Biology

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Water

• Water is a dipolar molecule

• Hydrogen’s slightly (delta) positive & Oxygen slightly (delta) negative

• Forms Hydrogen bonds

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Water: Temperature Control

• High latent heat of vaporisation - large amount of energy required to change from liquid to gas

• Evaporation is an efficient cooling mechanism

• High specific heat capacity - large amount of energy needed to change, temperature

• Thermally stable environment for aquatic organisms

• Aquatic organisms use less energy on temperature control

• Internal temperature of organisms change slowly

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Water: Transport

• Water is a good solvent - Ionic compounds dissolve in water e.g. Na+

• Cohesion - water molecules stick together (H-bonds)

• Adhesion - water molecules stick to other things (H-bonds)

• Water columns can be pulled up xylem (cohesion-tension theory)

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Water: Other

• Biological / metabolic reactions require water e.g Condensation and Hydrolysis reactions

• Ice is less dense than water (it floats)

• Ice provides habitat for, organisms e.g Polar Bear

• Ice insulates water below - remains liquid - organisms don’t freeze

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Transport Across Membranes: By diffusion

• Small nonpolar molecules

• From high concentration to low concentration

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Transport Across Membranes: By osmosis

• From a high water potential to a low water potential

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Transport Across Membranes: By facilitated diffusi

• Channel protein - small charged molecules e.g. Na+

• Carrier protein - large particles e.g. glucose

• Down concentration gradient;

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Transport Across Membranes: By active transport

• Carrier protein

• Against concentration gradient;

• Using ATP/energy (from respiration)

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Transport Across Membranes: By endocytosis

• Engulfing by cell surface membrane to form vesicle/vacuole

• Uses ATP

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Transport Across Membranes: By exocytosis

• Fusion of vesicle with cell surface membrane;

• Uses ATP

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Carbohydrate digestion

• Amylase

• Starch to maltose

• Maltase

• Maltose to glucose

• Hydrolysis

• Of glycosidic bond

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Why are enzymes specific?

• Tertiary structure of enzyme (means)

• Active site is only complementary to substrate (name it if you can)

• Active site changes shape to become complementary (induced fit)

• By forming enzyme-substrate complex

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Inhibitors

• Inhibitors reduce / prevent formation of ES complex

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Inhibitors: Competitive inhibition

• Inhibitor similar shape to substrate

• Binds to active site of enzyme

• Inhibition can be overcome by more substrate

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Inhibitors: Non-competitive inhibition

• Inhibitor binds to site on enzyme other than active site

• Prevents formation of active site / changes (shape of) active site

• Cannot be overcome by adding more substrate

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Proteins & DNA: Structure of Proteins

• Polymer of amino acids

• Joined by peptide bonds

• Formed by condensation

• Primary structure is order of amino acids

• Secondary structure is folding of polypeptide chain due to hydrogen bonding

• Tertiary structure is 3-D folding due to hydrogen bonding and ionic/disulfide bonds

• Quaternary structure is two or more polypeptide chains

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Proteins & DNA: How a mutation can create a non-fu

• Change/mutation in base sequence of DNA/gene

• Change in amino acid sequence/primary structure

• Change in hydrogen/ionic/disulfide bonds

• Change in the tertiary structure

• Change in active site (enzyme) or variable region (antibody)

• Substrate / antigen no longer complementary

• No Enzyme-Substrate complex or Antigen-Antibody complex formed.

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Proteins & DNA: DNA Replication

• Strands separate / H-bonds break

• DNA helicase • Both strands act as templates

• Free DNA nucleotides attach

• Complementary/specific base pairing e.g. AT and GC

• DNA polymerase joins nucleotides

• Forming Phosphodiester bonds

• H-bonds reform

• Semi-conservative replication

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Protein Synthesis: Transcription

• Strands separate / H-bonds break

• DNA helicase

• Template strand is copied into mRNA

• Free RNA nucleotides attach

• Complementary/specific base pairing e.g. AU and GC

•RNA polymerase joins nucleotides

• Forming Phosphodiester bonds

• H-bonds reform

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Protein Synthesis: Translation

• mRNA moves to ribosome in the cytoplasm

• tRNA binds to mRNA

• tRNA anticodons pair with mRNA codons

• Specific amino acid attached to tRNA

• Formation of peptide bond between amino acids

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Meiosis

• Cell division to form gametes (eggs and sperm)

• Two divisions forming Four Haploid Daughter cells

• Genetically non identical (due to crossing over and independent assortment)

• Crossing over - creates a new combination of alleles

• Independent assortment - creates a new combination of chromosomes

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Meiosis: Prophase I

• Nuclear membrane breaks down

• Chromosomes condense 

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Meiosis: Metaphase I

• Homologous pairs of chromosomes line up next to each other on the equator

• Spindle attaches to chromosomes at the centromere

• Crossing over of chromatids takes place

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Meiosis: Metaphase I

• Homologous pairs of chromosomes line up next to each other on the equator

• Spindle attaches to chromosomes at the centromere

• Crossing over of chromatids takes place

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Meiosis: Anaphase I

• Homologous pairs separate - one to each pole (independent assortment)

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Meiosis: Telophase I

• Nuclear membranes reforms

• Cell divides (cytokinesis)

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Meiosis: Prophase II

(They never ask about this xD)

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Meiosis: Metaphase II

• Chromosomes line up on the equator

• Spindle attaches to chromosomes at the centromere

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Meiosis: Anaphase II

• Centromeres split

• Chromatids move to opposite poles

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Meiosis: Telophase II

• Nuclear membranes reforms

• Chromosomes uncoil

• Cell divides (cytokinesis)

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Cell Cycle: Interphase

• G1 – Cell grows and organelles multiply

• S – DNA replicates

• G2 - Organelles multiply ready to Divide

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Cell Division

Mitosis or Meiosis

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Immune Response

• Phagocyte recognise antigens on bacteria as foreign

• Engulf bacteria      • Bacteria in vacuole

• Lysosome fuses with / empties enzymes into vacuole

• Bacteria digested / hydrolysed

• Phagocytes present pathogens antigen (antigen presenting cell)

• Antigens on phagocyte active T-cells (T-lymphocytes)      • T-Killer cells – destroy pathogen

• T- Helper cells present antigens and activate B-cells

• Clonal Selection – B-cell with required antibody divides by mitosis to form plasma cells

• antibodies are complementary to antigen (form antigen-antibody complex)

• B-cells from memory cells             • Secondary response if infected again with same antigen

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Immune Response: Vaccines

• Vaccines contain antigens #

• Dead / weakened pathogens

• Clonal selection of B-cells (mitosis)

• B-cells produce antibodies

• Memory cells produced

• On second exposure - Rapidly produce antibodies / produces more antibodies

• Antibodies destroy pathogen

• Secondary response – don’t feel symptoms

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Immune Response: Heart Disease

• Atheroma is cholesterol / plaque / LDL / fatty material

• In artery wall / endothelium of artery

• Atheroma linked to blood clot / thrombosis

• Blocks coronary artery (to heart muscle/ tissue / cells)

• Reduces oxygen & glucose supply (to heart muscle / tissues / cells)

• (Heart muscle / tissue / cells) unable to respire

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Immune Response: Control of Mammalian Heartbeat

• SAN initiates heartbeat / acts as a pacemaker

• SAN sends electrical impulses across atria causing atrial contraction

• AVN delays electrical impulses

• Allowing atria to empty before ventricles contract

• AVN sends wave of electrical impulses down Bundle of His / Purkyne fibres

• Causing ventricles to contract from base up / ventricular systole

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Immune Response: Control of Mammalian Heartbeat

• SAN initiates heartbeat / acts as a pacemaker

• SAN sends electrical impulses across atria causing atrial contraction

• AVN delays electrical impulses

• Allowing atria to empty before ventricles contract

• AVN sends wave of electrical impulses down Bundle of His / Purkyne fibres

• Causing ventricles to contract from base up / ventricular systole

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Immune Response: Adaptations of Arteries

• Elastic tissue stretches under pressure/when heart beats

• Recoils/springs back

• Evens out pressure/flow

• Have muscle that can contract to

• Reduces diameter of lumen/vasoconstriction

• Changes flow/pressure

• Epithelium smooth

• Reduces friction/blood clots/less resistance

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Gas Exchange: How is X adapted for efficient diffu

• Large surface area

• So fast diffusion

• Thin epithelium

• So short diffusion distance

• So fast diffusion

• Ventilation & Circulation

• Maintain a high concentration gradient

• So fast diffusion

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Gas Exchange: Fish Gills

• Large surface area provided by lamellae/filaments

• Increases diffusion/makes diffusion efficient

• Thin epithelium/distance between water and blood

• Water and blood flow in opposite directions (countercurrent)

• Maintains a high concentration gradient along all of the lamellae

• As water always next to blood with lower concentration of oxygen

• Circulation replaces blood saturated with oxygen

• Ventilation replaces water (as oxygen removed)

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Gas Exchange: Insects

Gas Exchange:

• Air enters through spiracles

• Through tracheae

• Diffusion gradient in trachea

• Tracheae closely associated with cells

• Oxygen diffuses into cells

• Ventilation replacing air in tracheae

Prevent Water loss:

• Body covered with (waterproof) waxy cuticle

• Spiracles are able to close

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Gas Exchange: Formation and Return of Tissue Fluid

Formation:

• High blood / hydrostatic pressure / pressure filtration

• Forces water / fluid out

• Large proteins remain in capillary

Return:

• Low water potential in capillary / blood

• Due to (plasma) proteins

• Water enters capillary / blood

• By osmosis

• Correct reference to lymph

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Oxygen Loading and Unloading in Lungs

• Haemoglobin has a high affinity for oxygen and forms oxyhaemoglobin

• Haemoglobin is found in red blood cells

• Oxygen loading in lungs

• at high p.O2

• Unloads/ releases O2 to respiring cells/tissues

• at low p.O2

• Unloading linked to higher carbon dioxide concentration

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Cell Fractionation

• Cell homogenisation to break open cells

• Filter to remove debris/whole cells

• Use isotonic solution to prevent damage to organelles

• Keep cold to prevent/reduce damage by enzymes

• Centrifuge pellets formed

1. Nuclei

2. Chloroplasts (if present)

3. Mitochondria

Last Ribosomes

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Bohr Effect

• Increased respiration

• Increased CO2 in blood

• Blood becomes more acidic which

• Lowers haemoglobin’s affinity for oxygen / haemoglobin releases more oxygen / oxygen dissociates/unloads more readily

• To muscles/tissues/cells

• For rapid respiration

• Oxyhaemoglobin dissociation curve shifts to the (BohR – Right)

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Transmission Electron Mircoscopes

Advantages:

• Small objects can be seen

• Wavelength of electrons shorter

• TEM has high resolution

Limitations:

• Cannot look at living cells

• Must be in a vacuum

• Must cut section / thin specimen

• Preparation may create artefact

• Does not produce colour image

• Does not form a 3D image

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Mitosis

• Cell division for growth and repair

• One Division forming Two Daughter cells

• Genetically Identical 

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Mitosis: Prophase

• Nuclear membrane breaks down

• Chromosomes condense 

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Mitosis: Metaphase

• Chromosomes line up on the equator

• Spindle attaches to chromosomes at the centromere

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Mitosis: Anaphase

• Centromeres split

• Chromatids move to opposite poles

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Mitosis: Telophase

• Nuclear membranes reforms

• Chromosomes uncoil

• Cell divides (cytokinesis)

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Comments

Naomi Of Mirkwood

why no comments guys.. I have spent 15  hours on this.. my village is dead cause some hobbits let a dragon out and burn do

Naomi Of Mirkwood

Sorry some people hacked me

thefarthing

Sick resource bro. There's your comment

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