Cell structure & intracellular transport

eukaryotes vs prokaryotes, functions of organelles, microscopy (light fluorescent and EM), subcellular fractionation and flw cytometry, nuclear transport, membrane transport and vescicular transport

what three properties does any living thing need to have? (GMR)

growth, metabolism and reproduction

organisms which have a nucleus are classed as…?

eukaryotic

organisms which do NOT have a nucleus are classed as…?

prokaryotic

prokaryotic membranes are composed of which three layers?

capsule, cell wall and plasma membrane

the plasma membrane controls … with the outside world

communication

what is the name of the area in prokaryotes which contains DNA?

nucleoid

the ER is responsible for the synthesis of the majority of which two biomolecules?

lipids and proteins

golgi is responsible for … of lipids and proteins (3 words)

modification, sorting and packaging

endosomes are responsible for sorting of … material

endocytosed

peroxisomes are responsible for oxidation of … molecules

toxic

lysosomes are responsible for intracellular …

degradation

prokaryotes have a cell wall made of which molecule?

peptidoglycan

peptidoglycan is a polymer of… (2 things)

amino acids and sugars

3 techniques used in the lab to study cell structure and function

subcellular fractionation, microscopy and fluorescence activated cell sorting (FACS)

three types of microscopy

light, fluorescence and electron microscopy

two types of electron microscopy (TEM and SEM)

transmission and scanning EM

type of EM which looks at thin cross sections of tissue by passing a beam of electrons through the sample → 2D image obtained

transmission EM

type of EM which scatters electrons off the surface of the sample (used to look at surface details of cells) → 3D image obtained

scanning EM

what type of microscopy is this?

transmission EM

what type of microscopy is this?

scanning EM

what type of microscopy is this?

fluorescence microscopy

type of microscopy that examines fluorescent substances in a microscope by illuminating the specimen with short-wavelength light?

fluorescence microscopy

what type of microscopy is this?

light microscopy

technique used to isolate cellular components through centrifugation of lysed cells and through successive centrifugations at increasing RCFs (relative centrifugal forces)

subcellular fractionation

a technique which uses laser beams to determine the characteristics of cells?

flow cytometry

machine which has a fluidic system that transports the cells from a test tube into a narrow stream of fluid, where cells are passed individually through a laser beam

flow cytometer or fluorescent activated cell sorterer (FACS)

in flow cytometry cells are separated based on properties such as… (3 examples)

size, granularity and protein expression

what is the name of the membrane which encloses the nucleus?

nuclear envelope

is the nuclear envelope a single or double membrane?

double

a sequence of amino acids known as the … on the protein is used to direct proteins to their final destinations

signal sequence

KDEL is the signal sequence (or retential signal) which directs proteins to or tells them to stay in which organelle?

the ER

KDEL stands for which amino acids

lysine, aspartic acid, glutamic acid and leucine

during protein transport through nuclear pores, the pores act as …

selective gates

during protein transport across membranes, proteins get unfolded and are transported via…

protein translocators

during protein transport by vesicles, what membrane related process allows proteins to enter organelles?

membrane fusion

what type of molecules can freely diffuse through nuclear pores between the nucleus and cytosol?

small water soluble molecules

what is the name of the signal sequence proteins in the cytosol must have to enter the nucleus?

nuclear localisation sequence (NLS)

are proteins that are transported into the nucleus unfolded or folded?

folded

proteins which form the nuclear pore complex

nucleoporins

long, stalk-like structures which project from both sides of a nuclear pore

protein fibrils

on the nuclear side, protein fibrils form a structure in what shape?

basket like

does nuclear transport require energy?

yes

a protein which contains the nuclear localisation sequence (NLS) binds to … receptors and is guided to the nuclear pore

nuclear transport receptors

the nuclear transport receptor interacts with which structure or the nuclear pore to guide the protein to the pore?

protein fibrils

what happens to the nuclear transport receptor once it has delivered the NLS-containing protein to the nucleus?

it returns to the cytosol

which nucleotide triphosphate molecule does nuclear transport utilise?

GTP

complex of which two molecules binds to the nuclear transport receptor (NTR), causing it to release the NLS-protein?

ran-GTP

after the ran-GTP and NTR complex is transported back to the cytosol, ran-GTP gets hydrolyzed to … 

ran-GDP

what happens when ran-GTP is hydrolyzed to ran-GDP?

the NTR is released

name of the translocase complex on the OM of the mitochondria, which recognises and binds mitochondrial signal sequences to initiate protein import

translocase of the outer membrane (TOM)

do proteins cross the mitochondrial membranes folded or unfolded?

unfolded

which translocase complex facilitates import of protein through the IM of the mitochondria?

translocase of the inner membrane (TIM)

what happens to the protein when it enters the mitochondrial matrix?

it is refolded and the signal sequence is removed

which proteins aid with translocation and refolding during mitochondrial protein import?

chaperone proteins

which enzyme cleaves the signal sequence off proteins when the enter mitochondria?

signal peptidase

proteins which are destined for which organelles first enter the ER? (GEELS)

golgi, ER, endosomes, lysosomes and cell surface

which structures transport proteins out of the ER?

vescicles

which two things direct a ribosome translating an ER protein to the ER membrane?

the signal sequence and the signal recognition particle (SRP)

what is the name of the channel which lets soluble proteins get translated directly into the ER lumen

translocation channel

what is the name of the enzyme which cleaved the signal sequence off proteins once they are in the ER

signal peptidase

what is the name of the two sequences membrane proteins have which allows them to become embedded in the membrane

hydrophobic stop transfer sequence and hydrophobic start transfer sequence

which sequence on the transmembrane proteins halts the insertion process (of moving through the channel), causing the protein to be anchored in the membrane instead of being fully translocated across it

hydrophobic stop transfer sequence

which sequence initiates the insertion of a protein into the ER membrane (aka initiates the movement through the channel)

hydrophobic start transfer sequence

what are the two types of proteins moved from the cytosol to the ER?

soluble and transmembrane proteins

out of soluble and transmembrane proteins, which completely cross the ER membrane and are released into the lumen?

soluble

out of soluble and transmembrane proteins which only partly cross the ER membrane and become embedded?

transmembrane

the signal recognition particle (SRP) binds to the ER signal sequence on a protein being translated. translation then slows down until the SRP binds to the … on the ER membrane

SRP receptor

in addition to directing proteins to the ER, the ER signal sequence functions to open the …

translocation channels

multi pass transmembrane proteins also contain which sequence?

internal signal sequence

vescicle budding is driven by the assembly of a …

protein coat

what are the two proteins which may compose the protein coat of a vescicle?

clathrin or coat protein complex (COP) proteins

vescicles originating from the ER or golgi destined for endosomes or lysosomes are generally coated with which protein?

clathrin

vescicles shuttling between the ER and golgi are generally coated with which proteins?

COP proteins

when clathrin molecules are free in the cytosol they shape what three-legged strucutre?

triskelions

what is the name of the proteins which mediate the contact between the receptors and clathrin molecules in vescicles?

adaptins

in general which 4 molecules are needed to form a vescice?

cargo, receptors, adaptins and clathrins

example of a protein which is constantly secreted from cells?

serum albumin

example of a protein which is secreted from cells only once an appropriate signal is received?

insulin

type of protein secretion from cells which is continuous?

constitutive secretion

what is the membrane mediated degradation of cellular components called?

autophagy

what is the membrane mediated uptake of bacterial cells and dead, damaged or infected cells called?

phagocytosis

what is the membrane mediated uptake of vescicles called?

endocytosis

which three membrane mediated processes all ultimately lead to the formation of a lysosome?

endocytosis, phagocytosis and autophagy

do all three; nuclear transport, membrane transport and vescicular transport require energy?

yes