Chapter 3 Flashcards
the nucleus
contains genome enveloped by the nuclear membrane. Where replication, transcription and splicing occur
the genome
organized into linear molecules of dsDNA in eukaryotes and sDNA in prokaryotes
the nucleolus
“little nucleus” functions as a ribosome factory, not separated from the nucleus.
nucleolus is composed of
loops of DNA, RNA, polymerase, rRNA and the protein components of the ribosome
the nucleolus is largest in cells that are producing large amounts of proteins (T/F)
True, the bigger the size the more synthesis of ribosomes
Site of transcription of rRNA byRNA pol I
nucleolus
where does all translation take place?
cytoplasm
nuclear envelopes is composed of
Two lipid bilayers, the inner nuclear membrane and the outer nuclear membrane

orientation of the nuclear envelope
the inner nuclear membrane faces the nuclear interior. Outer nuclear membrane faces the cytoplasm and is contiguous “sharing a common border” with the ER lumen

Nuclear envelope structure
punctuated w large nuclear pores to allow passage of materials in out of the nucleus. Molecules < 60 kilodaltons can freely diffuse
How do molecules larger than 60 kilodaltons enter the nucleus
if they contain the nuclear localization sequence (lysine rich)
mitochondria
site of oxidative phosphorylation. Singular circular DNA molecule, exhibits maternal inheritance
the matrix
interior of the mitochondria bounded by the inner and outer mitochondrial membrane. Contains pyruvate dehydrogenase and enzymes of the Krebs cycle
Krebs Cycle
location of the electron transport chain and ATP synthase
Endoplasmic reticulum (ER)
large system of folded membrane accounting for over half of the membrane of some cells
Plays a role in directing traffic to different parts of the cell
endoplasmic reticulum
Rough ER
site of protein synthesis for proteins targeted to enter the secretory pathway
Smooth ER
contains enzymes involved in steroid hormone biosynthesis (gonads) or degradation of environmental toxins (liver)
The two sites of proteins synthesis in eukaryotic cells
(1) ribosomes free in the cytoplasm (2) ribosomes bound to the surface of the rough ER
Destinations of ribosomes bound to the surface of the rough ER
(1) are secreted into extra cellular environment (2) integral membrane proteins (3) membrane interior of ER, Golgi or Lysosomes
the interior of the ER, Golgi apparatus, lysosomes and the extra cellular environment are not continuous (T/F)
false
Proteins start translation
in the cytoplasm
Signal recognition particle (SRP)
ER has SRP receptors which doc the complex and is pushed through the ER lumen and moved through the Golgi to the plasma and released by exocytosis
removed after translation and at the N-terminus
Transmembrane domains
sections of hydrophobic amino acid residues. threaded through the ER lumen during translation and undergoes secretory pathways.
not at the N-terminus and not removed after translations

























