Cell Structure Flashcards
(25 cards)
What is magnification
how much bigger an image appears than the origonal thing
Image/Actual = Magnification
What is resolution
THe ability of an optical instrument to see or produce an image where you can clearly distinguish between two separate objects
Optical microscope advantages and disadvantages
Cheap
easy to use
portable
can see living specimens
Lower res
lower magnification
laser scanning microscope
Use a laser light to scan an object row by row like a 3d printer to generate a 3d image
High resolution
TEM
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
SEM
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
What is a differential stain
a coloured chemical that binds to some structures but not others generating contrast
which satin is used on DNA
acetic orcein
what stains cytoplasm
eosin
what stains lipid
Sudan Red
nucleus structure and function
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
RER
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
SER
No ribosomes on the exterior
Catalyses reactions involved with lipid metabolism such as
-The synthesis of cholesterol
- synthesis of lipids
- synthesis of steroid hormones
Golgi apparatus
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
Mitochondria
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
Chloroplasts
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
Vacuole
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
Lysosomes
Small bags formed oil the Golgi that keep powerful enzymes separate from the rest of the cell
Can engulf foreign pathogens
Cilia and undolipodia
protrusions from the cell that help to waft mucus or generate movement
Contain microtubules that are used to generate movement
Ribosomes
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
Centrioles
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
making and secreting a protein
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
Compare prokaryotes to eukaryotes
Both have:
Plasma membrane
cytoplasm
ribosomes
dna/rna
Only prokaryotes have:
Smaller size
no nucleus
no membrane bound organelles
circular DNA
peptidoglycan cell wall
How do prokaryotes divide
Binary fission
