Lecture 6 Flashcards
What is the simplest collection of matter that can be alive?
cells
True or False: all cells are related by their descent from earlier cells
True
What are the common features that all cells have?
Plasma membrane, Semifluid substance called cytosol, DNA (includes genes), and ribosomes
Where is cytosol?
In the cytoplasm
Describe prokaryotes compared to eukaryotes(5).
Eubacteria and archaea, smaller, less complex, no true nucleus, singular circular chromosome
Describe Eukaryotes compared to Prokaryotes (6).
Single-celled or multicellular
larger
more complex
true nucleus
linear chromosomes
membrane-bound organelles
What is a plasma membrane?
a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
What determines the size of a cell?
metabolic requirements set the upper limits on the size of cells
What happens as a cell increases in size?
its volume grows proportionally more than its surface area
What does the inside of a eukaryotic cell have?
internal membranes that divide the cell into compartments (the organelles)
How can you visualize cells?
Through a microscope
How does a light microscope work?
visible light is passed through a specimen and then through the glass lenses
The lenses refract the light so that the image is magnified
How can you view things smaller than a cell?
Electron Microscope
Who was June Almeida?
gifted electron microscopist
first to produce the image of a coronavirus
studied rubella, hep B, and HIV
pioneered using the electron microscope to diagnose viral diseases
Study cell structure image
.
What is contained in the nucleus?
most of the cells genes
What is the function of the nuclear envelope?
encloses the nucleus, separating it from the cytoplasm
What is the structure of the nuclear envelope?
double membrane; each membrane consisting of a lipid bilayer
DNA + Protein=____
chromatin
Where is the nucleolus located?
within the nucleus
What is the function of the nucleolus?
ribosomal RNA synthesis and ribosome assembly
What are ribosomes made up of?
ribosomal RNA (rRNA) and protein
What is the function of ribosomes?
carry out protein synthesis (take instructions from mRNA and turn into protein) in two locations
Where are ribosomes located?
in the cytosol (free ribosomes)
on the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes) (Rough ER)
What is the function of the endomembrane system?
regulates protein traffic into and out of cells
What does the endomembrane consist of?
Nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, and plasma membrane
How are the components of the endomembrane connected?
either continuous or vis transfer vesicles
What is the endoplasmic reticulum?
accounts for more than half of the total membrane in many eukaryotic cells and is continuous with the nuclear envelope
What is smooth ER like?
lacks ribosomes
What is rough ER like?
surface is studded with ribosomes
What does the golgi apparatus consist of?
flattened membranous sacs called cisternae
What is the function of the golgi apparatus?
Modifies products of the ER
sorts and packages materials into transport vesicles
What is a lysosome?
a membranous sac of hydrolytic enzymes that can digest macromolecules ( both foreign “food” and self)
Where do the lysosome enzymes work best?
in the acidic environment inside the lysosome (like the stomach)
How are hydrolytic enzymes and lysosomal membranes made?
by rough ER and then transferred to the Golgi apparatus for processing
What is phagocytosis?
when some cells engulf another cell
How are food vacuoles formed?
phagocytosis
How are molecules digested in the cell?
Lysosomes fuse with the food vacuole and digest molecules
What is autophagy?
when lysosomes use enzymes to recycle the cell’s own organelles and macromolecules
Describe vacuoles in an animal cell
Generally small and multiple… mature plant cells usually have one central one
Where are contractile vacuoles found?
in many freshwater protists
What is the function of contractile vacuoles?
To pump excess water out of cells
Where are central vacuoles found?
mature plant cells
What is the function of central vacuoles?
hold organic compounds and water
What is the cytoskeleton?
A network of fibers extending throughout the cytoplasm
What is the function of the cytoskeleton?
to organize cells structure and activities
also anchors many organelles
What three structures compose the cytoskeleton?
microtubules, microfilaments, intermediate filaments
What is the structure of microtubules?
largest hollow tubes made of tubulin dimers
What is the function of microtubules?
miotic spindle for chromosome separation during cell division
“tracks” for transport of organelles and vesicles
What is the structure of microfilaments?
smallest, coiled chains of actin monomers
What is the function of microfilaments?
cell shape, structure
cell motility
What is the function of intermediate filaments?
cell shape/organization
Where are intermediate filaments found?
in animals
Which tubule/filament is the least dynamic?
intermediate filaments
Where are microtubules found in animal cells?
growing out of the centrosome near the nucleus (centrioles+ proteins)
In animal cells, the centrosome has a pair of ____, each with nine triplets of microtubules arranged in a ring.
centrioles
What makes up the microtubule organizing center (MTOC)?
centrioles+proteins
What is the function of cilia and flagella?
propel unicellular eukaryotes through water
What do microtubules control?
the beating of flagella and cilia
True or false: cilia and flagella have the same beating pattern
false
