Cells Flashcards
cell
basic structural and functional unit of life
where do all cells come from?
from other cells
starts by single cell and divides many times
where do tissues and organs come from?
cells
differentiated by characteristics and proteins specific for bodily functions
biochemical activities of cells are dictated by their ___
structure and composition
bodily fluids
nutritious soups that bathe our cells
types of bodily fluids?
interstitial fluid -bathe organs
cerebrospinal fluid- in spinal cord and brain
plasma- blood vessels
cellular secretions
gastric fluids for digestion
saliva/mucous for lubrication
extracellular matrix
proteins and sugars secreted by cells that organize into jelly mesh
support tissue and function
plasma membrane
separates intracellular fluid from extracellular fluid
four components of plasma membrane?
- phospholipid bilayer- semipermeable barrier (hydrophobic tails, hydrophilic heads)
- proteins- transport and signaling
- cholesterol- membrane fluidity
- carbohydrates- identification and signaling
fluid mosaic model
fluid- movement and change
mosaic- many parts working together
how do phospholipids orient themselves in aqueous solutions?
polar heads face interior and exterior of the cell wall with the tails forming the center of the membrane
function of the plasma membrane?
- mechanical barrier
- selective permeability
- electrochemical gradient
- communication
- cell recognition
functions of membrane proteins?
- transport
- receptors
- attachment to extracellular matrix
- enzymes
- cell-cell adhesion
- cell-cell recognition
what do cell adhesion molecules do?
allow cells to anchor, migrate, attract other cells, mechanically sense tension, transmit intracellular signals
3 types of cell physical connections
- tight junction
- desmosome
- gap junction
tight junction
sealing junction encircling a cell separates one fluid filled area from another
where are tight junctions found in the body?
blood brain barrier
blood testis barrier
skin
digestive tract linings
desmosome
anchoring junctions along the sides of cells
where are desmosomes found in the body?
high stress zones (lots of mechanical pressure)
heart muscle
skin
gap junction
communication junctions allows chemicals to pass between cells
connects cytoplasm, no need to go through extracellular and attach to protein to start cascade
where are gap junctions found in the body?
electrically excitable tissue
heart
smooth muscle tissue
what type of physical connection would be found between runner’s heal skin cells?
desmosomes (high stress area)
tight junctions (some present for barrier)
cell signaling
ligands bind to receptors to stimulate chemical signaling
via neurotransmitters and hormones
receptors can act ____ or ____ to respond to the signal
directly or indirectly
how do secondary messengers amplify signals?
activate other enzymes or ion channels
form cascade of reactions
epinephrine
fight or flight response hormone
which tissue would least likely be the target of epinephrine? muscle, intestine, arteries and veins, or pupil?
intestine- stops when in fight or flight
(muscles to move, arteries to pump more blood to brain and muscle, pupil to better focus)
passive transport
movement from high to low concentration
moving toward equilibrium
types of passive transports?
diffusion
osmosis
filtration
active transport
movement from low to high concentration against their concentration gradient
requires energy through ATP
requires carrier proteins
moves cells away from equilibrium
example of active transport?
pumps
simple diffusion
transport of small or nonpolar molecules (O2/CO2)
move directly through lipid bilayer
facilitated diffusion
transport of large or polar molecules (glucose, water, amino acids, and ions)
transported through integral proteins embedded in membrane (carriers and channels)
osmosis
diffusion of water across semi permeable membrane
water moves from area with low solute concentration into areas of high solute concentration
due to equilibrium
isotonic
normal
solution has same solute concentration as cytosol
hypertonic
crenated
solution has greater solute concentration than cytosol
water moves out
hypotonic
lysed
solution has lower solute concentration that cytosol
water moves in
what type of solution is given IV to patient who is dehydrated?
hypotonic
has less solute concentration so water moves into cells to rehydrate
what type of solution is given for patient with edema?
hypertonic
high solute concentration outside cell draws water out of cells
primary active transport
uses ATP to transport solutes across the membrane against their concentration gradient
secondary active transport
protein couples the movement of an ion down its gradient to another molecule against its gradient
sodium potassium pump
creates an electrochemical gradient across membrane
cell uses the movement of Na or K to move other molecules
Sodium out, Potassium in
vesicular transport
vesicles transport large particles and large volumes
exocytosis
moves substances out of cell
endocytosis
move substances into cell
phagocytosis
cellular eating
type of endocytosis
engulfs large particles with pseudopodia
white blood cells
pinocytosis
cellular drinking
type of endocytosis
brings extracellular fluid and solutes into cell
routine sampling
receptor-mediated endocytosis
specific
membrane receptors bind specific molecules
LDL cholesterol receptors and insulin
nucleus
control center
nuclear envelope
double membrane with large pores to control transport
nucleolus
where ribosomes are made
leave and attach to ER
chromatin
DNA would around histone proteins
genetic library
what type of chromatin is used if a gene needs to be expressed?
euchromatin- loosely wound, able to get proteins to bind to gene
DNA
includes genes which have instructions to make proteins
RNA
single stranded copy of DNA that can move to cytoplasm
mRNA
messenger RNA
carries instructions for protein
tRNA
transfer RNA, with help of rRNA, translation at the ribosome
genetic law
DNA – transcription –> preRNA – RNA processing –> mRNA —translation –> polypeptide
ribosomes
made of proteins and rRNAs
site of protein synthesis- translation
endoplasmic reticulum
rough and smooth
continuous with nuclear membrane
function- proteins are folded and modified in rough ER
golgi apparatus
flattened membranous sacs with lots of vesicles (received from ER)
functions in modification, concentration, and packaging of proteins
glycosylation
carbohydrate chain added to protein in golgi
how are vesicles transported across golgi?
vesicles from ER fuse with cis face
proteins exported from trans face in secretory vesicles
what are the three fates of proteins leaving golgi?
proteins for secretion by exocytosis
proteins destined for membranes to fuse with and incorporated into
digestive enzymes that eventually fuse with or become lysosomes
smooth ER function is tissue specific
liver- lipid breakdown and cholesterol metabolism, break down glycogen, detoxifies drugs and poisons
testes- synthesis of steroid based hormones
muscle- stores Ca2+ for contractions
intestine- absorption and synthesis of fats
mitochondria
provides most of cell’s ATP
evolved from prokaryotes- double membrane, contain own DNA, can self replicate
peroxisomes
detoxify cells, neutralize free radicals and hydrogen peroxide (byproducts of anaerobic respiration)
contain powerful enzymes like oxidases and catalases
glutathione GSH
most abundant intracellular antioxidant
primarily in liver but can be made in most cells
removes hydrogen peroxide
difference between lysosomes and peroxisomes?
lysosome- digest worn out organelles
peroxisome- digest dangerous materials/byproducts
lysosomes
small organelles containing digestive enzymes
4 functions of lysosome?
- protection- breaking down bacteria, viruses, and toxins
- recycling- nonfunctional organelles
- digestion- breaking down glycogen and lipids
- nutrition- releases Ca2+ from bone (materials the body needs)
lysosomal storage diseases
Tay Sachs- unable to digest lipids
Pompe- unable to digest glycogen
autophagy
“self cleaning”
excess organelles or cytoplasm are digested by lysosomes
proteasomes
destroy misfolded or unneeded proteins
in ER to protect from bad proteins
apoptosis
programmed cell death
mitochondria break apart, caspase enzymes are released, cell advertises itself to macrophages
cytoskeleton
skeleton of cell
dynamic- changes as cell’s needs change
three types of cytoskeleton units?
microfilaments - resist compressions, used for cell movement and shape
intermediate filaments - resist pulling forces, support cells
microtubules- cell division, intracellular transport
microvilli
supported by actin microfilaments greatly increase surface area of digestive cells to absorb nutrients
cilia
whip like extensions on surface of cells
ex: in respiratory cells to clear debris from airway
smoking effects on cilia?
excess mucous produced
become paralyzed and eventually destroyed
risk of lung infections
cell division
mitosis- nuclear division
cytokinesis- cytoplasmic division
essential for growth and tissue repair
3 aspects of making new healthy cells?
replication of DNA is tightly regulated
well organized structures and process for dividing up DNA
checkpoints to control division
cell cycle
interphase- G1, S, and G2
mitotic phase - mitosis and cytokinesis (prophase, metaphase, anaphase, and telophase)
DNA polymerase
makes new DNA using existing strands using nucleotide base pairing
how is cytoskeleton in action in mitosis?
spindle complex made up of microtubules and centrioles in metaphase
actin microfilaments constrict cells in cytokinesis
factors that influence control cell division
surface to volume ratio (bigger cells don’t need to divide)
growth factors and hormones
nutrients
contact inhibition
require place to adhere
limited number of divisions
checkpoints
how is contact inhibition important for cell division control?
the cell wont divide if inhibited by other cells in space
how is limited number of divisions important for cell division control?
telomeres get shortened each division
the cell will lose genetic material if telomeres are gone
what proteins are involved in checkpoints?
cyclins and cyclin dependent kinases
cancer
uncontrolled, increased cell division
frequent errors in DNA replication
factors of cancer cells
- reproduce in defiance of normal restrictions/limits
- cells do not obey checkpoints in cycle
- tumor suppressors and proto-oncogenes are often mutated
how are cancer cells genetically unstable?
unable to repair DNA damage
fail to maintain integrity of chromosomes but continue to divide
what type of chromatin do cancer cells have more of?
heterochromatin (tightly wound)
silenced tumor suppressor genes so cell cant control cycle
characteristics of cancer cells?
uncontrolled growth
lost contact inhibition
invasive
dedifferentiated
metastatic
migrate and move away from anchored site
colonize to new area of body
dedifferentiated
cancer cell does not look like original cell, more like a stem cell
carcinomas
epithelial cancers
80% of human cancers
oral, digestive, respiratory, breast, reproductive, urinary
sarcomas
connective tissue / muscle cancers
leukemia/lymphomas
white blood cell cancers
immune system cells
neuroblastoma
nerve cancer
mutation
cancer begins with single event passed to all daughter cells
primary tumor
detectable tumors that contain billions of cells
cancer cells in one area
does cancer show up immediately after carcinogen exposure?
no
how do different individuals have variations in cancer progression?
each cancer is an accumulation of mutations from different cells
treatment is different for different series of mutations
metastases
secondary tumors
what is the difference between benign tumor and malignant tumor?
malignant tumor has broken basal lamina layer and starts to travel
benign tumors havent broken tissue layer
metastsis
responsible for 90% of cancer deaths
1. cell breaks free of normal constraints
2. uses blood or lymph vessels to travel
3. establishes colony in distant organ
how does cancer become metastatic?
over-expression of migration factors- turn on genes to rearrange cytoskeleton to travel or genes to degrade extracellular matrix
loss of adhesion molecules- down-regulate adhesion genes
angiogenesis
formation of new blood vessels
supply tumor with blood to grow more
tumor microenvironment
cancer cells talk to surrounding cells and connective tissues to do things for cancer cell
ex: remodel extracellular matrix, cell to cell signaling
causes of mutations?
carcinogens
radiation
viruses
mistakes in DNA replication
carcinogens
chemicals that mutate DNA
radiation
UV, Xrays, and gamma rays
how does environment influence cancer?
individuals who migrate to new country show same cancer rate as those already living there
due to diet and lifestyle
how do viruses cause cancer?
15%
virus insert genome into host cells DNA and cause mutations
commandeer cellular machinery to break restraints on DNA replication
proto-oncogenes
a gene that normally promotes cell cycle
cancer- inappropriately activated, cells divide all the time
tumor suppressors
a gene that normally inhibits cell cycle
cancer- inappropriately inactivated, cell has no checkpoints
p53
tumor suppressor gene that controls cell cycle and apoptosis
levels rise if cell is stressed
turns on inhibitors of cell cycle or apoptotic genes
many cancers block p53 and allows for cell proliferation
cancer treatments
surgery to remove tumors
drugs - treat simultaneously to avoid drug resistance
chemotherapy
radiation therapy
cancer drug actions
re-differentiated cells- turn into normal adult cell and less like stem cell
induced cell death
inhibit new blood vessels- no angiogenesis
boost immune system- to recognize and destroy cancer cells
how do acquired mutations give cancer cells selective advantages?
no growth restrictions
pump drugs out
avoid immune detection
