Cells and Microscopes-basic components of living systems

Question 1

magnification

Answer 1

-how many times larger the image is than the actual size of the object being viewed

Question 2

resolution

Answer 2

-the ability to see individual objects/ points as separate entities

Question 3

why is an electron microscope more effective than a light microscope

Answer 3

-a beam of electrons has a wavelength a thousand times smaller than light. This means objects which are much smaller and closer together can be seen without diffraction blurring the image

Question 4

magnification calculation

Answer 4

-magnification = size of image / actual size of object

Question 5

disadvantages of electron microscope

Answer 5

• v expensive

- specimens can be damaged by the electron beam

Question 6

transmission electron microscope

Answer 6

-a beam of electrons is transmitted through a specimen and focused to produce an image. Resolving power= 0.5nm

Question 7

scanning electron microscopes

Answer 7

-a beam of electrons is sent across the surface of a specimen and the reflected electrons are collected.

Question 8

artefact

Answer 8

a visible structural detail caused by processing the specimen and not a feature of the specimen.

Question 9

laser scanning confocal microscopy

Answer 9

• moves a single spot of focused light across the specimen which causes fluorescence from the components with a ‘dye’
• the emitted light from the specimen is filtered through a pinhole aperture. the light radiated from very close to the focal plane is detected

Question 10

diff between prokaryotic and eukaryotic

Answer 10

• prokaryotic= single celled organisms with a simple structure of a single undivided area called the cytoplasm
• eukaryotic= make up multicellular organisms. Have a complicated internal structure, containing a membrane-bound nucleus and cytoplasm which contains many membrane-bound cellular components (organelles)

Question 11

role of membranes

Answer 11

-selectively permeable and control the movement of substances into and out of the cell and organelles

Question 12

role of DNA in the nucleus

Answer 12

• directs the synthesis of all proteins required by the cell (however this protein synthesis occurs in the ribosomes outside the nucleus)
• DNA controls the metabolic activities of the cell as many of these proteins are the enzymes necessary for metabolism to take place
• DNA is too large to be transported out of nucleus so it is transcribed into smaller RNA molecules, which are exported via nuclear pores

Question 13

Nuclear envelope

Answer 13

-where DNA is contained to protect it from damage in the cytoplasm
-contains nuclear pores that allow molecules to move into and out of the nucleus
-

Question 14

chromatin

Answer 14

• made up of proteins called histones

- coils and condenses to form chromosomes

Question 15

nucleolus

Answer 15

• an area within the nucleus
• responsible for producing ribosomes
• composed of proteins and RNA

Question 16

RNA

Answer 16

-used to produce ribosomal RNA which is combined with proteins to form ribosomes necessary for protein synthesis

Question 17

role of mitochondria

Answer 17

-site of the final stages of cellular respiration, where the energy is stored in the bonds of complex, organic molecules made available to use for production of ATP

Question 18

structure of mitochondria

Answer 18

• have a double membrane
• inner membrane highly folded to form structures called cristae and the fluid interior is called the matrix
• membrane forming the cristae contains enzymes used in aerobic respiration
• contain a small amount of DNA =can produce their own enzymes

Question 19

role and structure of vesicles

Answer 19

• membranous sacs that have storage and transport roles
• consist simply of a single membrane with fluid inside
• used to transport materials inside the cell

Question 20

role and structure of lysosomes

Answer 20

• specialized forms of vesicles that contain hydrolytic enzymes
• responsible for breaking down waste material in cells
• responsible for breaking down pathogens ingested by phagocytic cells

Question 21

role and structure of cytoskeleton

Answer 21

• network of fibres necessary for the shape and stability of a cell
• organelles are held in place and it controls cell movement and the movement of organelles within cells

Question 21

role and structure of cytoskeleton

Answer 21

• network of fibres necessary for the shape and stability of a cell
• organelles are held in place and it controls cell movement and the movement of organelles within cells

Question 22

3 components of cytoskeleton

Answer 22

-microfilaments, microtubules, intermediate fibres

Question 23

microfilaments

Answer 23

• contractile fibres formed from the protein actin
• responsible for cell movement and cell contraction during cytokinesis- the process in which a cytoplasm divides to form 2 daughter cells

Question 24

Microtubules

Answer 24

• determine the shape of the cell (globular tubulin proteins polymerise to form tubes that determine shape)
• act as tracks for the movement of organelles e.g vesicles

Question 25

intermediate fibres

Answer 25

-gives mechanical strength to cells and help maintain integrity

Question 26

centrioles

Answer 26

• component of cytoskeleton
• composed of microtubules
• 2 associated centrioles form a centrosome, which assembles and organises spindle fibres during cell division

Question 27

flagella

Answer 27

• whip like extensions

- used for to enable cells motility

Question 28

why do objects need to be stained

Answer 28

• coloured dye binds to structures, facilitating the absorption of wavelengths of light to produce an image
• differential staining; the contrast between heavy and lightly stained areas distinguish different structures

Question 29

outline how to prepare a sample of blood to be observed under microscope

Answer 29

• onto a slide
• add Leishmans stain which stains the nuclei of leucocytes purple
• add a buffer and rinse

Question 30

specialised cell types in blood

Answer 30

red blood
platelets
neutrophils-lobed nucleus, engulf foreign material
lymphocytes
monocytes-respond to inflammation

Question 31

role and structure of golgi apparatus

Answer 31

• planar stack of membrane bound, flattened sacs
• vesicles bud off trans face via exocytosis
• modifies and packages proteins for transport
• synthesises glycoproteins

Question 32

role and structure of vesicles

Answer 32

• temporary membrane bound sacs containing water and chemicals (neurotransmitters)
• storage of enzymes
• involved in exo/endocytosis and transport of material into cytoplasm

Question 33

structure of endoplasmic reticulum

Answer 33

• cisternae, network of tubules and flattened sacs which extend from cytoplasm and connects to nuclear envelope
• 2 types, rough er and smooth

Question 34

smooth endoplasmic reticulum

Answer 34

-lipid synthesis

Question 35

rough endoplasmic reticulum

Answer 35

-ribosomes attach for protein synthesis and transport

Question 36

explain how to use an eyepiece graticule and stage micrometre to measure the size of a structure

Answer 36

• place micrometer on stage to calibrate eyepiece graticule
• line up scales on graticule and micrometer
• count how many graticule divisions are in 100 nano meters on micrometer
• length of 1 eyepiece division = 100/no of divisions
• use calibrated values to find actual length

Question 37

describe function of membranes inside cells

Answer 37

• provide internal transport system
• selectively permeable to manage transport of materials into/out of organelles
• isolate organelles from cytoplasm for specific metabolic reactions

Question 38

Outline how the organelles in pancreatic cells work together to produce and release these
protein molecules from the cells

Answer 38

• nucleus , contains gene (for protein) / site of
  transcription / produces mRNA ;
  2 ribosomes / rough endoplasmic reticulum / RER, site
  of, protein synthesis / translation ;
  3 vesicles for transport (of protein) ;
  4 Golgi (apparatus / body), processes / modifies /
  (re)packages, proteins ;
  5 (vesicles) fuse to, cell surface / plasma, membrane