Lecture 2 Flashcards
what controls cell function
genes (DNA) segment
how do you get a different version of a protein?
RNA transcribes from the same gene
catalyze reactions in the cell
enzymes
Transcription
DNA to RNA
Translation
RNA to protein
the genetic code consists of ____ bases as a “code word” which controls the sequence of _______ in a protein molecule
triplet
amino acids
DNA vs RNA purpose?
DNA contains genetic code
RNA used for protein synthesis
DNA vs RNA location it is found?
DNA found in chromosomes, mitochondria
RNA found in cytosol
DNA vs RNA Shape and structure?
DNA - double helix connected by H bonds
RNA - single helix that folds upon itself
DNA vs RNA bases?
*the nitrogen base
DNA :
Adenosine - Thymine*
Cytosine - Guanine
RNA :
Adenosine - Uracil*
Cytosine - Guanine
difference between thymine and uracil
uracil lacks one methyl group
four types of RNA?
ribosomal RNA (rRNA)
transfer RNA (tRNA)
messenger RNA (mRNA)
MicroRNA
Goal of transcription is to get DNA information to from ______ to _______
nucleus to cytosol
codon in DNA is transferred to one strand of RNA through transcription in the ______. By using ________ we then make _____ to diffuse through nucleous to cytoplasm
nucleus
RNA polymerase
mRNA
where does translation occur?
ribosomes
How does translation occur?
mRNA goes through ribosome and forms protein molecule
tRNA transports amino acids needed to build a protein
what is the manufacturing plant?
ribosomes
what happens to newly forms proteins?
some have amino acids on ends that immediately attach to receptors on ER
some go directly to cytosol
proteins that give shape and structure to cell or organelles?
example
structural proteins
proteins that catalyse biological readctions
enzymes
proteins that bind to other molecules and transmit signal
receptor proteins
proteins that have specific functions
functional proteins
what allows cells to respond to environment and differentiate. Cardiac and renal tubule cell contain same genes… how do they differentiate?
genetic regulation
they are expressed differently
how are enzymes regulated
intracellular chemicals act as inhibitors and activators
- enzyme inhibition
- negative feedback
- enzyme activation
what determines growth characteristics and reproduction of cell
DNA
what cells do not reproduce
neurons
all cells develop from the ______.
fertilized ovum
How does differentiation of a cell occur
pluripotent stem cell (non-specific) undergoes mitosis to turn into a specialized cell
the more differentiated a cell becomes the less it can ______.
proliferate (rapidly reproduce)
major stages of mitosis
- prophase
- metaphase
- anaphase
- telophase
what is programmed cell death called and what happens
apoptosis
mediated by proteins called caspases (callapses cell and doesn’t damage surroundings)
what is cell death called that results from acute injury? and what happens
necrosis
contents spill into surrounding tissue causing local inflammation
adjacent cell injury
cell communication through gap junctions
directly from cell to cell
cell communicattion through synaptic
across synaptic cleft
cell communication through paracrine and autocrine
by diffusion in interstitual fluid
cell communication through endocrine
by circulating body fluids
how deos the cell membrane regulate the entry and exit of materials
selectivity filter
through the cell membrane’s _________ it interacts with external signal to transmit the signals into an internal message
communication system
Composition of the cell membrane
42% lipids (phospholipids)
55% proteins
3% carbohydrates (external side of membrane)
what make up a phospholipid?
glycerol, fatty acid, cholesterol
phosphate end in hydrophilic
fatty acid end is hydrophobic
what is the charged carbohydrate coat on the outer cell?
glycocalyx
the glycocalyx is ______ charged.
what is their role?
negatively
repell other neg charged substances
attatch cells to each other
acts as receptor, attaches to insulin
component of immune response
cell membrane proteins that attatch loosley to the lipid surface on either side
peripheral
cell membrane proteins that span the entire cell membrane
integral
what do peripheral proteins used for
cell adhesion molecules
enzymes
controllers for substances thru membrane
cell skeleton
surface markers
antigens
surface glycoproteins are _________.
cellular adhesion molecules (CAM) and complexes
what is the purpose of cellular adhesion molecules (CAM)
- hold cell/tissue together
- regulate shape, growth, differentiation
- help cell respond to environment
- cell cell adhesion molecules (inflammation, wound healing, embryo development)
what happens when cell cell adhesion molecules are not there
metastatic tumor cells
four groups of cell adhesion receptors
cadherins
selections
igG
integrins
receptors that facilitate movement of neutrophils through the endothelial wall.
cadherin receptors
receptors that capture neutrophils move them along endothelium, platelet adherence
selectins
receptors that are members of the immunoglobulin superfamily and secure adhesion of neutrophils with the endothelium
igG
receptor that has role in inflammation, migration of leukocytes
integrins
what does mutation in cadherins do
promote malignent cells to invade tissue and metastasize
role of integral membrane proteins
receptors
communicate between inside and outside of cell
transporters (carrier proteins)
enzymes
over _____ of receptors for integral proteins
20 families
communication processes driven by chemical messengers to mediate cell growth, differentiation, and survival
signal transduction
how does signal transduction pass signal from cell to cell
secretory cell and receptor on surface of target cell work together
steps of signal transduction
reception - signal molecule activates a specific recpor on the target cell
transduction - second messenger transmits signal into cell
response - cell changes shape movement gene expression, etc.
what is the cell membrane inpermeable to?
large molecules such as proteins and nucleic acids
what is the cell membrane selectively permeable to?
small molecules such as ions and metabolites
what molecules move freely across cell membrane
highly lipid soluble
- CO2
- ammonia
- oxygen
- nitrogen
- alcoohol
what type of molecule rely on transport, channel, and carrier proteins to cross cell membrane?
water, urea
(aquaporins move water)
type of membrane transport
bulk transport (endo/exocytosis)
diffusion
active transport
what is ingestion of the cell of large substances by invagination of the cell membrane fusing to form a clathrin (protein) coated vesicle
endocytosis
types of endocytosis
phagocytosis
pinocytosis
phagocytosis
cell eating
large particles (bacteria)
only certain cells can do this (WBC)
pinocytosis
cell drinking
take in macromolecules (proteins) and extracellular fluid
what is exocytosis?
How does it occur?
cell discharges material
- vesicle moves to cell surface
- membrane fuses
- material is expelled
types of diffusion
simple diffusion
facilitated diffusion
how does simple diffusion occur?
occurs by kinetic movement of cells
-directly through membrane
-or through large transport protein
how does facilitated diffusion occur?
requires a carrier protein that binds to the molecule and carries it in (chaperone)
what are types of membrane channels
ion channels
gated chanels
what are the types of gated channels?
voltage gated
ligand gated
what is the voltage gated channel ?
effected by change in membrane potential
Na+, K+, Ca++
- important in nervous system
what is a ligand gated channel?
intra/extra cellular binding of a regulatory molecule that allows channel to open
- hormones
what are channelopathies?
complications associated with mutations of ion channel proteins
- cystic fibrosis
what happens with cystic fibrosis compared to normal?
Treatment?
CFTR gene mutation affects channels responsible for Cl transport
normal chloride transport thru CFTR protein channel maintains salt, fluis, and pH homeostasis
Treatment varies depending on affected channel
what is Vmax?
and conformational change limits the rate of diffusion
In facilitated diffusion, solute cannot exceed the carrier proteins capabilities.
you reach a steady point of rate of diffusion.
how is active transport done
concentration in extracellular fluid is lower than inside the cell
creates concentration gradient that will require energy for nutrient transport
types of active transport
primary
secondary
primary active transport uses energy from ?
from the breakdown of ATP or other high energy compounds
Secondary active tranport uses energy from ?
use energy created by primary active transport that has been stored
examples of primary active transport
- sodium potassium pump
- Calcium pump
- H+ K+ pump
sodium potassium poump is the basis of our _____. HOW?
nerve function
establishes a negative electrical voltage inside the cells to transmit signals
in the sodium potassium pump what goes in/out?
3 Na+ ions OUT of cell
2 K+ ions INTO cell
how does sodium potassium pump control cell volume?
Na+ leaves cell and wayer follows bc fluid follows the solute.
what does the calcium ATPase pump do
remove Ca++ from cell
what does H+ K+ ATPase pump do?
controls acid base balance in the stomach and distal tubules kidneys
explain generally how secondary active transport works?
one solute moves along the electrochemical gradient
another substance moves against the electrochemicalgradient using the stored energy from primary transport
Types of transporters in secondary transports
co transporters (symporters)
counter transporters (antiporters)
what is a co-transporter/ symporter?
carries two different substances in the same direction through the membrane
EX:
- glucose transport in intestines and kidneys
- amino acids, Cl, iron, iodine
what are counter-transporters/antiporters?
moves two or more different molecules or ions across the membrane in opposite directions
EX:
- Na+, Ca++
- 3 Na out or in and 1 Ca in opposite direction
