Lecture slides 9-11 Flashcards
Antibiotics
- There are many ________.
-some are specific to certain types of_______:
-based on their ability to _______________.
-naturally occurring antibiotics
-bacteria
-target prokaryote-specific structures
Antibiotics
Two common targets are:
1) prokaryotic ribosomes (responsible for protein synthesis)
2) prokaryotic cell walls
Antibiotics
-prokaryotic cell walls
a)_________ ___________ present in our ________.
-Enzyme that _____________ of ___________ between __________.
-(__________ falls apart ,__________.)
b)______________.
- Lysozyme
-antimicrobial - bodily fluids (tears, milk, saliva, mucous)
-catalyzes hydrolysis
-b 1-4 linkages
-NAG and NAM
-peptidoglycan
-cells lyse
-Penicillin
Antibiotics: How does Penicillin work?
As bacterial cell grows, it __________.
-synthesizes more peptidoglycan
-the _______ is __________.
- inhibition leads to a ____________.
-works best on ________.
- As the cell grows ___________.
-eventually the cell_______.
-enzyme
- inhibited by penicillin (and derivatives)
-weakened peptidoglycan
-Gram positive cells
-new peptidoglycan is not formed
- bursts (lysis)
Is there anything else outside the bacterial cell wall?
Many bacteria also have a “capsule” surrounding the cell wall
Capsule
-mostly _________.
-further protects________.
- can be used to ____________.
- capsule is very rare in _______.
- polysaccharides
- cell from environment
- stick bacteria to surface
-Archaea
Pili (two types)
-fimbriae (attach to surfaces or host cells)
-sex pilus (for transfer of DNA between bacteria cells
Pili
-fimbriae (attach to surfaces or host cells)
e.g., Neisseria gonorrhoeae the
causative agent of gonorrhea
uses __________.
fimbriae to attach itself to
mucus membranes.
sex pilus (for transfer of DNA between bacteria cells)
-_______ is transferred to another _______
- DNA
- bacteria (termed bacterial
conjugation)
In a __________, many bacteria exhibit _______, the ability to _______________.
- Chemotaxis is the movement toward or away from ___________.
-Motile bacteria move in a series ______________.
- Duration of the run is longer if the ________ increases during the run.
-heterogeneous environment
- taxis
- a stimulus
- a chemical stimulus
- of “runs” and “tumbles”.
- concentration of the “attractant”
Another external structure:
Flagella (for movement)
- Flagella of bacteria, archaea, and
eukaryotes are composed of __________.
- Rotation can be ____________.
-CCW_____.
-CW______.
- different proteins and likely
evolved independently - clockwise
or counterclockwise (to
allow changes in direction) - “run”
- “tumble”
Bacterial flagella motors are
composed of many individual
components!
- E. coli uses a ________ to power the motor.
(some other bacteria use a ________)
- This is a type of ______ that
couples H+ ___________. - The overall rate of proton flow through the
motor is around ________.
- ~600 H+____________.
- Thus the motor can spin at about ______
- proton-based (H+) electrochemical gradient
- Na+ gradient
1.
-ion channel
- nflux to physical rotation of
the rotor/flagellum (like a turbine).
- -200 000 H+ per second
(when motor is not under load)
- go through the motor per revolution
- 300 Hz
Archaea Cell Walls
- no __________.
- various _______ surrounding the plasma membrane (__________)
-outer membrane
- coverings
- depends on species
Archaea Cell Walls
- no ______ but related molecules have been found in some species
- some Archaea are covered by _______________________.
- In general, they have ____________ due to a number of unique
differences______________.
- true peptidoglycan
- Archaea-specific lipopolysaccharides
- stronger membranes
- e.g., an ether linkage, rather than ester in their triacylglycerols.
Eukaryotic Cell Walls
- Animal cells do not have _______ but, _______________.
Cell Wall function:
-_______________
-_______________
- Cell wall = ________ chains embedded
in a matrix of other _____________.
-cell walls
- plants and fungi do!
-provides shape and function
- strong cell walls of plants help hold them upright
-cellulose
- polysaccharides
and proteins
Plant Cell walls
- young plant cell secretes a _____________.
-the ____________.
- as cell matures,___________.
- some secrete ______________.
- others add a _____________.
- A cell may have many layers per _________
- made of a matrix of ________.
- e.g., cells in ________ have many layers of ____________.
- thin cell wall outside the
plasma membrane
-primary cell wall
-cell wall is strengthened - hardening substances into the primary cell wall
- secondary cell wall
- secondary cell wall
- strong materials
- wood
-cellulose, lignin, proteins
Plant Cell walls
-Between primary cell walls of adjacent plant cells is the____________.
-The middle lamella is composed of:
- ________________ (this effectively glues
the adjacent cells together)
-middle lamella
-sticky
polysaccharides called
pectins
Note: Pectin is not the same thing as __________ Pectin is a
more general term referring to a mixture of _________ , e.g., pectin typically has __________ .
- amylopectin
- polysaccharides that are more complex
in structure - a 1-4 linked D-galacturonic acid (an oxidized
form of galactose) as its monosaccharide.
Plant Cell walls
-Because of the thick cell wall and middle lamella, plant cells are __________.
- To allow “communication” between cells, plant cell walls contain_________.
- allows passage of___________.
- Thus, the interior of all cells can be_________.
- These pores can ___________ depending on the
environmental conditions or age of the plant.
- isolated from
each other. - pores (tunnels)
between cells. - H2O and small solutes between cells
- connected
- open and close
Animal cells
- No cell wall but they secrete ______________.
- ______________.
- Some cells attach to the _____ using additional _______.
- most common is _________.
- _______ also binds to a specific class of integral
membrane proteins called _______.
- proteins and polysaccharides
- = extra cellular matrix (ECM)
- ECM
- specialized proteins
- fibronectin (interacts with collagen)
-Fibronectin
-integrins
Animal cells
- ECM consists mostly of _______.
- ________ is embedded in a network of other ____________
- glycoproteins and protein fibres (e.g.,
collagen, which is the most abundant protein in our body) - Collagen
- glycoproteins,
called proteoglycans
Proteoglycan
Proteoglycan
- e.g., _________
- layer of cells that forms a ____________________________
- epithelial cells
- barrier between your cells and the
environment (skin, intestine)
Adjacent animal cells can be connected by 3 types of junctions
(depending on the specific type of cell):
Tight Junctions, Desmosomes, Gap junctions
1) Tight Junctions
-membranes of neighbouring cells are essentially _____.
- prevents absorption of materials from one side of a row of cells
into the _____________________.
1. bands of _______ in plasma membrane
that circle each cell and contact similar
proteins on adjacent cells
- fused
- intercellular region between them
e.g., cells lining the intestine - protein
2) Desmosomes
- ____________together at certain points
- made of __________.
- abundant in tissues such as epidermis and muscle that are
subject to ________.
- tightly fasten cells
- strong protein filaments that cross the intercellular space e.g., attach skeletal muscle cells together
- mechanical force
3) Gap junctions (or communication junctions)
-multi-subunit structures that form ________.
- allow free exchange of ________.
- this allows tissues to ________.
- Connexon = ___________
- 2 connexons form a ______________
- Pore can be ___________
- a channel between adjacent cells
- small molecules (e.g. ions)
- coordinate responses to stimuli (e.g., between heart or smooth muscle cells)
Summary of junctions in animal cells
- Tight junctions prevent
fluid from __________.
- moving
across a layer of cells
Basic features of all cells (review)
Plasma membrane
Semifluid substance called cytosol
Chromosomes (carry genes)
Ribosomes (make proteins)
Prokaryotic cells are characterized by having:
- No ________
- DNA in an __________.
-No ______
- Cytoplasm bound by _________.
-nucleus
- unbound region called the nucleoid
-membrane-bound organelles
- cell wall
Cytoplasm = interior of a _____________
-prokaryotic or eukaryotic cell
Cytosol =
the fluid portion of the cytoplasm (i.e., without
structures or membranes)
Organelle =
any membrane bound structure in a eukaryotic cell
BACTERIAL CELL (Review)
Eukaryotic cell
Origin of Eukaryotes and the Endosymbiont Hypothesis
- most recent common eukaryotic ancestor probably arose__________.
- Why did eukaryotes evolve membranous organelles?
- one idea: first thing required is ability to _____________.
-Metabolic requirements ___________.
- Surface area (SA) to volume (V) ratio of cells __________.
- As surface area increases by a factor of n2, volume increases by a factor of n3
- Small cells have a greater _____________
- about 2.1 billion years ago.
- fold membranes
- set upper limits on cell size
- is critical
- surface area relative to volume
One simple model of endosymbiosis:
The Endosymbiont Hypothesis
-mitochondria and chloroplasts arose in eukaryotes by _________.
- a mutually beneficial relationship derived from one cell __________.
- e.g., in the evolution of _________:
- Mitochondria are __________ from
an ancient bacterium.
- Most closely-related extant bacteria
are the __________,
- Chloroplasts are
descended from an
ancient _________.
- endosymbiosis
-living inside
-another cell - mitochondria
- descended
- a-proteobacteria (Gram -)
- cyanobacterium
(photosynthetic bacterium)
Evidence for endosymbiosis:
- Mitochondria and chloroplasts
- have their own________
- genes are organised like _________.
- have their own _________ that are similar to ________.
( prokaryotes have ___ ribosomes eukaryotes have ____)
- DNA (circular)
- prokaryote genome
- ribosomes
- prokaryote ribosomes
- 70S
- 80S
Evidence for endosymbiosis:
Mitochondria and chloroplasts
What you need to know:
- Ribosomes are big complexes of __________,
- Eukaryote & Prokaryote ribosomes differ in _________.
- protein and RNA molecules
- size and components (70S vs. 80S)
Eukaryotic Cell Structure
- What are the membrane bound organelles in a eukaryote?
- The Endomembrane system
Contains:
Nuclear envelope
Endoplasmic reticulum (ER)
Vacuoles
Vesicles
Lysosomes
Golgi
Plasma membrane
The Endomembrane system
-They are all related by either :
1) physical continuity
or
2) vesicles that transfer from
one to another
Other membrane-bound organelles are not part of the endomembrane system
peroxisomes, mitochondria, chloroplasts
- The Nucleus
-stores______ and is the site of _______.
-contains multiple ________.
Nuclear envelope
- is a ______________ (each membrane is a phospholipid bilayer)
- separates the __________.
- Nuclear pore complexes
span both ________
-regulates movement of _________.
-DNA
-transcription
- linear chromosomes
- double membrane
-nucleoplasm from the cytoplasm
- bilayers
- substances in and out of nucleus
Nuclear lamina
-Provides structural support for ________
- composed of an intermediate filament called _______, which
assembles on the __________.
- the nucleus
- lamin
- inner surface of the nuclear envelope
The nucleus stores genetic information.
- DNA associates with __________.
-Chromatin = ___________.
Why package DNA?
- organise _________
- protect_______
- make it easier to move ___________.
- proteins that allow it to be packaged.
- DNA and protein (associated together because of electrostatic
interaction (DNA is negatively charged, histones are positive) - the nucleus
- DNA from damage
- replicated DNA into daughter cell during
cell division
The nucleus stores genetic information.
Chromatin can be highly condensed
Nucleolus (ribosome production factory)
-this is a visible sub-compartment of the _________.
- site of __________
- site of assembly of __________ (each half of the ribosome
enters the nucleus _______________)
- nucleus (not bound by membrane)
- ribosomal RNA (rRNA) synthesis
- ribosome protein subunits
- separately via nuclear pores
- The Endoplasmic Reticulum
- Both types are in __________.
- Cells that produce a lot of proteins will tend to have a more _________.
- Cells that produce a lot of lipids (fats) and steroid hormones will have
more ________.
- plant and animal cells
- rough ER
- smooth ER.
- The Endoplasmic Reticulum
- Rough ER (rER)
- covered in ______
- rER ribosomes are associated with the ___________ that are destined for the __________.
- e.g., pancreas (makes
lots of________)
- Ribosomes
- translation of proteins
- endomembrane system (e.g., Golgi, lysosome, plasma
membrane, etc.). - insulin
- The Endoplasmic Reticulum
- The function of the rough ER:
- site of__________
- site of protein __________
- e.g., many chaperones assist ___________.- misfolded proteins are either ________.
- protein synthesis and assembly (e.g. 4 peptides -> hemoglobin)
- quality control
- protein folding in the rER
- refolded or degraded
Ribosomes (protein factories)
- particles made of ___________.
- Ribosomes assemble ________________ (using ________ monomers)
- In the _______ (____ ribosomes)
- on the outside of __________ (______ ribosomes)
- ribosomal RNA and protein
- ALL peptides
-amino acid - cytosol
- free
- endoplasmic reticulum
- bound
- The Golgi Apparatus: Shipping and Receiving Centre
- Golgi apparatus consists of _____________.
- flattened
membranous sacs called cisternae
Golgi apparatus function:
- modifies products of the _____.
- ( e.g., changing carbohydrates on _______________)
- sorts and packages materials into__________
- it manufactures some __________
- (e.g pectins in plants
come from the ________)
- ER
- proteins, phospholipids
-transport vesicles - macromolecules
- golgi
Golgi apparatus function:
- Lysosomes: Digestive Compartments
- cell “________”
- Lysosome is a membranous sac of __________ that can digest _________. (e.g. it is involved in digesting food particles, e.g., from ______)
- stomach
- hydrolytic enzymes
- macromolecules
- phagocytosis).
- Vacuoles
Variable function depending on the cell
-_________ may have one or several vacuoles,
derived from __________.
- Plant cell or fungal cell
- endoplasmic reticulum and Golgi apparatus
- Mitochondria and Chloroplasts
- Both are bound by a _________.
- Both contain _________.
- double membrane (i.e., two separate lipid bilayers)
- several copies of their own DNA (mtDNA or cpDNA)
- Peroxisomes
(also called microbodies)
-_______ membrane bound organelles (_______)
- perform ______ (breakdown of molecules or assembly)
in which ___________
-single
-spherical
- reactions
- H2O2 (hydrogen peroxide) is a by-product
