Introduction to Cell structure Flashcards
The external boundary that serves as a barrier, controlling entry and exit of substances
-The site of communication between cells and their environments
Plasma membrane (PM)
Segregates the internal structure of the nucleus from the cytoplasm
Nuclear Envelope
Cells that secrete peptides and proteins have extensive
-A membranse structure to which ribosomes are attatched
Rough ER’s
What are the two main intracellular compartments?
Nucleus and Cytoplasm
The nucleus has a subdomain known as the
Nucleolus
The cytoplasm has which two sub domains?
- ) Membrane bound organelles
2. ) Cytosol
Synthesize and secrete immunoglobulins and have extensive rough endoplasmic reticulums
Plasma Cells
Cytoplasm outside of the organelles, containing soluble enzymes, inclusions (glycogen, granules, and lipids), cytoskeletal elements, and free polysomes
Cytosol
mRNA + ribosomes
Polysomes
What are the three major structural areas of the nucleus?
Nuclear Envelope, Nuclear Pore, and Nuclear Lamina
Double membrane that segregates nuclear contents
Nuclear envelope
The outer membrane of the nuclear envelope is continuous with the ER and has
Ribosomes
The nuclear envelope encloses
Chromatin and nucleoplasm
Contains the genetic material of the cell
Chromatin
Contains soluble nucleotides and proteins
Nucleoplasm
What are the two types of Chromatin?
Euchromtin and heterchromatin
Actively transcribed DNA
Euchromatin
Inactive DNA that is highly condensed and usually near the periphery of the nucleus
Heterochromatin
The site of ribosomal RNA synthesis and the site of the assembly of ribosomal subunits
Nucleolus
The ribosomal subunits consist of rRNA and several proteins that were first synthesized in the cytosol and then transported to the
Nucleus
A structure composed of pecific intermediate filament proteins (the LAMINS)
Nuclear lamina
Form a dense felt-like area under the nuclear membrane, which helps maintain nuclear structure
Lamins
Phosphorylation and dephosphorylation of the nuclear lamins regulate the stability of the nuclear envelope during
Mitosis
Results in the break down of the nuclear envelope during prophase of mitosis
Phosphorylation of lamin B
Large complex structures (30 different proteins) organized with octogonal symmetry that transport macro- and micromolecular structures in and out of the nucleus
Nuclear Pores
Leave the nucleus through the nuclear pore
Molecules involved in protein synthesis (mRNA, tRNA, ribonucleoproteins)
Made in the cytoplasm fro mRNA and enter the nucleus through the nuclear pore
Proteins used in gene regulation (histones, polymerases, etc)
Contains the cytoskeleton (which forms the structural framework of the cell), cytoplasmic inclusions, soluble enzymes/ions, and free polysomes
Cytosol
What are three special types of proteins contained in the cytosol?
Actin, Tubulin, Intermediate filaments
Contain filaments called microfilaments
Actin
Contain structures called microtubules
Tubulin
Similar to nuclear lamins
Intermediate filaments
Metabolic products such as lipids (in the form of lipid droplets) and glycogen (polymer of glucose), are not enclosed by a cell membrane and are stored in the cytosol as
“inclusions”
The cytosol contains numerous soluble proteins and enzymes involved in
Intermediate Metabolism
Particles composed of rRNA and Multiple proteins that are assembled as large and small subunits
Ribosomes
The large and small subunits of ribosomes combine with mRNA to promote
Translation
Ribosomes attached to the ER will produce proteins that enter the
Secretory pathway
In the cytosol, free polysomes synthesize specific proteins that are used
Within the cell (not secreted)
Importantly, nuclear proteins that regulate replication and gene expression, such as DNA polymerases and transcription factors, as well as proteins of the ribosome itself, are made on
Free ribosomes
Ribosomal proteins made in the cytoplasm associate with rRNA produced in the
Nucleolus
