Chapter 2 Flashcards
What is the ultrastructure of a cell?
The detailed structure of a cell that can only be seen using an electron microscope.
Define resolution
The shortest distance between two objects that are still seen as separate objects.
Define magnification
How many times the image size is bigger than the actual size.
Why do electron microscopes have a higher resolution that light microscopes?
Electrons have a shorter wavelength than light waves.
What is a cell?
The basic unit of a living organism.
What is a cell organelle?
Smaller, cellular structures inside a cell which carry out different functions.
Why is the cytoplasm not a cell organelle?
It is mostly made up of water (70%)
Describe the nucleus.
Double membrane bound organelle which has perforations known as the nuclear pore.
What are the functions of a nucleus?
Controls all cell activities.
Stores genetic informations.
Codes for proteins.
Describe the mitochondria
A double membrane bound structure where the inner membrane folds to give the cristae.
What is the function of the mitochondria?
It is the site of respiration.
Describe the ribosome
A structure with no membrane and is composed of two subunits (smaller and larger) where the smaller has a binding site.
Describe the Golgi body
A fluid filled, flattened and curved structure.
Describe the centriole
A structure that is: Hollow Not membrane bound Made of nine sets of microtubule triplets Cylinder shape
What is the function of a centriole?
It makes the spindle fibres which plays a role in the separation of chromosomes during mitosis.
Describe the chloroplast
A double membrane bound structure where the inner membrane forms the thylakoid.
What is the function of the chloroplast?
It is the site of photosynthesis. The thylakoid is where the light dependant reactions take place and the stroma is where the light independent reactions take place.
What separates the chromosomes in plant cells during mitosis?
Microtubules
Describe the vacuole
One membrane bound structure, known as the tonoplast. Inside is a fluid (cell sap) which contains ions, glucose and water.
What is the function of the tonoplast?
Supports the cell by keeping it turgid.
Which structures are only found in animal cells?
Centrioles
Microvilli
Which structures are only found in plant cells?
Chloroplast Vacuole Middle Lamella Cellulose cell wall Plasmodesmata
What are the similarities and differences between prokaryotic and eukaryotic cells?
(Feature-Prokaryotic,Eukaryotic)
Nucleus- none, present
DNA- circular, linear
DNA organisation- fold and condense DNA, associated with proteins (histones)
Extra chromosomal DNA- Plasmids, Only present in mitochondria and chloroplast
Organelles- not membrane bound, membrane bound
Cell wall- peptidoglycan, none in animals, chitin in fungi and cellulose in plants.
Ribosomes- 70S (16nm), 80S (22nm)
Cytoskeleton- present, present but more complex.
Reproduction- binary fission, asexual or sexual.
Cell type- Unicellular, unicellular or multicellular
Cell surface membrane- present, present
What are the similarities between prokaryotic and eukaryotic cells?
Cell surface membrane, ribosomes (but of different sizes), DNA and RNA