Section 2 Flashcards

Question

What is resolution?

Answer 1

How well a microscope can distinguish between two objects that are close together A microscope can't distinguish two between objects which are smaller than its resolution

Answer 2

Use light to form an image Lower magnification and resolution Pictures can be in colour Specimen can be alive Can only see a nucleus no other organelles

Answer 3

Use electrons to form an image Higher magnification and resolution Pictures in black and white Specimen has to be dead Can see all organelles

Answer 4

Use electromagnets to focus a beam of electrons through the specimen Denser parts of the specimen absorb more electrons which makes them appear darker

Answer 5

Scan a beam of electrons across the specimen knocking off electrons from the specimen which are gathered in a cathode ray tube to form an image. Can be 3D so can be used on thicker specimens but have a lower resolution than TEMs

Answer 6

1) Pipette small drops of water onto the slide 2) Using tweezers place a thin section of the specimen on top 3) Add a drop of stain e.g iodine/ eosin 4) Add the coverslip by lowering it slowly at an angle so it covers the specimen with no air bubbles

Answer 7

Things seen down the microscope which aren't part of the specimen e.g air bubbles, dust, fingerprints They are usally made during the preperation of the slide Can be distingushed by doing multiple images and seeing if its still there - if its not its likely an artefact

Answer 8

1) Homogenisation - breaking up the cells Grind the cells up in a blender to break open the membrane and put the organelles into solution The solution must be ice cold to reduce enzyme activity, isotoic to prevent damage by osmosis and buffered to maintain pH 2) Filtration Filter through a gauze to seperate large cell debris 3) Ultracentrifugation Put solution into a tube into a centrifuge spin at a low speed to get the heaviest organelle - nucleus at the bottom of the tube (the pellet) the rest of the organelles are floating in the supernatant which is drained off and poured into another tube and spun at a faster speed and the process repeates Order of organelles in supernatant - nuceli, chloroplasts, mitochonria, lysosomes, ER, ribosomes

Answer 9

Mitosis Interphase --> Gap phase 1 - cells grows and new organelles and proteins are made Synthesis - cell replicates its DNA Gap phase 2 - cell keeps growing and proteins needed for cell division are made End of interphase Mitosis again

Answer 10

DNA unravels and replicates Organelles replicate ATP increase

Answer 11

Two chromatids joined by a centromere Two strands on the same chromosome are called sister chromaids

Answer 12

Chromosomes condense and bundles of proteins called centrioles move to opposite ends of the cell forming spindle fibers Nuclear envelope breaks down and chromosomes are free in the cytoplasm

Answer 13

Chromosomes line up along the middle of the cell and attach to the spdinle fibers by their centromere

Answer 14

Centromeres divide seperating each pair of sister chromatides Spindle fibers contract pulling chromatids to opposite poles by the centromere

Answer 15

Chromatids uncoil and become long and thin again (not condensed) and are chromosomes again Nuclear envelope forms around each group of chromosomes Cytokinesis finished forming two daughter cells that are genetically identical

Answer 16

Interphase Prophase Anaphase Metaphase Telophase

Answer 17

Chemical drugs prevent the synthesis of enzymes needed for DNA replication Radition and drugs damage DNA and if the cell detects it it will kill itself

Answer 18

1) Add HCl to a boiling tube and heat in a water bath 2) Cut the tip of a growing room with a scaple 3) Put it tube and incubate for 5 min 4) Use tweezers to remove it and rinse with cold water. Leave to dry on a paper towel 5) Place on microscope slide 6) Use a needle to break open the tip and spead out cells thinly 7) Add stain 8) Put cover slip on and fliter paper on top and squash the cells 9) Look through a microscope

Answer 19

1) Clip the slide onto the stage 2) Select the lowest powered objective lense (lowest mag) 3) Turn the coarse adjustment knob to bring the stage up to the lense 4) Look down the eyepiece with the ocular lense inside and move the stage down until the image is in focus 5) Ajust the focus with the fine adjustment knob 6) Can swap to a higher powered objective lense and refocus

Answer 20

The proportion of cells in a tissue smaple that are undergoing mitosis - how quickly the tissue is growing

Answer 21

mitotic index = number of cells with visible chromosomes / total number of cells observed

Answer 22

A transparent ruler with no units that fits onto the eyepiece

Answer 23

A microscope slide with an accurate scale (units) and is used to work out the divisions on the eyepice graticule at a certain magnification

Answer 24

Fluid (constantly moving phospholipids bilayer) Mosaic - protiens are scattered through the bilayer Channel proteins and carrier proteins - allow larger molecules and ions to pass Receptor proteins - detect chemicals from other cells The chemicals signal the cell to respond in some way Proteins with a carbohydrate attached are glycoproteins and lipids with carbohydrates attached are glycolipids + Cholesterol

Answer 25

Form a barrier to water soluble substances Hydrophillic head and hydrophobic tail so the center of the bilayer is hydrophobic and doesn't allow water soluble substances like ions and polar molecules to diffuse through Small non polar substances and water (osmosis) can diffuse through the membrane

Answer 26

Gives the membrane stability, fits between the phospholipids and binds to the hydrophobic tails causing them to pack more closely together restricting the movment

Answer 27

Below 0 degreese Phospholipids don't have much energy so can't move much. Chennal and carrier proteins denature increasing the permability. Between 0 and 45 Phospholpipids can move around as they have more energy this increases the permability of the membrane Above 45 Phospholipid bilaye starts to break down becoming more permable. Water inside the cell expands putting presure on the membrane. Channel and carrier proteins denature increasing permability

Answer 28

1) Use a scaple to cut five equal sized pieces of beetroot and rinse to remove extra pigment 2) Add to five different test tubes with 5cm of water in 3) Place each tube in a water bath at 10, 20, 30.. etc degreese for the same amount of time 4) Remove the beetroot 5) Use a colourimeter 6) Turn on and leave for five min to stablise and set up a blue filter 7) Add water to a cuvette so its 3/4 full and put in colourimeter and cailbrate to 0 8) Repeate for the other solutions 9) Higher absorbance = more pigment released = higher permability of membrane

Answer 29

The likelihood of water molecules to diffuse out of or into a solution Pure water has a water potential of zero - adding solutes lowers its water potential so the water potential of any solution is always negative

Answer 30

Isotonic - same water potential so no net movement of water Hypertonic - Solution with a lower water potential than inside the cell (the cell will shrink as water moves out by osmosis) Hypotonic - Solution with a higher water potential than inside the cell (the cell will swell as watre moves in by osmosis)

Answer 31

1) Make a serial dilution series (decreasing in conc by the same amount each time) 2) Measuring changes in masses - Cut equal chips of potatoes and put them into equal groups and measure the mass of each group Place one group into each sucrose solution and leave for 20 min Remove and pat dry weight each group again and calculate percentage change 3) Producing a calibration curve - Plot percentage change in mass against conc of sucrose solution and use it to find the water potential of the potatoe cells (when mass change = 0)

Answer 32

e.g starting with an inital sucrose conc of 2 M and diluting each solution by a factor of 2 1) Line up 5 test tubes in a rack 2) Add 10cm of the initial 2 M sucrose solution to the first tube and 5cm of wter to the other four tubes 3) Using a pipette draw 5cm of the solution from the first tube and add to the water in the second tube to make a 1 M conc 4) Draw 5cm from the 1 M conc and add it to the third pipette to make a 0.5 M conc 5) repeate for all tubes

Answer 33

1) Start with a solution of a known conc e.g 1 M 2) Find the scale factor by dividing the conc of this solution by the conc of the solution you want so 1M / 0.4M = 2.5M 3) This means the solution you want is 2.5 times waker than the one you have. To make it 2.5 times weaker use 2.5 times less of it 15cm / 2.5 = 6cm transfere this into a tube 5) top up with water to get the volume you want 15 - 6 = 9 so add 9 of distilled water

Answer 34

1) Sodium ions are actively transported out of the epithelial cells in the ileum into the blood by the sodium potassiu pump. This creates a conc gradients - there is no a higher conc of sodium ions in the lumen of the ileum than inside the epithelial cell 2) This casues sodium ions to diffuse from the lumen of the ileum into the epithelial cell down the conc gradient via sodium- glucose co-transporter proteins. The protein carrier sodium and glucose into the cell so the conc of glucose increases 3) Glucose diffuses out of the cell into the blood down conc gradients through a protein channel by facilitated diffusion

Answer 35

speed of carrier proteins number of carrier proteins rate of respiration (ATP) NOT conc gradient

Section 2 Flashcards

Cells