Chapter 6 Flashcards
basic features of all cells
plasma membrane, cytosol (semifluid substance), chromosomes (carry genes), ribosomes (make proteins)
what are prokaryotic cells characterized by?
no nucleus, DNA in nucleoid, no membrane-bound organelles, cytoplasm bound by plasma membrane
what are eukaryotic cells characterized by?
DNA in nucleus bounded by a nuclear envelope, membrane-bound organelles, cytoplasm in region between plasma membrane and nucleus
what is the plasma membrane?
a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
how is volume affected as cell increases in size?
as cell increases in size, the volume grows proportionately more than its surface area
What does plant cell have that animal cell does not?
have a cell wall, chloroplasts, and a large central vacuole
what do animal cells have that plant cells do not?
have a centrosome
how do ribosomes work with the DNA?
ribosomes use information from the DNA to make proteins
what is the nucleus?
contains most of the cells genes and is usually the most conspicuous organelle
what is the nuclear envelope?
encloses the nucleus, separating it from the cytoplasm
what is the nuclear membrane?
a double membrane, each consisting of a lipid bilayer
what is chromatin?
the dna and proteins of chromosomes together
why does chromatin condense?
chromatin condenses to form discrete chromosomes as a cell prepares to divide
what are chromosomes?
dna is organized into discrete units called chromosomes in the nucleus
what are ribosomes?
ribosomes are complexes made of ribosomal RNA and protein and carry out protein synthesis
where do ribosomes carry out protein synthesis?
cytosol (free ribosomes), outside of the endoplasmic reticulum or nuclear envelope (bound ribosomes)
what is the function of the endomembrane system?
the endomembrane system regulates protein traffic and performs metabolic functions in the cell
what does the endomembrane system consist of?
nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, plasma membrane
what does the endoplasmic reticulum do?
the endoplasmic reticulum accounts for more than half of the total membrane in eukaryotic cells, Smooth ER: lacks ribosomes, Rough ER: has ribosomes
what are the functions of the smooth er?
synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions
functions of the rough er?
has bound ribosomes, which secrete glycoproteins, distributes transport vesicles, secretory proteins, and is membrane factory for the cell
functions of the golgi apparatus?
modifies products of the ER, manufactures certain macromolecules, sorts and packages materials into transport vesicles
what is a lysosome?
a lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules
where do lysosomal enzymes work best?
in acidic environment inside the lysosome
how is a food vacuole formed?
when a cell engulfs another cell by phagocytosis
what do lysosomes do?
fuse with food vacuole to digest molecules, and use enzymes to recycle cell’s own organelles and macromolecules in a process called autophagy
what are vacuoles?
large vesicles derived from the ER and golgi apparatus
What do central vacuoles do?
Only found in plants, they hold organic compounds and water
what do contractile vacuoles do?
found in protists, they pump excess water out of cells
What are mitochondria
Mitochondria are sites of cellular respiration
What is cellular respiration?
A metabolic process that uses oxygen to generate ATP
what are chloroplasts?
site of photosynthesis for plants and algae
what are peroxisomes?
oxidative organelles
what is not part of the endomembrane system?
mitochondria, chloroplast, peroxisomes
What is the endosymbiont theory?
Suggests that an early ancestor of eukaryotes engulfed an oxygen-using nonphotosynthetic prokaryotic cell, wehre the engulfed cell and host formed a relationship and evolved into mitochondria
Where are chloroplasts found?
In leaves and other green organs of plants and in algae (protists)
chloroplast structure includes
thylakoids and stroma (internal fluid)
what do peroxisomes do?
produce hydrogen peroxide and convert it to hydrogen and oxygen
what is the cytoskeleton?
a network of fibers extending throughout the cytoplasm that organizes cell’s structures and activities, and anchors organelles
what is the cytoskeleton composed of?
microtubules, microfilaments, intermediate filaments
all cells have?
ribosomes and chromosomes
what is the role of the cytoskeleton?
to support the cell and maintain its shape, interacts with motor proteins
what are the components of the cytoskeleton?
microtubules: thickest, microfilaments (actin): thinnest, intermeditate: diameters in middle range
microtubules:
tubulin polymers; hollow rods 25 nm, function to shape cell, guide movement, and separate chromosomes during cell division
microfilaments:
actin filaments: two intertwined strands of actin, 7 nm, tension-bearing elements, contraction, division of animal cells, also contain myosin, resist pulling forces in cell, bear tension
intermediate filaments:
fibrous proteins coiled into cables, anchorage of nucleus, 8-12 nm, fix organelles in place
what are centrosomes?
in animal cells, microtubules grow out of centrosome (called microtubule organizing center)
what is cytoplasmic streaming?
a circular flow of cytoplasm within cells, which speeds distribution of materials within cell
what is the cell wall?
an extracellular structure that distinguishes plant cells from animal cells
who has cell walls?
prokaryotes, fungi, and some unicellular eukaryotes
purpose of the cell wall
protect plant cell, maintain its shape, and prevents excessive uptake of water
what are plant cell walls made of?
cellulose fibers embedded in other polysaccharides and protein
What is the extracellular matrix?
animal cells are covered in the ECM, made up of gylcoproteins such as collagen, proteoglycans, and fibronectin
What is the extracellular matrix?
animal cells are covered in the ECM, made up of gylcoproteins such as collagen, proteoglycans, and fibronectin
