UNIT 1 - cells and proteins Flashcards
what is a genome?
an organisms genome is its complete set of DNA
what does a genome include?
the protein coding genes and the non-protein coding genes
what are non-protein coding genes transcribed into?
- tRNA
- rRNA
- RNA molecules that control expressions of the other genes
what is a proteome?
the proteome is the entire set of proteins that can be expressed from a genome
what is unique about the size of the proteome?
it is larger than the number of genes. especially in eukaryotes. this is due to alternative RNA splicing which allows more than one protein to be expressed from a single gene.
what is removed in RNA splicing?
introns are removed from RNA transcripts
what is retained during RNA splicing?
exons are retained during RNA splicing
what does the set of genes expressed by a given cell type depend on?
they can vary over time and under different conditions
what are some factors that effect the proteins expressed?
some factors that effect the proteins expressed by a given cell type are:
- metabolic activity within the cell
- cellular stress
- the response signalling molecules
- diseased vs healthy cells
what is unique about the size of eukaryotic cells and what does this mean?
because of their size, they have a relatively small surface area to volume ratio. the surface area of their plasma membrane is too small to carry out all the vital functions of membranes and their specialised proteins associated with them.
what do eukaryotic cells have that increase the total area?
eukaryotic cells have a system of internal membranes that increases the area of the membrane
what does the endoplasmic reticulum form?
a network of membrane tubules continuous with the nuclear membrane
what is the endoplasmic reticulum?
a network of membrane tubules within the cytoplasm of a eukaryotic cell, continuous with nuclear membranes
what is a lysosome?
a modified Golgi vesicle containing hydrolytic enzyme/hydrolases
function of vesciles?
transport materials between membrane components
what is synthesised in the ER?
the components of membranes, phospholipids and proteins
what is a phospholipid?
they are a type of lipid that form the main component of the cell membrane
what is synthesised in the smooth endoplasmic reticulum?
lipids
where are lipids synthesised?
in the smooth endoplasmic reticulum and inserted into its membrane
what is the difference between RER and SER?
RER has ribosomes on its cytosolic face whereas SER doesn’t
where does the synthesis of proteins begin?
cytosolic ribosomes
where are cytosolic proteins located?
the synthesis of cytosolic proteins finishes in the cytosolic ribosomes and will remain in the cytosol
how is the RER formed?
transmembrane carry a signal sequence that halts translation and directs the ribosome synthesising protein to a dock with the ER forming the RER
what is a signal sequence?
a signal sequence is a short stretch of amino acids at one end of a polypeptide that determines the eventual location of protein in a cell
what is an allosteric enzyme?
Enzymes that change conformation in response to a modulator
what is an alpha helix?
Polypeptide chain coiled into a helix with hydrogen bonding occurring to maintain the arrangement
what is alternative RNA splicing?
Removal of non-coding introns from a primary mRNA transcript to leave only the coding exons; several mature transcripts can be produced from a single primary transcript
what are beta-pleated sheets?
Polypeptide chain arranged in rows with the chain folding in parallel or anti-parallel arrangements
conformation meaning?
Structural arrangement of the polypeptide chains within a protein
co-operatively meaning?
Changes in binding of a target molecule to one subunit of a multiunit polypeptide. this changes the affinity of the other subunits for the target molecule
what is a disulphide bridge
they are strong covalent bonds between R groups that contain sulfur which stabilise the tertiary and quaternary structures of many proteins.
what is the endoplasmic reticulum?
A network of membrane tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane
what is an exon?
Section of RNA that is usually retained during splicing
what is a glycoprotein?
A protein with a carbohydrate added by post-translational modification
what is the golgi apparatus?
A series of flattened discs that packages proteins into vesicles inside the cell before the vesicles are sent to their destination
what is hydrogen bonding?
Attractions between polar molecules in which hydrogen is bound to a larger atom, such as oxygen or nitrogen