cells and microscopy

Question 1

What is a differential stain?

Answer 1

Differential stains are used to colour multiple organelles to make them more distinguished when using a microscope

Question 2

How do you carry out a wet mount?

Answer 2

1. Use a pipette to place a small drop of water onto the centre of the glass slide
2. Use forceps to place a thin slice of specimen onto the drops of water, thin enough to pass light through
3. Add a few drops of stain (e.g iodine)
4. Slowly add a cover slip

Question 3

What is a dry mount?

Answer 3

Specimen is directly on the slide and covered with a slip

Question 4

What is a squash slide?

Answer 4

A wet mount is prepared and the cover slip is pressed to squash cells

Question 5

What is a smear slide?

Answer 5

Edge of slide is used to smear the sample to create a thin, even coating on a separate slide

Question 6

How do you use a light microscope?

Answer 6

1. Clip prepared slide onto stage
2. Select the objective lens with lowest power
3. Use the coarse focus to bring the stage up
4. Use eyepiece and coarse focus to focus the image
5. Use the fine focus to make it clear

Question 7

What is the resolution and magnification of a light microscope?

Answer 7

Resolution- max of about 0.2 micrometers

Magnification- max of about times 1,500

Question 8

Transmission electron microscopes (TEM)

Answer 8

• use electromagnets to transmit a beam of electrons through a specimen

• denser parts absorb more electrons, so are darker

• high resolution

• internal structures of organelles

• viewed in a vacuum so the specimen is either nonliving or dead

• thin specimen

Question 9

What is the resolution and magnification of transmission electron microscopes?

Answer 9

Resolution- max around 0.5 micrometers

Magnification- max of around times 1,500,000

Question 10

Scanning electron microscopes (SEM)

Answer 10

• scan a beam of electrons across the surface of a specimen then reflected electrons are used to form an image

• 3-D images

• nonliving or dead specimen and they can be thicker

Question 11

What is the resolution of magnification of a scanning electron microscope?

Answer 11

Resolution- max of around 5nm
Magnification- max of around times 1,500,000

Question 12

What is magnification?

Answer 12

How many times larger an image is than the object

Question 13

What is resolution?

Answer 13

The ability to distinguish between two separate points

or how detailed the images

Question 14

What is the formula for magnification?

Answer 14

Magnification = image size/actual size

Question 15

What is the eyepiece graticule?

Answer 15

Inside the eyepiece

Question 16

What is the stage micrometer?

Answer 16

Mounted on to the stage

Question 17

How do you calibrate a microscope?

Answer 17

1. Fix stage micro meter onto stage
2. Look through eyepiece to lineup micrometre and graticule
3. Count the number of graticule divisions that fit into one micrometer division

Question 18

What is the formula for graticule division?

Answer 18

Graticule division= size of one micrometer/number of graticule divisions

Question 19

What are eukaryotes?

Answer 19

Multicellular organisms made up of eukaryotic cells

for example, animals plants fungi protests

Question 20

What are prokaryotes?

Answer 20

Single celled organisms made up of prokaryotic cells like bacteria

Question 21

What is the cell surface membrane?

Answer 21

• plasma membrane
• phospholipid bilayer
• made up of lipids (glycoprotein, glycolipids), proteins (extrinsic proteins and intrinsic proteins) and cholesterol
• partially permeable

Question 22

What is the cytoskeleton?

Answer 22

• structure and support

Microfilaments
• made of protein actin, cell movement and muscle contraction

Microtubules
• made of protein tubulin
• scaffold like structure, acts as a track for transport

Intermediate filaments
• maintain the position of organelles

Question 23

What are prokaryotes?

Answer 23

Single celled organisms and they are much smaller than eukaryote cells

• ribosomes- smaller than 80S and are 70S
• genetic material- large circular strand of DNA
• pili- attaching cells to other cells

Question 24

What is the function and structure of the nucleus and nucleolus?

Answer 24

Function: store genetic information on how to make proteins
Nucleolus produces new ribosomes

Structure: bounded by a double membrane (envelope) with pores to allow transport of mRNA. It contains chromosomes made of DNA

Question 25

What is the function and structure of cilia and flagella?

Answer 25

Function: involved in either moving the cell around or moving liquid such as mucus across the surface of the cell Structure: hair like structures found on the surface of cells. In cross-section they have an outer membrane, a ring of 9 pairs of micro tubs and a pair of microtubules in the middle

Question 26

What is the function and structure of mitochondria?

Answer 26

Function: site of aerobic respiration and produces ATP Structure: consists of an outer and inner membrane, with an inner membrane space between them. The inner membrane, which is folded into cristae surrounds the matrix

Question 27

What is the function structure of the rough endoplasmic reticulum?

Answer 27

Function: ribosomes join amino acids together in protein synthesis. The membrane forms vesicles to transport proteins. Structure: forms an extensive membrane system of flattened sacs called cisternae which are continuous with the nuclear membrane. Has ribosomes attached (Some ribosomes are found free in the cytoplasm)

Question 28

What is the function structure of the Golgi apparatus?

Answer 28

Function: modify protein/produce glycoproteins. Package proteins into vesicles for secretion and make lysosomes. Structure: stack of flattened membrane sacs with vesicles fusing to the sacs on one side and vesicles budding off the other side

Question 29

What is the function and structure of smooth endoplasmic reticulum?

Answer 29

Function: site of lipid and steroid synthesis. The membrane forms vesicles to transport the lipids Structure: forms an extensive membrane system of flattened sacs called cristernae

Question 30

What is the function and structure of the plasma membrane?

Answer 30

Functions: include- controlling what enters and leaves the cell and involved in cell recognition Structure: consist of phospholipid bilayer with proteins and glycoproteins is embedded in it

Question 31

What is the function and structure of centrioles?

Answer 31

Function: formed spindle fibres during cell division to move chromosomes around the cell Structure: only found in animal cells. A pair of cylindrical structures. Each one being made up of 9 triplets of microtubules

Question 32

What is the function and structure of lysosomes?

Answer 32

Function: destroy worn out organelles or bacteria that have been engulfed during phagocytosis Structure: membrane bound sac containing hydrolytic enzymes

Question 33

What is the function and structure of the cytoskeleton?

Answer 33

Function: To support the cell’s organelles and keep them in position. To strengthen the cell and help maintain it shape to transport materials on the cell to cause cells such as phagocytes to move around. Structure: Micro filaments are solid strands and are made of protein actin. Microtubules are made of the protein tubulin and are cylinders made up of many subunits of tubulin joined together.