Chapter 4 Flashcards
cluster of atoms held together by chemical bonds
molecule
structure within a cell that performs a specific function
organelle
simplest entity that has all the properties of life; a membrane-bound unit containing DNA and cytoplasm
cell
structures composed of more than one tissue type
organ
related organs performing a common function
organ system
an individual, independent, living entity
organism
form boundaries on surfaces (outermost layer of skin, line airway and stomach), control what goes in and out, held by tight junction
epithelial tissue
cells imbedded in a matrix (ex. blood: RBC surrounded by a liquid matrix called plasma & bone which has a calcified matrix collagen fibers & adipose tissue)
connective tissue
skeletal, smooth (blood vessels, GI tract), cardiac
smooth tissue
neurons conduct electrical signals
nervous
chemical pathway from simple to complex
anabolism
chemical pathway from complex to simple
catabolism
Living things….
cellular organization, sensitivity (respond to stimuli), growth, reproduce, homeostasis
Cell theory
1) all organisms are composed of cells 2) the cell is the basic building block of life = chemical reactions within 3) all cells come from preexisting cells
Why are cells small?
need high/reasonable surface-to-volume ratio and big cell = diffusion distance increases = not efficient
two atoms SHARE one, two, three electron pairs –> stable bond
covalent bonds
water molecule is formed by ___ bonds between one oxygen atom and two hydrogen atoms
covalent
oppositely charged ions attract each other forming an ___ bond
ionic
unequal attraction of electrons by the atoms that share them in a covalent bond
polar molecule
the attraction of the positive (hydrogen) end of the polar molecule to the negative end of another polar molecule is called
hydrogen bond
hydrogen bonds may be weak but can be present in ____ and influence the shape of molecules (DNA double helix is held together by H bonds)
very large numbers
water forces the hydrophobic groups together and this is why non polar groups tend to localize ____ of most soluble proteins
within the interior
lacks a nucleus; DNA coiled into a nucleoid is in direct contact with the cytoplasm (some have more than one nucleoid)
prokaryotic cells
contain a large, membrane bounded nucleus; has organelles
eukaryotic cells
All prokaryotic cells have a plasma membrane, nucleoid, and cytoplasm containing ____
ribosomes
Prokaryotic: located outside plasma membrane may be a ___
cell wall containing peptidoglycan
plasma membrane –> cell wall –> outer membrane –> ___
capsule
In bacteria the chlorophyll (no chloroplast) is located in
the infoldings of the plasma membrane
some prokaryotes swim using
flagella
___ which projects from the surface of some bacteria is involved in mating
pili
prokaryote flagellum is made up of
flagellin
Eukaryotes contain an internal cytoskeleton which
maintains cell shape and moves materials
rigid cell wall of cellulose and large central vacuole
plants
eukaryotes’s cytoskeletal protein is made up of
myosin and actin
ER closest to nucleus
rough (ribosomes)
mature RBC
blood cells originate from blood bone marrow; last bout 120 days then broken down in liver
no nucleus cuz going to lose genetic material anyways
DNA is contained in
mostly nucleus + mitochondria and chloroplast
DNA + protein –>
chromatin
when nucleus is about to divide the chromatin ___ forming chromosomes
condenses and coils tightly
each __ (“colored body”) contains one long molecules of DNA comprising many genes
chromosomes
the nucleus contains (one or more) nucleolus the site of
ribosome assembly
fluid material within the nuclear envelope
nucleoplasm
viruses are made up of __, surrounded by ____
nucleic acid, protein sheath (sometimes lipid envelope)
viruses are not alive because
lack cell membranes, nucleus, and organelles; cannot reproduce on their own; no metabolism
X formation is ___ to division
prior
mitotic spindle is attached to each ____ and pulls them apart to the poles
sister chromatid
all cells synthesize proteins on __
ribosomes
Where are ribosomes located in eukaryotes?
free in cytoplasm, attached to rough ER, in energy producing organelles (mitochondrial matrix, chloroplast stroma)
ribosomes consist of a type of ___ together with protein, comprising a large and small subunit which associate during protein synthesis
RNA
____ makes the peptide bond
ribozyme
A series of interrelated membranes and compartments in the eukaryotic cells
Endomembrane system = ER + Golgi
extensive system of folded membranes forming sacs and tubes
ER
cells which synthesize proteins for export contain large amounts of ____
ER
lack ribosomes; site for hydrolysis of glycogen; steroid synthesis
smooth ER
contains attached ribosomes; makes proteins for export; site for addition of short sugar chains to proteins glycoproteins
rough ER
insulin is made and stored in ___
pancreatic beta cells (right below stomach)
enclosed spaces
lumen
series of flattened membranous sacs that modifies, packages, and sorts proteins
Golgi apparatus
synthesizes some polysaccharids for the cell wall
Golgi apparatus
vesicles from the rough Er fus with the ___ region of the Golgi (near nucleus) and secretory vesicles are pinched off the the ___ region (close to cell surface)
cis, trans
powerhouse of cell
mitochondria
food is converted into ATP =
energy currency of cell
mitochondria are small/big
small (bacteria size)
inner membrane of mitochondria
cristae
mitochondrial matrix contains
ribosomes and DNA
almost all eukaryotes contain mitochondria except whose living
without oxygen
more mitochondria are present if cells are ___ like in heart muscle
very active
serves for food manufacture or storage in plants and some protists (ex. chloroplast)
plastids
plastids are surrounded by
two unfolded membranes
inner membrane of chloroplast forms a stack of flattened disk-like sacs called
thylakoids
stacks of thylakoids are called
grana
chlorophyll is contained in
the thylakoid membrane
___ (fluid) within inner membrane of chlorplast contains suspended grana, ribosomes, and DNA
stroma
contains hydrolytic digestive enzymes; participate in phagocytosis
lysosomes
What is the pH of lysosomes
5
peroxisomes are found in
plants and animals
glyoxysomes are found in ___, it stores ___ which is converted in carbs when plant is about to germinate
plant seeds, lipids
peroxisomes are important in liver and kidney to
detoxify
Tay Sach’s disease
defect in lysosomes
lysosomes carry out autophagy which is
self-breakdown
T or F: plants have lysosomes
false
vacuoles are present in ___
plant cells; store waste products and provide turgor
maintains cell shape, facilitates cell movement, and certain fibers act as tracks for “motor proteins”
cytoskeleton
cell wall are present in __, ___, and some __
plants, fungi, protists (and bacteria)
surrounds animal cells and is composed of proteins (e.g. collagen, glycoproteins, and proteoglycan)
extracellular matrix
division of the nucleus
mitosis
division of cytoplasm
cytokinesis - microfilaments form a noose around the middle of the cell it adds or subtract to change length of actin
strands of actin, involved in movement during animal cell division and muscle contraction
microfilaments
tough, fibrous protein molecules twisted into rope-like structures, which stabilize cell structure
intermediate filaments
hollow cylinders made of tubulin
microtubules
involved in structure and function of cilia and flagella, centrioles, and movement of cellular organelles
microtubules
motor proteins such as __ use energy from ATP to change their shape and move things
dynein and kinesin
cilia are formed of
microtubules
structure of cilia
9 pairs of microtubules + 2 in the middle
animals don’t have cell wall but may have
extracellular matrix
vacuoles are __ in animal cells
absent or small
some animal cell have flagella it’s absent in plants except for
sperm in a few species
centrioles ___ in plants
are absent
all cells are bounded by a __
plasma membrane
plasma membrane provides __ which has the ability to transport certain molecules
permeability barrier
plasma membrane plays a key role in response of cells to __
external stimuli
membranes are involved in energy __
transduction
biological membranes are composed of
lipids, proteins, and carbohydrates
provide physical integrity of plasma membranes
lipids
perform specific function (e.g. transport, receptors) for plasma membrane
proteins
serve as recognition sites on the cell surface
carbohydrates
the basic foundation of the plasma membrane
lipid bilayer
phospholipids ___ form bilayer sheets in which the ___ tails point inward
spontaneously, hydrophobic
fluidity of a bilayer depends on __ and ___
composition and temperature
important component of plasma membrane of animal cells orients in bilayer with polar head group close to polar head group of phospholipid
cholesterol
unsaturated: C=C puts a kink in a chain so it does not pack well together in membrane –>
harder to freeze
on the outer surface of the plasma membrane, __ are attached to proteins or phospholipids
carbohydrates
protein that penetrates into the lipid bilayer
integral
most integral proteins are __, contain an alpha-helix of non polar amino acids extending across the hydrophobic interior of the membrane
transmembrane
located outside of the lipid bilayer on the cytoplasmic surface attached by non covalent bonds to the polar head groups of the lipid bilayer or to the integral membrane proteins
peripheral proteins
covalently attached to a phospholipid or fatty acid embedded in the bilayer
lipi-anchored proteins
__ provides much info we know about membrane structure
RBC
beneath the cytoplasmic surface of the RBC, ___ forms a mesh
spectrin
role of membrane proteins
transport, receptors, form junctions between cells
cells can recognize and bind to each other via ___
surface membrane proteins
stick together by same membrane proteins
homotypic binding
stick together by different membrane proteins
heterotypic binding
cell junction stitched all the way around
tight junction
“spot welds” don’t go all the way around but more concerned with structural integrity
desmosomes
protein pore or channel between two adjacent cells
gap junctions
connexin protein makes a channel called
connexon
gap junctions are important in __
the heart, facilitates the spread of an action potential
meditate the attachment of animal cells to extracellular matrix
inegrin
passive, non mediated movement down concentration gradient most simple
diffusion
when molecules become uniformly distributed a state of __ exists
equilibrium
diffusion of water molecules across a selectively permeable membrane
osmosis
Ions such as Na+ and other charges do not readily cross membranes but can pass through water filled pores created by ____
intrinsic membrane proteins (channels)
certain molecules (eg glucose) bind to carrier proteins in the membrane and are transported across
facilitated diffusion
facilitated diffusion may become ___ if all the protein carriers are in use
saturated
transport across a membrane by a carrier-mediated process against concentration gradient
active transport
requires direct participation of ATP
primary active transport
does not use ATP directly but rather the energy in an ion gradient established by primary active transport
secondary active transport
transports macromolecules, large particles, and small cells into eukaryotic cells
endocytosis
during endocytosis, the plasma membrane envelops materials and forms ___ inside cells
vesicle
large particles or cells are engulfed
phagocytosis
small dissolved solutes or fluids enter
pintocytosis
a specific membrane receptor binds to a particular macromolecule at sties called coated pits (e.g. uptake of cholesterol in association with LDL)
receptro-mediated
material in vesicles are secreted from the cell when vesicles fuse with the plasma membrane
exocytosis
work associate energy
kinetic
stored energy
potential
energy from the sun flows in the biological world and stored as ___ in the chemical bonds of sugar molecules formed by photosynthesis
potential energy
first law of thermodynamics
energy cannot be created or destroyed
second law of thermodynamics
during any energy conversion, some energy is released as heat which adds to entropy (increasing disorder) of the system
the sum of all chemical reactions within a cell or organism
metabolism
product of one reaction becomes the reactant in the next reaction
metabolic pathway
chemical reaction establish
equilibrium
what is the ratio of the concentration of products and reactants at equilibrium
equilibrium constant Keq
high Keq –>
reaction goes far towards completion
the breaking of chemical bonds in the course of chemical reactions produces changes in ___
Gibbs free energy
Give an example of an anabolic reaction
glucose + fructose + (energy) –> sucrose
Give an example of a catabolic reaction
sucrose is hydrolyzed –> energy is released
in a biological system, the released energy may be __ in new chemical bonds or used as __
recaptured, kinetic energy
the energy released by the breakdown of glucose is used to drive the synthesis of ___
triglycerides
Total energy
enthalpy, H
G =
H-TS
If delta G < 0
free energy is released, exergonic
If delta G > 0
free energy is required, endergonic
the further toward completion the point of equilibrium lies, the ___ free energy is released
more
The proteins of tight junctions form a ___ barring the movement of dissolved materials through the space between epithelial cells
quilted seal
__ link adjacent cells tightly but permit materials to move around them in the intercellular space
Desmosomes
Gap junctions let adjacent cells ___
communicate
__ and __ are abundant in epithelial cells
tight junctions and desmosomes
__ are found in some muscle tissue and nerve tissue win which __ between cells is important
gap junctions, rapid communication
True or False: All three junctions are not necessarily seen at the same time in actual cells
true
A __ solution has a higher solute concentration than the other solution
hypertonic
__ solutions have equal solute concentrations
isotonic
A __ solution has a lower solute concentration that the other solution
hypotonic
How fast a substance diffuses depends on
diameter or molecules or ions, temperature of solution, concentration gradient
__ keeps plants upright and is the driving force for the enlargement of plant cells
turgor pressure
sometimes a stimulus is the binding of a chemical signal __ to open gated channel
ligand
Protein __ coats the cytoplasmic side of the plasma membrane at the coated pit
clathrin
the endocytosed contents are surrounded by
a clathrin-coated vesicle
__ is the method by which cholesterol is taken up by most mammalian cells
receptor-mediated endocytosis
When a cell need cholesterol, it produces specific __ which are inserted into the plasma membrane in clathrin coated pits
LDL receptors
A newly formed polypeptide may contain a __ which is a short stretch of amino acids that indicates where in the cell the polypeptide belongs
signal sequence
A signal sequence binds to a specific __ at the surface of the organelle
receptor protein
in the absence of a signal sequence, the protein will __ in the same cellular compartment where it was synthesized
remain
protein synthesis always begins on free ribosomes and have default location for a protein is the __
cytosol
Once the protein has bound to a specific receptor protein, the receptor forms a __ in the membrane and the protein enters the organelle
channel
a specific hydrophobic sequence of about __ at the beginning of a polypeptide chain directs it into the ER
25 amino acids
Nucleic acids inside protocells could replicate using the ___ from ___
nucleotides from outside
found in cytoplasm (on ribosome), binding of mRNA and tRNA and protein synthesis
rRNA
found in cytoplasm, carrier of gene sequence
mRNA
found in cytoplasm, adapter between mRNA and protein sequences
tRNA
in plants, SER
metabolizes carbohydrates
membranes of the nucleus, ER, and Golgi form a
network connected by vesicles
Blood Cholesterol Levels
200 mg/dL, 200-239, 240+
LDL cholesterol levels
130 mg/dL, 130-159, 160+
Blood cholesterol made in
liver
cholesterol is coated with a layer of protein to make __ which can move in blood
lipoprotein
