Life at the cellular level 1 Flashcards
what are the two types of stem cells?
- multipotent stem cells: these can differentiate into many cell types
- pluripotent stem cells: these can differentiate into ALL body cells
what general properties do cancerous cells have (4)
- divide without any control
- fail to co-ordinate with normal cells
- fail to differnetiate
- displace and replace normal cells
what is cell differentiation?
a process of changes a cell goes through which causes it to become more specialised
- as part of this some cells fuse (cell fusion)
what is apoptosis?
a process of programmed cell death that forms a part of controlling development
what is cell proliferation?
an increase in the number of cells resulting from the balance between cell division and apoptosis
what are the diffrent types of cell adhesion junctions? (6)
- occluding junctions (tight junctions)
- adherens junctions
- desmosomes
- gap junctions
- actin-linked cell matrix junctions
- hemidesmosomes
describe the function of occluding junctions
seal gaps between cells creating a physical barrier against diffusion between cell layers
decribe the structure of adheren junctions
actin filamnet bundles in adjacent cells link the two together
describe the structure of desmosomes
intermediate filaments (keratin) in adjacent cells are linked
describe the structure and function of gap junctions
gap junctions have an aqeous channel linking the cytoplasm of two cells
- this allows movement of small water soluble molecules and cell to cell communication
explain contact dependent cell signalling
siganlling cell has a membrane bound signal molecule that is complementary to a receptor on a targer cell
explain paracrine cell signalling
siganlling cell releases signal molecules (local mediators) that travel to locailsed cells with complementary recptors
what happens during fast cell signalling?
an intracellular signalling pathways is triggered that causes a function/s within the cell to be altered (takes between a few seconds to few minutes)
what happens during slow cell siganlling response?
the signalling triggers a chnage in protein synthesis (can take between a few minutes to hours)
what general features do mitochondria have? (5)
- outer membrabe contains pores (Porin protein)
- inner membrabe form cristae
- matrix has binding sites for calcium and enzymes
- has its own circular DNA (self replicates)
- has ribomsomes
what general features does a nucleus have? (4)
- contain DNA, nucleprotein and RNA
- have nuceoli which are the site of RNA sythesis and ribosomal assembly
- surronded by a nuclear envelope
- nuclear envelope has nuclear pores through which mRNA travels out
what are the two forms of DNA found in the nucleus?
- heterochromatin: coiled DNA sections
- euchromatin: unzipped sections of DNA - active parts of DNA that are transcribed
what function does endoplasmic reticulum have?
- RER co-ordinates protein transport and modification
- SER is mainly used to breakdown compounds (e.g glycogen) or synthesis new compounds (e.g lipids)
what function does golgi apparatus have?
coordinates protein transport and modification
what are lysosomes used for? (3)
- used to separate enzymes from the rest of the cell
- used in autophagy
- used to breakdown englufed material (in phagosome)
what is the function of the cytoskeleton? (4)
- hold organelles in postion
- help with the movement of organelles
- interact with extracellualr matrix
- stabilise cell structure and shape
what general features are present in the cytoskeleton (3)?
- microfibrils made of actin
- intermediate filaments made of fibrous proteins
- microtubules made of tubulin (alpha and beta tubulin)
what is contact inhibition?
inhibition of cell division because of the many contact points cells make with each other
