Important processes Flashcards
Photosynthesis: Light independant reaction
- known as the Calvin cycle
- occurs in the Stroma
- uses: CO2, NADPH, ATP
- temperature can effect the rate at which this takes place
1) CO2 reacts with RuBP to form two GP molecules. This reaction is catalysed by the enzyme Rubisco
2)GP is then reduced to form 2 TP molecules, using energy from ATP and by accepting a H from NADPH
3)one carbon from TP leaves the cycle each time which builds up to a hexose sugar (useful organic substances - glucose)
4) Rest of the molecule is used to regenerate RuBP with the energy from ATP
Limiting factors:
- Temperature
- carbon dioxide
- light intensity
- agricultural practises
Photosynthesis: light dependant reaction
- 1st stage of photosynthesis
- Takes place in the chloroplast on the thylakoid membrane
- creates ATP and NADPH which can be used for light independent stage
1) Photoionisation:
- light energy absorbed by chlorophyll
- picked up by electrons
- electrons get excited
- ionised (lost an electron)
- some of the energy released from the exit of electrons goes towards making ATP and reduced NADP
2) Photolysis
- water split into oxygen, electrons and protons
- proton (H+) picked up by NADP to make NADPH
- electrons pass along chain of protein carriers (Electron transport chain) - releasing energy
- Oxygen used for respiration
3) Chemi osmosis
- energy released from the electron movement is used to pump protons across the chloroplast membranes via active transport
- Electrochemical gradient between each side of membrane
- Protons then pass through ATP synthase via facilitated diffusion back down the concentration gradient
- As they move through ATP synthase it phosphorylates the ADP Into ATP
Transcription and Splicing
1- Hydrogen bonds between DNA bases break (DNA helicase)
2- Only one DNA strand acts as a template
3- Free RNA nucleotides align by complimentary base pairing
4- In RNA uracil is used in place of thymine
5- RNA polymerase joins RNA nucleotides together
6- by phosphodiester bonds
7- Pre-mRNA is spliced to form mRNA (introns are removed)
8- mRNA leaves the nucleus via the nuclear pores
Translation
1) mRNA attaches to ribosomes (rough endoplasmic reticulum)
2) tRNA anticodons bind to complimentary mRNA codons
3) tRNA brings a specific amino acid
4) amino acids join by peptide bonds
5) amino acids join together with the use of ATP
6) tRNA released after amino acid joined polypeptide
7)the ribosome moves along the mRNA to form the polypeptide until it reaches a stop codon
Nitrogen cycle
Aerobic respiration
Glycolysis:
- glucose is phosphorylated by two ATP molecules that were invested
- the breakdown of ATP releases a phosphate to the glucose to make it unstable
- now that its unstable it splits in half to form 2 triose phosphate molecules
- the triose phosphate is then dehydrogenated by NAD so NAD becomes NADH (reduced)
- the release of the hydrogen releases enough energy to form 2 ATP molecules
- converts triose phosphate to pyruvate
PRODUCTS: 2 NADH,2 ATP, 2 Pyruvate
Link reaction:
- Pyruvate moves from the cytoplasm into the matrix by active transport
- The pyruvate is then decarboxylated (CO2 removed) and oxidised (lose hydrogen to NAD) to form Acetate
- The acetate combines with Coenzyme A to form Acetyl Coenzyme A
PRODUCTS: 2 acetyl CoA, 2 CO2, 2 NADH
Krebs Cycle:
- takes place in the matrix
- 4 carbon molecule (Oxaloacetate binds with acetyl CoA)
- causes CoA to dissociate from acetate
- Acetate merges with the oxaloacetate to form a 6-carbon compound (citrate)
- Citrate is then decarboxylated twice to make a 4 carbon compound
- during this two hydrogen molecules also released and accepted by NAD to form NADH
- 4 carbon compound then is reformed back to Oxaloacetate by releasing energy when the hydrogen were given off
- The energy is then used for the formation of ATP (ADP + Pi > ATP)
- Hydrogens that were released during this part of the process were accepted by NAD and FAD
PRODUCTS: 2 CoA, 2 Oxalocetate, 4 CO2, 2 ATP, 6 NADH, 2 FADH
Oxidative phosphorylation:
- occurs in the cristae of the mitochondria
- when FADH and NADH are in the cristae, they bind to a protein and dissociate their hydrogen atoms
- The Coenzymes FADH and NADH are then oxidised back to normal FAD and NAD
- Hydrogen atoms that were removed approach proteins that are embedded within the inner membrane
- The proteins encourage the hydrogens to split into {single electron (e-), single proton (h+)}
- The electrons then pass along a chain of three electron carrier proteins
- as they travel through, the electrons lose energy to the proteins
- the energy is then used by the carrier protein to pump a proton from the matrix to the inter membrane space
- Concentration of protons will be high in the intermembrane than the matrix
- electrochemical gradient is formed
- as a result the protons diffuse back into the matrix
- travel via ATP synthase (chemiosmosis)
- as it travels through kinetic energy is released and is used to drive the formation of ATP
- Final electron acceptor (binds to hydrogen to form H2O
Anaerobic respiration
Glycolysis:
- glucose is phosphorylated by two ATP molecules that were invested
- the breakdown of ATP releases a phosphate to the glucose to make it unstable
- Now that its unstable it splits in half into 2 triose phosphate
- The Triose phosphate is then dehydrogenated by NAD so NAD becomes NADH
- the release of hydrogen releases enough energy to form 2 ATP molecules
- converts Triose phosphate to pyruvate
Oxygen isn’t present
Plant cells: Alcoholic Fermentation
- pyruvate decarboxylated to form Ethanol
- NADH is then oxidised to form NAD
- Hydrogen is released and the NAD is put back into glycolysis reaction
Animal cells: Lactate Fermentation
- Pyruvate is reduced to form lactate
- NAD is reused and put back into glycolysis
Cardiac Cycle
1) Atrial diastole
DNA replication (semi conservative)
1) DNA helicase unwinds double helix
2) Both strands acts as templates
3) free DNA nucleotides line up in the complementary base pairs
4) DNA polymerase joins nucleotides
5) Forming phosphodiester bonds
6) each new DNA molecule consists of one original template
Countercurrent flow
- Water and blood flow in opposite directions
- Maintains concentration gradient and equilibrium not reached so water is always next to blood with a lower concentration of oxygen
- Along whole length of gill (lamellae)
Phagocytosis
1- Phagocyte is attracted to the pathogen by chemical products
2- moves towards the pathogen along a concentration gradient
3- Phagocyte has several receptors on its cell surface membrane that attach to chemicals on the surface of the pathogen
4- Lysosomes within the phagocyte migrate towards the phagosome formed by engulfing the bacterium
5- Lysosomes release their lysozymes into the phagosome, where they hydrolyse the bacterium
6- The hydrolysis products of the bacterium are absorbed by the phagocyte
mitosis
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meiosis
Stages
- DNA replication
- crossing over and separation of homologous pairs
1) DNA replication
2) two divisions in meiosis
3) crossing over and separation of homologous chromosomes
4) Separation of sister chromatids
5) Produces 4 haploid cells
reabsorption of glucose or amino acids in the ileum
- sodium ions are actively transported out of the epithelial cell via the potassium pump into the capillary, and potassium ions travel into the cell
- as a result there is now a low concentration of sodium ions inside the epithelial cell compared to the high concentration in the lumen of the ileum
- Therefore sodium ions move into the cell via facilitated diffusion, However when they bind to the transport protein and it allows glucose/amino acids to bind and move in with the sodium ions via co transport
- once the glucose/amino acids are in the cell they move into the capillary via facilitated diffusion
Kidney stuff ?
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