis and the Krebs cycle
Electron transport chain
A group of proteins that accept and donate electrons in series
Phosphorylation
The addition of a phosphate group to a molecule
Reduced NAD
The energy rich form of the hydrogen carrier
Genomics: definition
The study of the whole sets of genetic information (genomes) in the form of base sequences
What is TAQ polymerase?
Taq polymerase is the heat-stable (thermostable) DNA polymerase extracted from the thermophilic bacteria Thermus aquaticus.
What are the three stages involved in PCR?
Denaturation – DNA sample is heated (~90ºC) to separate the two strands
Annealing – Sample is cooled (~55ºC) to allow primers to anneal (primers designate sequence to be copied)
Elongation – Sample is heated to the optimal temperature for a heat-tolerant polymerase (Taq) to function (~75ºC)
What are the uses of PCR?
Used to amplify large quantities of a specific sequence of DNA from an initial minute sample
Each reaction doubles the amount of DNA – a standard PCR sequence of 30 cycles creates over 1 billion copies (230)
COVID testing and other diseases like sickle cell anemia
What is meant by a ‘codon‘?
A triplet of bases. Each one codes for one amino acid.
What is the difference between aerobic and anaerobic respiration?
Anaerobic respiration involves the partial breakdown of glucose in the cytosol for a small yield of ATP
Aerobic respiration utilises oxygen to completely break down glucose in the mitochondria for a larger ATP yield
What are the four stages involved in aerobic respiration?
Glycolysis, link reaction, Krebs cycle and the electron transport chain
What are the stages of glycolysis?
Phosphorylation (addition of a phosphate group from ATP), hydrolysis (addition of water) and oxidation (glucose is oxidised)
Outline what happens in glycolysis
What are the products of glycolysis per glucose molecule?
2 pyruvate, 2 NAD and 2 ATP (net gain of 2x ATP)
Fill the blanks: in the link reaction, … passes from the … into the … Here it is completely oxidised forming … and ….
Pyruvate, cytoplasm, mitochondria, water and carbon dioxide
What is the overall equation for the link reaction?
pyruvate+NAD+coA goes to acetyl coA+CO2+reduced NAD
What are the products per glucose molecule in the link reaction?
2 acetyl coA(into Krebs cycle), 2 reduced NAD(into electron transport chain), 2 carbon dioxide (waste)
What does the acronym DODO POO represent in relation to the Kreb cycle?
D- decarboxylation
O- oxidation
P- phosphorylation
In anaerobic respiration in animals, what is pyruvate converted to?
Lactic acid
In anaerobic respiration in plants and yeast, what is pyruvate converted to?
Carbon dioxide and ethanol
What are two applications of the fermentation process of yeast for humans?
Bread – Carbon dioxide causes dough to rise (leavening), the ethanol evaporates during baking
Alcohol – Ethanol is the intoxicating agent in alcoholic beverages
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