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178 Cards in this Set
- Front
- Back
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What is the maximum magnification for a light microscope? |
1500x |
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How does a light microscope work? |
2 lenses- objective lens near specimen and eyepiece to view. Objective lens produces a magnified image and the eyepiece magnified it further. This allows for a much higher magnification and reduced chromatic aberration. Illumination used to provide light |
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What is the maximum magnification in an electron microscope? |
500 000x |
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Why is staining used in microscopy? |
Increases the contrast in organelles and make it more visible |
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Give 3 uses of staining |
Observe location of certain chemicals in a cell Increase contrast Differentiate between organisms that can be hard to tell apart |
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Name 2 techniques used in staining |
Gram stain technique- used to separate bacteria into 2 groups Acid- fast technique- used to differentiate between species of Mycobacterium from other bacteria |
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What are the rules for drawing microscope images |
Sharp pencil Straight lines Bigger than half a page Label lines don't cross over Rule label lines |
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How do electron microscopes work? |
Bean of electron of about 1nm. Image is focused using electromagnets. Has a higher resolution and magnification than light microscopes. |
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What are the advantages and disadvantages to using light and electron microscopes? |
Adv of light: • can be either dead or alive • simple to prepare • image viewed directly Disadv of light: • not as high resolution or magnification Adv of electron: • high resolution and magnification Disadv of electron: • uses corrosive chemicals to prepare • must be viewed via a fluorescent screen as electrons can't be viewed by human eye • must be a vacuum otherwise electrons will be absorbed by air |
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What are the 2 types of electron microscopes and the differences between them? |
Transmission electron microscope- pass a thin beam of electrons through a thin slice of image. Has best resolution (0.5nm). 2D images. Objects are grayscale Scanning electron microscope- pass a beam of electrons over a surface of specimen. Resolving power is 3-10nm. 3D images. Objects are coloured |
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What is laser scanning confocal microscopy? |
Moves a single spot of focused light across a specimen. Causes fluorescence rom components labelled with dye. Emitted light from specimen is filtered through pinhole aperture. Spot is illuminated across image and 3D image produced. Used in diagnosis of disease of the eye. |
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What is the difference between eukaryotic and prokaryotic? |
Eukaryotic- large cells, large ribosomes, DNA inside nucleus, mitochondria present and internal plasma membranes Prokaryotic- small cells, small ribsomes, free DNA and no nucleus, no mitochondria or internal plasma membranes |
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Name some monosaccharide reactions |
Fructose + galactose= sucrose Galactose + glucose= lactose |
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What is the difference between magnification and resolution? |
Magnification is a measure of enlargement Resolution is the amount of detail visible and the ability to differentiate between 2 specimen that are hard to tell apart |
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What is the equation for magnification? |
Magnification= image size/ actual size |
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Name some facts about cellulose |
Made of beta glucose in a condensation reaction Orientation of glucose molecules means straight line chains are made. Hydrogen bonds form between the parallel chains. In a chain, every other beta glucose flips around so the 2 OHs are closer to one another. These form a 1:4 glycosidic bond |
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What is the function of The nucleus The nucleolus Mitochondria
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Nucleus- contains coded genetic code. Surrounded by double membrane which forms nuclear envelope. Holds DNA in loose chromatin Nucleolus- site of ribosome formation. Made of proteins and RNA Mitochondria- site of respiration in cells. Cristae (inner membrane which is highly folded) gives a high surface area. Energy released from glucose and stores in form of ATP. Fluid called matrix. Cristae are covered in enzymes an is site of respiration and ATP synthesis
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How does hydrogen bonding form in water? |
Hydrogen share 2 electrons but because oxygen is more electronegative, the electrons are attracted more to the oxygen, leaving oxygen slightly negative (delta-) and hydrogen slightly positive (delta+) |
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What are the characteristics of water |
Boiling point is much higher than ammonia and hydrogen fluoride- each water molecule can potentially form 4 h-bonds with surrounding water molecules. Right amount of hydrogens and lone pairs Ice is less dense than water- hydrogen bonds fix the positions of the polar molecules slightly further apart Cohesive properties- moves as one mass |
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How are the properties of water useful for living? |
Acts as a solvent- minerals like amino acids can easily be dissolved which helps transport these dissolved molecules in and out of cells Acts as a transport medium- due to cohesion and adhesion, it allows water to act against gravity and travel up plants - capillary action Acts as a coolant- large amount of energy required to overcome the bonds which is important for enzymes Water is stable- allows organisms to live in cold climates if ice floats on the top |
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What are the chemical elements that make up the following: Carbs Lipids Proteins Nucleic acids |
Carbs- C, H and O Lipids- C, H and O Proteins- C, H, O, N and S Nucleic acids- C, H, O, N and P |
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What is the difference between alpha and beta glucose? |
On carbon 1- the H is above the ring for alpha and below the ring for beta |
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What is formed when 2 alpha glucose react? |
Maltose is formed and water Joined by a condensation reaction and glycosidic bonds are formed Reverse reaction is hydrolysis reaction where a glycosidic bond is broken |
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What is a Monosaccharide Disaccharide Polysaccharide Give examples |
Monosaccharide- single unit of sugar (glucose, fructose and ribose) Disaccharide- two monosaccharides (lactose and sucrose) Polysaccharide- two or more monosaccharides (starch, glycogen and cellulose) |
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How does the structure of cellulose relate to its function? |
Hydrogen bonds form between chains to help further strengthen cell wall |
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How does the structure of starch relate to its function? |
Amylose- allows it to be more compact and less soluble than alpha glucose due to the 1,4 glycosidic bond resulting in a helix shape Amylopectin- chain to branch |
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How does the structure of glycogen relate to its function? |
1,6 glycosidic bonds are more frequent which causes free ends where it is easily hydrolysed and glucose can easily be removed when needed |
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What are the functions of... Centrioles Ribosomes Golgi apparatus Endoplasmic reticulum |
Centrioles- composed of microtubules. When 2 combine, they form centrosome which is involved in assembly and organisation of spindle fibres in cell division Ribosomes- site of mRNA translation. Made of ribosomal RNA Golgi apparatus- proteins are modified here. Stack of flattened membranous sacs. Receive proteins from cis face Endoplasmic reticulum- flattened sacs called cisternae. Connected to membrane of nucleus: Smooth ER- responsible for lipid and carbs synthesis and storage Rough ER- ribosomes bound to it and is responsible for synthesis. And transport of proteins |
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What is the order for the production and secretion of proteins?
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1. DNA is found in the nucleus. 2. DNA unzips to form 2 separate strands of DNA 3. mRNA takes a copy of the DNA but changes Thymine to Uracil and moves out the nucleus via the nuclear pore 4. Proteins are synthesised on ribosomes bound to rough ER. 5. Proteins pass into the RERs cisternae and are packaged into the transport vesicles. 6. Vesicles containing newly synthesised proteins move towards Golgi body via the transport function of the cytoskeleton 7. The vesicles fuse with the cis face of the Golgi body and the proteins enter 8. The proteins are structurally modified before leaving the Golgi body via the trans face 9. Secretory vesicles carry proteins that are to be released from the cell. Vesicles move towards and fuse with the cell surface membrane, releasing their contents by exocytosis. |
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What are the roles of vesicles lysosomes |
Lysosome- specialised form of vesicle that contain hydrolytic enzymes. Break down waste material in cell including old organelles. Break down pathogens ingested by phagocytic cell Important roles in apoptosis |
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What is the test for starch?
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A few drops of iodine dissolved in potassium iodide solution mixed with sample. If solution changes colour from yellow/brown to purple/ black then starch is present |
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What are reducing sugars?
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All monosaccharides and some disaccharides and can donate electrons or reduce another molecule/ chemical
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What is the test for reducing sugars?
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2. Add equal volume of Benedict's regent 3. Heat mixture gently in a boiling water bath for 5mins |
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What is Benedict's reagent?
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An alkaline solution of copper(II) sulphate solution
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What happens to the ions in the reducing sugars test? |
Reducing sugars will react with the copper ions in Benedict's reagent. Results in addition of electrons to the blue Cu2+, reducing them to brick red Cu+ ions. When a reducing sugar is mixed with Benedict's reagent and warmed , a brick red precipitate is formed indicating a positive result |
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How do you test for non-reducing sugar using Benedict's reagent?
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Non-reducing sugars will not react with Benedict's reagent and solution will remain blue after warming, indicating a negative result.
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Why will sucrose give a positive result when boiled with HCl?
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The sucrose has been hydrolysed by the acid to glucose and fructose, both reducing sugars |
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What type of molecule are lipids? |
Non polar molecules- electrons in outer orbitals that form bonds are more evenly distributed than in polar molecules- no positive or negative areas within molecules and this is why lipids are insoluble in water. Known as macromoleucles- not polymers |
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What are triglycerides made of?
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Combining glycerol and 3 fatty acids |
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How are triglycerides formed? |
Hydroxyl groups interact, leading to the formation of 3 water molecules and bonds between the fatty acids and the glycerol molecule. These are called ester bonds and this reaction is esterification, which is an example of a condensation reaction |
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What s the difference between saturated and unsaturated lipids? |
C-C double bonds are unsaturated |
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What is the difference between monounsaturated and polyunsaturated? |
Polyunsaturated- 2 or more double bonds |
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What are phospholipids?
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Modified triglycerides and contain phosphorus along with the carbon hydrogen and oxygen |
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Why are phospholipids soluble in water?
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phosphate ions (PO4 3-) have extra electrons and so are negatively charged , making them soluble in water
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What is the structure of a phospholipid?
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They have a non polar end or tail and a charged end or head. Non polar tails are repelled by water (hydrophobic) and the charged heads will interact with water (hydrophilic) |
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How do phospholipids interact with water? |
They will form a layer on the surface of the water with the phosphate heads in the water and the fatty acid tails pointing toward the centre of the sheet, protected from the water by the hydrophilic heads |
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What are the roles of phospholipids? |
Forming cell membranes- able to separate an aqueous environment in which cells usually exist from the aqueous cytosol within cells. |
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What is the lipid emulsion test? |
1. Put material in test tube 2. Add ethanol and shake 3. Ethanol layer poured off into another test tube 4. Water added to ethanol 5. Milky emulsion confirms presence of a lipid |
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What is the composition of fatty acids |
Composed of a hydrocarbon chains of varying lengths with methyl group at one end and a carboxyl group at the other |
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What are Monoglycerides Diglycerides Triglycerides |
Monoglycerides- single fatty acid molecules bonded with glycerol and one water molecule produced Diglycerides- 2 fatty acid molecules bonded with glycerol and 2 water molecules produced Triglycerides- 3 fatty acid molecules bonded with glycerol and 3 water molecules produced |
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What are the functions of triglycerides? |
Structural in cell membrane Buoyancy aid Waterproofing Insulator Water store |
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How can you tell if a phospholipid has a double bond or not? |
Kink in the tail |
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What is the function of vacuoles Chloroplasts |
Vacuoles- Important for maintaining turgor so that the contents of the cell wall push against the cell wall and maintain a rigid framework Chloroplasts- responsible for photosynthesis in cells. Have a double membrane structure and fluid called stroma. Network of membranes which form flattened sacs called thylakoids. |
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What is the function of flagella? |
Movement of the cell |
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What are the proteins called that wrap around chromosomes? |
Histones |
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What is the function of the cytoskeleton? |
Network of fibres necessary for the shape and stability of a cell. Organelles are held in place by the cytoskeleton and it controls cell movement and the movement of organelles. It is composed of microfilaments, mictotubules and intermediate fibres |
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What are the functions of Microfilaments Microtubules Intermediate fibres? |
Microfilaments- contractile fibres fro protein actin. Responsible for cell movement and cell contraction during cytokinesis Microtubules- globular tubulin proteins which polymerise to form tubes that are used to form a scaffold like structure which determines the shape of a cell. Control movement of organelles Intermediate fibres- give mechanical strength to cells and help maintain integrity |
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What are carrier and channel proteins?
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Carrier- facilitates both passive and active transport across membrane, often by changing shape Channel- facilitates diffusion of ions/ polar molecules across membrane via a hydrophilic channel |
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What is the difference between extrinsic and intrinsic?
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extrinsic- protein that are on the outside of the bilayer intrinsic- protein that can pass through bilayer |
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What is the fluid mosaic model?
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Model used to describe a membrane- can move and is made up of different components |
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What is a phospholipid glycoprotein glycolipid cholesterol? |
phospholipid- forms a bilayer to make membrane. Composed of a phosphate head and fatty acid tails glycoprotein- intrinsic protein with attached carb chain. Involved in cell adhesion and cell signalling glycolipid- lipids with attached carb chain. Act as antigens allowing immune system to recognise the cell as self Cholesterol- adds stability to cell membranes. Prevents phospholipids from grouping too closely and crystallising |
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What are sterols? |
Known as steroid alcohols they are a type of lipid found in cells. Complex alcohol molecules based on a 4 carbon ring structure with a hydroxyl group at one end. They have a hydrophilic and hydrophobic characteristics. |
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What are the functions of cholesterol? |
The formation of cell membranes becoming positioned with the hydroxyl group at the periphery of the membrane- adds stability to cell membranes and regulates their fluidity by keeping membranes fluid at low temps |
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What is an ester bond? |
C=O | O |
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What is the formula for glycerol? |
C3H8O3 |
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What group of molecules do cholesterol make? |
Vitamin D, steroid hormones and bile |
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What are peptides? |
Polymers made up of amino acids |
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What type of reaction forms a peptide bond? |
Condensation |
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How many different types of amino acid are found in our cells? |
20- 5 are non essential as our bodies can make them. 9 are essential and can only be obtained from what we eat. 6 are conditionally essential as we only need them as infants and growing children |
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What happens when many amino acids join and form peptide bonds? |
A polypeptide is formed and this reaction is catalysed by enzyme peptidyl transferase in ribosomes. |
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How are peptides broken down? |
The enzyme protease catalysed the reverse reaction and turn peptides back into amino acids. A Water molecule is used to break peptide bond in a hydrolysis reaction. |
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What is the cell wall in prokaryotic cells made from? |
Peptidoglycan |
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What organelle allows the prokaryotic cell to attach to other prokaryotic cells? |
Pili |
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How does the flagella move the prokaryotic cell? |
Energy supplied via chemiosmosis- attached to bacterium via basal body and rotated via a molecular motor. Basal body attaches to filaments. Molecular motor causes hook to rotate giving the filament a whip like movement |
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Give some examples of saturated fatty acids? |
Palmitic acid Capric acid Lauric acid |
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Give some examples of unsaturated fatty acids? |
Oleic acid Linoleic acid Elaidic acid |
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What does the primary structure of proteins do?
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this is the sequence in which the amino acids are joined. The only bonds involved are the peptide bonds |
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What does the secondary structure of proteins do?
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oxygen, hydrogen and nitrogen atoms of the basic, repeating structure of the amino acids interact. Hydrogen bonds may form within the amino acid chain, pulling it into a coil shape called an alpha helix. These chains can also lie parallel to each other joined by hydrogen bonds, forming sheet like structures, these causes the structure to appear pleated, hence the name beta pleated sheet |
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What does the tertiary structure of proteins do?
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The folding of a protein into its final shape. This brings the R groups closer together so they interact to produce further folding |
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Which interactions occur within the tertiary structure?
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Hydrogen bonds- high temperatures and alterations to pH can split these bonds Ionic bonds- form between oppositely charged R groups. Split by a change in the pH Disulfide bonds- covalent bonds and form between sulphur R groups. Can be split by reducing agents |
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What does the quaternary structure of proteins do?
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results from the association of 2 or more individual proteins called subunits. The interactions between the subunits are the same as in the tertiary structure except that they are between different protein molecules rather than within one molecule
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What is the test for identifying proteins?
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1. 3cm^3 of liquid sample mixed with equal volume of 10% sodium hydroxide solution 2. 1% copper sulphate solution added a few drops at a time until solution turns blue 3. Mix and leave to stand for 5mins |
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What is a peptide bond?
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O H || | C - N |
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How do you separate amino acids?
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Thin layer chromatography |
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What are the different types of proteins and give examples?
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globular- compact, water soluble and roughly spherical shaped. Form when proteins fold into their tertiary structures so hydrophobic R groups are kept away from aqueous environments and the hydrophilic R groups are outside the protein, making it soluble- used for regulating many process necessary for life e.g. insulin. Conjugated- globular proteins containing a prosthetic group e.g. haemoglobin and catalase Fibrous proteins- formed from long, insoluble molecules due to high proportion of amino acids with hydrophobic R groups in primary structures e.g. keratin, elastin and collagen
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How do amino acids join together? |
When the amine and carboxylic acid groups react. The hydroxyl in the carboxylic acid group of the amino acid reacts with the hydrogen in the amine group of another amino acid |
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How do amino acids join together? |
When the amine and carboxylic acid groups react. The hydroxyl in the carboxylic acid group of the amino acid reacts with the hydrogen in the amine group of another amino acid |
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What is the general structure of an amino acid? |
Back (Definition) |
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What is the general structure for fatty acids? |
C-(CH2)2nCH3 || O |
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What is the structure of glycerol? |
H | H-C-O-H | H-C-O-H | H-C-O-H | H |
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Which is unsaturated and saturated- plant oils or animal fats? |
Plant oils are unsaturated- tend to be healthier in human diet Animal fats are saturated |
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What are the 3 components of a nucleotide?
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A negative phosphate group which is inorganic and acidic A nitrogenous base which is a complex organic molecule |
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What are the bonds called that link 2 nucleotides called? |
Phosphodiester bond |
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What are the bases called and what group do they fall under?
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Thymine- pyrimidine (smaller) Guanine- purine Cytosine- pyrimidine Uracil- pyrimidine |
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How many phosphodiester bonds form between A-T C-G? |
A-T= 2 bonds C-G= 3 bonds |
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How is a molecule of DNA described as?
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Antiparallel |
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How can DNA be extracted? |
2. Mix sample with detergent- breaks down cell membrane 3. Add salt- breaks H bonds 4. Add protease enzyme- breaks down proteins associated with DNA 5. Add layer of alcohol- used to precipitate out DNA 6. DNA seen as white strands between sample and alcohol |
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What is diffusion? |
the net or overall movement of particles from a region of higher concentration to a region of lower concentration until equilibrium and is a passive process. |
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What factors affect simple diffusion? |
- concentration difference: the greater the concentration difference the faster the diffusion -surface area: the larger the surface area, the faster the diffusion - thickness of membrane: the thinner the membrane, the faster the diffusion |
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How is simple diffusion different to facilitated diffusion?
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Facilitated diffusion uses carrier and channel proteins |
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What factors affect facilitated diffusion? |
- no. of proteins |
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How is diffusion different to active transport?
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Active transport requires ATP and goes against a concentration gradient
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What is Fick's law? |
Rate of diffusion is proportional to Surface area x conc. difference/ thickness of surface |
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What is active transport? |
The movement of molecules or ions into or out of a cell from region of lower concentration to a region of higher concentration |
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What affects active transport? |
Surface area Temperature Thickness of membrane Concentration difference No. of proteins |
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What is Exocytosis Endocytosis? |
Exocytosis- bulk transport of material out of cell Endocytosis- bulk transport of material into cell. There are 2 types: phagocytosis- movement of solids and pinocytosis- movement of liquids |
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How is DNA replicated? |
1. DNA helicase unzips 2 strands by breaking H bonds between the nucleotides 2. Free nucleotides are activated and are attracted to complementary bases 3. DNA polymerase joins the new nucleotides to each other by covalent bonds and creates phosphate sugar backbone 4. Results in 2 new strands of DNA each with the original and newly synthesised strand. It is then coiled back again by another enzyme |
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What are the 2 theories surrounding DNA replication? |
Conservative- parent DNA acts as template for new daughter molecule which is assembled from new nucleotide. Parent stand is unchanged Semi- conservative- parent DNA separates into 2 new strands, each acts as a template for formation of complementary strands- half of original and half of new |
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What is osmosis? |
A particular type of diffusion- movement of water from a region of higher conc to a region of lower conc across a partially permeable membrane and is a passive process |
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What is water potential? |
The pressure exerted by water molecules as they collide with a membrane or container |
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What happens to an animal cell when placed in a solution of Higher water potential than the cytoplasm Lower water potential than the cytoplasm |
Higher- the solution is hypertonic. Water moves by osmosis into cells, making the cell burst and swell- cytolysis Lower- the solution is known as hypotonic. Water moves out of cells by osmosis causing cells to shrink- crenation |
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What happens in plant cells when placed in a solution with Higher water potential than cytoplasm Lower water potential than cytoplasm |
Higher- solution is hypertonic. Water moves into cells by osmosis causing pressure against cell wall- turgid Lower- solution is hypotonic. Water moves out of cells by osmosis causing cytoplasm to be pulled away from cell wall- plasmolysed |
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What is a solution called when it has the same concentration as the cytoplasm? |
Isotonic |
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What is transcription?
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The process in which the base sequence of genes have to be copied and transported to the site of protein synthesis |
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What are the steps to transcription? |
2. Each base along the antisense strand attracts complementary RNA nucleotides- Elongation 3. Enzyme RNA polymerase moves along DNA forming phosphodiester bonds between RNA nucleotides 4. Transcription stops at the end of the gene ad mRNA is built 5. mRNA detaches from DNA template and moves out of nucleus via nuclear pore |
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What is translation? |
The process in which ribosomes decode mRNA into a sequence of amino acids |
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What are the steps to translation?
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2. Ribosomes code mRNA into a sequence of amino acids. 3. tRNA is necessary for translation of mRNA. The anticodon will bind to a complementary codon on mRNA following the normal base pairing rules. tRNA molecules carry amino acid corresponding to that codon 4. When anticodons bind to complementary codon, amino acids are bought together in correct sequence to form primary structure of protein 5. Amino acids are added one at a time. Ribosomes catalyse assembly of proteins |
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What does ATP stand for?
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Adenosine triphosphate |
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What is ATP composed of? |
the pentose sugar ribose A nitrogenous base - adenine 3 inorganic phosphates |
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How is ADP different from ATP?
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ADP contains one less phosphate group |
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What happens when ATP is hydrolysed?
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Because ATP is not stable it is not a good long term store. When water is added, the weak bond holding the last phosphate onto the other phosphate is broken. The reverse is a condesnation reaction. |
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What is the degenerate code? |
There are 64 possible base triplets. This includes the start codon and 3 stop codons to signal the end of the sequence. Having a single codon to signal the start of a sequence assures that triplet of bases are read from base 1, instead of 2 or 3 so code is non-overlapping. Many amino acids can be coded for by more than one codon. |
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What are enzymes? |
They are globular proteins which interact with substrate molecules and they have a high specificity |
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What is the lock and key mechanism? |
The substrate fits into the active site like a lock and key. The enzyme has been left unchanged to make the products |
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What is the induced fit model? |
The initial interaction between the enzyme and substrate is weak but these weak interactions rapidly induce changes in enzymes tertiary structure that strengthen binding, putting strain on substrate molecule. This weakens a particular bond and lowers activation energy |
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How does temperature affect enzyme rate? |
Enzymes increase the rate of reaction without increasing temp. Instead, they lower the activation energy and create a shortcut |
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What is Q10? |
- increase in rate of reaction with 10C rise in temp . Usually about 2-3. |
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How does pH affect enzymes? |
In acid, H+ ions break bonds between R groups which leads to less interaction between R group. In alkaline, H+ ions are less so bonds aren't broken so R groups still bonded together which leads to more interactions in R groups which results in a loss of the original 3D structure |
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How does enzyme and substrate concentration affect rate of reaction? |
When concentration of substrate is increased, no. of substrate molecules are increased which results in a higher rate of reaction (vice versa) |
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What is Vmax? |
The point where all active sites are occupied and no more enzyme substrate complexes can be formed |
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How do competitive enzymes affect rate of reaction? |
When attached to active site, the substrate is no longer able to make an enzyme substrate complex and this slows down rate of reaction. Eventually, the substrate will soon find an active site |
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How does a non competitive inhibitor affect rate of reaction? |
The shape of active site changes when this inhibitor binds to the allosteric site which prevents the enzyme substrate complex from forming so less products are formed. More substrate doesn't affect rate of reaction as active site is still changed- reaction levels off |
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What are the steps to prophase? |
2. Protein microtubules form spindle-shaped structures linking the poles of the cell 3. Two centrioles migrate to opposite poles of cell 4. Spindle fibres attach to specific areas on centromeres and start to move chromosomes to centre of cell 5. Nuclear envelope disappears |
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What are the steps to metaphase? |
Chromosomes move by spindle fibres to form a place in centre of cell, called metaphase plate and then held in position |
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What are the steps to anaphase?
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Chromatids move towards poles. |
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What are the steps to telophase? |
Chromatids are now called chromosomes Two new sets of chromosomes assemble at each pole and nuclear envelope reforms around them Chromosomes start to uncoil and nucleolus reforms |
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What is cytokinesis?
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In animals- cell surface membrane pulled inwards by cytoskeleton to fuse around middle In plants- vesicles assemble and these vesicles fuse with each other and divides the cell into 2 |
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What are stages of the cell cycle? |
G1- where cellular components, excluding chromosomes are duplicated Synthesis phase-synthesis of new DNA and it is copied and checked for mutations G2- double checks duplicated chromosomes for errors and makes any repairs Mitosis- dividing of nucleus Cytokinesis- cell divides into 2 |
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How is the cell cycle regulated? |
Checkpoints- these assure that there is no DNA damage and that growth factors, cell size and nutrients are all in check |
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What are the stages to mitosis? |
Interphase Prophase Metaphase Anaphase Telophase |
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What are the different ways to prepare slides? |
Dry mount- solid specimen are viewed whole/ cut into very thin slices- sectioning e.g. Hair pollen and dust Wet mount- specimens suspended in liquid and cover slip at an angle e.g. Aquatic organisms Squashed slides- wet mount prepared first then a lens tissue is used to gently press down the cover slip e.g. Root tips for cell division Smear slides- edge of slide is used to smear the sample, creating a thin, even coating on another slide and cover slip placed over sample e.g. Smear blood to view blood cells |
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What are cofactors? (enzymes) |
Molecules that increase the rate of reaction or are required for enzyme function. They are not proteins. They may transfer atoms from one reaction to another |
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What is a coenzyme? |
Organic molecules that bind to enzymes and help them function. Work with enzymes but aren't enzymes themselves and are mainly derived from vitamins. They sit at the active site and aid in recognising, attracting or repulsing a substrate/ product. They also shuttle chemical groups from one enzyme to another. They bind loosely to enzymes |
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What are prosthetic groups? |
Cofactors that bind tightly to proteins or enzymes, often attached by covalent bonds. Some cofactors can bind multiple different types of enzymes and may bind enzymes loosely as coenzymes and others tightly as prosthetic groups |
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What are the definitions of Apoenzyme Holoenzyme |
Apoenzyme- inactive, needs to undergo a change in shape in tertiary structure to be activated- achieved by addition of cofactors Holoenzyme- when cofactor is added and enzyme is activated |
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Give some examples of enzymes and their cofactors |
Carbonic anhydrase and it cofactor Zn 2+ which is necessary for metabolism of CO2 Amylase and it's cofactor Cl- which is necessary for the metabolism starch into maltosr |
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What is the resolution for a light microscope? |
200nm |
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What are some examples of Intercellular reaction of enzyme Extracellular reaction of enzyme |
Intercellular- catalase which catalyses breakdown of hydrogen peroxide into water and oxygen Extracellular- amylase which breaks down starch polymers partially into maltose Trypsin- catalyses digestion of proteins into smaller peptides |
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How do you calculate retention (proteins) |
Rf = distance travelled by component/ distance travelled by solvent |
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Draw alpha and beta glucose |
Back (Definition) |
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What are the steps in Meiosis?
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Prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Meiosis 2: Prophase 2 Metaphase 2 Anaphase 2 Telophase 2 |
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Describe Meiosis 1?
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Reduction division when pairs of homologous chromosomes are separated into 2 cells. Each intermediate cell will only contain one full set of genes instead of 2 |
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What happens in stages prophase1? |
Chromosomes condense , nuclear envelop disintegrates, nucleolus disappears and spindle formation begins. Homologous chromosomes pair up, forming bivalents. Crossing over and DNA is exchanged. |
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What happens in metaphase1?
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Homologous pairs of chromosomes assemble along the metaphase plate. |
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What happens in anaphase1?
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Homologous pairs of chromosomes are separated. Independent assortment of chromosomes occur |
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What happens in telophase1? |
2 new daughter cells and these cells enter meiosis 2. |
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Describe meiosis 2?
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Second division that is similar to meiosis1. Pairs of chromatids present in each daughter cell are separated, forming 2 more cells. 4 haploid daughter cells are produced in total.
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What happens in prophase2?
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Chromosomes are already condensed and visible. They move towards the centre of the cell. |
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What happens in metaphase 2? |
Chromosomes line up along metaphase plate |
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What happens in anaphase2? |
Chromosomes separate at centromere. The separate chromatids pulled to opposite poles to make half the amount of DNA per cell than the parent |
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What happens in telophase2?
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4 new daughter cells formed. Cells are haploid and the chromosomes disperse. |
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What are stem cells? |
Undifferentiated cells which originate from mitosis or meiosis |
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What does undifferentiated mean? |
An unspecialised cell |
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What is a potency? |
A stem cells ability to differentiate into different cell types |
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What phase of the cell cycle is a specialised cell in? |
G0 |
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What does totipotent mean?
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A stem cell that can differentiate into any type of cell. They are found in fertilised eggs/ zygotes and also in the umbilical cord |
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What does pluripotent mean? |
A stem cell that can differentiate into any type of tissue but not whole organisms. Found early embryos. |
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What does multipotent mean?
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A stem cell that can only form a range of cells within a certain type of tissue. Found in the bone marrow
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Where are plant stem cells found?
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Meristematic cells- found sandwiched between the phloem and xylem tissue (vascular cambium) |
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What is the difference between erythrocytes and neutrophils?
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neutrophils- white blood cells |
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What can stem cells be used for in medicine?
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To cure Heart Disease To cure Type 1 Diabetes To help cure spinal injuries |
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What can stem cells do to benefit biological knowledge?
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Used to test for side effects or toxicity of new drugs Studied to see how they develop into different cell types |
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Name some specialised animal cells and how they have become specialised to adapt to their function?
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Neutrophils- can squeeze through gaps and contain lysosomes to help attack pathogens to defend immune system Sperm cells- have tail for movement and lots of mitochondria. They have acrosome t help digest egg membrane to help genetic material to female gamete |
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Name some specialised plant cells and how they have become specialised to adapt to their function?
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Root hair cells- Have long extensions to help maximise uptake of water Guard cells- change shape and stoma closes to prevent water loss and this helps CO2 to enter plants |
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How are erythrocytes and neutrophils derived from stem cells in the bone marrow? |
Erythrocytes don't have a nucleus and minimum organelles to maximise their oxygen carrying capacity and need to be replaced constantly. Stem cell colonies in the bone marrow produce around 3billion erythrocytes per kilo of body mass a day Neutrophils have an essential role in the immune system and they only live for about 6hours. The stem cell colonies in the bone marrow produce 1.6billion per kilo per hour and this figure increases during infection |
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How are erythrocytes and neutrophils derived from stem cells in the bone marrow? |
Erythrocytes don't have a nucleus and minimum organelles to maximise their oxygen carrying capacity and need to be replaced constantly. Stem cell colonies in the bone marrow produce around 3billion erythrocytes per kilo of body mass a day Neutrophils have an essential role in the immune system and they only live for about 6hours. The stem cell colonies in the bone marrow produce 1.6billion per kilo per hour and this figure increases during infection |
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How are erythrocytes and neutrophils derived from stem cells in the bone marrow? |
Erythrocytes don't have a nucleus and minimum organelles to maximise their oxygen carrying capacity and need to be replaced constantly. Stem cell colonies in the bone marrow produce around 3billion erythrocytes per kilo of body mass a day Neutrophils have an essential role in the immune system and they only live for about 6hours. The stem cell colonies in the bone marrow produce 1.6billion per kilo per hour and this figure increases during infection |
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How are xylem and phloem tissues produced in the meristems? |
Cells originating from the vascular cambium differentiate into the different cells present in the xylem and phloem tissues. In this way the vascular tissue grows as the plant grows. The stem cells in the meristems are pluripotent. |
