Life at the cellular level 1 Flashcards Preview

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Flashcards in Life at the cellular level 1 Deck (23):

what are the two types of stem cells?

1. multipotent stem cells: these can differentiate into many cell types
2. 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
- 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