Microscopy and cell ultra structure

Question 1

Equation of maginification

Answer 1

Magnification= image size/ actual size of specimen

Question 2

Define resolution

Answer 2

How well the microscope can distinguish between two points that are close together.

Question 3

Define magnification

Answer 3

How much bigger the image is compared to the actual size.

Question 4

what is Gram staining

Answer 4

Separates bacteria into two groups, gram positive and gram negative. They add crystal violet and then iodine to fix it in place. They then wash it with alcohol. If stained it is stained it is gram positive and is susceptible to penicillin.

Question 5

what is Acid fast staining

Answer 5

Acid fast staining is used to differentiate species of micro-bacterium. Carbolfuchsin is applied and washed away. If stained is retained and is red it is micro-bacterium, other bacteria is blue.

Question 6

What is max magnification and resolution of a light microscope

Answer 6

Max resolution- 0.2u

Max magnification- x1500

Question 7

Transmission electron microscopes Max resolution and max magnification

Answer 7

Max resolution- 0.0002um

Max magnification- more than x1,000,000

Question 8

Scanning electron microscopes Max resolution and max resolution

Answer 8

Max resolution- 0.002um

Max magnification- less than x500,000

Question 9

Advantages and disadvantages of transmission electron microscopes

Answer 9

• provide higher resolution images
• can be used to look at internal structures
• higher magnifications
• but on produces flat images

Question 10

Advantages and disadvantages of scanning electron microscope

Answer 10

Images produced are 3D rather than 2D
Shows surface features
However it has a lower resolution

Question 11

what is a Dry mount slide

Answer 11

Specimens are viewed whole or cut into very thin slices. This is called sectioning. After a cover slip is placed over.

Question 12

what is a Wet mount slide

Answer 12

Specimens are suspended in a liquid. A cover slip is placed over it.

Question 13

what is a Smear slide

Answer 13

An edge is used to smear the sample creating a thin even coating. A cover slip is then placed over.

Question 14

Function of nucleus

Answer 14

Controls all the activity of the cell.

Contains genetic code of the cell

Question 15

Function of nucleolus

Answer 15

Responsible for producing ribosomes

Question 16

Function of nuclear envelope

Answer 16

A double membrane to protect it from damage in the cytoplasm

Question 17

what is the Rough endoplasmic reticulum

Answer 17

Covered with ribosomes and and is the site of protein synthesis

Question 18

what is the Smooth endoplasmic reticulum

Answer 18

Interconnected system of tubules with no ribosomes. Responsible or carbohydrate and lipid synthesis and storage.

Question 19

what does the Golgi apparatus do

Answer 19

It modifies proteins e.g. Adds carbohydrates chains/sugars or folds them into a specific shape. It then repackages the protein into a vesicles (which buds off). They also make lysosomes and lipids.

Question 20

what are Ribosomes and what is its structure

Answer 20

Is the site of protein synthesis, where amino acids are assembled into proteins. A 2 subunit organelle made from RNA and protein.

Question 21

what is the Mitochondria and what does it do

Answer 21

Carry out later stages of respiration and produce ATP. Has a structure called Cristal and a solution called matrix.

Question 22

what are Lysosomes

Answer 22

A single membrane sac containing hydrolysis enzymes lysozyme. They digest unwanted structures such as dead cells or old organelles.

Question 23

what do Centrioles do

Answer 23

Helps form spindle fibres involved in division of the cell.

Question 24

what Plasma membrane do and what is i made up of

Answer 24

Made of lipid and protein. Regulates movement of substances in and out of cells. It also has receptor molecules which allow it to respond to chemical hormones.

Question 25

what does Cilia and what is it made from

Answer 25

Hair like structures that beat creating a current to move fluid and objects.

Question 26

Components of cytoskeleton

Answer 26

• microfilaments
• microtubules
• intermediate fibres

Question 27

role of Microfilaments

Answer 27

Movement of the cell and cytoplasm during cytokinesis.

Question 28

role of Microtubules

Answer 28

They polymerise to form tubes that determine the shape of the cell. They also act as tracks for organelles moving around the cell.

Question 29

role of Intermediate fibres

Answer 29

Give strength to cells and help maintain integrity.

Question 30

what does the Flagella

Answer 30

2 microtubules surrounded by nine pairs of microtubules. They enable cell mobility

Question 31

what is Chloroplast

Answer 31

A double membrane which encloses the stroma. It is the site of photosynthesis

Question 32

function of Cell wall

Answer 32

Supports the plant cell. Made from peptidoglycan.

Question 33

Why is staining needed

Answer 33

So organelles become move visible

Question 34

How do transmission electron microscopes produce images

Answer 34

A focus beam of electrons are transmitted through the specimen to produce a 2d image. Denser parts absorb more electrons and appears darker.

Question 35

How do scanning electron microscopes produce images

Answer 35

SEMs scan a beam of electrons across the specimen. Electrons knock off and produce an image

Question 36

How laser scanning confocal microscopes produce images

Answer 36

Specimens are tagged with fluorescent dyes and a laser is shined on the specimen. This produces a fluorescent light which is picked up by a detector to produce a 3D image with high resolution.