Theme 1 Cell Structure Flashcards
endoplasmic reticulum
organelle in which proteins and lipids are synthesized
golgi apparatus
modifies proteins and lipids produced by ER
- sorts them to their different destinations
lysosomes
contain enzymes that break down macromolecules
peroxisomes
contain diff enzymes involved in metabolic reactions
mitochondria
produce most of the ATP needed to power the cell
cytoskeleton
a network of protein filaments that provide the cell w an internal structural framework
cell wall
present in plant cells only
rigid barrier composed of polysaccharides
chloroplasts
give plant cells photosynthetic abilities
plasmodesmata
connect neighbouring plant cells
vacuoles
organelles in plant cells that create structural rigidity by maintaining turgor pressure against cell walls
cytosol
the jelly like internal env’t of the cell that surrounds the organelles inside the plasma membrane
nucleoid
region in prokaryotic cell that contains DNA
plasmids
circular molecules of DNA in prokaryotes that carry a few genes each
major diff b/w prokaryotes and eukaryotes
prokaryotes:
- no nucleus, smaller in size, no membrane bound organelles
eukaryotes:
- nucleus present allows for transciption and translation to occur in separate regions of the cell and allows for regulation of gene expression
- have membrane bound organelles
the diff b/w electron microscopy and fluorescence microscopy
electron: we can understand different types of structures to learn about the different functions of the cell
fluorescence: we can look at overall features such as composition of diff parts where different colours represent certain substances
about how many bacteria cells does the human microbiome contain?
how many adult human cells?
about 100 trillion bac
10 trillion human cells
our microbiome is __?
dynamic bc it changed throughout life
what is diff b/w babies born vaginally than by c-section?
exposed to different microbes and so they have different gut microbes
why are cell phones so gross bacterially?
we touch them all the time w hands, face, ect, and they generate heat which allows bacteria to grow and reproduce
why fecal transplants?
pseudomembranous colitis: inflammation of colon caused by bacteria in colon and is antibiotic resistant
- adds normal gut microbes and eliminates C. dificile infection restoring normal intestinal flora
other implications for fecal transplants?
- type 2 diabetes treatment
- weight loss (skinny mice fecal transplant to fat mice)
4 classes of macromolecules are:
proteins
polysaccharides
phospholipids
nucleic acids
what is a cell?
a membrane bound structure containing macromolecules
phospholipid
a glycerol molecule linked to a phosphate and 2 fatty acids
aka fatty acid tails
are amphipathic: hydrophilic phosphate group head and hydrophobic FA tails
amphipathic
having hydrophobic and hydrophilic parts
how many carbons are typically found in a FA chain?
16 or 18
what is the difference between saturated and unsaturated bonds?
saturated: each available carbon has hydrogen bonded to it, making FA chain straight
unsaturated: contains double bonds b/w carbon atoms in FA chain, leaving it kinked
steroid molecules
ie cholesterol
- 4 hydrocarbon ring structure
what does it mean to be polar or non polar in terms of interacting w water?
polar molecules are hydrophilic meaning they can interact with water
non polar molecules are hydrophobic
micelles
lipids w bulky heads and single hydrophobic FA tails are arranged in to ball like spherical structures
- important for nutrient absorption
lipid bilayer
lipids w less bulky heads are arranged in 2 layers where heads are on outside and hydrophobic tails are on inside
- this is how the cell membrane is arranged
- explains how cell membrane is self healing
liposomes
enclosed bilayer structure that forms spontaneously when phospholipids are thrown into env’ts w neutral pH like water
can trap macromolecules in the middle
membrane fluidity
the ability of the phospholipids to move laterally within the cell membrane
NOTE: phospholipids can’t easily flip from upper to lower layers in a bilayer without using too much energy
factors affecting fluidity of cell membranes
- unsaturated or saturated FAs: double bonds produce kinks that increase fluidity
- number of carbons in the FA tails (shorter tails = more fluid)
- temp (higher temp = more fluid)
- amt of cholesterol present (less is more fluid)
cholesterol and its influence on the fluidity of the cell membrane
it makes up 30% of membrane lipids
- at low temp, it prevents phospholipids from packing too tightly thus increasing fluidity
- ie prevents dramatic changes in membrane from fluid to solid state
lipid rafts
less fluid regions of the lipid membrane: not always uniform
- can gather proteins in these areas too
- less fluid bc of longer and saturated FA tails packing together and also making taller; also higher conc of cholesterol here
how is fluidity related to permeability of the cell membrane?
less fluid membrane results in lower permeability
more fluid membrane results in higher permeability
selectively permeable nature of cell membranes
cell membranes can control the movement of substances into and out of the cell:
- sm hydrophobic molecules and ions move w conc. gradient
- large polar molecules can’t move through
transmembrane
are embedded in the cell membrane and allow hydrophilic molecules to move across
has hydrophobic middle region and hydrophilic ends allowing it to interact w cell membrane and its env’t
integral membrane proteins
permanently assoc w cell membranes, can’t be removed w/o destroying the cell
- most are transmembrane proteins
peripheral membrane proteins
temporarily assoc w cell membrane through weak bonds, etc. they can be removed easily
- can associate on internal or external side of the membrane
passive diffusion
when a molecule moves along its concentration gradient, crosses phospholipid bilayer
- does NOT use energy
ex. small molecules, water
passive transport/ facilitated diffusion
movement along a conc. grad. , requires proteins molecules that assist in transmembrane movement of the solutes
- NO energy required
ex. ions, most hydrophilic molecules
active transport
movement AGAINST a concentration gradient, fuelled by hydrolysis of ATP
osmosis
the passive transport of water across membranes
- water diffuses from less concentrated solutions to more concentrated solution
aquaporins
protein channels that only transport water through osmosis
dependent upon conc grad., NO use of energy
isotonic
extracellular fluid concentration is the same as it is inside the cell
- no net movement of water
hypotonic
extracellular fluid has a lower concentration than inside the cell
- net movement of water inside cell, can cause swelling and bursting of cell
hypertonic
extracellular fluid has higher solute concentration than inside cell
- net loss of water in cell to exterior env’t
primary active transport
dependent on the direct expenditure of ATP
secondary active transport
indirect expenditure of ATP where neighbouring transport proteins follow action of pump
Na+/K+ pump
pumps 3 Na+ out and 2 K+ in
