Chapter 3 Flashcards
What is in the cytoplasm?
-cytosol
-organelles
-cytoskeleton
What is another name for ECF?
Interstitial fluid
What are the concentrations inside and outside of the cell?
-Potassium (K+) high in concentration inside of the cell
-Sodium (Na+) low in concentration outside of cell
How are the phospholipids in the plasma membrane oriented?
-head is polar
-tail is nonpolar
-tails point toward one another
What is on the outer part of the plasma membrane?
Peripheral proteins
What can’t get through the plasma membrane?
charged particles
What are the hexagons associated with the plasma membrane?
-Sugar
-Identifier
-Might be bound to proteins/phospholipids
What are glycoproteins?
-Protein with carbohydrate attached
Where is cholesterol in the plasma membrane and what is its purpose?
-Embedded in plasma membrane
-Makes membrane more flexible
-Necessary for healthy cells because of flexibility/fluidity.
What is a membrane protein channel’s structure/function?
Tunnel through plasma membrane
What is a membrane protein carrier’s structure/function?
-Opens things up
-More intentional
-Binds and transports substances in or out of the cell
What is a membrane protein receptor’s structure/function?
-outside of cell
-Molecule binds onto them
-triggers change in membrane protein or cell
What is a membrane protein enzyme’s structure/function?
-Will always be a protein
-Catalyzes chemical reactions inside cell
What is a membrane protein structural support’s structure/function?
-Membrane proteins bind other proteins in the ECF and/or the cytosol, supporting cell
What is a membrane protein linking adjacent cell’s structure/function?
-Link adjacent cells in a tissue together
-like velcro
How is diffusion characterized?
-will always be passive
-needs concentration gradient
-SOLUTE will move until equilibrium is reached
What is simple diffusion?
-Type of diffusion that does not need protein to go through plasma membrane
-nonpolar; can move through membrane easily
-Hydrophilic (steroid hormones, oxygen, CO2)
What is facilitated diffusion?
-Connects ICF to ECF
-Needs channel to go through (Na+ and K+ for example)
-Polar
What happens with facilitated diffusion of polar and ionic compounds?
Molecule binds to carrier and carrier changes shape and opens carrier to inside of cell
What is osmosis?
-WATER moves from an area of lower solute concentration to an area of higher solute concentration area until equilibrium is reached
-requires semi-permeable membrane
-passive
What is tonicity?
The sum of all dissolved substances (a way to compare osmotic pressure gradients between 2 solutions)
What does isotonic mean?
-both fluids have approximately the same concentration
-no net movement of water
-no volume changes
What does hypertonic mean?
-higher solute concentration outside cell
-water leaves cell
-cell shrivels
-crenation (shrunken cell that looks spiny because cytoskeleton is poking out)
What does hypotonic mean?
-Higher solute concentration inside cell
-water enters cell
-swells cell and cell may burst
What is the active transport NA+ K+ Pump?
K+ moves into cell
Na+ moves out of cell
Moves Na out/K in against concentration gradients
MAINTAINS gradients
How is the transmembrane potential characterized?
inside of cell negative compared to outside at rest
plasma membrane and active transport help maintain potential (electrical gradient)
What is endocytosis?
-use vesicles to move larger things
-vesicles are membrane-bound containers formed from plasma membrane
-bringing outside to inside using vesicle
What is phagocytosis?
-type of endocytosis that brings very large particles into cell
-usually bacteria or damaged or dead cells of parts of cell
How does phagocytosis occur?
-Bacteria binds to receptor in plasma membrane
-Pseudopods reach and surround particles
-Phagosome (vesicle) fuses with lysosome and it is digested
What is pinocytosis?
-type of endocytosis
-takes small samples of ECF
-way of sampling
How does pinocytosis occur?
-forms tiny vesicle
-transport vesicle loses protein coat and fuses with endosome
-either returns to plasma membrane, sent to lysosome, or may exit out of opposite side of cell
What is exocytosis?
-things inside of cell released to outside
-cell forms vesicles
-fuses with plasma membrane and is released to outside
Which organelles are membrane-bound?
mitochondria, peroxisomes, ER, golgi apparatus, lysosomes
Which organelles are not membrane-bound?
ribosomes and centrosomes
What do mitochondria do?
-makes ATP (consumes O2, CO2 waste)
-Has its own DNA
What do peroxisomes do?
Use hydrogen peroxide (H2O2) to destroy toxins and fatty acids in the body
-synthesizes some phospholipids
What are ribosomes structure/function?
-Physically made up of RNA
-Protein synthesis
Where are ribosomes fixed and free?
Free in cytosol and bound in ER
What is the endoplasmic reticulum?
-network membranes involved in synthesis mainly for secretion (leaving cell)
What is the structure/function of the Rough ER?
-studded with ribosomes
-involved in protein processing
What is the structure/function of the Smooth ER?
-no ribosomes
-lipid synthesis (such as steroids and cholesterol)
What is the function of the Golgi Apparatus?
-involved in packaging products from the ER into vesicles for secretion (exocytosis)
–Also makes lysosomes
What are lysosomes?
-vesicle-looking with digestive enzymes inside (powerful)
-3 functions include cleaning up the inside of the cell, getting rid of residue, and apaptosis (cell destroying itself)
What conditions (1) cause a lysosome to be activated?
-A primary lysosome fuses w/ the membrane of another organelle, such as mitochondrion
What conditions (2) cause a lysosome to be activated?
-A primary lysosome fuses w/ an endosome containing fluid or solid materials from outside the cell
What conditions (3) cause a lysosome to be activated?
-The lysosomal membrane breaks down during autolysis following injury to, or death of the cell
What is in the cytoskeleton?
-actin (microfilaments)
-intermediate filaments
-microtubules
What are microtubule structures?
-Centrioles
-cilia
-flagella
What do centrioles do?
-inside the centrosome
-involved in mitosis
What do cilia do and where are they?
-involved in sweeping across cell surface
-long
-surface of cell (in airways, in reproductive)
What are flagella and where are they?
-allow cell to “swim”
-tail that whips to propel cell forward
-only in sperm
What is the structure/function of microvilli?
-have microfilaments at core
-extensions of plasma membrane
-serve to increase surface area for absorption
What is the nucleus?
-command center of cell
-contains DNA
-Nuclear envelope with pores
-Nucleolus responsible for rRNA and making ribosomes
What is the function of DNA?
protein synthesis
What is chromatin?
-one extremely long DNA molecule
-Nucleotides strung together form proteins
What is the structure/function of a nucleosome?
-strand of DNA coiled around group of histone proteins
-like beads on string
-supercoils into visible chromosome for cellular division
What is transcription and where does it happen?
-happens in nucleus
-DNA to mRNA
What is translation and where does it happen?
-in cytoplasm on ribosomes
-Ribosome reads code from mRNA
-Assembles amino acids into polypeptide chain
What is processing and where does it happen?
-By RER & Golgi Apparatus; produce protein
-A gene codes for a specific protein
What happens in the initiation stage of transcription?
-transcription factors bind to promotor
-RNA polymerase (does copying) unravels DNA and binds to promoter
What happens in the elongation stage of transcription?
-Building RNA in complementary nucleotides
-3 letter code on DNA is triplet
-3 letter code on mRNA is codon
-3 letter code on tRNA is anticodon
What happens in the termination stage of transcription?
-end of gene is reached
-mRNA transcript is released
What is the first step of translation?
-Initiator RNA binds the mRNA start codon in the ribosome
What is at the other end of tRNA?
anticodon; complementary to codon on mRNA
What does the anticodon bring in?
-amino acid
What is the A site?
-site that is accepting site for new tRNA’s to bring amino acids
What is the P site?
-for building peptide bonds
What is the E site
-exiting site
What happens in processing?
-Protein is folded and modified into final protein, most of which occurs in the cytosol or rough ER.
A long, thin strand of DNA and its associated proteins is called
chromatin
Human cells that lack centrioles cannot
divide
Where does protein synthesis occur?
ribosomes
Which of the following functions is not associated with the peroxisomes?
-digesting worn-out organelles
-breaking down fatty acids
-synthesizing certain phospholipids
-oxidizing toxic substances
digesting worn-out organelles
Which organelle has a second inner membrane that has folds called cristae, and a matrix?
mitochondrion
Which of the following organelles is not part of the endomembrane system?
-lysosomes
-peroxisomes
-golgi apparatus
-Smooth ER
peroxisomes
Which cellular extensions can increase the surface area of the plasme membrane up to 40%?
microvilli
What organelle modifies polypeptides so they can fold into fully functional proteins?
Rough ER
Which of the following functions does not relate to the smooth ER?
-Protein synthesis
-detoxification reactions
-calcium ion storage
-lipid synthesis
protein synthesis
Which of the following functions is not associated with intermediate filaments within the cell?
-associating with motor proteins to move vesicles and organelles throughout the cell
-forming a network under the membrane around the nucleus to support its shape and size
-forming a network within the cytoplasm that gives the cell mechanical strength
associating with motor proteins to move vesicles and organelles throughout the cell (function of microtubules)
Within the nucleus, where does ribosome assembly occur?
Nucleolus
______ are tightly coiled and condensed barlike structures that separate during anaphase
Chromosomes
The Na+/K+ pump transports _____ out of the cell for every _____ moved into the cell
three sodium ions; two potassium ions
Which of the following functions is associated with many plasma membrane proteins?
-promotes fluidity of the membrane
-oxygen transport
-molecular transport through the membrane
-forms a lipid bilayer
molecular transport through the membrane
Neurotransmitters are released from secretory vesicles in neurons by a process called
exocytosis
_____ stabilizes the structure of the plasma membrane when the temperature changes
Cholesterol
Sodium ions move through the plasma membrane through a carrier protein using no energy in ____
facilitated diffusion
Ingesting cellular debris occurs in a process called
phagocytosis
Carbon dioxide is a small molecule that moves through the phospholipid bilayer with its concentration gradient by ______
simple diffusion
Two types of active transport vesicles are
endocytosis and exocytosis
During which phase of mitosis are sister chromatids separated and pulled to opposite poles?
anaphase
What is the correct order of the phases in the cell cycle?
Interphase, Prophase, Metaphase, Anaphase, Telophase
A final mRNA transcript of 300 nucleotides would code for ____ amino acids
100
A ______ is a three nucleotide sequence of mRNA that specifies a single amino acid
codon
During which phase of the cell cycle does the mitotic spindle form?
Prophase
What brings amino acids to the ribosome during translation?
Transfer RNA (tRNA)
What are the 2 major steps of gene expression that produce a protein from a gene?
transcription and translation
What tRNA codon is complementary to the mRNA codon GUA?
CAU
What is the role of RNA polymerase in transcription?
RNA polymerase binds to the DNA promoter and builds an mRNA molecule
