life at cellular level 1 Flashcards
what is a cell
the living unit of all things
why are cells so small
the bigger the cell, the smaller the SA:V, the smaller the exchange of gases
difference between prokaryotic and eukaryotic
prokaryotic: 1- no membrane bound organelles 2-DNA in loops- no nucleus-no membrane 3-bacteria cells 4-no mitochondria
different types of stem cell
TOTIPOTENT; can differentiate into any cell. Difference with pluripotent is that it can give rise to embryo and placenta.
MULTIPOTENT-can differentiate into many different types of cell
PLURIPOTENT- Can differentiate into any cell
what is the plasma membrane made up of?
phospholipid bilayer- hydrophobic tail and hydrophilic heads
proteins embedded into the layer which allow the membrane to carry out a series of functions.
what functions does the cell-membrane have? (6)
1- transport 2-cell-adhesion 3-bonds to cytoskeleton and extracellular matrix 4-receptor 5-enzyme activity 6- cell to cell recognition
Function of bonding to cytoskeleton and extracellular matrix?
helps maintain the structure of the cell
Function of acting as a receptor?
Chemicals can bond to proteins embedded in the membrane. this might cause them to change shape and in turn initiate a chemical response inside the cell
function of acting as an enzyme?
proteins embedded in membrane can catalyse an activity or a whole metabolic pathway.
different types of transport?
- facilitated diffusion- Requires concentration gradient and carrier molecules
- diffusion-non-polar molecules which are lipophilic
- pinocytosis: Non -specific. Small molecules move into cell in many individual vesicles
- Receptor-mediated endocytosis
- Phagocytosis: Specific form of pinocytosis
Cell death
Apoptosis- programmed cell death.
- Apoptosis and cell proliferation are what control cell development.
- Cell death can either be physiological(apoptosis) or pathological( response to an injury).
- Physiological- membrane bleb- few hours- no damage to adjacent cell
- Pathological- membranes rupture- days- inflammation- damage to adjacent cells-necrosis
Cell signalling
- Paracrine- signalling cell releases local mediator to target cells
- Endocrine- hormone released into bloodstream-binds to receptors on target cells
- Autocrine
- Contact-depending: depends on cell adhesion
- Synapsing
Cell organelles
Mitochondria:
-Outer membrane: contains porin
-Inside membranes: Cristae
-own DNA and ribosomes
Nucleus:
-Nucleoli-sites of rRNA synthesis.
-Nuclear envelope closely associated with RER
-DNA, nucleoproteins,RNA
ER
-rough-has ribosomes attached, works with Golgi in production of proteins and modification of proteins
-Smooth used for assembly of lipid compounds or breakdown of certain compounds e.g. drugs
Lysosomes;
-used for autophagy-destruction of cell-self material or engulfed particles
Cytoskeleton:
-made up of microfilaments, intermediate filaments and microtubules
-holds organelles in place, helps move them
Perixosome:
- contains catalase ( regulate hydrogen peroxide conc.)
- contains oxidase: involved in beta-oxidation