Structure&function Of Eukaryotic Cell Membrane,intercellular Connections And Communications

Question 1

Prokaryotic

Answer 1

Without nucleus

Question 2

Eukaryotic

Answer 2

With nucleus

Question 3

Composition of cell membrane

Answer 3

Protein(55%)
Lipids(40%)
Carbohydrates(5%)

Question 4

Phospholipid
Head is..
Tail is..

Answer 4

Hydrophilic
Hydrophobic

Question 5

Head contains..

Answer 5

Glycerol&phosphate

Question 6

Tails are made up of

Answer 6

Fatty acid

Question 7

Lipoprotein functions as

Answer 7

Enzymes&ion channels

Question 8

Glycoprotein functions as..

Answer 8

Receptors for hormones&nuerotransmitters

Question 9

Integral proteins are..

Answer 9

Proteins that pass through entire thickness of cell membrane from on side to another. Tightly bound with cell membrane.

Question 10

Examples of integral proteins

Answer 10

-cell adhesion protien
-cell junction protein
- carrier protein
-channel protein
-Hormone receptors
-antigens

Question 11

Peripheral proteins..

Answer 11

Found peripheral to the lipid bilayer,both inside and outside it

Question 12

Types of peripheral protein and their function..

Answer 12

1. Intrinsic protein-located on the inner surface of lipid blayer and serves as enzymes,some are anchored to cytoskeleton on cell
2. Extrinsic (surface) protein. Protein located on the outer surface of lipid bilayer. Not associate tightly with cell membrane. Also serves as cell adhesion molecules(CAM) that anchor cells to neighbouring cells and basal lamina.

Question 13

Channel protien acts as..

Answer 13

Serve as channel for water-soluble substances lik glucose &electrolytes.

Question 14

Carrier protein..

Answer 14

Transport of substances across cell membrane by active&passive transport.

Question 15

Receptor protein ..

Answer 15

Binds nuerotransmitters&hormones

Question 16

Function of carbohydrates in cell membrane..

Answer 16

1. Carbo molecules negatively charged-do not permit negatively charged substances to move in and out of the cell.
2. Glycocalyx from nighbouring cells-tight fixation of cells with one another.
3. Receptor for some hormones

Question 17

Membrane carbohydrates play important role in..

Answer 17

Cel-cell recognition either a glycoprotein or glycolipids.

Question 18

Type of intercellular junctions..

Answer 18

-tight junction(zona occludens)
-desmosomes
-gap junctions(communicating )

Question 19

Tight junctions ..

Answer 19

Bind cells with strength
Impermeable junctions-leak proof

Question 20

Desmosomes..

Answer 20

Anchoring junctions
Prevent cells from being pulled apart

Question 21

Gap junctions..

Answer 21

-Allow molecules to pass from one cell to other. These space allow chemicals, ions to pass through thereby allowing cell to cell communication.
-connexons are tube between gap junctions.
-protein channels: connexin
-direct flow to neighbour:electrical,chemicals
-CAM:direct surface for contact, chemicals

Question 22

Location of junctions..

Answer 22

1. Gap junctions-cardiac&smooth muscle(electrical impulse can easily spread from one cell to the next)
2. Tight junctions- epithelia of intestine, renal epithelia of kidney, renal tubule,gall bladder

Question 23

Desmosomes occurs as..

Answer 23

Belt desmosomes,spot desmosomes,hemidesmosomes

Characterised by local thickening of adjacent cells membrane of two epithelial cells

Question 24

Hemidesmosomes..

Answer 24

-present at basal border of epithelial cells
- help to attach the epithelial cells firmly to underlying connective tissue.

Question 25

Intercellular communication refers to..

Answer 25

Communicsion between cells

Question 26

Cells that produces signaling molecules are

Answer 26

Signaling cells

Question 27

Cells that receive signals are..

Answer 27

Target cells

Question 28

Type of intercellular communication..(PENNA)

Answer 28

1. Paracrine 2.Endocrine 3. Neurotransmitter 4. Neuroendocrine 5. Autocrine

Question 29

-Local chemical messengers-exert effect on neighbouring cells at site of their secretion - do not enter blood-rapidly inactivated Examples: factor-beta,fibroplast growth factors

Answer 29

Paracrine

Question 30

- endocrine cells release hormones that act on a distant target cells in the body -example:thyroxine

Answer 30

Endocrine signalling

Question 31

Specifity determined by receptor potein

Answer 31

Hormones

Question 32

-Neuron secretes signal molecue called nuerotransmitter(NT) -NT acts on receptor on neighbouring cells

Answer 32

Neurocrine

Question 33

Neuron secretes signal molecule Cells receives neuronal input and as a consequence of this input,release message molecules to the blood. This brings about integration between nervous and endocrine systems.

Answer 33

Neuroendocrine signalling

Question 34

-hormones released into blood by neurosecretory neurons. -distributed through to distant target cells.

Answer 34

Neurohormone signalling

Question 35

Chemicals secreted by neurons that diffuse across a small gap to target cells.

Answer 35

Neurotransmitters

Question 36

Chemicals released by neurons into blood for action at distant targets. Examples:oxytocin,ADH

Answer 36

Neurohormones

Question 37

A cell secretes hormone or chemical messenger that binds to autocrine receptor on that same cell,leading to changes in the cell

Answer 37

Autocrine