Harry Sedgwick teacher: Chris Morrel Subject: biology

The Cell - - Two different types of cell - - Prokaryotic cells - Eukaryotic cells - (anything made from it is - (anything made from it is A prokaryotic organism) a eukaryotic organism) - These are bacteria - found in animals and plants - Cell ultra structure - - Organelles - structures inside the cell -

#Chromosomes- Usually in the form of chromatin- Contains genetic information- Composed of DNA- Thicken for cellular division- Set number per species (i.e. 23 pairs for human)

#Nuclear membrane- Surrounds nucleus- Composed of two layers- Numerous openings for nuclear traffic

#Nucleolus- Spherical shape- Visible when cell is not dividing- Contains RNA for protein manufacture

#Centrioles- Paired cylindrical organelles near nucleus- Composed of nine tubes, each with three tubules- Involved in cellular division- Lie at right angles to each other

#Chloroplasts- A plastid usually found in plant cells- Contain green chlorophyll where photosynthesis takes place

#Cytoskeleton- Composed of microtubules- Supports cell and provides shape- Aids movement of materials in and out of cells

#Endoplasmic reticulum- Tubular network fused to nuclear membrane- Goes through cytoplasm onto cell membrane- Stores, separates, and serves as cell's transport system- Smooth type: lacks ribosome’s- Rough type (pictured): ribosome’s embedded in surface

#Golgi apparatus- Protein 'packaging plant'- A membrane structure found near nucleus- Composed of numerous layers forming a sac

#Lysosome- Digestive 'plant' for proteins, lipids, and carbohydrates- Transports undigested material to cell membrane for removal- Vary in shape depending on process being carried out- Cell breaks down if Lysosome explodes

#Mitochondria- Second largest organelle with unique genetic structure- Double-layered outer membrane with inner folds called cristae- Energy-producing chemical reactions take place on cristae- Controls level of water and other materials in cell- Recycles and decomposes proteins, fats, and carbohydrates, and forms urea

#Ribosome’s- Each cell contains thousands- Miniature 'protein factories'- Composes 25% of cell's mass- Stationary type: embedded in rough endoplasmic reticulum- Mobile type: injects proteins directly into cytoplasm

#Vacuoles- Membrane-bound sacs for storage, digestion, and waste removal- Contains water solution- Contractile vacuoles for water removal (in unicellular organisms)

#Cell wall- Most commonly found in plant cells- Controls turgidity - Extra cellular structure surrounding plasma membrane- Primary cell wall: extremely elastic- Secondary cell wall: forms around primary cell wall after growth is complete

#Plasma membrane- Outer membrane of cell that controls cellular traffic- Contains proteins (left, gray) that span through the membrane and allow passage of materials- Proteins are surrounded by a phospholipids bi-layer.

Magnification = size of image resolution = the ability to distinguish between Actual size of cell points or objects that are close together (the Higher the resolution the closer the points can be)

- a typical eukaryotic cell - (An animal cell) H/w - A typical prokaryotic cell -

- Differences between eukaryotic and prokaryotic cells -Some prokaryotic cells have a capsuleA prokaryotic cell has a mesosome (infolding of the plasma membrane)A prokaryotic cell has a bacterium flagellum Prokaryotic cells have no nucleus - they have a loop of DNA (naked DNA)There is binary fusion - no mitosis (because no nucleus)No membrane bound organelles It has small (70s) ribosome’s - eukaryotic has large (80s) ribosome’sProkaryotic - very simple compared to eukaryotic!!! - The mitochondrion -

- Chloroplasts -

- Rough endoplasmic reticulum and Golgi apparatus -

- Cell membrane -

- Outside the cell - - Extrinsic membrane proteins - are imbedded in the outer phospholipids layer. They often act as chemical receptors for the cell - Intrinsic membrane proteins - pass right through the lipid layers and have a variety of functions. Many transport molecules through the membrane either into or out of the cell. - A few questions - 1. Estimate the thickness of the cell surface - (1mm in drawing and magnification x 190,000) 0.001m = 1mm 0.001/190,000 = 0.000000005m = 5nm 2. How many x bigger would the thickness of the actual size of the cell if the drawing was double? The cell surface was double the surface it would be 50 nanometers so 10x bigger

Transport across cell membrane - Diffusion - movement from a region of high concentration to a region of low concentration. This requires no energy! And it has to be small molecules e.g. water C02 etc. (this is a passive process) - Factors which affect the rate of diffusion - - Surface area of cell membrane e.g. this can be shown as microvillus - The thickness of the membrane - Relative concentration on the 2 sides of the membrane - The temperature of the surrounding area etc. - The size and nature of the molecules (ions and polar molecules can’t go through) Facilitated diffusion - larger polar molecules and ions can diffuse but with help, (similar diffusion but requires either carrier proteins or channel proteins)

Active transport - - Movement of molecules against the concentration gradient - Energy is required - provided by aerobic respiration - Specific proteins in the membrane transport the molecules across - Low concentration ------------> high concentration

Osmosis - this is the passage of water from a region of high concentration of water (low solute solution - ) across the semi-permeable membrane to a region of low concentration of WATER (a concentrated (high solute) solution - )

- A measure of the ability of water molecules to move across the membrane from high to low water concentration. - Pure water - = 0 but cell cytoplasm - = negative

(Distilled water - =0kpa (killer Pascal’s)

Plant cell -

Animal cell -

Bulk transport across the membrane - - Movement of materials in bulk rather than as single molecules - - Phagocytosis - (movements of solids across the membrane) - Endocytosis - taken into the cell - Exocytosis - secreted out of the cell - Pinocytosis - (movement of liquids across the membrane) - Endocytosis - taken into the cell - Exocytosis - secreted out of the cell

Half term! Begins

Circulatory system -

- Cardiac cycle - - One heart beat is one cardiac cycle - There are two-parts to a cardiac cycle-diastole (relaxation) and systole (contraction) - There is also -atrial diastole (relaxation of atria) -and ventricular diastole (relaxation of ventricle) - This is the same for systole - ventricular systole (contraction of ventricle) - Atrial systole (contraction of a atria) - Cardiac cycle - 1. Atrial diastole (relax) and ventricular diastole 2. Atrial systole (contraction) and ventricular diastole 3. Atrial diastole and ventricular systole 4. Atrial diastole and ventricular diastole - Atrial diastole - atria relaxed and blood enters atria so it fills up - Atrial systole - atria contract which increases blood pressure so bloods forced through the bicuspid / tricuspid valve into ventricles. - Ventricular systole - atrial diastole because no pressure so the ventricles contract Because of pressure and bicuspid/tricuspid vales close and the semi-lunar valves open. Blood runs out of the heart into pulmonary and aorta arteries therefore the semi lunar valves close to prevent backflow-ventricular diastole.

Heart sounds - lub blood hitting the closed AV valves during ventricular systole (ATRIOVENTRICULAR) Dub blood hitting the closed semi lunar valves during ventricular Blood pressure (p) differences in the cardiac cycle - Pa = pressure in atria Pv = pressure in ventricles Paorta = pressure in aorta

- Arial systole - Pa > Pv - AV valves open - Ventricular systole - Pv > Pa - AV valves close - Pv > Paorta semi lunar valves open = increase in pressure- Ventricular diastole - Paorta > Pv - semi lunar valves closeCardiac output - The volume of blood ejected from the heart/minute. Stroke volume - the volume of blood ejected from the heart during Ventricular systole.

<- formula triangle (might not need in exam)Nodes: - SAN node (right side) - AV node (middle)

Organ systems > organs > tissues > cell

Respiratory system - - Ventilation (breathing) - Movement of air in and out of the lungs - Gaseous exchange- exchange of O2 and C02 between the blood and the atmosphere across The AVEOLI of the lungs. - Cellular respiration (AEROBIC) - production of energy (ANEROBIC respiration produces lactic acid) Need for ventilation system - - To maintain concentration gradients across the alveoli - Oxygen and carbon dioxide move across the alveoli by diffusion - down the concentration gradient - Inhalation increases oxygen gradient from the alveolus to blood - Exhalation decreases carbon dioxide gradient from the blood to alveolus Features of alveoli for gaseous exchange - - Large surface area (for increased diffusion) - Single layer of flattened cells (for more diffusion) - Moist lining (for diffusion to occur) - Dense network of blood capillaries Fick’s law - rate of diffusion = surface area (large) x difference in concentration (large) Thickness of the membrane (thin) Mechanism of inhalation - - External intercostals muscles contract. - causing ribcage to move up and out. - Diaphragm contracts and flattens. - Abdominal muscles relax. - Volume of thorax increases-decreases in pressure in thoracic cavity pressure. - Air moves into lungs. Mechanism of exhalation - - External intercostals muscles relax. - Causing ribcage to move down and inwards. - Diaphragm relaxes and becomes dome shaped. - Abdominal muscles contract. - Volume of thorax decreases-increases pressure in thoracic cavity pressure. - Air moves out of lungs

Tidal volume – volume of air inhaled and exhaled during normal breathing. (Normal ½ litres)Vital capacity – maximum volume of air that can be expelled. Residual volume – volume of air left in lungs after deep exhalation. Pulmonary ventilation – the total volume of air inhaled / minute (normally 15 times a minute)Pulmonary ventilation rate = tidal volume x breathing rate. (Normally around 7½ litres) Dm3min-1 dm3 min-1 Control of breathing rate (control of breathing rate) –

Microscopes -2 advantages and disadvantages of an electron microscope – - An electron microscope has better resolution than a light microscope - An electron microscope has better magnification so more organelles are discovered - An electron microscope is very expensive - An electron microscope kills the cells during this processCell fractionation/homogenization – the process in which cells are split apart to see the details in the cells.Homogenization – cells are broken down in a homogenizer so that the cell

membrane is broken and not the organelles so then you can look at the cell insides with detail.Centrifugation – when the liquid is spun after homogenization then the larger molecules accumulate towards the bottom of the test tube.MODULE 2 - syllabus -

The Cell cycle -

General life cycle -

1. Mitosis – produces genetically identical cells (daughter cells) that have the same number of chromosomes. 2N -> 2N + 2N -> 2N + 2N + 2N + 2N etc. Functions: growth, repair of tissues, replace of cells, asexual reproduction 2. Meiosis – division of the nucleus to produce daughter nuclei (cells) with half the number of chromosomes (haploid) 2N -> N + N (meiosis 1)-> N + N + N + N (meiosis 2) – end up with 4 haploid gametes. The daughter nuclei are genetically different.Function: production of gametes for sexual production. 4 stages of mitosis -

Mitosis practical -

The Immune response –

- Physico-chemical barriers – Skin (protective barrier), Mucus membranes (trap bacteria etc), Nasal hairs (traps bacteria), Cilia (waft up mucus), Saliva (lysozyme – enzyme breaks down bacterial cell walls), Tears (same as saliva but in eyes), HCL in stomach (breaks down stuff),Blood Clotting (platelets etc clots to make scabs over cuts).

- Non specific immune response – Leucocytes (white blood cells) - - Phagocytes (responsible for non-specific immune response) - Phagocytosis by phagocytes (engulfing pathogens (any organism that causes disease)) - Inflammatory response (produces histamine – increase leakage of plasma through the capillary walls. Increase flow of blood to site of infection)Complement proteins – - Chemotaxis (leucocytes follow a chemical trail to the site of infection) - Opsonisation (bacteria coated with protein which attracts phagocytes to attack) - Lysis (bursting of pathogens)

- Specific immune response – - Reaction to specific ANTIGENS – Protein/glycoprotein’s carried on the cell surfaces of invading organisms. - Antigen – antibody reaction – - Antibodies are protein molecules that are produced and released in response to specific antigens. - Antibodies will attack and destroy the SPECIFIC antigens. - The immune response includes – - Recognition of antigen and engulfed by macrophage (phagocyte). - Foreign antigens are left on the surface of the macrophage. - The Foreign antigens are presented to T-helper cells - If a T-helper cell recognizes the antigens it activates the rest of the immune system - B-cells divide very rapidly by mitosis to produce – B-plasma cells (produce specific antibodies against antigen) And B-memory cells (produce long term immunity)

- Lymphocytes produce antibodies and they are responsible for specific immune

response. - Two main types – T-cells – responsible for the cell mediated response - identify - B-cells – responsible for the production of antibodies – gets response

Principles of immunology –

- Antigens – antigens are large, organic molecules found on the surface of the cell membrane. Every individual has their own unique cell surface molecules, which the immune system recognizes. So when a pathogen like a bacterium invades the body, the antigens on its cell surface are identified as foreign by the immune system.

- Antibody’s – when the body detects foreign antigen, it makes antibodies – protein molecules that bind to specific antigens giving an antigen-antibody complex.

- Blood grouping – red blood cells (Erythrocytes) carry special antigens (called agglutinogens) on their surface. There are two types of red blood cell antigen – A and B. These determine Blood groups – a person with type A antigens will be blood group A, a person with type A and B antigens = blood group AB and so on… If you don’t have any antigens on your red blood cells your blood group O. Blood plasma caries special antibodies called agglutinogens, again there are two types – A and B. If blood antigens and antibodies of the same type mix, agglutinogen occurs – the agglutinins bind to the agglutinogens on the blood cells, forming a clump. This can be fatal because the clumps can block arteries. So we don’t have agglutinogens and agglutinins of the same type in our bodies, if we have type A agglutinogens, we’ll have type B agglutinins and so on…

For each antigen (A + B) there is an antibody (anti-A and anti-B) - - Anti-A will cause cells with antigen A to clump together (agglutination) - Anti-B will cause cells with antigen B to clump together (agglutination) - So therefore – anti-B/A cells will only react when B/A antigens are present. This is how we test blood.

Where do you find anti-B and anti-A antibodies? – They are found in the blood plasma. The antibodies are specific to the blood type.

Blood group Antigen A Antigen B Antibody Anti-A

Antibody Anti-B

A Yes no no yesB no yes yes noAB yes yes no NoO no no yes yes

Rhesus factor (Rh) – Rh + = carry rhesus antigens, no normal antigens Rh - = no antigens, antibodies not normally found in plasma (anti – D) The person has the ability to produce anti-d antibodies if they Come into contact with RH+ blood.

DNA -

PCR (polymerase chain reaction) - function is to take parts of specific DNA by process of alternate heating and cooling.

Genetic fingerprinting/profiling – - DNA cut into fragments of different lengths using restriction enzymes. - DNA is placed on a gel and on electric field applied called electrophoresis. - The DNA fragments move towards the positive electrode - smaller fragments move faster, separating the fragments of different lengths - labelled gene probes are used to locate various base sequences along the fragments - Gene probes form patterns on photographic plate - Applications of DNA profiling – - Criminal investigations - identifying relationships of people who have been dead for a long time - identifying a person’s origins Adaptations of cereal - Respiration – two types :– 1. aerobic (requires oxygen). This is 19 times more efficient than anaerobic. - 2. anaerobic (low oxygen concentration). This makes lactic acid and ethanol which is toxic.

Rice – is adapted so it can survive in waterlogged swampy conditions. - There are no air spaces in the soil so the plant has a special tissue called aerenchyma in its leaves, roots and stems which has large air spaces in them so it makes the roots flow to the top so it can diffuse oxygen from it. - It can also tolerate large quantities of ethanol so I can anaerobicaly respirate to provide energy to its roots.

Maize – grows in hot places and is adapted to a high light intensity. - it uses C4 photosynthesis which works well at high temperatures and hot conditions. - It uses a different enzyme to fix the C02 and it works well with low C02 conditions.

Sorghum – is adapted to survive in hot and very dry conditions. - It has many xerophytic characteristics and it is very well adapted to its environment. - It has long roots so that it can search for water very deep down in the soil. - it has very thick waxy cuticles. - there are few stomata so that it reduces water loss. They are also shrunk so that there is a buildup in water vapour that slows diffusion down. - It can roll its leaves like maize to reduce water loss. - it can also use C4 photosynthesis.

Artificial environments –

- Famers can help the plants grow by giving optimum conditions (above).

Photosynthesis – Production of complex organic compounds from simple inorganic compounds (C02 + H20) using light energy.

Factors affecting photosynthesis – - light, C02 and temp intensity –

Questions – 1. Two ways that rice is adapted to live in swampy fields are because it can

respirate anaerobicaly and it has air spaces called aerenchyma2. Four ways in which sorghum is adapted structurally is it has long roots for

deep penetration of the soil, It has shrunken stomata, It can role its leaves and it has waxy cuticles.

3. Maize reduces its water loss by having closed stomata

Fertilisers – These replace nutrients lost from the soil. These are nitrates (protein for growth and repair etc), phosphates (DNA) and potassium.

There can be organic or inorganic fertilisers: – organic fertilizers are the natural products, Advantages - they do not leach/eutrophicate the soil as much, they are cheap, they recycle animal waste and it helps with soil structure. Disadvantages - Although it is hard to maintain in large quantities, they are expensive to transport, slow release of nutrients and they are difficult to spread accurately - Inorganic fertilizers are manmade products, Advantages – they can be manufactured for the specific crop, can be spray accurately and have a fast release of mineral ions.

Disadvantages – It is expensive, damages soil structure and the soil leaches more and eutrophication increase.

Leaching of the soil is washing out of the minerals from the soilEutrophication is when fertilizer soaks into rivers from the soil so it contaminates it.