Chapter 4 Flashcards
iology of the Cell
the plasma membrane forms
the outer layer, limiting barrier separating the internal contents of the cell from the interstitial fluid
the nucleus is
the largest structure in the cell, enclosed by a nuclear envelope
contains DNA and nucleolus and nucleoplasm
cytoplasm is
general term for all cellular contents between the plasma membrane and nucleus
consists of cytosol, organelles, and inclusions
cytosol is also called
intracellular fluid, contains many ions
membrane bound organelles are
enclosed by a membrane similar to the plasma membrane
non membrane bound organelles examples
ribosomes, centrosomes, cytoskeleton
inclusions are
clusters of a single type of molecule, like melanin or glycogen
three general functions of the cell
maintenance/integrity of cell shape
obtaining nutrients/synthesis of nutrients
disposal of waste
three main lipids of the plasma membrane
phospholipids
cholesterol
glycolipids
phospholipids are
the majority of lipids in the plasma membrane, amphipathic
phospholipids create the
bilayer framework of the plasma membrane
cholesterol is
a four ring lipid that is scattered throughout the inner hydrophobic region of the bilayer
cholesterol function in the plasma membrane
stabilization and strengthening at extreme temperatures
glycolipids are
lipids with attached carbohydrate groups
glycolipids create the
glycocalyx
the glycocalyx does what?
creates a fuzzy coating around each cell, providing stability of the cellular environment
two categories of plasma membrane proteins
integral and peripheral
integral proteins are
embedded within and extend completely across the bilayer
many integral proteins are
glycoproteins
peripheral proteins are
not embedded in the bilayer but are attached loosely to either external or internal surfaces of the membrane
transport protein function
regulation of movement of substances across the plasma membrane
cell surface receptors function
bind specific molecules called ligands to activate a response
identity markers function
communication with other cells that they are not foreign
enzymes function
catalysts
anchoring sites function
securing the cytoskeleton to the plasma membrane
cell adhesion proteins function
cell to cell attachment, binding cells together
diffusion is
the movement of ions or molecules down their concentration gradient
where does diffusion get energy from?
kinetic energy of molecules moving along their concentration gradient
is diffusion active or passive?
passive
three important characteristics of diffusion?
dependent on a concentration gradient
involves the spreading out of ions/molecules
can reach equilibrium if unopposed
two main forms of diffusion
simple and facilitated
simple diffusion allows for
small and nonpolar molecules to move in or out of the cell along their conc. gradient
facilitated diffusion allows
small solutes that are charged ion or polar to move through the plasma membrane assisted by proteins
how is simple diffusion controlled?
concentration gradient only
two forms of facilitated diffusion
channel mediated
carrier mediated
channel mediated diffusion allows
movement of small ions across the plasma membrane through water filled protein channels
channels for channel mediated diffusion are either
gated or leak channel
carrier mediated diffusion allows
polar molecules to cross the plasma membrane down their conc. gradient
how are carrier proteins named?
how many substances they transport
uniporter example
leak channels are _____ open/closed?
always open
gated channels are ____ open/closed?
closed usually and open in response to a stimulus
osmosis is
a form of passive transport where water moves passively along its conc. gradient through a semipermeable membrane
how is water movement controlled in the cells when osmosis is a passive process?
aquaporins, protein channels for water movement
osmosis general rule
______ follows ______
water follows solutes
osmotic pressure is
the pressure exerted by the movement of water across a semipermeable membrane
tonicity is
the ability of a solution to change the volume/pressure of the cell by osmosis
in an isotonic solution, there is
no net movement of water, it is at equilibrium with the cell
in a hypotonic solution, there is
increased movement of water into the cell because the water concentration is lower inside the cell
in a hypertonic solution, there is
increased movement of water out of the cell because the concentration of water is lower outside of the cell
extreme hypotonic solutions can cause
lysis of the cell
extreme hypertonic solutions can cause
dehydration of cells
active transport is
the movement of a solute aganist its conc. gradient across a membrane
active transport requires
energy
two forms of active transport
primary and secondary
primary active transport receives energy from
ATP breakdown
secondary active transport uses the energy
of a molecule traveling down its concentration gradient to give energy to move another molecule against its concentration gradient
what is phosphorylation in terms of primary active transport
when ATP is broken down, it provides a phosphate group added to the membrane protein
Secondary active transport is also called
cotransport or coupled transport
example of primary active transport
NaK ATPase
secondary active transport example - symport
Na glucose symporter
secondary active transport example - antiport
Na H+ antiporter
vesicular transport involves
vesicles, membrane bound sacs filled with various fluids
vesicular transports allows for
transport of large molecules or large amounts of molecules across the plasma membrane
two forms of vesicular transport
endocytosis and exocytosis
exocytosis is
where large substances/volumes are secreted from/out of the cell
endocytosis is where
large substances/volume are transported into the cell from the external environment
vesicular transport is also called
bulk transport
three types of endocytosis
phagocytosis
pinocytosis
receptor mediated endocytosis
organelles are
organs of the cell
two types of organelles
membrane bound and non membrane bound
five membrane bound organelles
endoplasmic reticulum (smooth and rough)
golgi appartatus
lysosome
peroxisome
mitochondria
four non membrane bound organelles
ribosomes
centrosome
proteasome
cytoskeleton
three structures on the cell surface
cilia
flagella
microvilli
dna is
a nucleic acid molecule made up of repeating monomers called nucleotides
smooth and rough ER functions
Rough ER function: synthesis of proteins, modification and storage of proteins, vesicle formation
Smooth ER function: synthesis of lipids (steroids), carbohydrate metabolism, detoxification, and vesicle formation
why are smooth and rough ER different
rough ER has attached ribosomes
golgi appartatus function
synthesis of proteoglycans, modifies and stores proteins from the rough ER, forms digestive enzymes for lysosomes, vesicle formation
lysosome function
digestion of unwanted/unneeded biological macromolecules. Lysosomes also participate in autophagy and autolysis, digestion of the cell when it is damaged or dies.
peroxisome function
breakdown of molecules and producing hydrogen peroxide during the process, synthesis of specific lipid types
mitochondria function
cellular respiration, ATP production. Also contain their own DNA, mtDNA, which is passed down maternally
ribosome function
protein synthesis
centrosome function
organizing microtubules within the cytoskeleton and assisting in cellular division
proteasome function
digestion of marked proteins. Proteins will be marked with ubiquitin for digestion which is recognized by the proteasome. Digestion fragments are recycled within the cell. Known as the “protein garbage disposal”
cytoskeleton function
structural support of the cell, assistance in cell division, cellular movement (muscle contraction)
cilia function
movement of certain substances. Examples: mucus in the lungs to the throat. Female oocyte (egg) in the fallopian tube, moves toward the uterus after fertilization
flagella function
cellular movement. They are more common in microorganisms like bacteria, there is only one human cell with flagella; sperm cells. The flagella is used to move the sperm cell toward the human egg cell.
microvilli function
not movement related, used to increase surface area in locations for nutrient absorption (small intestine)
the human cell contains how many pairs of DNA molecules, chromosomes?
23 pairs, 46 total molecules
DNA nitrogenous bases
adenine
guanine
thymine
cytosine
the cell control center is
nucleus
transcription is
the process of DNA being “read” to produce a new strand of RNA.
RNA nitrogenous bases
adenine
uracil
guanine
cytosine
three functional forms of RNA
messenger
transfer
ribosomal
a start codon:
always contains the three bases AUG, and codes for methionine amino acid, signaling the start of translation
translation is
when RNA is read to synthesize proteins
stop codons:
either UAA, UAG, or UGA. these do not code for an amino acid and signal for translation to cease
two major cell cycle phases
interphase and mitotic
interphase breaks down into
G1 phase, S phase, and G2 phase.
mitotic phase breaks down into
prophase, metaphase, anaphase, telophase, and cytokinesis.
G1 phase is for
growth and preparation for DNA replication
S phase is for
DNA replication stage (also called synthesis stage)
G2 phase is for
growth and preparation for DNA division
mitosis consists of
Prophase, metaphase, anaphase, and telophase
cytokinesis is
the division of cellular cytoplasm into two cells.
what occurs during prophase?
chromatin becomes supercoiled so chromosomes are movable and don’t tangle.
The nucleolus breaks down and disappears and centrioles are moved toward opposite poles of the cell. The nuclear envelope begins to break down at the end of this stage.
what occurs during metaphase?
spindle fibers attach to centromeres of chromosomes and pull to align chromosomes at the equatorial plate of the cell.
what occurs during anaphase?
ister chromatids are separated by spindle fibers and moved to opposite ends of the cell. Cytokinesis begins.
what occurs during telophase?
chromosomes uncoil to chromatin, the nucleolus reforms, a new nuclear envelope forms around the new cells, and cytokinesis continues.
during cytokinesis
the nuclear envelope is closed fully around the two new daughter cells and they are cleaved from each other.
apoptosis is
is the process of programmed, intentional cell death. It occurs in an orderly, well-defined and continuous process to destroy and remove cellular components as needed.
apoptosis is intitiated by
ligand-receptor signaling, in which inactive, self-destructive enzymes within the cytosol are turned on and initiate a series of actions.
six apoptotic actions
Destruction of DNA polymerase
Digestion of the DNA into small fragments
Digestion of the cytoskeleton
Formation of small, irregular blebs on the plasma membrane
Condensation of the cytosol and destruction of organelles
Release of proteins within mitochondria and activating specific digestive enzymes in cytosol
