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Year 12 Biology > Topic 1 > Flashcards

Topic 1 Flashcards

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1
Q

Fluid Mosaic Model

A

fluid- fatty chins of the phospholipids are like thick oily liquid
mosaic-external surface (viewed from above) has mosaic appearance, various embedded proteins in uniform background

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2
Q

Function of plasma membrane

A
  • Selectively controls molecules entering and leaving the cell- diffusion, osmosis, facilitated diffusion, active transport, bulk transport
  • establishes compartments in cell, separates cell components
  • restricts movement of substances between one part of cell from another
  • have receptors involved in intercellular communication via nerves/hormones
  • involved in cell recognition and adhesion-can recognise and respond to self/non-self molecules
  • produce electrical activity
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3
Q

Phospholipid structure

A
  • hydrophilic head made of phosphate groups

- two hydrophobic tails consisting of fatty acid chains

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4
Q

what does phospholipid structure allow

A

flexible, soft. and self repairing-allows shape change

  • e.g RBC can squeeze through capillaries
  • nucleus can be pierced and then repair itself
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5
Q

why are phospholipids amphipathic

A

they contain a hydrophilic and hydrophobic portion

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6
Q

Transport proteins passive transport) function

A

allows some substances to move through membrane via facilitated diffusion

  • two different types carrier and channel proteins
  • these become saturated- has maximum rate of transportation
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7
Q

transport proteins

A

a gated protein channel, opens to transport a specific molecule, in response to contact with another molecule

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8
Q

transport proteins (active transport)

A

protein pump involved in active transport- requires ATP input
also referred to as carrier proteins

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9
Q

catalytic proteins

A

enzymes speed up rate of chemical reactions across the membrane

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10
Q

receptor proteins

A

hormones and other substances bind to them- affects cell activities
-different cell types have different receptor proteins e.g glycoproteins

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11
Q

recognition proteins

A

act as markers-antigens

  • enable immune system to recognise self from non self
    e. g glycoproteins
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12
Q

adhesion proteins

A

join cells together-multi-cellular organisms

occluding, communication and anchoring junctions

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13
Q

cytoskeleton proteins

A

anchor cytoskeleton to membrane

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14
Q

cholesterol function

A

regulates membrane consistency, firmness and stability
also maintains fluidity by separating fatty acid tails-to avoid crystallisation
-reduces some solutes permeability

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15
Q

glycolipids functions

A

play role in tissue recognition

glyco- meaning carbohydrate

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16
Q

glycoproteins functions

A

cell surface markers-antigens

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17
Q

Simple diffusion

A

net movement of a substance across the phospholipid bilayer from a region of high solute concentration to region of low solute concentration of that substance

  • passive process-energy not required
  • occurs along concentration gradient- must be concentration difference between two regions
  • gases, small uncharged/ hydrophobic molecules can diffuse
18
Q

osmosis

A

net movement of water from a region of low solute concentration to high solute concentration across a selectively permeable membrane

  • occurs down concentration gradient- energy not required
  • occurs between phospholipid molecules- occurs more slowly than specific protein channel movement
19
Q

dilute solution pressure

A

low osmotic pressure, more solvent, less solute

20
Q

concentrated solution pressure

A

high osmotic pressure, more solute, less solvent

21
Q

hypotonic solution movement

A

net movement of water into cell- due to higher solute concentration in cell compared to surrounding solution

22
Q

hypertonic solution movement

A

net movement of water out of cell- due to lower solute concentration in cell compared to surrounding solution

23
Q

isotonic solution movement

A

no net movement of water- equal solute concentrations in both cell and surrounding solution

24
Q

facilitated diffusion

A

transport proteins in plasma membrane assist diffusion of charged particles and larger molecules and hydrophilic molecules to diffuse across lipid bilayer

  • form water-filled connections across bilayer- allow specific water soluble molecules and ions through
  • occurs along concentration gradient, doesn’t require energy
25
Q

channel proteins

A

channels, which open and close to allow specific water soluble molecules and ions through

  • selective- only allow specific molecules through
  • open and close in response to certain signals e.g change in voltage or binding of another molecule
26
Q

carrier proteins

A

combine with molecule or ion and carry it across plasma membrane

  • once molecule has bound to protein- changes shape and releases its content
  • -selective- only allow specific molecules through
  • -open and close in response to certain signals e.g change in voltage or binding of another molecule
27
Q

active transport

A

movement of molecules or ions from a region of low concentration to region of high concentration

  • occurs against concentration gradient- requires energy in the form of ATP
  • involves carrier proteins for each substance
  • extremely important process- allows plants to uptake nutrients in low concentrations and excrete waste
28
Q

exocytosis

A

actively transported out of cell by moving in small vesicles

  • membrane of vesicles are filled with non permeable secretions
  • vesicles fuses with plasma membrane, releasing content outside cell
  • requires ATP
29
Q

Endocytosis

A

three types

  • pinocytosis
  • phagocytosis
  • receptor mediated cytosis
  • all require ATP( energy)
30
Q

phagocytosis

A

transports solids from outside to inside e.g bacteria, food particles

  • part of plasma membrane engulfs the solid-forms vesicles- moves into cytosol
  • vesicle fuses with another vesicle-containing digestive enzymes that digest contents
31
Q

pinocytosis

A

transport of liquid containing dissolved material into cell

  • -part of plasma membrane engulfs the solid-forms vesicles- moves into cytosol
  • vesicle fuses with another vesicle-containing digestive enzymes that digest contents
32
Q

receptor mediated endocytosis

A
  • process of internalizing molecules/viruses

- depends on interaction of molecule with specific receptor in cell membrane

33
Q

factors affecting diffusion rate

A 
size of particle
temperature
concentration difference
diffusion distance
surface area
permeability
34
Q

factors affecting active transport rate

A 
number/type of proteins(carrier)/pumps per unit area
surface area
ATP availability
temperature 
pH
35
Q

factors affecting membrane

A

pH
molecules that disrupt lipid bilayer
temperature

36
Q

what determines selectivity of membrane

A

phospholipid bilayer, number and type of protein channels, carrier proteins and protein pumps

37
Q

Ribosomes

A

smallest organelle

  • composed of rRNA and protein
  • not membrane bound
  • site of protein synthesis
  • stationary type: embedded on rough ER
  • mobile: inject proteins directly into cytoplasm
38
Q

Endoplasmic Reticulum (ER)

A
  • tubular network, fused to plasma membrane, forming channels of membrane
  • stores, separates and serves as cells transport system
  • smooth ER- lack ribosomes, make lipids-abundant in steroid hormone producing cells
  • rough ER- ribosomes embedded in surface-makes proteins and some proteins are modified here.
39
Q

golgi apparatus

A

proteins are modified

  • packaging of molecules in vesicles
  • composed of numerous layers to form sac
  • abundant in product exportation cells
40
Q

excretory vesicles

A
  • packaged into excretory vesicles
  • vesicles break free from Golgi
  • move to/merge with plasma membrane
  • proteins removed from cell by exocytosis
41
Q

protein synthesis steps

A

rRNA stored in nucleoli

  • passes out into cytoplasm- becomes part of ribosomes
  • mRNA is produced in nucleus-passes out into cytoplasm and binds to ribosomes
  • protein synthesis is initiated by binding of mRNA to ribosome
  • proteins are synthesised by either free ribosomes with tRNA carrying specific amino acids which usually function as enzymes within cytoplasm or are synthesised by ribosomes with TRNA carrying specific amino acids into position.
  • (no.2)proteins pass into cavity of ER then to golgi apparatus
  • protein is further modified and packaged for export in vesicle via exocytosis.

Year 12 Biology (16 decks)

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