Cell Structure

Question 1

What is cell theory

Answer 1

Cell theory states that all living organisms are composed of one or more cells

Question 2

What’s field of view (FOV)

Answer 2

The circular area visible down a microscope

Question 3

What’s magnification

Answer 3

The number of times larger an image appears compared to the real specimen

Question 4

What’s resolution

Answer 4

The ability to DISTINGUISH two distinct objects separately and see detail

Question 5

How does magnification effect field of view

Answer 5

Field of view decreases as the magnification increases

Question 6

How can you measure the diameter of the field of view

Answer 6

Using a stage micrometer

Question 7

What’s a stage micrometer

Answer 7

A specialised microscope slide (1mm with 10 divisions)

Question 8

What’s the magnification formula

Answer 8

image size / actual size x magnification (set up like triangle)

Question 9

3 advantages of a light microscope

Answer 9

Cheap, easy to use, views living specimens, portable, natural colour

Question 10

2 disadvantages of a light microscope

Answer 10

Low mag (x1500), limited res (200nm)

Question 11

Name the 3 types of microscopes

Answer 11

Light microscope, transmission electron microscope (TEM), scanning electron microscope (SEM)

Question 12

How does a light microscope work

Answer 12

Light passes through the specimen and is focused using the glass lenses

Question 13

How does a TEM microscope work

Answer 13

Electrons pass through the specimen and are focused by electro magnets onto a fluorescent screen

Question 14

advantages of TEM

Answer 14

High mag (x2000000), high res (0.1nm)

Question 15

Disadvantages of TEM

Answer 15

Large, expensive, specialist training, black and white images, dead specimens (vacuumed)

Question 16

Advantages of SEM

Answer 16

High mag (x2000000), high res (0.1nm but usually less, 5-20nm), can view in 3D

Question 17

Disadvantages of SEM

Answer 17

Large, expensive, black and white images

Question 18

What microscope would be most useful for viewing:
1) living daphnia in pond water
2) internal structure of mitochondrion
3) ribosomes
4) cells from a cervical smear to spot abnormalities
5) influenza virus particles

Answer 18

1) LM 2) TEM 3) TEM 4) LM 5) SEM

Question 19

How do you prep a specimen

Answer 19

1) FIXATION, to preserve tissue
2) DEHYDRATION, to absorb water
3) EMBED in wax, prevents distortion
4) SECTION, thin slices
5) MOUNT, support tissue on slide
6) STAIN, makes structures visible and increases contrast

Question 20

Why are thin specimen sections required (LM)

Answer 20

To allow light to pass through

Question 21

Why are stains used

Answer 21

Because most biological specimens are almost transparent, makes structures visible and increases contrast

Question 22

What’s differential staining

Answer 22

A stain that stains different structures different colours to aid identification

Question 23

What do you use to measure the actual size of a specimen

Answer 23

Eyepiece graticule

Question 24

Steps to set up eyepiece graticule

Answer 24

1) POSITION stage micrometer on microscope stage to focus scale (x4 mag)
2) FOCUS the eyepiece graticule until scales align with micrometer
3) COMPARE, scales and work out length of one eyepiece graticule
4) REPEAT, for each objective lens
5) REMOVE stage micrometer and place on the specimen
6) MEASURE length of specimen in eyepiece units using graticule
7) CONVERT measurements to actual length with appropriate calibration

Question 25

Summarise the calibration of the eyepiece graticule for different objective lenses

Answer 25

Mag of eyepiece lens. Mag of objective. total mag. eyepiece unit x10. x4. x40. 25um. x10. x10. x100. 10um. x10. x40. x400. 2.5um.

Question 26

List the rules for biological drawings

Answer 26

Sharp pencil, smooth continuous lines, no shading, label lines with ruler no arrow heads and no crossing labels, title and scale

Question 27

What’s compartmentalisation

Answer 27

The role of membranes in forming organelles

Question 28

What’s diversion of labour

Answer 28

Each organelle having a specific function within the cell for efficiency

Question 29

What’s a eukaryotic cells

Answer 29

Cells containing a nucleus

Question 30

What’s a prokaryotic cell

Answer 30

Cells with no nucleus or membrane bound organelles

Question 31

List all the organelles in an animal cell

Answer 31

Intermediate filament, ribosome, rough endoplasmic reticulum (RER), nucleus, nucleolus, chromatin, Golgi apparatus, golgi vesicle, cytoplasm, vacuole (in some), secretory vesicle, smooth endoplasmic reticulum (SER), lysosome, microfilament, centrosome, microtubule, plasma membrane, mitochondia

Question 32

What’s the function of the nucleus

Answer 32

Carries genetic information

Question 33

What’s the function of the ribosome

Answer 33

Site of protein synthesis

Question 34

What’s the function of a mitochondria

Answer 34

Site of aerobic respiration to produce ATP

Question 35

What’s the function of chloroplasts

Answer 35

Site of photosynthesis to produce sugars

Question 36

What’s the function of the RER

Answer 36

Transports proteins made by the ribosomes on its surface and packages them into vesicles

Question 37

What’s the function of the SER

Answer 37

Lipid synthesis

Question 38

What’s the function of the Golgi body

Answer 38

Receives proteins from RER, modifies and repackages them

Question 39

What’s the function of the lysosomes

Answer 39

Hydrolysis’s unwanted materials inside the cell

Question 40

What’s the function of vesicles

Answer 40

Transports materials around the cell

Question 41

What’s the function of the cell surface membrane

Answer 41

Partially and selectively permeable barrier

Question 42

What’s the function of the cytoskeleton

Answer 42

Supports and maintains cell and allows changes in cell shape

Question 43

What’s the function of a pair of centrioles

Answer 43

Forms spindle fibres

Question 44

What’s the function of cilia

Answer 44

Uses ATP to move fluids by beating

Question 45

What’s the function of the undulipodium

Answer 45

Uses ATP to move the whole cell

Question 46

What’s the function of a cell wall

Answer 46

Gives shape and supports the cell

Question 47

What’s the function of the vacuole

Answer 47

Makes the cell turgid

Question 48

Describe the production and secretion of proteins

Answer 48

1. A gene is transcribed into mRNA in the nucleus 2.mRNA leaves the nucleus via a nuclear pore 3. mRNA assembles with a ribosome that attaches to the RER 4. the ribosome reads the mRNA code and synthesises and packages the protein which is packaged and transported in a vesicle 5. Proteins transported in vesicles along microtubules by motor proteins to Golgi (requires ATP) 6. Golgi modifies and repackages proteins into vesicles 7. Transported to cell surface membrane (ATP) 8. Vesicle fuses with membrane 9. Membrane opens and modified proteins are released for use outside the cell (exocytosis)