The Cell Flashcards
All cells share what features?
- They are all bounded by a selective barrier, called the plasma membrane.
- Inside all cells is a semifluid, jellylike substance called cytosol, in which subcellular components are suspended.
- All cells con- tain chromosomes, which carry genes in the form of DNA.
- And all cells have ribosomes, tiny complexes that make pro- teins according to instructions from the genes.
What is the major difference between prokaryotic and eukaryotic cells?
The location of their DNA.
- eukaryotic cell: most of the DNA is in an organelle called the nucleus, which is bounded by a double membrane
- prokaryotic cell:the DNA is concentrated in a region that is n_ot membrane-enclosed_, called the nucleoid
What is cytoplasm?
The interior of either type of cell:
- in eukaryotic cells: this term refers only to the region be- tween the nucleus and the plasma membrane. Within the cytoplasm of a eukaryotic cell, suspended in cytosol, are a variety of organelles of specialized form and function.
- These membrane-bounded structures are absent in prokaryotic cells
What does the plasma membrane function
as?
A selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell.
What are Eukaryote cells?
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The nucleus contains?
Most of the genes in the eukaryotic cell. (Some genes are located in mitochondria and chloroplasts.)
It is generally the most conspicuous organelle,averaging about 5 μm in diameter.
What is the nuclear envelope?
Encloses the nucleus , separating its contents from the cytoplasm.
The nuclear envelope is a double membrane.
- The two membranes, each a lipid bilayer with associated proteins, are separated by a space of 20–40 nm.
The envelope is perforated by pore structures that are about 100 nm in diameter.
What does the intricate protein structure called a pore complex do? ( in nuclear envelope)
Lines each pore and plays an important role in the cell by regulating the entry and exit of proteins and RNAs, as well as large complexes of macromolecules.
nuclear lamina
a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.
How is DNA organised?
discrete units called chromosomes, structures that carry the genetic info
chromatin
The complex of DNA and proteins making up chromosomes
nucleolus
- prominent structure within the nondividing nucleus
- appears through the electron microscope as a mass of densely stained granules and fibers adjoining part of the chromatin.
What happens in the nucleolus?
- RNA called ribosomal RNA (rRNA) is synthesized from instructions in the DNA.
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proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes.
- These subunits then exit the nucleus through the nuclear pores to the cytoplasm, where a large and a small subunit can assemble into a ribosome.
Ribosomes
ARE Complexes made of ribosomal RNA and protein, whcih are the cellular components that carry out protein synthesis
(Note that ribosomes are not membrane bounded and thus are not considered organ- elles.)
endomembrane system
- includes the nuclear envelope, the endoplasmic reticulum, the Golgi ap- paratus, lysosomes, various kinds of vesicles and vacuoles, and the plasma membrane.
- system carries out a variety of tasks in the cell; synthesis of proteins, transport of proteins into membranes and organelles or out of the cell, m_etabolism and movemen_t of lipids, and detoxifica- tion of poisons.
