Parts of the Cell Flashcards
What are the 4 functions of the cell membrane
physical isolation, regulation of exchange with the environment, sensitivity to the environment, structural support
What constitutes as the cytoplasm?
cytosol + organelles
What is another name for extracellular fluid?
interstitial fluid
What is the structure of the cell membrane?
-lipid bilayer
What makes up the hydrophilic end of the cell membrane?
-hydrophilic end (phosphate and choline)
What are the three types of membrane lipids?
Phosphoglycerides (phospholipids), Cholesterol, Glycolipids
What is the function of membrane phosphoglycerides?
-surround and anchor proteins
What is the most prevalent membrane lipid?
phosphoglycerides (phospholipids) ~ 50%
What is phosphatidylcholine?
a membrane phosphoglyceride/phospholipid
What is phosphatidylserine?
a membrane phosphoglyceride/phospholipid
What is phosphatidylethanolamine?
a membrane phosphoglyceride/phospholipid
What is the function of membrane cholesterol?
stabilizes membrane
What is the function of membrane glycolipids?
intercellular communication
What are sphingolipids?
a membrane glycolipid
What are gangliosides?
a membrane glycolipid
What are 5 functions of membrane proteins?
-attach cytoskeletal filaments to cell membrane
-attach cells to extracellular matrix
-transport molecules into and out of cells
-act as receptors for chemical signaling between cells
-possess specific enzymatic activity
What are two types of membrane proteins?
integral membrane protein and peripheral membrane proteins
Which membrane protein comprises a significant fraction of the proteins encoded in an organism’s genome?
integral membrane proteins
Which membrane proteins are permanently attached to the biological membrane?
integral membrane proteins
Are peripheral membrane proteins always attached to the biological membrane?
No, they adhere only temporarily
Where are peripheral membrane proteins located?
-attached to integral proteins or they penetrate the peripheral regions of the lipid bilayer
-could also be the regulatory protein subunits of many ion channels and transmembrane receptors
Where and what are membrane carbohydrates?
-mainly on extracellular surface, as a coating called the glycocalyx
What are 4 functions of membrane carbohydrates?
lubrication and protection
anchoring and locomotion
specificity in binding
recognition
What are three types of transport across cell membranes?
Diffusion, Active transport, Bulk transport
What is diffusion transport used for?
gases, lipophilic or small molecules
What is active transport used for?
Na2+ ions
What are 4 types of bulk transport?
endocytosis, pinocytosis, phagocytosis, exocytosis
What is endocytosis?
-substances are brought into the cell
-the substances are surrounded by part of the cell membrane which then buds off inside the cell to form a vesicle containing the ingested material
-invagination, fusion, budding
What is pinocytosis?
-small molecules suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane
-the resulting pinocytotic vesicles subsequently fuse with endosomes to hydrolyze (break down) the particles
-cell process, fusion, internalization
What is phagocytosis?
-cell uses its plasma membrane to engulf a large particle creating an internal compartment called the phagosome
-extend cell process, engulf and fuse membrane, internalization
When is phagocytosis often used?
-to remove pathogens like bacteria
What is exocytosis?
-opposite of endocytosis
-a form of active transport
-transports molecules out of the cell by secreting them through an energy-dependent process
-apposition and tethering, hemifusion, fusion and release
What is the nucleus made up of?
-bounded by a nuclear envelope
-contains cellular DNA
- nucleoli (rRNA, mRNA, tRNA)
-nucleoproteins
How does the nucleus communicate with the cytoplasm?
through nuclear pores on the nuclear envelope
What is chromatin?
a complex of DNA and protein found in eukaryotic cells
What is the function of chromatin?
packaging long DNA molecules into more compact denser structures
What is euchromatin?
it is the “beads on a string” structure that results when DNA wraps around histone proteins forming nucleosomes
What is heterochromatin?
when multiple histones wrap into a 30nm fibre consisting of nucleosome arrays in their most compact form
What are the two types of nucleus chromatin?
heterochromatin and euchromatin
What is the function of nuclear pores?
form channels for transport of small molecules and restrict large molecules from entering the nucleus
What is the endoplasmic reticulum?
network of membranous tubules, vesicles, and cisternae
What are the two types of ER?
rough ER(surface is studded with ribosomes) and smooth ER
What is the function of the rough ER?
protein synthesis
What is the function of smooth ER?
lipid synthesis, membrane synthesis and repair
What is the Golgi apparatus?
membrane system involved in sorting, packaging, and transporting cell products
What are cisternae?
the sacs or folds
What are the functions of the Golgi apparatus?
-modification of macromolecules by addition of sugars
-proteolysis of peptides into active forms
-sorting of macromolecules in to membrane-bound vesicles
-transport of lipids around the cell, and the creation of lysosomes
What are lysosomes?
membrane-bound spherical organelle containing hydrolytic enzymes
What is the function of a lysosome?
-breaks down many kinds of biomolecules engulfed by the cell
-involved in various cell processes such as plasma membrane repair, cell signaling, and energy ____
What makes up a lysosome?
it has a specific composition of its membrane proteins and luminal proteins
What is the lysosomes’s lumen’s pH?
~4.5-5.0, optimal for the enzymes involved in hydrolysis (analogous to the activity of the stomach
What is the mitochondria?
a membrane-bound organelle with outer and inner membranes separated by inter-membranous space
What is the function of the mitochondria?
responsible for ATP production
What is in the mitochondria’s matrix?
-many enzymes and small amounts of mitochondrial DNA
What are the three main components of the cytoskeleton?
microfilaments, intermediate filaments, and microtubules & tublulin
What is a special feature of the cytoskeleton?
all components are capable of rapid growth or disassembly dependent on the cell’s requirements
What are microfilaments?
long, thin filaments of actin
What are the functions of microfilaments?
-cytokinesis
-amoeboid movement
-cell motility
-changes in cell shape
What are some intermediate filaments?
desmin
glial fibrillary
acidic protein
keratin
lamin
neurofilaments
vimentin
What is the most stable component of the cytoskeleton?
intermediate filaments
Where are intermediate filaments found?
in particularly durable structures such as hair, scales, fingernails
What are the functions of microtubules and tubulin?
provide platforms for intracellular transport and are involved in a variety of cellular processes such as the movement of secretory vesicles, organelles
What makes up the hydrophobic end of the cell membrane?
-hydrophobic end (glycerol with fatty acid tails)
