CELS 191 Lecture 9 Flashcards
(23 cards)
what are ribosomes composed of
ribosomal RNAs which are folded around proteins
where are ribosomes found
bound ribosomes are found in the rough ER and free ribosomes are found in the cytoplasm
in bound ribosomes where does the protein insert
in the lumen - the space between the ER membranes
what are the 2 parts of the ribosome and what are their functions
the large subunit synthesises the polypeptide chains and small sub units joins the RNA and reads the RNA code
where are the ribosomal subunits made
in the nucleus
ribosomes carry out translation, what is translation
the process where messenger RNA (mRNA) is decoded to synthesise proteins
what is a codon
a set of three nucleotides in an mRNA sequence that are read together by the ribosome
what brings the amino acids to the ribosome to build the polypeptide chain
tRNA - transfer RNA brings the amino acid that corresponds to the codon being read by the mRNA
what is the nucleus
the most prominent organelle in a cell that contains most of the cells genes and serves as a storage for inherited genetic information as well as being the cells control centre
what is the nuclear envelope
a layer around the nucleus composed of two membranes (inner and outer) - the outer membrane is continuous with the rER
what is the perinuclear space
the space between the inner and outer membranes of the nuclear envelope that acts as the organising centre for proteins
what are nuclear lamina composed of and what is their function
they are composed of intermediate filaments (which are composed of a protein called lamin) and help maintain the shape of the nucleus and organise the packing of the DNA within the nucleus
what are nuclear pores and what is their function
channels made of proteins that span the entire nuclear envelope and regulate the movement of molecules including proteins and RNA between the nucleus and the cytoplasm
what substances are moving from the nucleus to the cytoplasm
mRNA, tRNA and ribosomal subunits
what substances are moving from the cytoplasm to the nucleus
control signals, building materials and energy
what is the nucleolus
a non-membrane bound prominent structure within non-dividing cells - it is responsible for making ribosomal RNA and ribosomal subunits
what are histones H2-H4 and what is their function
proteins that interact with the double helix of DNA interacts with (H2-H4) to form a 10nm diameter fibre with ‘beads’ called nucleosomes
what is H1s function
it further interacts with DNA to cause the 10nm fibre to coil to form the 30nm fibre which then loops for form a 300nm fibre
during cell division what do the 30nm fibres coil to form
metaphase chromosomes
what is the difference between euchromatin and heterochromatin
euchromatin is less electron opaque and contains genes being used by that cell - heterochromatin is more electron opaque and contains genes not being used by the cell
is the relationship between heterochromatin and euchromatin static or dynamic
dynamic
of heterochromatin and euchromatin which allows for transcriptional machinery to access specific regions and being transcription
euchromatin because it is less tightly packed and therefore allows easier access
