Cell Structure

Question 1

What is magnification

Answer 1

how much bigger an image appears than the origonal thing
Image/Actual = Magnification

Question 2

What is resolution

Answer 2

THe ability of an optical instrument to see or produce an image where you can clearly distinguish between two separate objects

Question 3

Optical microscope advantages and disadvantages

Answer 3

Cheap
easy to use
portable
can see living specimens

Lower res
lower magnification

Question 4

laser scanning microscope

Answer 4

Use a laser light to scan an object row by row like a 3d printer to generate a 3d image
High resolution

Question 5

TEM

Answer 5

Dehydrated and chemically fixed specimen
beam of e- passes through the specimen which is sustained by metal salts
This forms a 2d high mag and res image of the specimen

Question 6

SEM

Answer 6

coated in metals. E- bounce off the specimen and this forms a 3d image of the specimen that is a lower mag but the same res as tem

Question 7

What is a differential stain

Answer 7

a coloured chemical that binds to some structures but not others generating contrast

Question 8

which satin is used on DNA

Answer 8

acetic orcein

Question 9

what stains cytoplasm

Answer 9

eosin

Question 10

what stains lipid

Answer 10

Sudan Red

Question 11

nucleus structure and function

Answer 11

double membrane (nuclear envelope )
inner nucleolus that does not have a membrane
Contains genetic information
Nuclear pores allow mrna and other larger substances to leave
where ribosomes are made
stores the genome

Question 12

RER

Answer 12

System of membranes conta0ining fluid filed cavities (cistern) that are coated in ribosomes
This is an intercellular transport system. The cistern form channels for transporting substances from one area of a cell to another
Provides a large surface area for ribosomes to act

Question 13

SER

Answer 13

No ribosomes on the exterior
Catalyses reactions involved with lipid metabolism such as
-The synthesis of cholesterol
- synthesis of lipids
- synthesis of steroid hormones

Question 14

Golgi apparatus

Answer 14

Stack of membrane bound flattened sacs
This modifies proteins by:
–adding sugar molecules to make glycoproteins
–adding lipid molecules to make lipid proteins
– folds into their 3d shape
Proteins are packaged into vesicles that are pinched off then either:
___Stored within the cell
___ moved to the plasma membrane where they exit via exocytosis

Question 15

Mitochondria

Answer 15

2-5 µm
double membrane with a fluid filled space between them. The inner membrane os highly folded into cristae

This is the site of aerobic respiration
Self replicating
Abundant in cells where lots of metabolic activity occurs

Question 16

Chloroplasts

Answer 16

4-10 µm large molecules
Only in plant cells
double membrane, inner is continuous with stacks of flattened stacks called thylakoids. Each stack or pile of thylakoid is called a granum.

This is the site of photosynthesis
The first stage of photosynthesis, when light is trapped by chlorophyll and used to make ATP, occurs in the grana
The second stage occurs in the stroma

Question 17

Vacuole

Answer 17

Membrane bound (Tonoplast)
Only plants have a large permentant vacuole
It is filled with water and solutes and maintains cell stability because when full it pushes against the cell wall, making the cell turgid

Question 18

Lysosomes

Answer 18

Small bags formed oil the Golgi that keep powerful enzymes separate from the rest of the cell
Can engulf foreign pathogens

Question 19

Cilia and undolipodia

Answer 19

protrusions from the cell that help to waft mucus or generate movement
Contain microtubules that are used to generate movement

Question 20

Ribosomes

Answer 20

Small spherical organelles about 20nm in diameter
Made out of ribosomal RNA
Made in the nucleus as 2 separate subunits that are assembled outside the nucleus.
Synthesis proteins during photosynthesis
Can be found free in the cytoplasm

Question 21

Centrioles

Answer 21

consist of two bundles of microtubules at right angles to each other.
These attach to chromosomes and pull them to opposite sides of the cell

Question 22

making and secreting a protein

Answer 22

The gene that has the genetic information for the desired protein is transcribed into RNA this is called mRNA

Many copies of this mRNA is made and they pass out of the nucleus via a nuclear pore in the nuclear envelope

At the ribosome the genetic information is translated and the protein is assembled

The protein molecule passes into the cisternae of the RER and are transported within the cell

Vessicles with the protein inside them are pinched off the RER and pass to the Golgi

These vesicles fuse with the Golgi where the protein is modified for release
The vesicle is picked off of the going and fuses with the cell membrane where it exits via exocytosis

Question 23

Compare prokaryotes to eukaryotes

Answer 23

Both have:
Plasma membrane
cytoplasm
ribosomes
dna/rna

Only prokaryotes have:
Smaller size
no nucleus
no membrane bound organelles
circular DNA
peptidoglycan cell wall

Question 24

How do prokaryotes divide

Answer 24

Binary fission