Cell organelles Flashcards
When is cell is polarised, what does this mean?
There are spatial differences in structure and function- asymmetric
What way does the apical membrane face?
faces the lumen or external environment
What way does the basal membrane face?
Facing the basement membrane, or inside of the body
What size are Eukaryotes generally?
5 micrometers or more
What size are Prokaryotes generally?
1-5 micrometers
What does the nucleolus do?
Makes ribosomal RNA
What do glycolipids provide in the PM?
provide binding sites for proteins
What do oligosaccharides side chains do in the PM?
provide bindings sites for proteins, and act as cell recognition sites
Where do you find integral proteins on the PM?
they span the length
Where do you find peripheral proteins on the PM?
one side of the lipid bilayer
What are the 2 roles of the plasma membrane?
1) mediates communication
2) Regulates transport of solutes
Is the head of a phospholipid hydrophobic or hydrophilic?
Hydrophilic
What is the hydrophilic head of a phospholipid formed of?
Choline, phosphate and glycerol
What are the tails of a phospholipid formed of?
hydrocarbons
What makes a hydrocarbon tail of a phospholipid bent?
A CIS double bond
Is a phospholipid head polar?
Yes
Is a phospholipid tail polar?
no, non polar
Adding bent tails to a phospholipid bilayer make it ……. fluid
less
Cholesterol makes the phospholipid bilayer more or less fluid
less
Why can ethanol pass through a membrane passively ?
Because it is a small molecule and is not charged
Water and Urea are only slightly permeable to membranes due to what 2 characteristics?
1) the molecules are small but polar
2) the molecules are uncharged
Why is glucose impermeable to the cell surface membrane passively?
it is a large molecule and is polar
Why can’t ATP, Proteins and Amino Acids pass through the membrane passively? 2 things
they are charged and polar
What do Anchors do as proteins in the membrane?
link intracellular actin filaments to extracellular matrix proteins
is the outer membrane of the mitochondria permeable?
Yes
Is the inner membrane of the mitochondria permeable?
not so permeable
How does the mitochondria make its own proteins?
It has its own DNA
In the ETC how is a H ion gradient harvested?>
ATP synthase
What is the role of the Golgi apparatus?
to sort, pack and modifiy proteins
What is the basic structure of peroxisomes?
cytoplasmic vesicles
What do peroxisomes do, and using what process?
Break down ethanol and fatty acids, oxidation
What is the basic structure of lysosomes?
cytoplasmic vesicles
What is the function of lysosomes?
to digest intracellular bodies using degradative enzymes
What does the ER do?
synthesis of lipids and proteins
What does the nucleus hold, and what happens there?
DNA, genome and RNA synthesis
What do endosomes do?
carry endocytosed material
Actins average diameter is?
7nm
Actin’s role is to…..
aid movement of proteins eg. myosin
Actin can be found in which structure of the gut?
microvilli
Microtubules’ average diameter are?
20nm
Microtubules are polymers of what?
Tubulin dimers
A centrosome is a type of…..
microtubule
The 2 roles of microtubules are too….
Shape a structure and aid movement of proteins
Create a train track system
Stem cells are not terminally….
differentiated
Do stem cells divide without limit?
yes
What does totipotent stem cell mean?
have the capacity to self-renew by dividing and to develop into the three primary germ cell layers of the early embryo and into extra-embryonic tissues such as the placenta
What does pluripotent stem cell mean?
capacity to self-renew by dividing and to develop into the three primary germ cell layers of the early embryo and therefore into all cells of the adult body, but not extra-embryonic tissues such as the placenta. MAKE MANY BUT NOT ALL CELL TYPES
Most adult stem cells are….
multipotent stem cells
what does multipotent stem cells mean?
have the capacity to self-renew by dividing and to develop into multiple specialised cell types present in a specific tissue or organ
How do Induced Pluripotent stem cells work?
1) Stem cells are taken from the skin of a patient
2) they are despecialised
3) made into part you want
What is an advantage of using Induced Pluripotent stem cells?
- less ethical issues as no embryos involved
- no immune response as own stem cells used
- anything can be replaces In theory
What is a disadvantage of Induced Pluripotent stem cells?
- could lead to cancer
2. More research needs to be done on pathways
What is Apotosis
programmed cell death
How is apoptosis stimulated?
by a signalling process which activate intracellular suicide proteases
What are the 3 steps in apoptosis?
- structure breaks down
- Cytoskelton collapses
- mini cells are created and engulfed by phagocytosis
What is necrosis?
Cell lysis / bursting
Wha the 3 steps to necrosis?
- cell membrane is destroyed
- cell content is released
- phagocytosis and enzymes degrade further
What can apoptosis be used to tackle?
cancer
