AS CONTENT

• 1. nucleus contains chromasomes with DNA whihc code for proteins
• The nucleus contains chromosomes with DNA which code for proteins.
• Nuclear pores in the nuclear envelope allow for mRNA to leave the nucleus, a process known as transcription.
• Products of Transcription leaves the nucleus and attaches to ribosomes, marking the beginning of protein synthesis/translation.
• Polypeptides are made on the RER and packaged into vesicles, which then go to the Golgi body to be packaged and modified.
• The Golgi body produces vesicles which leave the cell by exocytosis.
• competitive inhibitors have a complementary shape to the substrate therefore competes for the active site of the enzyme decreasing its activity . the amount of product formed stays the same however the reaction rate decreases . increase in substrate concentration reverses the effect as it outcompetes them
• non-competitive inhibitors bind to the allosteric site changing the shape of enzyme by breaking hydrogen bonds present , stopping the rate of enzyme-substrate complexes from forming . increasing the substrate concentration has no effect.
• lock and key theory : the lock and key theory describes the active site having a fixed shape meaning that an enzyme can only catalyse one reaction only and the active site will only bind to one substrate
• Induced fit theory : the induced fit model describes how the active site will change shape in order to accommodate to the substrate this therefore weakens tertiary structure and hydrogen bonds in the enzymes so the reaction occurs at a lower activation energy
• effect of temperature on enzyme activity : increased temperature increases kinetic energy meaning more enzyme substrate complexes are able to form as they collide with sufficient energy . however is temperature is too high reaction rate decreases as this breaks hydrogen bonds disrupting the tertiary structure of proteins which can lead to denaturation and no enzyme substrate complexes forming
• effect of ph. : small Ph changes cause reversible change in enzyme structure , extreme PH changes cause enzymes to become denatured . increase in H+ ions increases acidity increased OH- ions increases alkalinity , this therefore affects hydrogen bonding in the enzyme affecting its ability to make enzyme substrate complexes
• Transcription : 1. DNA helicase br4eaks hydrogen bonds between the bases in the helix 2. DNA unwinds exposing free nucleotides 3. RNA polymerase binds to the template strand inserting MRNA codons 4 post-transcriptional modification occurs exons and introns are present and introns are spliced
• Translation : 1. the ribosome binds to the start codon of the MRNA 2. the trna molecule binds to the ribosome 3. a peptide bond is formed in a condensation reaction between 2 amino acids 4. ribosome moves along the mrna one codon at a time until a stop codon is reached
• DNA replication : 1. DNA helicase breaks hydrogen bonds between complementary bases whihc unzips the DNA and exposes the free nucleotides 2. DNA polymerase then forms bonds with adjacent nucleotides where a new strand is formed 3. Semi-conservative replication will therefore occur
• Meiosis and genetic variation : meiosis will produce haploid gametes ,meiosis produces genetically unidentical daughter cells by crossing over in prophase I and independent assortment in metaphase i and ii
• scale bar steps : 1. measure scale bar in mm 2. measure the specimen in mm 3. divide image by scale bar 4. multiply this value by actual size of scale bar
• Cytokinesis in animals involves the cleavage furrow and centrioles produce spindle fibres
• Degenerate - some amino acids code for more than 1 MRNA codon
• Mitochondria are cylindrical so have a large surface area to volume ratio To increase gas exchange
• Repeat until a constant mass is reached
• Biological molecule containing sulfur - protein
• Membrane width = 7nm
• calcium - important structural component of bones and teeth and found in cell walls
• condensation reaction : when 2 units are joined together producing water
• hydrolysis reaction : when 2 units are broken down removing water
• starch is the main source of glucose for plants , it is a polymer of alpha glucose , consists of amylose : which is linear , contains 1-4 glycosidic bonds and amylopectin : which contains 1.4 and 1.6 glycosdidc bonds and is branched
• polysaccharides are insoluble so have no osmotic effect and carry a lot of energy in the C-H and C-C bonds ,
• cellulose properties : structural polysaccharide , derived from beta glucose , beta glucose monomers allows for adjacent glucose molecules to rotate by 180. , hydrogen bonding occurs aswell , strong crosslinks form microfibrils
• glycogen : main storage for animals , 1,4 glycosidic bonds and 1,6 glycosidic bonds , formed due to alpha glucose
• chitin : structural polysaccharide , made form beta glucose , found in the exoskeleton of insects and fungal cell walls . contains 1,4 glycosidic bonds , allows for 180. free rotation , forms microfibrils and contains added amino acids
• uses of triglycerides : used as energy reserves, thermal insulation and protection of internal organs
• primary structure : the sequence of amino acids
• tertiary structure : 3D shape of the protein . contains peptide bonds , hydrogen bonds , disulphide bridges ionic bonds and hydrophobic and hydrohalic intercqtions
• collagen is a fibrous protein containing hydrogen bonds and is found in the muscle and tendons
• haemoglobin is a fibrous protein which contains 2 beta chains and haem groups and carries oxygen in the blood
• LWAYS MENTION WATER MOVES IN OR OUT BY OSMOSIS
• Benedict’s reagent a positive test goes from Green to brick red
• secondary structure - the 2D shape formed from an alpha helix and a beta pleated sheet which is maintained by hydrogen bonds

  
• Nucleus - controls all cellular activities and stores all genetic information in the form of DNA