Unit 3 - The Cell (part 2) Flashcards
plastids
- amyloplasts
- chromoplasts
- store starch in root
- store pigments for fruits and flowers
who invented microscopes?
Robert Hooke
Anton van Leeuwenhoek
centrioles
where spindle fibers/ microtubuoles origionate
- microtubules
- microfilaments
- thickest fibers, move chromosomes
- thinest fibers, move actin and moves the cell inwards in cell dvision
cell walls
- made of
- secondary cell wall
- holes
protect cell, maintain shape, prevent excessive uptake of water
- cellulose, microfibrils
- makes it extra strong
- has small holes so somethings can enter the cell
Intracellular junctions
- tight junctions
- desmosones
- gap junctions
Only in cells that are close together
- membranes fuse and form continuous flow of cytoplasm. helps stop leakage
- fasten cells together
- channels between adjacent cells so cytoplasm can move freely
sodium potasium pump
aka cotransporter
- moves sodium & potasium back and forth against their concentration gradients
- uses energy (ATP)
- 2 K enter cell and 3 Na are pushed out
Neurons
- charge
- potassium + sodium
- (+) outside, (-) inside
- sodium (Na) outside, potassium (K) inside
- many passive K+ channels, few sodium
Action potential
-process
an electrical signal used to communicate from neuron to neuron
- when voltage in terminal becomes (+) channels open up which allows calcium in. Calcium frees vesicles containing neurotransmitters. These bond with chemically gated sodium ion channels
- allows RUSH of sodium into cell
- makes cell more positive and when it reaches threshold voltage gated channels are also opened allowing even more sodium in
- at max potassium gates open and potassium floods and the cell tries to reach resting potential again
osmosis in cells
- animal
- plants
- hypertonic: shirveled
isotonic: normal
hypotonic: lysed - burst - hypertonic: shriveled
isotonic: flacid (bad)
hypo: normal (turgid)
cholesterol in membrane
- warm temps
- cold temps
- restrains movement & increases fluidity
- prevents tight packing, increases fluidity
Ion channels
- passive
- active
- voltage gates
- chemical gates
- control movement of ions across membrane. always open
- have gates that can open and close
- a certain charge will open them
- presence of a chemical will open them
depolarization
inside the cell becomes more positive
before action potential
repolarization
inside becomes negative again after action potential
where is action potential created
axon hillock
integral proteins
penetrate membrane
- hydrophobic where they contact phospholipids
- hydrophilic where they contact aqueous areas
what passes the membrane?
lipids, lipid soluble, O2, small molecules, nonpolar
what doesn’t pass the membrane?
ions, glucose, polar, hydrophillic
LABELED NEURON CARD
look at it rn
dendrites
receives signal
axon
sends signal
Schwann cells
- myelin sheets
- nodes
- one cell wrapped around an axon
- space between myelin sheets
facilitated diffusion
-protein used
moving impermeable things across the membrane through SPECIFIC proteins (passive transport)
-transport proteins
Diffusion
- concentration gradient
- passive transport
- tendency of molecules to spread into available space
- molecules move from areas of high concentration (of their own molecule) to areas of less concentration, regardless of other molecules
- requires no energy
peripheral proteins
not embedded in lipid bilayer
loosely bound to the surface of the protein
plasma membrane
- components
- sugar on outside
- movement of phospholipids
selectively permeable (some things can pass)
- lipids (phospholipids), proteins, carbohydrates
- helps cells recognize each other
- lateral, no flip-flopping
Osmosis
- hypertonic
- hypotonic
- isotonic
diffusion of water to areas of high [ ] of solute
- high [ ] solute
- low [ ] solute
- = [ ] solute
aquaporins
transport proteins of water for mass diffusion
signal recognition particle (SRP)
binds to signal peptide & attaches it and its ribosome to a receptor protein in the ER
Vacuoles
- food vacuole
- contractile vacuoles
- central vacuoles
membrane bound sacks
- from phagocytosis, fuses with lysosome
- pump excess water out of cell
- in plants, stockpiles proteins, inorganic ions etc.
lysosomes
-phagocytosis
sack of hydrolytic enzymes that digest proteins taken in the cell through endocytosis – including harmful ones
-when food into is brought into the cell in a membrane
smooth ER
creates lipids, helps in metabolization of glucose
rough ER
synthesizes proteins inside membranes
cytoskeleton
-uses
network of fibers that extend through cytoplasm
-support and maintain shape
endocytosis
cells take things IN
nucleus
- membrane
- chromatin
- double membrane, allows for pores so RNA can leave
- DNA and associated proteins before separation
ribosome
- components
- use
- free vs. bound
- large and small subunit (protein), rRNA
- to synthesize protein from mRNA
- in cytoplasm vs. in ER
prokaryotes
small, single celled, no nucleus
eukaryotes
multi celled, has nucleus
(transmission) electron microscope
object must be dead
3D perspective
light microscopes
visible light passes through the specimen
lens refracts light
views living things
can not see organelles
scanning electron microscope
study surface and structures
plasmodesmata
holes that allow cysotol to pass between plant cells
ECM/ extra cellular matrix
-made of
in animals, make area between cells strong
can attach to membrane of cells
-collagen fibers
zygote
fertilized egg
histone proteins
(+) amino acids bind to (-) DNA
dna wrapps over and over around them to get coiled
-chromatid
chromosome
2 sister chromatids held together by centromere
made of chromatin
Interphase
-cell grows
-copies DNA
-prepares for division
-G1: growth
-S: DNA copied
G2: preparation
order of phases
interphase prophase metaphase anaphase telophase cytokinesis
prophase
- chromosomes tightly coiled
- nuclei disappear
- mitotic spindle begins to form
prometaphase
- nuclear envelope fragments
- microtubules from spindle interact with chromosomes at kinetechores
metaphase
spindle fibers push chomosomes to METAPHASE PLATE - middle
anaphase
- centromeres divide, sisters separated
- pulled to poles of the cell
telophase
- cell elongates
- 2 nuclei start forming
- unpacking
human cells and chromosome #
- somatic cells
- gametes
- body cells - 46 chromosomes
- sperm and eggs - 23 chromosomes
S phase
DNA replication
aneuploidy
common in caner cells
- 3 chromatids instead of 2
how does the cell enter mitosis?
- chemicals in cell start it
- low [ ] before cell is ready and high [ ] as it starts mitosis
- called cyclin
- they activate kinase which is always present
- starts mitosis then cyclin is destroyed (making the MDF inactive)
cell division factors
- density (inhibition if surround by many cells)
- anchorage (cells only grow when anchored to extra cellular matrix)
- sometimes PDF (platelet derived growth factor) is necessary for __fibrolests__ to divide
reception - ligand
molecule which binds to receptor (specific)
-changes shape change in lower region of receptor (in cell)
signal transduction pathway
-amplification
series of steps by which a signal on a cells surface is converted into a cellular response
- 1 molecule can trigger an enzyme which makes many products which will trigger many enzymes and make even more products
phosphorylation
addition of a phosphate group
secondary mesengers
small, non-protein, water soluble molecules and ions that spread throughout the cell, participate in path ways
ex. cyclic AMP, Ca
G protein and cell reproduction
- shape change in G protein when ligand binds to receptor
- frees alpha subunit which moves laterally and makes adenylyl cyclase active
- with addition of ATP, cyclin AMP is made
- it binds with kinase…
transcription factor
final activated molecule in signaling pathway
scaffolding molecule
1 molecule which can release multiple kinases when altered by addition of secondary messengers
apoptosis
-caspases
programmed or controlled death of a cell
components of cell chopped and packages into vesicles that are digested by white blood cells
-enzymes that cut up proteins
termination of signal
when ligand [ ] goes down less receptors are bound and revert to inactive state
extrinsic apoptosis
signal sent to cell (ligand) telling it to die
intrinsic apoptosis
cell decides to die (cell stress or DNA damage)
