Cell Structure

Question 1

What is the function of the Golgi apparatus?

Answer 1

To process and and package proteins into vesicles and lipids to be sent elsewhere

Question 2

What is the function of ribosomes?

Answer 2

Where proteins are made

Question 3

What is the function of the nucleus?

Answer 3

Contain DNA

Question 4

What is the function of nucleolus?

Answer 4

To make ribosomes

Question 5

What is the function of the smooth endoplasmic reticulum?

Answer 5

Synthesis and processes lipids

Question 6

What is the function of mitochondria?

Answer 6

Produces ATP and releases energy and is the site of respiration

Question 7

What is the function of the cell surface membrane?

Answer 7

To regulate the movement of substances in and out the cell

Question 8

What is the function of centrioles?

Answer 8

To form the spindle for cell division

Question 9

What is the function of the rough endoplasmic reticulum?

Answer 9

To Fold and process proteins made at ribosomes

Question 10

What is the function of the nuclear pore?

Answer 10

Allows RNA to move between the nucleus and cytoplasm

Question 11

What is the function of the Golgi vesicle ?

Answer 11

Stores lipids and proteins made by the Golgi apparatus and transports them out the cell

Question 12

What is the function of a lysosome?

Answer 12

Contains digestive enzymes called lysozymes

Question 13

What is the function of the cell wall?

Answer 13

To support cells and prevent them from changing shape

Question 14

What is the function of the cell vacuole?

Answer 14

Helps maintain pressure inside the cell and keep the cell rigid

Question 15

What are the similarities of eukaryotic cells vs prokaryotic cells?

Answer 15

•cell wall
•ribosomes
•cytoplasm
•cell membrane
•cell surface membranes are made from a phospholipid bilayer

Question 16

What are the differences between eukaryotic cells vs prokaryotic cells?

Answer 16

•cell wall in prokaryotic cells are made from murein whereas cell wall in eukaryotic cells are made of cellulose
•DNA is circular in prokaryotic cells whereas it is linear in eukaryotic cells
•Ribosomes are larger in eukaryotic cells
•DNA is enclosed in nucleus in eukaryotic cells whereas it is free in the cytoplasm in prokaryotic cells
•Organelles are membrane bound in eukaryotic cells
•No capsule or pili in eukaryotic cells whereas it is present in prokaryotic cells

Question 17

What is the structure of a virus?

Answer 17

•viruses are made up of nucleic acids
•the nucleic acids are surrounded by a protein called a capsid
•viruses are smaller than bacteria
•attachment glycoproteins

Question 18

What are viruses not considered as living ?

Answer 18

•they have no nucleus, plasma membrane, cytoplasm or ribosomes
• they are not made as cells
•they cannot reproduce independently

Question 19

What are the function of viruses?

Answer 19

1) to replicate, viruses have to invade and hijack the reproductive mechanism of a living cell
2) viruses have attachment glycoproteins that bind to complementary receptors on host cells
3) they then inject DNA or RNA into the host cell
4) the host cell divides as normal and the virus is replicated

Question 20

What is the definition of resolution?

Answer 20

How well a microscope can distinguish between two points close together

Question 21

What is the definition of magnification?

Answer 21

How much bigger an image from a microscope is compared to the specimen

Question 22

What are the principles of a optical (light microscope) ?

Answer 22

Light is directed on to a specimen using mirrors

Question 23

What is an advantage of a optical microscope?

Answer 23

•dead or alive specimens
•uses colour

Question 24

What is a disadvantage of a optical microscope?

Answer 24

Lower resolution and magnification

Question 25

What are the principles of a transmission electron microscope (TEM)?

Answer 25

Electromagnets focus a beam of electrons through a thin slice of specimen, denser parts of the specimen absorb more electrons than other parts

Question 26

What are the advantages of a TEM microscope?

Answer 26

•generates image on computer (false colour can be added after) •resolution and magnification is good

Question 27

What are the disadvantages of a TEM microscope?

Answer 27

•only in black and white •can only view dead specimens •2D images only •can contain artefacts

Question 28

What are the principles of scanning electron microscope ( SEM) ?

Answer 28

An electron beam is scanned across a specimen, knocks electron off the specimen and gather in a cathode ray tube to form a image

Question 29

What is an advantage of a SEM microscope?

Answer 29

•image shows the 3D surface •generates image on a computer •specimens do not have to be thin •good resolution and magnification (but lower than TEM)

Question 30

What is a disadvantage of a SEM microscope?

Answer 30

•only in black and white •dead specimens only •can contain artefacts

Question 31

How do you measure the actual length of a specimen?

Answer 31

1) calibrate the eyepiece graticule (in eyepiece) 2) micrometer of known length on stage 3) line them up to work out the scale of divisions

Question 32

Why do electron microscopes have a higher resolution and magnification than light?

Answer 32

Electron microscopes have shorter wavelength

Question 33

What is the equation of magnification?

Answer 33

Magnification= size of image/actual size of specimen

Question 34

Describe the process of cell fractionation and ultracentrifugation.

Answer 34

1) homogenisation First you blend/break up the cells to release organelles into a solution, this solution need to be ice cold to reduce the activity of the enzymes it also need to be isotonic to have the same water potential to prevent water from moving via osmosis and it also need to be buffered to prevent damage to the organelles, we are then left with a homogenised solution 2)Filtration Homogenised cell solution is filtered through a gauze to separate large cell debris from organelles 3) Ultracentrifugation Cell fragments are poured into a tube and then spun at a low speed, heaviest organelles are moved to the bottom of the tube to form a thick sediment called the pellet, the rest of the organelles dart suspended in the fluid above the pellet (supernatant), the process is repeated at higher and higher speeds until all the organelles are separated out