Cytology Flashcards
Ch. 6
All cells have these four things:
- Plasma membrane
- Cytosol
- Chromosomes
- Ribosomes
Where is the DNA found in both eukaryots and prokaryots
Eukaryots = Nucleus
Prokaryots = Nucleoid
Name three differences between eukaryots and prokaryots
Eukaryots:
- Membrane-bound organelles
- DNA found in nucleus
- Cytosol found between plasma membrane and nucleus
Prokaryots
- No membrane-bound organelles
- DNA found in nucleoid
- Cytosol bound by plasma membrane
What is the corrolation between cell size and surface area
When the cell size increases, the surface area to volume ratio decreases and vice versa.
When the volume is increased, more nutrients are required and more waste is produced. If the surface area is decreased, there is a decrease in availible area for materials to flow through the plasma membrane, leading to slower transportation.
What is the nuclear envelope
- Envelope that encloses nucleus to separate from cytoplasm
- It is a double membrane, each layer has proteins and pores for passage
- The envelope membrane is continuous through the pore complexes
What is the function of nuclear pore complexes
Regulate entry and exits of substances coming in and out of the nucleus
What is the nuclear lamina
- Lines the inside of inner nuclear membrane
- Comprised of protein filaments
- Maintains nuclear shape and supports nuclear envelope
- May help organize nuclear material
What is the nuclear matrix
- Protein fibers extending through the nuclear interior
- May help organize genetic material
How many DNA molecules are in a non-replicated chromosome
1
What is chromatin
DNA-protein complex made from histones
What is the nucleolus
- Found in center of nucleus
- Produces and assembles ribosome subunits and rRNA
Are ribosomes membrane-bound
NO
This is why they can be found in prokaryots
What is a ribosome
rRNA-protein complex that carries out protein synthesis
What role fo ribosomes play in carrying out genetic instructions
Concept Check 6.3 - 1
Ribosomes in the cytoplasme translate the genetic message, translated from DNA in the nucleus by mRNA, into a polypeptide chain
Describe the molecular composition of nucleoli and their function
Concept Check 6.3 - 2
Nucleoli consist of DNA and the ribosomal RNAs made according to its instructions, as well as proteins imported from the cytoplasm. Together the rRNAs and the proteins are assembled into ribosomal subunits.
What are the function of the endomembrane system
- Protein synthesis and transport
- Metabolism
- Lipid movement and detox
How is the membrane of the endomembrane system related
- Through direct physical continuity
- Through transfer of membrane segments
What is the endoplasmic reticulum
- Network of membranous tubules (cisternae) where proteins are synthesised and transported [to golgi]
What is the ER lumen
The internal ER compartments / inside cisternae space
What are the four functions of the smooth endoplasmic reticulum
- Lipid synthesis
- Detoxification
- Storage of Ca 2+
- Carb metabolism
Describe the process of protein synthesis in the rough ER
As a polypeptide chain grows from the bound ribosomes, the chain is threaded into the ER lumen through protein-complex pores in the ER membrane. Polypeptides fold into functional shapes as they enter the ER lumen.
What are transport vesicles
Membranous vehicules in transport from one part of a cell to another
What is the golgi apparatus
Warehouse of the cell for:
- receiving
- manufacturing
- sorting
- shipping macromolecuels to other destinations in the cell
Comprised of flattened membrane sacs (cristae) in trans and cis directions
(cis = close to ER, trans = where vesicles pinch off and travel elsewhere)
Which molecules are actually made in the golgi apparatus of plant cells
Pectins and other non-cellulose polysaccharides