MODULE 1 (PPT) Flashcards
is the smallest unit of living things.
cell
The basic building blocks of all organisms
cell
The Cell Theory (3)
The cell is the fundamental unit of structure and function in all living things.
All organisms are made up of one or more cells.
Cells are from other cells through cellular division.
The cell theory expanded version (3)
Cells carry genetic material passed to daughter cells during cellular division.
All cells are essentially the same in chemical composition.
Energy flow (metabolism and biochemistry) occurs within cells.
Different Cell Types (2)
Prokaryotes
Eukaryotes
organisms belonging to the domains Bacteria and Archaea.
Prokaryotes
includes protists, fungi, animals, plants
Eukaryotes
Prokaryotic cells – do not possess a true _________, i.e., their DNA is not confined within the nuclear _____________.
nucleus,
membrane
➢No sub-cellular organelles like mitochondria, Golgi bodies, or endoplasmic reticulum
Prokaryotic cells
Eukaryotic cells are made of functional subcellular
compartments – a true _________ and various membrane-bound _________.
nucleus,
organelles
The genetic material within the nucleus is complex. The DNA is associated with histone proteins and thus, called _______.
chromosomes
Eukaryotic cells vary depending on the nature of eukaryotic organisms. E.g. cells in a leaf contain _______
chloroplast
What do all cells share in common? (4)
- Cell membrane
- Cytoplasm
- Ribosomes
- DNA (and RNA)
Houses water and minerals, proteins, and organelles
Cytoplasm
Common features of all cells (5)
- Universal Genetic Code
- The same 20 amino acids
- Universally conserved genes
- Making proteins
- Chemiosmosis
- Metabolic pathways
All cells make most of their ATP using the same process (______) using: _______ (3)
Chemiosmosis,
Membranes
Proton gradients/ proton motive force
ATP synthase
is the biological medium here on Earth and is the most abundant substance in living systems
water
water make up ____% or more of the weight of most organisms.
70%
is the only common substance to exist in the natural environment in all three physical states of matter.
Acknowledging that life adapts to its environment through natural selection, ______ emphasized that for life to exist at all , the environment must first be suitable and that leads to water.
water;
Henderson
Water has four emergent properties such as
- Cohesion and adhesion of water molecules
- Moderation of temperature
- Evaporative cooling of water
- Water as the solvent of life
biomolecules (4)
- lipids
- nucleic acid
- carbohydrates
- proteins
Nucleic acids are macromolecules that exist as polymers called __________ (consisting of monomers called ________)
polynucleotides
nucleotides
A nucleotide is composed of three parts:
a nitrogenous
base, a five-carbon sugar, and
one or more phosphate groups.
The portion of the nucleotide without any phosphate groups is called a _________
nucleoside
is a biologically functional molecule that consists of
one or more polypeptides (polymers of amino acids), each folded and coiled into a specific
three-dimensional structure
proteins
Many proteins are roughly spherical (________),
while others are shaped like long fibers (________)
globular proteins;
fibrous proteins
Folding of proteins are done by
chaperonins
when proteins are transferred from an aqueous environment to a nonpolar solvent, it unravels and loses its native shape by a process called ________
denaturation
Structures of Proteins (4)
primary
secondary
tertiary
quaternary
It is a linked series of amino acids with a unique sequence.
is determined not by the random linking of amino acids, but by inherited genetic information.
primary structure
This is collectively referred to as coils and folds, which are the result of hydrogen bonds between the repeating constituents of the polypeptide backbone.
Secondary structure
a delicate coil held together by hydrogen bonding between every fourth amino acid.
a- helix
two or more strands of the polypeptide chain lying side by side (called b strands) are connected by hydrogen bonds between parts of the two parallel polypeptide backbones
b pleated sheet
It is the overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids.
Tertiary structure
It is the overall protein structure that results from the aggregation of these polypeptide subunits, ____________ (2)
quaternary structure;
the a and b subunits.
proteins function as: (8)
- ENZYMES, selectively accelerating chemical reactions, such as digestive enzymes on hydrolyzing bonds inn food molecules
- STORAGE OF AMINO ACIDS, such as the ovalbumin, protein of egg white serve as storage of amino acid for the developing embryo.
- COORDINATOR OF AN ORGANISM’S ACTIVITIES such as insulin regulating blood sugar concentration.
- motor proteins for MOVEMENT such as actin and myosin for the contraction of muscles.
- PROTECTION AGAINST DISEASE such as antibodies inactivating bacteria and viruses.
- TRANSPORT OF SUBSTANCES, such as hemoglobin transporting oxygen.
- RESPONSE OF CELL TO A CHEMICAL STIMULI
- SUPPORT such as collagen and elastin providing a fibrous framework in connective tissues
are the one class of biomolecules that does not include true polymers, and they are generally not big enough to be considered as macromolecules
Lipids
Lipid’s hydrophobic behavior is based on their molecular structure and the three types of lipids are
fats, phospholipids and steroids.
Fats are constructed from two kinds of smaller molecules: (2)
glycerol and fatty acids
These are formed if there are no double bonds between carbon atoms composing a chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. They lack double bonds, and their flexibility allows the fat molecules to pack together tightly.
Saturated fatty acid
It has one or more double bonds , with one fewer hydrogen atom on each double-bonded carbon. Its double bonds are ___which has kinks to prevent the molecules from packing together closely enough to solidify at room temperature.
unsaturated fatty acid;
cis
When phospholipids are added to water, they self-assemble into double-layered structures called “______”, shielding their hydrophobic portions from water.
bilayers
The _________ are on the outside of the bilayer in contact with the aqueous solutions inside
and outside of the cell. The ________ point toward the interior of the bilayer, away from the water.
hydrophilic heads; hydrophobic tails
These are lipids characterized by a carbon skeleton consisting of four fused rings.
steroids
__________, a steroid, is a crucial molecule in animals since it is a component of animal cell membranes and is also the precursor from which other steroids are synthesized, such as the sex hormones
cholesterol
the most common monosaccharide, is of central importance in the chemistry of life.
glucose (c6h12o6)
Disaccharides are double sugars, consisting of two monosaccharides joined by a _________.
glycosidic covalent linkage or bond
surrounds the cytoplasm within cells, which in eukaryotes is filled with membrane-bound organelles.
Cell Membrane/Plasma Membrane
who made the model of the cell membrane,
trilamellar membrane structure in the electron microscope
J.D. Robertson
Trilamellar Membrane Structure in the Electron Microscope:
electron-dense layer: _________
electron-transparent layer:_____
electron-dense layer: proteins bound to phospholipids
electron-transparent layer:
fatty acid layer
membrane fluidity depends on ____, fatty acid ____ and ____:
- Temperature
- fatty acid saturation and cholesterol
higher temperature leads to ______fluidity
increased
more _____ fatty acids leads to more fluidity
unsaturated
more ____ stiffens membranes by filling in gaps between p-lipids, decreasing fluidity
cholesterol
when mixed in water, the synthetic or artificial phospholipids form bilayer spheres. These synthetic structures are called
liposomes
Biological Membranes is semipermeable because of / is made up of (4):
- Transmembrane Proteins
- Peripheral Membrane Proteins
- Glycoproteins
- Glycolipids
- receptors for hormones or neurotransmitters
- antibodies, cell recognition, cell communication
- anchors to extracellular surfaces like connective tissues
- transporters
Transmembrane Proteins
Cytochrome c in the electron transport system on the mitochondrial cristae membrane is an example of?
Peripheral Membrane
- serve to regulate the transport or signaling activities of transmembrane protein complexes
- may mediate connections between the membrane and cytoskeletal elements
Peripheral Membrane Proteins
some functions of membrane proteins (6)
- facilitated transport
- active transport
- signal transduction
- cell-cell interactions
- anchors to cytoskeleton
- enzymatic
Membrane proteins covalently linked to oligosaccharides
Glycoproteins
These oligosaccharides are called ____, and sugar-linked proteins are therefore called glycoproteins.
glycans
are rare in the cytosol, but common on secreted proteins and membrane proteins.
✓Glycoproteins
phospholipids attached to oligosaccharides, and as noted, are part of the _____. Both are only found on the extracellular surface;
Glycolipids; glycocalyx
- are synthesized in much the same way as glycoproteins
- play a role in cell-cell recognition and the formation of tissues.
Glycolipids
T OR F
Glycoproteins and glycolipids also mediate the interaction of cells with extracellular molecular signals and with chemicals of the extracellular matrix
TRUE
Functions and activities of the cell membrane (5)
- Membrane Transport
- Osmosis
- Active Transport (?)
- Exocytosis and Endocytosis
- Communication: Cell-Cell Junctions & Cell-Matrix Junctions
- the movement of particles (solute) across or through a membranous barrier.
- consist of a phospholipid bilayer
Membrane Transport
Why is Membrane Transport significant?
● essential for cellular life
● Essential homeostatic mechanism for regulating cellular ionic balance of protons:
- pH (approx. 7.5)
- Na+ (usually 10 mmol/L or less)
- K+ (usually 200 mmol/L or more)
- Ca2+ (a free ionic conc.of 0.1 umol/L or less) and so on…
undergo allosteric change when they bind to a solute to be transported
Carrier proteins
As the solute is transported, the ______ protein undergoes a second conformational change, so that when the solute reaches the other side of the membrane, it no longer has a high affinity for the that protein. Upon release of the solute after transport, a final allosteric change restores the shape of the transport protein
carrier protein
protein molecules that span across the cell membrane allowing the passage of ions from one side of the membrane to the other.
Ion Channel Proteins
Ion channel proteins have an _______, which becomes accessible to ions after a conformational change in the protein structure that causes the ion channel to open.
aqueous pore
responsible for the excitability of cells, where Na+ , K+ and Ca++ channels collaborate in ion movements into and out of cells leading to neuronal or muscle cell responses.
Ion Channel Proteins
the diffusion of water across membranes from low to high solute concentrations
osmosis
hypotonic environment
high concentration inside
gain water
hypertonic environment
low concentration outside
lose water
in plant cells, what happens in hypotonic? ____
in hypertonic? ________
turgid
flaccid
plant’s water vacuole
tonoplasts
process that happens when plant cells are in hypertonic
plasmolysis - membrane shrinkage while
maintaining cell wall attachments.
what solution the plant cells have higher osmotic pressure??
hypotonic solution
osmotic pressure is also known as
water pressure;
osmotic pressure is the pressure exerted by a solvent as it moves through a semipermeable membrane to equalize the concentration of solute particles on both sides.
The maintenance of a correct balance of ions requires the ___________ of these ions across the membrane
active transport
_____ provides the energy for operation of a _____, an active transport protein complex linked to ATPase activity.
ATP hydrolysis; Na+/K+ pump
- is a mechanism for internalizing extracellular substances, usually large molecules like proteins, or insoluble particles or microorganisms.
- capturing a substance or particle from outside the cell by engulfing it with the cell membrane, and bringing it into the cell.
Endocytosis
- is typically the secretion of large molecules.
- its purpose is to expel material from the cell into the extracellular fluid.
Exocytosis
3 main types of endocytosis:
phagocytosis, pinocytosis, receptor-mediated
waste material is enveloped in a ______ and fuses with the interior of the ____________
membrane; plasma membrane
material transported by:
1. diffusion
2. osmosis
3. facilitated transport/diffusion
4. primary active transport
5. secondary active transport
6. phagocytosis
7. pinocytosis and potocytosis
8. receptor-mediated endocytosis
9. exocytosis
- small-molecular weight material
- water
- Na, K, Ca, glucose
- Na, K, Ca
- amino acids, lactose
- large molecules, whole cells, or cellular structure
- small molecules (liquids/water)
- large quantities of macromolecules
- waste materials, proteins for the ECM, neurotransmitters
- are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring cells or between a cell and the extracellular matrix in animals.
- allow the cells of multicellular organisms
to adhere to each other, function as a unit
and exchange information and nutrients.
cell junctions
t or f
cell junctions also maintain the paracellular barrier of epithelia and control paracellular transport
true
cell junctions (4)
tight junctions
adherens junctions
desmosomes
gap junctions
cell-matrix junctions
hemidesmosomes
actin-linked cell matric junction
Cell junctions in normal cells functions: (3)
✓ To bind cells tightly
✓ To give tissues structural integrity and;
✓ To allow cells in contact with one another to pass chemical information directly between them
in cancer cells, they do not form ________ and typically have fewer ______and _______in their membranes.
gap junctions;
cadherens and integrins
In animal cells, the _____ holds cells together to form a tissue and allow tissues to communicate with each other.
ECM
ECM is made up of: (2)
and which is the primary component
proteins (primary
component) and carbohydrates.
ECM includes all the connective tissues and fibres that are not part of a cell, but rather provide ___________
support
main functions of ECM (2)
cell communication within tissue
tissue formation
other functions of ECM (4)
- surround, support,and give structure to cells and tissues
- attach to, and communicate with nearby cells
- cell growth, cell movement, and other cell functions;
- repaires damaged tissues
- Web of proteins and carbohydrates at the cell surface
• Outside the cell membrane
• Connected to the cytoskeletal fibers and transmembrane proteins
• Enables animals to attach to and communicate with each other
• Holds tissues together
• Supports and protects plasma membrane
The extracellular membrane
The classes of macromolecules constituting the ECM in different animal tissues are broadly similar, but variations in the __________ of these different classes of molecules and in the ways in which they are ________ give rise to an amazing diversity of materials.
relative amounts
Organized
Connective tissues form the
framework of the vertebrate body, but
the amounts found in different organs
vary greatly—from cartilage and bone,
in which they are the major
component, to brain and spinal cord,
in which they are only minor
constituents.
Secretes components of ECM
Fibroblasts
Three main classes of extracellular macromolecules make up the matrix:
1) polysaccharide chains of the class called glycosaminoglycans (GAGs),
(2) fibrous proteins,
(3) a large class of noncollagenous glycoproteins,
are usually found covalently linked to protein in the form of proteoglycans
glycosaminoglycans (GAGs)
including collagen, elastin, fibronectin, and laminin, which have both structural and adhesive functions.
Fibrous proteins
which carry conventional asparagine-linked oligosaccharides.
Glycoproteins
unbranched polysaccharide chains composed of repeating disaccharide units.
GAGs (glycosaminoglycans)
two sugars in the repeating disaccharide of GAGs is always :
- amino sugar (N- acetylglucosamine or N acetylgalactosamine), which in most cases is sulfated
- usually a uronic acid (glucuronic or
iduronic).
GAGs are highly _____ charged.
negatively
Four main groups of GAGs:
1) hyaluronan,
2) chondroitin sulfate and dermatan sulfate
3) heparan sulfate
4) keratan sulfate
hyaluronan is also called (2)
also called hyaluronic acid or hyaluronate
• the simplest of the GAGs.
Hyaluronan
It consists of a regular repeating
sequence of up to 25,000
disaccharide units, is found in
variable amounts in all tissues and
fluids in adult animals and is
especially abundant in early
embryos.
Hyaluronan
are Composed of GaG Chains Covalently
Linked to a Core protein
Proteoglycans
all GAGs are covalently attached to
protein as ____, which are
produced by most animal cells.
proteoglycans
Membrane-bound ribosomes make the
polypeptide chain, or core protein, of a
proteoglycan, which is then threaded
into the _______ of the endoplasmic
reticulum.
• The polysaccharide chains are mainly
assembled on this core protein in the
________ before delivery to the
exterior of the cell by exocytosis.
lumen
Golgi apparatus
fibrous proteins (4)
collagen
elastin
fibronectin
laminin
which fibrous protein can be found sa bone, skin, tendons, ligamens, cornea, internal organs
collagen
a highly hydrophobic protein about 750 amino acids long, which, like collagen, is unusually rich in proline and glycine but, unlike collagen, is not glycosylated.
elastin
collagen is extremely rich in _________ and ______, both of which are important in the formation of the triple -stranded helix
proline and glycine
Elastin is composed largely of two types of short segments that alternate along the polypeptide chain:
hydrophobic segments, and alanine- and lysine-rich α-helical segments
responsible for the elastic properties of the molecule
hydrophobic segments
which are cross-linked to adjacent molecules by covalent attachment of lysine residues
alanine- and lysine-rich α-helical segments
• a large glycoprotein found in all vertebrates and important for many cell–matrix interactions.
• a large and varied assortment of glycoproteins that typically have multiple domains, each with specific binding sites for other matrix macromolecules and for receptors on the surface of cells.
fibronectin
• contribute to both organizing the matrix and helping cells attach to it
• also guide cell movements in developing tissues, by serving as tracks along which cells can migrate or as repellents that keep cells out of forbidden areas
• also bind and thereby influence the function of peptide growth factors and other small molecules produced by nearby cells.
fibronectin
the primary organizer of the sheet structure, and, early in development, basal laminae.
laminin
comprise a large family of proteins, each composed of three long polypeptide chains (α, β, and γ) held together by disulfide bonds and arranged in the shape of an asymmetric bouquet
laminin
are transmembrane heterodimers that Link the Extracellular Matrix to the Cytoskeleton
Integrins
are a superfamily of cell adhesion receptors that bind to extracellular matrix ligands, cell-surface ligands, and soluble ligands.
Integrins
are transmembrane αβ heterodimers and at least 18 α and eight β subunits are known in humans, generating 24 heterodimers
Integrins
- a family of fibrous proteins found in all multicellular animals
- are secreted in large quantities by connective-tissues cells, and in smaller quantities by many other cell types
collagen
most abundant proteins in mammals, where they constitute 25% of the total proteins mass
collagen
