Cells and proteins Flashcards
The proteome?
The entire set of proteins that is, or can be expressed by a certain genome.
More than one protein can be produced from a single gene due to…
Alternative gene splicing.
Non coding RNA genes
Genes that do not code for proteins transcribed to produce tRNA, rRNA and RNA molecules that control the expression of other genes.
The set of proteins expressed by a given cell type can vary over…
Time and under different condition
4 factors affecting the set of proteins expressed by a given cell type are:
Metabolic activity of the cell
Cellular stress response to signalling molecules
Diseased vs healthy cells
Because of their size, eukaryotes have a relatively small…
Surface area to volume ratio
The plasma membrane of eukaryotic cells is too small to…
Carry out all the vital functions of the cell
Name 13 parts of the cell
Cell membrane Golgi apparatus Golgi vesicles Nucleus Lysosome Ribosome Microtubules Pinocytotic vesicles Endoplasmic reticulum Centrioles Vacuole Mitochondria Smooth endoplasmic reticulum
Endoplasmic reticulum
Forms a network of membrane tubules continuous with the nuclear membrane
Golgi apparatus
A series of flattened membrane discs
Lysosome
Membrane bound organelles containing a variety of hydrolyses that digests proteins lipids, nucleic acids and carbohydrates
Vesicles
Transport materials between membrane compartments
Parts of the cell involved in synthesis of membrane components
Ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Lipids and proteins are synthesised in the…
Endoplasmic reticulum
What is the difference between rough endoplasmic reticulum and smooth endoplasmic reticulum?
RER has ribosomes on its cytosolic face while SES does not
Lipids are synthesised in…
The SER and inserted into its membrane
The synthesis of all proteins begins in the…
Cytosolic ribosomes
The synthesis of cytosol proteins is completed in the…
Cytosolic proteins, these proteins remain in the cytosol (liquid part of the cytoplasm)
Transmembrane proteins
Carry a signal sequence which halts translation and directs the ribosome synthesising the protein to dock with the ER forming RER
Signal sequence
A short stretch of amino acids at one end on the polypeptide that determines the eventual location of a protein in a cell
What are many secreted proteins synthesised as
Inactive precursors and require proteolytic cleavage to produce active proteins
What is proteolytic cleavage
Another type of post-translational modification
Example of secreted proteins
Digestive enzymes that requires proteolytic cleave to become active, another is insulin
Proteins are polymers of…
amino acid monomers
What are enzymes linked by
Peptide bonds to form polypeptides
Amino acids have the same basic structure, differing only in the…
R group present
What can R groups vary in
size shape charge hydrogen bonding capacity chemical reactivity
Amino acids are classified according to their R groups. What are they
basic (positively charged)
acidic (negatively charged)
polar (hydrophilic)
hydrophobic (non polar)
What does the diversity of amino acid R groups result in
Wide range of functions carried out by proteins
What is the primary structure
The sequence in which the amino acids are synthesised into the polypeptide
where are secreted proteins translated?
they are translated in ribosome on the RER and enter it’s lumen
Describe how vesicles are able to move around the cell
Along microtubules (to other membranes)
Describe the differences between the various protein synthesised in cells in terms of their final destinations
Cytosolic proteins are synthesised in cytosolic ribosomes; transmembrane proteins start in cytosolic ribosomes and finish in docked ribosomes/ RER; secretory proteins start in cytosolic ribosomes and finish in docked ribosomes/ RER
Describe TWO different types of post-translational modification
Addition of carbohydrate in golgi apparatus; proteolytic cleavage of digestive enzymes in gut
Name the FOUR different types of R groups and describe the characteristics of each.
hydrophobic are uncharged; basic are positively charged/ hydrophilic; acidic are negatively charged/ hydrophilic; polar have small balanced charges/ no net charge
Describe the primary and secondary level of protein structure.
primary is the sequence of amino acids; secondary is folding to produce helices/sheets/turns; held in shape by H bonds
Name FIVE types of bond that can hold the tertiary structure of protein in shape.
hydrophobic interactions ionic bonds disulfide bridges London dispersion forces hydrogen bonds
Describe the quaternary structure of a protein
arrangements of subunits; may have prosthetic groups
Explain what is meant by co-operativity between subunits of a protein
binding or dis-binding of substances at subunits; affects affinity of these substances for further subunits
