Molecules

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Structure of Amino Acids

3 different groups:

1. Carboxylic acid group

2. Amino group

3. R Group/side chain 

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Condensation Reactions

'where two molecules are joined together by removing a H atom and a OH atom. These atoms then form a water molecule'                    ANABOLIC REACTION!

Condensation reactions --> creation of dipeptide:

amino acid + amino acid = dipeptide

Hydrogen atom from amino group of one amino acid is removed.

One hydrogen and one oxygen atom is removed from the carboxylic acid group of another amino acid.

H + O + H = H20

BONDS FORMED = PEPTIDE BONDS

MANY AMINO ACIDS = POLYPEPTIDE

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Structures of Proteins

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Globular and Fibrous Proteins

GLOBULAR:

  • Roughly spherical/globular in shape
  • soluble in water
  • biochemical functions

EXAMPLE: enzymes, haemoglobin

These are folded so that the R group is on the outside. R group = hydrophilic SO globular proteins = soluble in water based products (plasma,cytoplasm)

FIBROUS:

  • polypeptide chains form long fibres or sheets
  • insoluble in water
  • structural functions

EXAMPLE: keratin, collagen

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Denaturation of Proteins

 1. Temperature

temperature increase = vibrations

large vibrations = breaking of weak bonds (hydrogen etc.)

this causes denaturation: the conformation of the protein is changed

OCCURS AT AROUND 45 DEGREES

2. pH value
pH concentration = concentration of the hydrogen atoms

hydrogen bonds depend on the attraction of H+ and O-

change in pH = change in attraction = hydrogen bonds break

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Haemoglobin Carrying Oxygen

(http://www.uncommondescent.com/wp-content/uploads/2011/10/alpha-and-beta-chains.jpg)HAEMOGLOBIN:

  • 4 polypepetide chains
  • each chain has a haem group attatched - a prosthetic group
  • each heme group has iron ion in the middle
  • iron ion binds with 1 oxygen molecule
  • 4 IRON IONS = 4 OXYGEN MOLECULES ON EACH HAEMOGLOBIN MOLECULE

haem group receives oxygen atom --> haemoglobin molecule changes --> exposes next haem group to the oxygen

This makes it easier for oxygen to be picked up.

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When Things Go Wrong

3 CONDITIONS:

1. Beta thalassaemia

  • common in Greeks/Italians
  • beta chains in haemoglobin shorter than normal = less oxygen carriage than normal

2. Diabetes

  • blood glucose levels high as cannot be regulated normally
  • glucose attatches to RBCs = glycosylated haemoglobin
  • picks up oxygen well but does not let go easily
  • organs and tissues receive less oxygen = damage
  • EXAMPLE: diabetic retinopathy - blindness - blood vessels in eye lack oxygen and become damaged

3. Sickle cell anaemia

  • valine instead of glutamic acid in haemoglobin
  • haemoglobin chains are long and stiff = RBCs change shape
  • RBCs become 'sickle' shaped and get stuck in capillaries
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Water

  • Attracted to other water molecules

the negative charges of oxygen atoms attract the positive charges of hydrogen atoms; force of attraction between water molecules known as HYGROGEN BONDS

  • Attracted to other polar molecules/molecules with a slight charge on the surface

the negative charge of oxygen molecules or positive charge of hydrogen molecules can attract to charges on other molecules

  • Universal solvent and excellent transport medium 

many substances can dissolve in it; forms a shell around molecules, causing them to dissolve

  • Polar molecule

areas of positive and negative charge

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Blood Plasma

8 COMPONENTS:

1. water

2. proteins (firbinogen - blood clotting & antibodies - immune response)

3. ions (sodium, potassium etc.)

4. hormones (insulin, oestrogen etc.)

5. oxygen

6. dissolved food substances (amino acids, glucose etc.)

7. heat (carried in blood plasma)

8. waste products (urea, CO2 etc.)

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Serum, Tissue Fluid & Lymph

SERUM = blood plasma - fibrinogen

This is used to treat patients in hospitals

TISSUE FLUID  = blood that has passed through capillaries

Capillaries are not permeable to most blood cells and large plasma proteins = don't pass thru

High blood pressure at arterial end of capillaries = small components in plasma are squeezed out

LYMPH =  tissue fluid that does not return to capillaries at venule end; must reach the lymphatic capillaries to be called lymph

lymph capillaries --> lymph vessels

contraction of muscles = fluid moves through lymph vessels

TRAVELS THROUGH, WITH VALVES TO PREVENT BACKFLOW, UNTIL IT REACHES THE BLOODSTREAM, WHERE IT IS RETURNED TO A VEIN IN THE NECK REGION.

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Diffusion

'Movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient'

  • PASSIVE - no extra energy required
  • occurs until there is an even distribution

molecules can diffuse across plasma membrane through phospholipid bilayer

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Facilitated Diffusion

WHEN IS IT NEEDED?

  • when molecules are soluble in water
  • when molecules are charged (ions etc.)

this means they cannot diffuse through phospholipid bilayer

SO FACILITATED DIFFUSION IS USED...   'diffusion helped by proteins'

USING

  • Protein channels 

some are lined with hydrophilic amino acids and water; some permanently open

  • carrier proteins

molecules bind to --> protein changes shape, releasing molecule on other side

  • no additional energy - PASSIVE PROCESS
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Osmosis

'the movement of water molecules from a region of high water potential to a region of lower water potential across a semi-permeable membrane'

Water potential = tendancy of a solution to gain or lose water (PURE WATER = 0)

water + solute = water potential decrease

THIS OCCURS UNTIL EQUILIBRIUM IS REACHED (EVEN DISTRIBUTION)

THE 'TONICS

1. Isotonic - solution and cell have equal water potential

2. Hypertonic- cell has higher water potential than solution

3. Hypotonic - cell has lower water potential than solution

water is small = fits through the phosholipids in the phospholipid bilayer =  all membranes permeable to water to a degree

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Keeping the Osmotic Balance

electrolyte = ions with + or - charge

+ charge = cations

- charge = anions

electrolytes are responsible for maintaining water potential

BUT SOLUTES - LIKE GLUCOSE - CAN DISSOLVE IN BLOOD PLASMA AND LOWER W.P

When testing electrolytes, measure:

sodium, potassium, chloride, bicarbonate, calcium, magnesium, phosphate ions

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Active Transport

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Endocytosis & Exocytosis

ENDOCYTOSIS:

taking molecules in

EXOCYTOSIS:

releasing molecules

EXAMPLE:

neutrophils engulf pathogens by phagocytosis, a type of endocytosis --> after digestion, the waste materials are released back out of the leucocyte by exocytosis

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Cholesterol

  • is taken into cells by endocytosis
  • transported through the blood attatched to proteins as it is non-polar
  • in the form of lipoprotein particles (low density lipoproteins LDPs)
  • LDLs bind to proteins which are taken into the cells themselves
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Measuring Blood Glucose

  • contain test strip with either glucose dehydrogenase or glucose oxidase
  • these enzymes turn the glucose in blood into gluconolactone
  • gluconolactone gives off electrical impulse that is detected by meter

1. wash hands throughly

2. swab hands with alcohol-based solution

3. ***** the top of the finger with a sterile lancet

4. place a small drop of blood on the glucose test strip

5. reading appears in 15 - 30 seconds

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The Saccharides

3 TYPES

1. Monosaccharies

  • simple sugars
  • GLUCOSE - repsiratory substrate, broken down easily by repsiration; soluble so transported in blood plasma

2. Disaccharides

  • 2 monosaccharides
  • GLUCOSE + GLUCOSE --> MALTOSE in condensatino reaction, forming glycosidic links (type of bond)

3. Polysaccharides

  • many monosaccharides joined by condensation reaction
  • many alpha glucose --> glycogen
  • glucose residue + 3 glucose molecules = branched molecule
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Glycogen

  • stored in liver and muscle cells
  • insoluble so doesn't dissolve in cytoplasm etc. and affect water potential
  • compact so a lot can fit in a small space
  • branched molecule so many areas where glucose can be released at a fast rate when needed

    Fats and Oils

    • are types of triglycerides

    TRIGLYCERIDE = 3 fatty acids + glycerol molecule (condensation reaction)

    FATTY ACID = hydrocarbon chain + carboxylic acid group

    AND FATTY ACID STUCTURE PIC

    https://getrevising.co.uk/https_proxy/9294 (http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Lectures/Biochemistry/saturated%20and%20unsaturated%20fatty%20acids.gif)

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Fatty Acids

SATURATED OR UNSATURATED

Saturatedmaximum number of hydrogen molecules in chain - its saturated with them

Unsaturated = double bond between some carbon atoms --> less space for hydrogen molecules --> less hydrogen molecules

OILS - unsaturated fatty acidshttps://getrevising.co.uk/https_proxy/9294 (http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Lectures/Biochemistry/saturated%20and%20unsaturated%20fatty%20acids.gif)

FATS - saturated fatty acids

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Lipids in the Body

TRIGLYCERIDE

  • storage molecule in adipose
  • more energy per gram than carbs
  • insoluble in water (can't change W.P)

ADIPOSE

  • body fat
  • heat insulator
  • reduces heat loss from bodily organs
  • protects bodily organs from mechanical damage

FAT SOLUBLE VITAMINS 

  • vitamin A and D
  • stored in liver cells in lipid globules
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Cholesterol

  • type of steriod
  • keeps the cell membrane fluid
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Phospholipids

  • polar molecules (charge)
  • form a bilayer
  • glycerol + 2 fatty acids chains + phosphate group


Transportation of Lipids

  • insoluble in water
  • so cannot dissolve in blood plasma to be carried around body
  • triglycerides -------> glycerol + fatty acids

GLYCEROL = dissolves in blood plasma

FATTY ACIDS = combine with plasma proteins --> carried in blood as globules

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Steps to Reducing Blood Loss

1. Put on gloves

2. reassure the person and ask them to sit or lie down

3. inspect the wound, cutting clothing if needed

IF THERE IS NOTHING IN THE WOUND:

4. apply a clean, large pad over the area and press down firmly

5. use a bandage to hold the pad in place

IF THERE IS AN OBJECT IN THE WOUND:

6. do not remove but place a clean pad in the shape of a ring around the wound to surround it

7. use a bandage to apply pressure to the areas around the wound and push together

8. if the wound is on a limb, raise the limb

9. if blood soaks through, do not remove but just place a clean pad over the top

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How Blood Clots

1st Step

  • damaged tissues causes collagen fibres to be exposed to air
  • platelets stick to this
  • platelets release a chemical, making them all stick together
  • plug formed
  • further blood loss prevented

REQUIRES CALCIUM!

2nd Step

  • WBCs collect at cut site
  • thromboplastin released
  • turns prothrombin into thrombin (unactive into active)
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Thrombin as an Enzyme

ENZYME

  • globular molecules that catalyse reaction by reducing activation energy required

ACTIVATION ENERGY = energy needed to activate the reaction

HOW?

enzyme-substrate complex --> enzyme have ability to exert forces on substrate due to closeness --> activation energy required is lowered

ENZYME SUBSTRATE COMPLEX = when the substrate is in the active site on an enzyme, using the lock-and-key mechanism

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Effect of Enzyme Concentration

TWO FACTORS

1. Enzyme concentration

2. Substrate concentration

SUBSTRATE CONCENTRATION:

too low = not enough substrate molecules to bind with enzyme OR 'a lot of free spaces'

too high = has no effect, to an extent, as the number of enzymes does not change

ENZYME CONCENTRATION

too low = not enough enzymes to bind with all substrates OR 'not enough free spaces'

too high = has no effect, to an extent, as the number of substrate molecules does not change

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Types of Blood Stored

1. Whole blood

  • contains all components of blood
  • severe blood loss

2. Leuco-depleted blood

  • as many leucocytes removed as possible
  • patients who recieve repeated transfusions as WBCs produce antibodies; too many = provoked immune system

3. Packed red cells

  • separated from the rest of the blood and stored
  • made into a solution with salt and sugar
  • those with anaemia/replacing red blood cells after childbirth or surgery
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Screening Blood

  • health checked before blood is given
  • blood group of donor tested
  • small sample of blood kept behind
  • antigens for the antibodies of the viruses being tested for added to blood
  • if antigens stick to antibodies, the virus is present and the blood is discarded
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Blood Transfusion - Temperature

EFFECTED BY:

TEMPERATURE

  • enzymes cause blood clotting
  • enzymes have optimum temp of 37 degrees

optimum = best

  • temp increase = vibrations of molecules = energy produced = faster ROR
  • but when temp is too high, it denatures enzymes
  • blood stored at 4 degrees
  • 0 degrees? ice crystals = cell membrane damage = cell denaturation
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Enzyme cofactors

'substances that are required for an enzyme controlled reaction to occur'

  • calcium ions = blood clotting enzymes work
  • released by damaged platelets; present in blood plasma

MUST BE REMOVED WHEN STORING BLOOD FOR TRANSFUSION TO PREVENT BLOOD CLOTTING

  • sodium citrate added to remove calcium ions
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How Blood Clots (Continued)

3rd Step

  • thrombin turns fibrinogen into a long mesh-like strucure of fibrin
  • fibrin piles and forms a mesh
  • the mesh covers the cut site as a blood clot
  • the clot becomes a scab
  • blood loss prevented
  • pathogen entering prevented
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Types of Blood Stored (Continued)

4. Platelets

  • patients with bone marrow failure;following transplants and chemotheraophy treatments;leukemia patients

5. Clotting factors

  •  people that have a type of clotting factor missing

6. Plasma

  • all components of blood removed; cardiac surgery; replace clotting factors after surgery
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Blood Transfusion - pH

PH

  • measure of how acidic or alkaline a solution is
  • more hydrogen = more acidic
  • enzymes are globular proteins = tertiary structure held by weak hydrogen bonds
  • hydrogen bonds depend on force of attraction
  • adding H+ (in acid form) changes this force of attraction and leads to the breaking of these bonds
  • breaking of bonds = change in shape = denaturation
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