2.1.1 cell structure and magnification

Question 1

How does the light microscope work and what is it’s image like?

Answer 1

focus beams of light. Image: dyed and 2D

Question 2

Magnification and resolution of the light microscope

Answer 2

mag: x1500-2000
resolution: low (200nm)

Question 3

Pros and cons of light microscope

Answer 3

pros: cheap, easy to use, portable, study living organisms, colour
cons: poor resolution, low magnification, often requires staining

Question 4

How does a laser scanning microscope work?

Answer 4

uses laser light to scan object point by point and assemble the pixel information into 1 image using a computer

Question 5

What is the image of a laser scanning microscope like? And what is the magnification and resolution?

Answer 5

image: florescent, high contrast, depth sensitivity
Mag: high
Res: high

Question 6

Pros and cons of a laser scanning microscope

Answer 6

Pros: depth sensitivity, whole specimen, live specimen
cons: lasers are dangerous, expensive, technical use and prep

Question 7

How does a transmission electron microscope work and what is the image like?

Answer 7

beam of electrons

image: black and white, 2D

Question 8

Magnification and resolution of a TEM microscope

Answer 8

mag: x2million
res: 0.004nm

Question 9

pros and cons of TEM microscope

Answer 9

pros: high mag and high res
cons: black and white, high cost, technical use and prep

Question 10

How does a scanning electron microscope work? What is the image like?

Answer 10

electrons are reflected from specimen onto screen

image: black and white, 3D

Question 11

magnification and resolution of a SEM microscope?

Answer 11

mag: x200,000
res: 0.004nm

Question 12

Pros and cons of a SEM microscope

Answer 12

pros: 3D, high(ish) mag and res
cons: high cost, technical use and prep, black and white

Question 13

How to prepare a microscope slide, and why do you do these steps

Answer 13

cut a thin slice (so light can pass through)
use stain (to make visible contrast between organelles)
lower cover slip slowly (prevents air bubbles)

Question 14

what are stains and what do they do? Give an example of an all purpose stain

Answer 14

Stains are coloured chemicals which bind to molecules in the specimen. Stains allow you to easily differentiate between different organelles. An example is methylene blue.

Question 15

equation linking actual image, image size and magnification

Answer 15

actual image = image size / magnification

Question 16

definition for magnification

Answer 16

number of times larger than an image is compared with the real size of the object

Question 17

definition for resolution

Answer 17

the ability to distinguish between 2 separate points

Question 18

Nucleus

Answer 18

contains DNA which directs the synthesis of proteins. Composed of chromatin (wrapped around histone proteins) which condenses into chromosomes

Question 19

nucleolous

Answer 19

where ribosomal RNA is synthesised

Question 20

nuclear envelope

Answer 20

has pores that allow small molecules (e.g. RNA) out of the nucleus

Question 21

rough endoplasmic reticulum

Answer 21

a network of flattened sacs called cisternae which ribosomes bind to. Responsible for synthesis and transport of proteins

Question 22

Smooth endoplasmic reticulum

Answer 22

made of cisternae, responsible for lipid/carbohydrate synthesis

Question 23

golgi apparatus

Answer 23

made of cisternae, post-translation modification of proteins. Packages proteins into vesicles

Question 24

ribosomes

Answer 24

made up of rRNA, site of protein synthesis

Question 25

mitochondria

Answer 25

site of aerobic respiration, produces ATP. Have a double membrane, and the inner is highly folder (cristae) to increase SA for respiration, the fluid inside is called the matrix

Question 26

lysosomes

Answer 26

sac of digestive enzymes that aid in intracellular digestion of bacteria

Question 27

chloroplasts

Answer 27

surrounded by double membrane. Thylakoids containing chlorophyll stack to from grana. Grana are joined by lamelllae.
Site of photosynthesis, contain circular pieces of DNA and ribosomes

Question 28

plasma membrane

Answer 28

controls exchange of materials, is partially permeable

Question 29

centrioles

Answer 29

made of microtubules, involved in assembly of spindle fibres during division

Question 30

cell wall

Answer 30

prevents plant cell from bursting when turgid, supports and protects the cell

Question 31

flagella

Answer 31

enables cell mobility by rotating

Question 32

cilia

Answer 32

hair-like structures, allow movement of substances over cell surfaces

Question 33

production and secretion of proteins

Answer 33

1) gene that codes for proteins is located in chromatin and is transcribed into mRNA
2) the nucleolus makes ribosomes
3) the ribosomes translates the mRNA and the protein is assembles
4) the RER process the proteins which are then sent in vesicles to the golgi body
5) the golgi body further processes the proteins and sends them in vesicles to the plasma membrane
6) vesicles fuse with plasma membrane to secrete proteins

Question 34

what is the importance of the cytoskeleton?

Answer 34

enables cell movement, aids transport within cells, strengthens and supports the cell

Question 35

What is the cytoskeleton made out of and what do these 2 components do?

Answer 35

microfilaments: solid strands made of actin. Cause some cell movement and movement of some organellles
microtubules: hollow strands made of tubulin. Organelles and other cell contents are moved across these fibres using ATP to drive this movement

Question 36

similarities between eukaryotic and prokaryotic cells

Answer 36

both have plasma membranes, cytoplasm, ribosomes and DNA

Question 37

differences between eukaryotic and prokaryotic cells

Answer 37

prokaryotic cells are much smaller
prokaryotic cells have no nucleus, no membrane bound organelles, cell wall of peptidoglycan
smaller ribosomes
loop of DNA (plasmids: small loops of DNA)

Question 37

differences between eukaryotic and prokaryotic cells

Answer 37

prokaryotic cells are much smaller
prokaryotic cells have no nucleus, no membrane bound organelles, cell wall of peptidoglycan
smaller ribosomes
loop of DNA (plasmids: small loops of DNA)