Module One, Lecture Nine Flashcards
Nucleus (14 cards)
What is the Nucleus?
The nucleus is the control centre of the cell. It is surrounded by a double membrane called the nuclear envelope and supported structurally by the nuclear lamina. The nucleus contains most of a cell’s genes
Describe the structure of Ribosomes…
- Each ribosome consists of two separate RNA-protein complexes, known as the small and large subunits.
- Complexes made of ribosomal RNAs and proteins
- Found in two locations; Bound = Attached to the rER / Free = In the Cytoplasm
What are some functions of the Ribosomes? ( 4 )
- A ribosome is the cellular machinery responsible for making proteins
- The subunits lock around the messenger RNA and then travel along the length of the messenger RNA molecule reading each three-letter codon
- Carry out translation
- The more protein synthesis a cell needs to do, the more ribosomes it has
What are the functions of the Nucleus? ( 5 )
- The most prominent organelle
- One nucleus per cell ( in most cases )
- Contains most of the cell’s genes
- Serves as a repository of inherited genetic information
- The cell’s control centre
Describe the structure of the Nucleus… ( 4 )
- Surrounded by the nuclear envelope
- Has channels called nuclear pores
- Contains tightly packed DNA
- Has a prominent area called the nucleus
Describe the structure / function of the Nuclear Envelope…
Also known as the nuclear membrane, it is a double-membrane structure that encloses the nucleus in eukaryotic cells, separating the genetic material from the cytoplasms and regulating traffic between the two compartments
What is the Nuclear Lamina?
Is a protein meshworking lining the inner side of the nuclear envelope, composed primarily of lamins and associated proteins
Describe the structure / function of Nuclear Pores…
Are protein-lined channels within the nuclear envelope that regulates the transport of molecules, including proteins and RNA, between the nucleus and cytoplasm in the eukaryotic cells
Describe the movements of materials between the Nucleus and the Cytoplasm… ( 3 )
- mRNA, tRNA and ribosomal subunits move from nucleus to cytoplasm
- mRNA ( messenger RNA ) carries information from a gene
- tRNA ( transfer RNA ) and ribosomal subunits are needed to build proteins
Describe the movements of materials between the Cytoplasm and the Nucleus… ( 4 )
- Control signals, building materials and energy move from cytoplasm to nucleus
- Controls when to turn a gene on or off
- The building “blocks” for RNA
- Energy for chemical synthesis
What is the Nucleolus?
It is a spherical structure within the cell’s nucleus, responsible for producing and assembling ribosomes, which are essential for protein synthesis
What is Euchromatin?
Less electron-opaque, contains genes being used by that cell
What is Heterochromatin?
More electron-opaque, contains genes not being used by that cell, dynamic relationship between euchromatin and heterochromatin
What does the Nucleus contain?
The nucleus contains a specialized nucleolus, where ribosomal RNA and ribosomal subunits are made then transported to the cytoplasms for assembly, which re further packaged into larger ( 30-nm ) and larger ( 300-nm ) fibers and, during cell division, into chromosomes
