2.1- bacteria and disease Flashcards
measuring lengths of cells- SI units of distance
km= 1 (103m)
cm= 1 (10-2m)
mm=1 (10-3m)
um=1 (10-6m)
nm=1 (10*-9m)
magnification definition
measure of how much bigger the image you see is than the real object
resolution definition
measure of how close two objects can be before they are seen as one
step by step- how to use a eyepiece graticule
1.place stage micrometer on top of stage
2.link up one division on eyepiece graticule with a fixed point on stage micrometer
3. count number of divisions on eyepiece graticule that correspond with a set measurement on stage micrometer
4. calculate distance in micrometres of one division on eyepiece graticule
5.The eyepiece graticule needs to be calibrated with the stage micrometer (the true ruler). By calibrating the two, you can determine what each length on the eyepiece graticule corresponds to in terms of actual micrometer measurements on the stage micrometer. After calibration, you can measure the length
about a light microscope
-uses a beam of light
-beam reflected by a mirror through specimen
- beam then passes through lens to magnify the image
SEM microscope
-emits an electron beam
-electrons bounce off surface of specimen and received at senor
TEM microscope
-emits an electron beam
-electron passes through specimen
-harder for electrons to pass through thicker parts which gives contrast in the 2D image produced
-electrons have smaller wavelength, so better resolution than SEM
advantages and disadvantages of using a light microscope
adv= —-can see living plants and animals directly
-relatively cheap, light and portable
dis=
-preservation and staining tissue can produce artefacts which makes us see things we have created
-limited magnification and resolution
advantages and disadvantages of using an electron microscope
adv=
huge magnification and resolution power, many details seen for first time
dis=
-all examined in a vacuum as air would make if fuzzy, so impossible to see living things
-extremely expensive
-specimens undergo severe treatment likely to result in artefacts
-large, must be kept at certain temp and pressure and maintain vacuum
3 jobs of cell surface membranes
- control what substances enter/ leave the cell
2.allow recognition by other cells e.g. immune system
3.allow cells to communicate
what is the phospholipid bilayer made up of
-Phosphate heads facing aqueous solution (extracellular space)
-phospholipid bilayer
-Hydrophobic tails facing inwards
fluid mosaic model- function of the membrane
-plasma membrane forms a barrier between cell and external environment
-offers mechanical support
-flexible to allow cells to grow, move and divide
-self sealing to stop bursting
-controls material passage
-recognition of other cells
-receptors for hormones and neurotransmitters
fluid mosaic model- function of intracellular membrane
-similar to plasma membranes
-acts as a reaction surface
-Provides intracellular compartments so isolating different chemical reactions.
components of the membrane- phospholipid bilayer
-Each consists of a hydrophobic tail (2 fatty acids) and hydrophilic head (phosphate).
-arranged with tails pointing in
-oily to give membrane flexibility and fluidity
-allows passage of certain lipid soluble substances
components of the membrane- intrinsic proteins
-span the width of the membrane
-act as protein channels to transport substances across membrane
-carrier proteins bind to ions or other molecules then change shape to move molecule across
components of the membrane- extrinsic proteins
-on outer and inner surfaces
-give mechanical support by attaching to cytoskeleton to anchor membrane
-many combine with carb groups to form glycoproteins
-some lipid molecules join with carb to form glycolipid
-glycolipids act as chemical receptors
components of membrane- cholesterol
-strengthens bilayer
-hydrophobic to prevent water loss
-helps decrease permeability
-makes membrane less fluid at high temps
-reduces lateral movement of other molecules
components of membrane- glycolipids
-act as recognition sites
-help maintain stability
-helps cells attach together
components of membrane- glycoproteins
-act as recognition sites
-help cells recognise and attach to each other
what does the term ‘protoplasm’ describe
-the cytoplasm and nucleus combined
about eukaryotic- cells
-have many organelles
-can become specialised for specific functions
-organised in to tissues, organs and organ systems
CUS- centrioles
-in each cell, in pairs near nucleus
-made of a bundle of mine tubules
-pull apart when a cell divides to produce a spindle of microtubules involved in movement of chromosomes
CUS- rough endoplasmic reticulum
-3D network of cavities bound by membranes, in cytoplasm
-sac like or tubular structure
-makes up large part of transport system
-location of synthesis of chemicals
-covered in 80S ribosomes
-main function is to provide a large surface area for synthesis of proteins
CUS- smooth endoplasmic reticulum
-synthesises, stores and transports lipids and carbohydrates
-links with membrane around nucleus
CUS- nucleus
-made up of; nuclear envelope, nuclear pores nucleoplasm, chromosomes and nucleolus
-acts as control centre
-contains genetic material in form of DNA and RNA
-manufactures ribosomal RNA and assembles ribosomes
CUS- nucleolus
-an extra dense area of almost pure DNA and protein
CUS-80S ribosomes
-made up of ribosomal RNA and proteins in a 1:1 ratio
-synthesises proteins
-made up of 40S and 60S subunits
-found in eukaryotic cells
CUS- 70S ribosomes
-made up of ribosomal RNA and proteins in 2:1 ratio
-synthesises proteins
-made up of 30S and 50S subunits
-usually found in prokaryotic cells
CUS- mitochondria
-consists of; double membrane (inner layer folds in to form cristae), cristae provides large surface area for the attachment of enzymes involved in respiration
-rest made up of matrix, contains proteins, lipids, ribosomes and DNA
-site of aerobic respiration and production of ATP
CUS- lysosomes
-break down food in to simple chemicals and destroy worn out organelles in the body
-if there is an issue with the cell, lysosomes rupture causing self destruction (apoptosis)
-made up of a powerful mix of digestive enzymes in cytoplasm of cells
CUS- golgi apparatus
-made up of a stack of flattened stacks (cristernae)
-proteins and lipids made in ER passed here
-golgi modifies (adds carbs) to proteins and lipids and then transfers to other parts of cell in golgi vesciles
-golgo also forms lysosomes involved in phagocytosis
CUS- chloroplasts
-made up of envelope, grana (stack of thylakoids) that contain chlorophyll
-involved in pgotosyntheis
CUS- permanent vacuole
-fluid filled space surrounded by a membrane
-surrounded by tonoplast which controls movement in and out
CUS- cytoskeleton
- 3D dynamic structure made up of microfilaments and microtubules that fill the cytoplasm and give it structure, keeping the organelles in place and enabling cell movements and transport within the cell.
protein transport
-made by ribosomes
-Fibrous proteins which have little tertiary structure or no tertiary structure are made in ribosomes in the cytoplasm.
-globular proteins are formed in ribosomes on RER
CUS- vesicles
-pinch off the golgi and fuse with the cell surface membrane to release contents
3 parts of cell theory
- all organisms are made of cells
2.all existing cells are produced by other living cells
3.cell is the most basic unit of life
hierarchy of cell organisation
1.organ system
2.organ
3.tissue
4.cell
5.organelle
what is a tissue
-a group of similar cells carrying out a particular function
types of tissues- epithelial
-found on lining of surfaces inside and outside of body
1.Squamous - found lining blood vessels
2.Cuboidal/columnar - living different tubes in the body
3.Ciliated - contain goblet cells so produce mucus
4.Compound - found on surfaces which are continually scratched like the skin.
what is an organ made up of
-made up of several different tissues that work to carry out a particular function
what is organ system
-multiple organs working together to carry out a particular function
