Topic E Flashcards
diffusion
net movement of molecules from regions of high to low concentrations
example of a membrane transport protein
glucose transporter (GLUT)
proteins move molecules across a membrane
membrane transport proteins
proteins that deliver cargo to target organelles
receptor proteins
example of a receptor protein
M6P receptors that deliver lysosome proteins
protein assembly
formation of large protein complexes using pushing or bending forces
example of protein assembly (bending force)
assembly of clathrin proteins during RME shapes membrane
example of protein assembly (pushing force)
growing microtubules push against plasma membrane
protein disassembly
disassembly of large protein complexes using a pulling force
example of protein disassembly
shrinking microtubules during anaphase move chromosomes (lec 37)
what type of organisms uses water pressure?
plants
what direction of movement do single motor proteins move in?
forward movement
kinesins are __ directed, ___ associated motor proteins
plus end… microtubule
dyneins are __ directed, ___ associated motor proteins
minus end… microtubule
myosins are __ directed, ___ associated motor proteins
plus end … actin filament
motor proteins that can be attached at their tails (double headed) + cytoskeleton proteins
motor protein bundles
examples of motor protein bundles
myosin (double headed protein) and actin filaments
(cytoskeleton protein)
ex. F-Actins + myosins do cytokinesis of animal cells (lec 38)
another ex. bundles of MTs and kinesins elongate animal cells during anaphase (lec 35)
net movement of water molecules
osmosis
cell movement in plants when there is rapid changes in water pressure
use ion channels (gated), if opened, water will follow the ions
example of rapid change in water pressure
Venus Flytrap (catching prey)
- insect touches hairs
- action potential
- gated ion channels open
- Ca 2+ enters outer cells
- water enters outer cells
example of cell movement in plants when there is gradual changes in water pressure
Squirting Cucumber (dispersing seeds) 1. decomposition of fruit interior (fruit reaches 27 atm) 2. weakening of attachment point (seeds travel up to 6 m)
during cell decomposition water will?
enter
functions of plant colour
- photosynthesis
- pollen/seed dispersal
- protection
- mutant appearance preferred by people
small organic molecules that absorb certain wavelengths of light
plant pigments
pigments use ____ mixing
subtractive
green plant pigment
chlorophyll
- in chloroplasts
- photosynthesis
orange/red plant pigment
carotenoids
- some in chloroplasts (photosynthesis)
- chromoplasts (colour)
red/purple/blue/ plant pigment
anthocyanins
- central vacuole
function of pigments
- colour
- UV protection (UV makes reactive oxygen species)
purpose of leaves
photosynthesis and gas exchange
structures of leaves
- broad leaves
- needles
- conifer (needles and cones)
- deciduous (sheds leaves in autumn)
what colour are plants with defective chloroplasts?
green with some white (ex. tapioca plant)
what colour are plants with no chloroplasts?
entirely white (ghost plants that feed on other plants)
are venus flytraps photoautotrophs or chemoheterotrophs?
photoautotrophs because they eat insects for nitrogen
reason for color change of green to orange/yellow
removal of chlorophylls (contain valuable nitrogen, needs to be salvaged), revealing carotenoids (don’t have nitrogen)
reason for color change of green to red
synthesis of new anthocyanins during chlorophyll removal
purpose of flowers
pollen dispersal using birds, bats and insects
do male or female flowers produce the same or different amounts of nectar?
female flowers produce more since male flowers contain the pollen (need to have animals go to both flowers)
structures of flowers
- single flowers ex. petunias
- flower clusters (inflorescences) ex. asters
- flowers + leaves ex. pointsettias
how do flowers attract animals?
- colour for birds and bees
- scent for beetles, nocturnal animals
how do flowers change colour?
- central vacuoles are acidic because of ATP powered proton pumps
- petal cells expand when water enters central vacuole
- central vacuole contains some pH sensitive pigments
NHXI is a H+ powered K+ ___ transporter that moves K+ ions ___ the central vacuole
antiport… into
purpose of fruits
seed dispersal using hungry animals
colours of fruit
immature fruit is green to synthesize sugars, mature fruit is red/orange/yellow/purple to attract animals (chloroplasts change into chromoplasts)
purpose of roots
anchor plant in ground, obtain water/minerals and storage. Usually unpigmented
mutant strains of potatoes and carrots make? (2 pigments)
carotenoids and anthocyanins
the mechanisms of cell crawling are due to?
actin and actin-binding proteins
2 examples of cells that use cell crawling and phagocytosis
amoeba and neutrophils (WBCs) both eat bacteria for food (WBCs also use bacteria for defence)
young neurons use cell crawling to ___ their axons to contact a target cell
extend
steps of cell crawling
- detection
- extension
- retraction
in the detection stage, diffusible molecules are used by what cells?
amoeba and WBCs
what type of projections are seen in amoebas and neurons during the extension stage?
large projections on amoebas and small projections on neuron growth cones
what mechanism is used for the extension stage?
protein assembly (pushing force)
what is dismantled in the retraction stage?
F-actin (back to G-actin)
what is used to contract the back of the cell?
contraction bundles
what speeds up to process of G-actin -> F-actin
activated profilins
what happens to unsuccessful amoebas, neutrophils and neurons?
amoeba and neutrophils go hungry, neurons are killed
3 types of human muscle cells
cardiac, skeletal, smooth
contents of a muscle cell/fibre
nuclei, myofibrils, sarcomere (actin + myosin), ER (store calcium, mitochondria, glycogen + lipids (fuel)
long cells are formed by
cell fusion (muscle cells) or cell growth (neurons)
what fuses to make muscle cells (myocytes)?
myoblasts
sarcomere structure
Z discs attached at each end, actin filaments attached to Z disc by their plus ends, myosins between each pair of Z discs, titins connect the thick filaments (~300 myosins) to the Z discs, tropomyosins conceal the myosin binding sites on actin filaments, troponin complexes regulate tropomyosin
these myosins are ___-headed, _____-end directed, actin associated motor proteins
double…. plus
contraction steps
- resting muscle cell
tropomyosins in the way - the thin filament is activated
[Ca2+] increases, troponins activated, tropomyosins moved - thick filament activated
myosins take turns walking along actin filaments (5 steps per second) - sarcomere contracts
myosins pull Z discs together (3 μm to 2 μm long) - the whole cell contracts
reason why muscle cells have stripes
as sarcomeres contract which bands shrink?
light bands
