Lecture 5 Flashcards
Do prokaryote cells have internal membranes?
They have no membrane bound organelles so no
What are the features of a prokaryote’s DNA?
- no nucleus
- DNA in unbound region = nucleoid
What size are prokaryote cells?
Very small
0.1-5 um
What are the 3 shapes a prokaryote can be?
- cocci (balls)
- bacilli (cylinder)
- spirochaetes (worm shapes)
How do prokaryote cells move?
Mobile with flagella
Rotary spinning action
- anticlockwise = run
- clockwise = tumble
What is the capsule of a prokaryote cell like?
Usually carbohydrate - slippery
What does the capsule of a prokaryote prevent?
Desiccation and dehydration
What does the capsule of the prokaryote increase?
Resistance to phagocytosis
Adhesion to solid surfaces (colonisation)
How much peptidoglycan does gram + bacteria have?
A lot
What membranes does a gram + bacteria have?
An inner cell membrane only
Does a gram + retain a primary stain?
What colour?
Yes it does
Purple/blue
Is a gram + bacteria similar to other cells? What does this mean?
Yes, means it is not ideal for antibiotics
How much peptidoglycan does a gram - bacteria have?
Very little
What membranes does a gram - have?
An inner and outer membrane
Does a gram - bacteria retain a primary stain? What colour?
No it doesn’t
Pink
What is the structure of peptidoglycan?
A sugar backbone attached to peptides
What is a key feature of peptidoglycan?
It has a strong and impermeable structure
Pili (fimbriae) what is it?
Little hair like projections
What do fimbriae help?
Adhesion to solid surfaces (disease and biofilm)
What do sex pili do?
Allow bacterial conjunction (genetic material exchange)
What is a nucleoid in prokaryote’s?
Large loop of DNA
Where else is there DNA in prokaryote’s?
The plasmids: short loops of extra chromosomal DNA
What does the plasmid DNA do?
- virulence
- resistance to antibiotics
- bacteriocin (natural antibiotic)
- fertility (conjunction)
What is an endospore?
Seed like condensed nuclear material
When are endospores produced?
In adverse conditions
What is the function of an endospore?
Attaches to the nucleoid to protect it from
- heat
- dryness
- chemicals
- desiccation
How are ribosomes in prokaryote’s different to that in eukaryotes?
They are about 50% smaller
What in prokaryote’s are the target site for antibiotics?
The ribosomes
What happens when antibiotics attack ribosomes in prokaryote’s?
Inhibition of proteins synthesis in bacteria
What is significant about the DNA in eukaryotes?
They’re in a double nucleus
- membranous nuclear envelope
Do eukaryotes have inner membranes?
Yes because they have membrane bound organelles
What does the membrane bound organelles allow?
More complex metabolic reactions
What size are eukaryotes?
Much larger than prokaryote’s
- 10-100um
What is the function of the smooth ER?
- synthesises lipids (eg sex hormones)
- detoxifies poisons (eg alcohol)
- stores calcium
What will a big drinker or alcohol have a lot of?
Smooth ER produced by the liver
What is the function of the rough ER?
Has ribosomes bound to it
- secretes glycoproteins
- sends transport vesicles
- manufactures cell membrane
What is the structure of Golgi body?
Flattened sacs called cristae
What is the function of Golgi body?
- modifies products of ER
- manufactures certain macromolecules
- sorts/packages materials into transport vesicles
- cis/trans faces
What is the structure of mitochondria?
- semi-autonomous (contains its own DNA)
- double membrane
- forms networks
What is the function of the mitochondria?
Changes energy from one form to another (sites of cellular respiration)
Organelles that animals have that plants don’t
- lysosomes
- centrosomes with centrioles
- flagella (flagellum)
Organelles plant cells have that animal cells don’t
- chloroplasts (animals can get from eating leaf)
- central vacuole/cell wall (plant cell structure/support)
- plasmodesmata (communication between plant cells)
