Cells and Organelles Flashcards
What happens to products that are destined for secretion from the Golgi apparatus?
Travel in vesicles that empty into the extracellular environment (exocytosis)
secretion products must accumulate within the Golgi before secretion, these products include proteins and hormones
In which type of cell are vacuoles found?
within all plant and fungal cells
Some animal and protist cells
Rarely in bacterial cells
What proteins and molecules are utilized by facilitated transport?
large, hydrophilic molecules that cannot directly travel across the belayer utilize Integral proteins
What is the extracellular matrix composed of?
Carbohydrates
Extensive network of fibrous structural proteins
Adhesion proteins
Glycocalyx:
A carbohydrate coat consisting of glycoproteins and glycolipids that covers the cell membrane of some animal cells and the outer face of the cell wall of some bacteria
What are the functions of glycocalyx?
Anchors to the exterior of the cell and can provide: adhesive capabilities for potential cell invaders, protective barrier to infection and can act as a marker for cell-to-cell recognition
Functions of central vacuole
Act as storage vacuoles for starches, pigments and toxic substances
Contains specialized membrane called tonoplast which helps maintaining cell rigidity by exerting turgor
Cytoplasmic streaming
Transports proteins, nutrients, and organelles throughout the cell in a organized manner
What is the array arrangement of each cilium and flagellum in microtubules?
9 + 2 array
An outer ring of 9 microtubule doubles, and two singles at the center
Passive diffusion
Molecules diffuse from a higher concentration to a lower concentration
Does not require energy
Molecules can diffuse through channel proteins
When proteins are used to aid in passive diffusion, it is known as _________________ diffusion.
Facilitated
What cells contain chloroplast?
select eukaryotic cells like plant cells and some protist like algae
NOT PRESENT in animal, fungal and prokaryotic cells
What are the functions of the nuclear lamina?
- Primary role is to provide structural (mechanical) support to the nucleus
- Regulates DNA organization, DNA replication and cell division and chromatin organization
Nuclear lamina
Dense, fibrous network of proteins associated with the inner membrane of the nuclear envelope
intermediate filaments + membrane associated proteins
Keratin
Protein concentrated in the skin, hair, and nails
Most common type of intermediate filament protein
Proteins used in passive diffusion
Porins: allow any hydrophilic molecule (that fits) pass through
Ion channels: allow ions (like calcium) pass through, down their concentration gradient
Glycosylation
A carbohydrate is attached to the protein which will then move toward the Golgi for packing, a common manipulation of proteins that enter the rough ER lumen
Functions of the lysosome
- vesicles produced by the golgi
- Contain hydrolytic/ digestive enzymes (that function at low pH) that can hydrolyze substances taken up by the cell via endocytosis to break down nutrients, bacteria, and other cellular debris
- Can break down a cell’s unneeded/defective components by a process called autophagy
- Can also contribute to apoptosis (programmed cell death) when they release their contents into the cell
Cytosis
Processes cells use to facilitate the bulk transport of large, polar (hydrophilic) molecules against their concentration gradient
active transport mechanism
What are the two main types of integral proteins involved in facilitated transport?
Channel proteins: serve as an open tunnel on both sides of the bilateral
and carrier proteins: allows molecules to bind to one side, then changes shape to bring the molecule to the other side
Where are anchoring junctions found?
In tissue that experience heavy mechanical stress
Ex: skin epithelium, cervix, uterus
Desmosomes
anchoring junction the provides mechanical stability to tissue by anchoring cells to each other via intermediate filaments
”staples”
What are the three types of spindle apparatus microtubules?
Kinetochore
Polar
Astral
What type of membrane proteins are receptor proteins?
They can be integral: receive signals from the extracellular environment that need to be transmitted inside the cell —> once signal is received, the protein triggers secondary responses within the cell
Or peripheral: receives chemical signals from the extracellular environment that do not need to be transmitted inside the cell —> receptor-mediated endocytosis relies on these proteins
Connexons
Small holes in the plasma membrane which are made up of 6 membrane proteins called connexins
When a connexon of one cell lines up with a connexon of another cel, a gap junction is formed
What is the function of microfilaments in cell division?
They are responsible for the formation of contractile rings that splits the cell during cytokinesis
What is the function of microtubules in cell division?
Created by MTOCs
Form the spindle apparatus which guides chromosomes to the opposite ends of the cell during karyokinesis (nuclear division of the chromosome)
What molecules utilize simple diffusion?
small, uncharged, nonpolar molecules
Pericentriolar material of a centrosome
A matrix of proteins that surround the centrioles
Play a role in microtubule nucleation (process in which several tubulin diners come together to form a microtubule) and securing/anchoring microtubules to the centrosome
What structures are part of the Endomembrane system?
Nucleus/nuclear envelope
RER
SER
Golgi apparatus
Lysosomes
Vacuoles
Cell membrane
What structures are present in both prokaryotic and eukaryotic cells?
Cell membrane, cytoplasm and ribosomes
Plasmodesmata
Tunnels between adjacent plant cells making it easier for cell-to-cel transport
Middle lamella
A sticky cement that attaches adjacent plant cell walls to each other, which makes it difficult for large molecules to permeate from one plant to the next
What is a key contributor to receptor-mediated endocytosis?
Clathrin: a protein that aids in receptor-mediated endocytosis by forming a pit in the membrane that pinches off as a coated vesicle - known as clathrin-mediated endocytosis
Function of lysosomes
Vesicles produced by the Golgi apparatus
Contain hydrolase enzymes that are only functional at low pH environments - they breakdown macromolecules and digest excess or worn-out organelles of the cells
Molecular digestion
What molecule would be freely floating in the cytosol?
RNA: once the mRNA is transcribed within the nucleus, it is released to the cytosol so that it can translated into proteins (tRNA and rRNA would be found too)
Cell-matrix junctions
Connect the extracellular matrix to the cytoskeleton of an animal cell
Two types: hemidesmosomes (intermediate filaments like keratin) and focal adhesions (actin filaments in the cell)
Hemidesmosomes
A type of cell-matrix junction
Connect the ECM to keratin intermediate filaments of the cytoskeleton
Focal adhesions
A type of cell-matrix junction
Connect the ECM to actin-based microfilaments of the cytoskeleton
The modern cell theory tells us:
1) all living things are composed of one or more cells
2) cells are the basic unit of structure, function, and organization in all organisms
3) all cells come from pre0existing, living cells
4) cells carry hereditary information
5) energy flow (e.g. metabolism) occurs within cells
6) all cells have the same basic chemical composition
Uniport, symport and antiport are examples of what type of transport?
Uniport is an example of facilitated transport
Symport and antiport are examples of secondary active transport
Membrane permeability from most permeable to least permeable:
Small, hydrophobic molecules: oxygen, carbon dioxide, nitrogen gas, steroid hormones
Small, uncharged, polar molecules: water, urea, glycerol, ammonia
Large, uncharged, polar molecules: glucose, sucrose
Ions: H+, Na+, HCO3-, K+, Ca2+, Cl-, Mg2+
Hopanoids
Serve the same function as cholesterol in prokaryotes- modulate membrane fluidity to provide structural support in prokaryotic cells
Example of glycoproteins in their role of cell-to-cell recognition:
ABO blood typing
Sterols
Same functions as cholesterol in plant cells- modulates membrane fluidity and provides structural support in the plasma membrane
What are microtubules composed of?
Tubulin
Function of microtubules
Cytoskeletal filaments largest in diameter that aid in mitosis by forming the mitosis spindle which pulls sister chromatids to opposite poles of the cell in anaphase
What are microfilaments made of:
Actin
Function of microfilaments:
- Cytoskeletal filaments smallest in diameter
- muscle contraction (within myofibrils)
- cellular motility
- vesicle transport
- cell junctions
- cytokinesis (forms the cleavage furrows)
- found in amoeba, pseudopods
what are hopanoids?
found in prokaryotic membranes, serve the same function as cholesterol - modulating membrane fluidity to provide structural support
what are eukaryotic flagella made of?
tubulin dimers arranged in a 9 + 2 array
what are prokaryotic flagella made of?
the protein flagellin
how do eukaryotic and prokaryotic flagella differ in the way they move?
eukaryotic flagella move in a bending motion whereas prokaryotic flagella move in a rotary motion
what drives eukaryotic and prokaryotic flagella movement?
eukaryotic flagella movement is driven by energy produced from ATP hydrolysis whereas prokaryotic flagella movement is driven by the energy obtained from proton pumps
what do channel proteins allow for the passage of?
hydrophilic (water-loving), polar and charged substances
recognition protein
- type of glycoprotein that have an attached aligosaccharide
- used to dinstinguish between self and foreign
- ex: MHC on macrophages
