cells and organelles 1 Flashcards
origin of cells
cells originate from preexisting cells.
definition of cells
smallest structural and functional unit of an organism.
All organisms are made of one or multiple cells.
Cells are derived from other cells through cell division.
advanced cell theory
Capability to generate Energy (metabolism and biochemistry) occurs within cells
=> like glucose being created through glycolysis
Cells carry hereditary materials (DNA)
DNA is transferred from one cell to another.
Cells possesses same basic chemical compositions - same inorganic/ organic molecules
cell plasma membrane
- protective sheath that encloses the cell as an independent reaction container.
- separates the intracellular fluid (ICF) from the extracellular fluid (ECF).
- semipermeable membrane
- regulates the exchange of molecules between the ICF and ECF.
- composed of a bilayer of lipid molecules with associated protein molecules.
properties of cells
they grow and reproduce (replicate).
Cells have a finite lifespan – they die (by design, age or disease). - red cells = 90 days
Cells internal processes allow them to change, adapt, or respond - cells respond to you taking coke for example increasing glucose levels (different cells performance different function).
plasma mobility
restrictive and not uniform
molecules or nutrients get transfered from the intestinal lumen to the basolateral domain to the connective tissue area and into the blood
5 major phospholipids
(phosphatidylcholine and sphingomyelin) = outer leaflet of membrane; (phosphatidylethanolamine, phosphatidylserine & phosphatidylinositol) = inner leaflet of membrane.
DNA
deoxyribonucleic acid.
chromosomes are carriers of DNA which are wrapped around a particular proteins that are called histones
gene
carriers of identity materials
when used electronic microscope
100 nm - 1 mm
cell membrane= amphipatic molecules
phosphate group = hydrophilic head = water loving on outside and
two hydrophobic fatty acid chains= embedded into cell membrane
what is embedded in the cell membrane - fluid mosaic model
not just fluid, proteins
cholesterol.
integral proteins, the phospholipid bilayer and the glycoproteins
cholesterol role
cholesterol is embedded into membrane with a polar hydroxyl
to give it rigidity and its therefore not so fluid
1. rigidity
2. fluidity = no stifness
phosphatidylserine
phospholipid translocates from the inner cell to the outer cell of the plasma membrane.
And that sends a signal for a dying cell and then a process known as phagocytosis eliminates cell
membrane protein groups/ function
integral = transmembrane
peripheral
=> diff functions = receptors/ transporters/ signalling/ adhesion
how do molecules get through the cell membrane
=> diffusion = hydrophobic molecules / small uncharged molecules
vs large polar molecules and ions
= membrane transport protein => channel = passive transport => based on concentration/ electrochemical gradient
vs carrier protein => molecules bind to protein, experience transformational change when on receptor binding site and enter => often powered by hydrolysis of AATP
types of membrane protein activities
Cell identity markers: membrane proteins that identify the cells of an individual. They are person specific
Linking proteins: gives structure to the plasma membrane, they also hold the cells together and participate in movement.
Enzymes: some membrane proteins are enzymes that drives biochemical reactions at the cell surface level.
Receptors protein: certain proteins on the surface function as receptor for the attachment of specific molecules e.g., hormones or neurotransmitters. Receptors are key in diseases e.g., antibodies and antigens.
prokaryotes
- simple, single-celled organism without a nucleus and membrane-bound organelles (e.g., mitochondria).
- spherical, rod-shaped, or spiral
- Simple cell division.
- The genetic materials in the central region = nucleoid -> consists of a single chromosome of a circular DNA.
- Prokaryotes = Bacteria
- Up to a few thousandths of mm (few microns) in size (1 – 10µm).
- Amongst oldest and most abundant type of life on earth (preceded complex cells).
membrane bound organelles
have their own membrane
mitochondria, the Golgi apparatus, endoplasmic reticulum
eukaryotes
Eukaryotes possesses more complex internal structure and with several chromosomes (DNA molecules) in the nucleus.
Consists of multiple liner DNA molecules.
They have a true nuclear membrane and often contain several specialised organelles e.g., Golgi apparatus, mitochondria, endoplasmic reticulum etc.
They are multicellular organisms.
Most complex eukaryotes are found in human, animals, plants (cytoplasm divided by membrane to enclose compartments/organelles, has a nucleus).
Up to a 10 thousandths of mm in size (10 microns or much more).
Amongst more recent cells to evolve, representing complex cells in multicellular organisms.
protein expression eukaryotes
DNA (with its genes) packaged in a central store called a nucleus.
DNA (with its genes) transcribed to produce mRNA (transcription).
Nucleus is enclosed by a double membrane the nuclear envelope (nucleus is one of a number of cell compartments).
mRNA (message) passes from the nucleoplasm to the cytoplasm via holes called nuclear pores.
Nuclear pores are selective aqueous channels for transport between nucleus and cytosol (mRNA passage but also in both directions).
mRNA is decoded and proteins made (translation) on specialised factories called the ribosomes.
prokaryotes expression
PROKARYOTES DNA is packaged but not enclosed by membrane.
what allows binding of DNA around histones
two amino acids -> lysine + arginine => forms complex = chromatin
Chromatin
Chromatin is packaged in two main ways – euchromatin; and more-dense heterochromatin = peripheric.
Most of the active genes are found in the euchromatin = scattered everywhere , inactive ones in heterochromatin.
