biology unit 1

Closed circulatory system

-blood leaves heart under high pressure
-oxygenated and deoxygenated blood don't mix
-valves in the vein prevent backflow of deoxygenated blood.

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Properties of Water

-very good transport medium
-liquid at room temperature
-many water molecule bond together forming hydrogen bond
-polar molecule dissolve in it
-many chemicals dissolve in this
- high boiling point

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Arteries

-blood leaving the heart at high pressure
-thick walls to withstand pressure
-thick elastic lining to allow contracting and recoiling of the vessel
-narrow lumen
-no valves

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Vein

- thin walls
-blood travelling at low pressure
-has valves
-thin lining of cells
-wide lumen

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Atrial systole

-blood flows at slow rate into both atrium
-the atrioventricular valves open and blood starts to flow into the ventricles
-the atria contracts pushing all the blood into ventricle

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Ventricular systole

-atrioventricular valves close
-ventricles contract and increase pressure
-semilunar valves open and blood is pushed out into arteries

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Diastole

-atria and ventricle relax
-the muscles recoil and lower the pressure
-semilunar valves close

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Atherosclerosis

-endothelium linin gets damaged
-inflammatory response triggers ,WBC move into walls and build up
-build up of atheroma due to cholesterol build up
-artery lose its elasticity
-artery becomes narrower, making it difficult for the blood cells to pass t

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Blood clotting
process

-inflammatory response is triggered
-soluble prothrombin is converted into thrombin
-thrombin catalyzes soluble fibrinogen into insoluble fibrin
- fibrin makes a mesh trapping blood cells and calcium ions to form a clot.

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Risk factor of
CVD

-high blood pressure
-obesity
-high LDLs
-smoking
-alcoholism
-genetic inheritance

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Treating CVD: surgery

-bypass graft, artery is taken from elsewhere in the body and are grafted on the blocked artery.
-coronary angioplasty, mechanically widening the lumen of an artery

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Treating CVD: antihypertensive

-diuretics, increase the volume of the urine to reduce blood volume decrease
-beta blockers, blocks the response to adrenaline to keep the heart rate stable
-ACE inhibitors, reduces the constriction of arteries so the flow is stable

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Statins

-block the enzymes in the liver that is responsible for making cholesterol and blocking LDL production
- muscle pains, pain, nausea

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Anti coagulant

-platelet inhibitor, make the platelets less sticky preventing them from sticking together

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Sugar: Monosaccharides

-single sugar unit
-such as, glucose, fructose, galactose

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Sugar: Disaccharides

-two monosaccharides joined together by condensation reaction forming 1,4 glyosidic bonds
-Sucrose=glucose +fructose
-maltose= glucose+ glucose
-lactose= galactose+ glucose
- suitable for storage because they are compact

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Starch

- made up of Amylose and Amylopectin
-major source of energy
-cellulose, is known as dietary fibers and helps the movement of material through digestive tract.
-glycogen, stored by bacteria &animals.it side branches so that it can b

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Starch: Amylose

-straight chains of glucose molecule
-1,4 glyosidic bonds between glucose bonds
-chain coils up into spiral shape

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Starch: Amylopectin

-branched chains of glucose chains
- has 1,4 &1,6 glyosidic bond
-easier to break down due to having branches

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Lipids

-insoluble in water but soluble in organic solvent
-most common lipids, triglycerides
{used as energy store, linked by condensation reactions, have ester bond, made up of 2fattyacids and 1 glycerol}
-cholesterol is another Lipid

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Lipids : Saturated &Unsaturated fat

-saturated bonds have no carbon carbon double bond
- unsaturated fats have one double bond

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BMI(body mass index):

- weight(kg)/height^2(m)

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Lipids: Cholesterol

-insoluble in water
-Low Density Lipoprotein(LDLs), main cholesterol carrier, circulate in the blood stream and bind to receptor sites, more lipids than protein
-High Density Lipoprotein(HDLs),more protein than lipids, transport cholesterol from body to

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Smoking affecting circulatory system

-Nicotine causes high blood pressure
-hemoglobin will carry carbon monoxide instead of oxygen reducing the amount of oxygen absorbed by the hemoglobin
-HDL level falls
-damages the lining of the artery

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Inactive: increasing the chance of getting CVD

-increased exercise can help prevent high blood pressure and help lower it
-it raises HDL cholesterol level without affecting LDL level

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The risk of getting CVD can be reduced by

-stop smoking
-maintain stable blood pressure
-moderate use of alcohol
-exercise more

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Cystic Fibrosis

-caused by a faulty CFTR protein , prevents the chloride ions to move out of the cells preventing osmosis of water,
-makes the mucus thick and sticky

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Mammalian gas exchange

- large surface area for the alveoli
-large network of capillaries surrounding the alveoli
-thin walls of the alveoli and capillaries meaning a short distance between them reducing the diffusion distance

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Rate of diffusion is affected by

- Surface area : rate of diffusion is directly proportional to surface area
-Concentration gradient: rate of diffusion is directly proportional to difference in concentration across gas exchange surface
-Thickness of the gas exchange surface: rate of di

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Primary Structure

Two amino acids join during condensation reaction to form a dipeptide joined by peptide bond

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Secondary Structure

The primary structure twist and fold into spirals to form an Alpha-helix or beta-pleated sheets

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Tertiary Structure

folding of the secondary structure in the globular/tertiary structure ,with bonds such as ionic ,disulfide, hydrogen

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Quaternary Structure

different polypeptide chain comes together to form a 3-D protein structure

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Globular Protein

-folded into a compact spherical shape
-soluble because of hydrophilic side chain on their outside
-form a 3-D shape making it important for their binding
-eg. Enzymes

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Fibrous Protein

-long chains of protein
-several polypeptide chains can be cross linked for additional strength
- insoluble
-eg. keratin

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Phospholipid Bilayer

-cell surface membrane consists of a bilayer (2 layers of phospholipid)
-In phospholipid there are 2 fatty acid and a phosphate group
-the phosphate head is polar and hydrophilic
-the fatty acid tails are non polar so they are hydrophobic

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Fluid mosaic model

-plasma membrane is described to be fluid as lipids and membrane proteins move around freely.
-membrane is described as mosaic as the membrane has different protein, cholesterol studded in them.

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Diffusion

The net movement of molecule from a region of high concentration to an area of low concentration down the concentration gradient
-passive

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Facilitated Diffusion

diffusion that takes place through carrier protein from an area of high concentration to area of low concentration
-polar/hydrophilic molecules travel via this diffusion
-passive transport

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Osmosis

diffusion of water molecules from a region of high water concentration to region of low water concentration via a partially permeable membrane
-passive, no energy required

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Active Transport

transport of molecules from an area of low concentration to an area high concentration against the concentration gradient through carrier proteins. this requires energy

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Exocytosis

-used for bulk transport of substances out of the cell.
-vesicles fuse with the cell surface membrane, releasing their contents.

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Endocytosis

-used for bulk transport of substances into the cell
-vesicles are created from the cell surface membrane, bringing their contents into the cell

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Effect of Cystic fibrosis : Digestive System

- pancreatic duct becomes blocked by sticky mucus, impairing release of digestive enzymes
-this reduces the rate of digestion as the food is not being digested as the enzymes are not breaking down the food.
-there is damage to the cell walls in the pancr

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Effect of Cystic Fibrosis: Reproductive System

-female become infertile as a mucus plug develops in the cervix stopping sperm from reaching the egg
-the sperm duct get blocked by sticky mucus, only a few sperms leave the testes.

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Enzymes

-Globular protein that are biological catalyst.
-speed up the reaction without being used up

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Lock &Key Theory

-a substrate with a complementary shape that fit into its active site
-the enzyme holds the substrate molecules in a way it reacts quickly
-when reaction is finished the products are released, leaving the enzyme unchanged

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Induced Fit Theory

- Active site is flexible, it fits around the shape of the substrate
- when substrate enters the active site the enzyme molecules molecule changes slightly fitting more closely round the substrate

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Gene

a gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain.

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Mononucleotide

the deoxyribose sugar, phosphate and the base joined together by a condensation reaction between the sugar of one and the phosphate of the next one

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DNA

- there are two long stranded of nucleotides twisted around to form a double helix. the sugar and phosphate are facing outwards while the bases join together by hydrogen bonds
-4 bases= Adenine pairs with Thymine, Guanine pairs with Cytosine
-DNA carrie

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DNA &RNA

-RNA is a single stranded
-RNA contains a ribose sugar instead of deoxyribose
-RNA has Uracil to bond with Adenine rather than Thymine

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Protein Synthesis: Transcription{in Nucleus}

-DNA double helix unwinds and the hydrogen bond breaks
-the template strand is used in the production of a mRNA molecule
-every triplet code on DNA gives rise to a complementary codon on messenger RNA
-the complete mRNA leaves the nucleus through a por

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Protein Synthesis: Translation{on Ribosome}

-ribosomes are small organelles made of RNA and protein
-ribosome are found free in the cytoplasm
-a transfer RNA molecule carrying an amino acid with 3 bases called anticodon
-these pair with complementary bases on mRNA codon
-the amino acids that the t

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Semi-conservative replication

-each DNA molecule contains one original DNA strand from parents and one free new strand
-the double helix unwinds, hydrogen bonds are broken by DNA helicase
-free nucleotides that pair up by complementary bases, DNA polymerase links adjacent nucleotide

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Genetic screening

-analysis of a person's DNA to check for the presence of a particular allele
-it is expensive, but it outweighs the health benefits

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Prenatal screening

testing a fetus for any genetic condition before birth

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Prenatal screening : Amniocentesis

-taking sample of amniotic fluid around 16weeks
-results take a lot of time to comeback
-it can be a traumatic
-lead to spontaneous abortion

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Prenatal screening : Chronic villus sampling

- taking fetal tissues from the placenta at 10-12 weeks
-great risk of spontaneous abortion
-fault on the X chromosome cannot be detected as they are inactivated.

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Pre-Implantation genetic diagnosis

-during IVF, after a few cell divisions a single cell is removed from each embryo.
-no harm occurs to embryo and it keeps dividing
-the genetic make-up is checked and if they are free of any faulty allele and are then placed into mother's uterus

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biology unit 1

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