(Cell) Cell Components Flashcards
Structure of nucleus (2)
Surrounded by nuclear envelope (double membrane) perforated by nuclear pores
Nuclear envelope continuous with endoplasmic reticulum (ER)
Function of nucleus (3)
Houses chromosomes
Contains nucleoli
Pores regulate entry and exit of materials
What are chromosomes made out of?
Chromatin
What is chromatin comprised of? (3)
DNA, the genetic material and proteins
What is made in the nucleoli?
Ribosomal subunits
Structure of ribosome (2)
Two subunits made of ribosomal RNA and proteins
Can be free in cytosol or bound to ER
Function of ribosomes
Protein synthesis
Structure of endoplasmic reticulum(ER) (3)
Extensive network of membrane-bounded tubules and sacs
Membrane separates lumen from cytosol
Continuous with the nuclear envelope
Function of the smooth ER (4)
Synthesis of lipids
Metabolism of carbohydrates
Ca2+ storage
Detoxification of drugs and poisons
Function of the rough ER (3)
Aids in synthesis of secretory and other proteins from bound ribosomes
Adds carbohydrates to glycoproteins
Produces new membrane
Structure of golgi apparatus (2)
Stacks of flattened membranous sacs Has polarity (cis and trans faces)
Function of golgi apparatus (3)
Modification of proteins, carbohydrates on proteins, and phospholipids
Synthesis of many polysaccharides
Sorting of Golgi products, which are then released in vesicles
Structure of lysosome
Membranous sac of hydrolytic enzymes
What cells of lysosomes present in?
Animal cells
Function of lysosome
Breakdown of ingested substances, cell macromolecules, and damaged organelles for recycling
Structure of vacuole
Large membrane-bounded vesicle
Function of vacuole (6)
Digestion Storage Waste disposal Water balance Cell growth Protection
Structure of mitochondrion (2)
Bounded by double membrane
Inner membrane has infoldings
What are the infoldings of the inner membrane in the mitochondrion known as?
Cristae
Function of mitochondrion
Cellular respiration
Structure of chloroplast
Typically two membranes around fluid stroma, which contains membranous thylakoids stacked into grana
What cells have chloroplasts?
Plant cells
Function of chloroplast
Photosynthesis
Structure of peroxisome
Specialized metabolic compartment bounded by a single membrane
Function of peroxisome
Contains enzymes that transfer hydrogen to water, producing hydrogen peroxide(H2O2) as a by-product, which is converted to water by other enzymes in the peroxisome
What is the “information central” of the cell?
Nucleus
What is the “protein factories” of the cell?
Ribosomes
What is the “biosynthetic factory” of the cell?
Endoplasmic Reticulum
What is the “shipping and receiving center” of the cell?
Golgi apparatus
What is the “digestive compartments” of animal cells?
Lysosomes
What is the “diverse maintenance compartments” of cells?
Vacuoles
What is the “chemical energy conversion” organelle of cells?
Mitochondria
What is the “capture of light energy” organelle of plant cells?
Chloroplasts
What is the “oxidation” organelle of cells?
Peroxisomes
What is the netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope?
Nuclear lamina
What does rRNA stand for?
Ribosomal RNA
What does mRNA stand for?
Messenger RNA
What is rRNA synthesized?
Nucleolus
What is the difference between free and bound ribosomes?
Free ribosomes are suspended in the cytosol
Bound ribosomes are attached to the outside of the endoplasmic reticulum or nuclear envelope
What are the two main organelles of the the cell’s genetic instructions?
Nucleus and ribosomes
What is the endomembrane system responsible for? (3)
Synthesis of proteins and their transport into membranes and organelles or out of the cell
Metabolism and movement of lipids
Detoxification of poisons
What are glycoproteins?
Proteins that have carbohydrates covalently bonded to them
What is the cytoskeleton?
A network of fibres extending throughout the cytoplasm
What are three properties of the cytoskeleton?
Microtubules (Tubulin Polymers)
Microfilaments (Actin Filaments)
Intermediate Filaments
Structure and Diameter of Microtubules
Hollow tubes; wall consists of 13 columns of tubulin molecules
25 nm with 15-nm lumen
Structure and Diameter of Microfilaments
Two intertwined strands of actin, each a polymer of actin subunits
7 nm
Structure and Diameter of Intermediate Filaments
Fibrous proteins supercoiled into thicker cables
8-12 nm
Protein subunits of Microtubules
Tubulin, a dimer consisting of alpha-tubulin and beta-tubulin
Protein subunits of Microfilaments
Actin
Protein subunits of Intermediate Filaments
One of several different proteins of the keratin family, depending on cell type
Main functions of Microtubules (4)
Maintenance of cell shape (compression-resisting “girders”)
Cell motility (as in cilia or flagella)
Chromosome movements in cell division
Organelle movements
Main functions of Microfilaments (6)
Maintenance of cell shape (tension-bearing elements)
Changes in cell shape
Muscle contraction
Cytoplasmic streaming
Cell motility (as in pseudopodia)
Cell division (cleavage furrow formation)
Main function of Intermediate Filaments (3)
Maintenance of cell shape (tension-bearing elements)
Anchorage of nucleus and certain other organelles
Formation of nuclear lamina
Where do microtubules grow out of?
Centrosome
What is the centrosome?
A region that is often located near the nucleus and is considered a “microtubule-organizing center”
What is within the centrosome?
A pair of centrioles
What are centrioles composed of?
Nine sets of triplet microtubules arranged in a ring
What is singular version of flagella and cilia?
Flagellum and Cilium
Flagella vs. Cilia motion
Flagella has an undulating motion that generates force in the same direction as the flagella’s axis
Cilia work more like oars, with alternating power and recovery strokes generating force in a direction perpendicular to the cilia’s axis
What is the outer cytoplasmic layer of a cell called?
Cortex
What protein is responsible for the bending movements of the organelle?
Dyneins
What are the thicker filaments interdigitated with the actin filaments made of?
A protein: Myosin
Localized contraction brought about by actin and myosin also plays a role in what?
Amoeboid movement
An amoeba mauve’s by extending and flowing in cellular extensions called:
Pseudopodia
What extracellular structure distinguishes an animal cell from a plant cell?
Plant cells have cell walls
Young plant cell first secretes a relatively thin and flexible wall called:
Primary wall
What is between the primary walls of adjacent cells?
Middle lamella
What is the middle lamella?
A thin layer rich in sticky polysaccharides
What are the sticky polysaccharides in the middle lamella known as?
Pectins
Some cells add what between the plasma membrane and primary wall?
Secondary cell wall
What elaborate structure do animal cells have?
Extracellular matrix (ECM)
What is the main ingredients of the ECM?
Glycoproteins
What is the most abundant glycoprotein in the ECM in most animal cells?
Collagen
What are collagen fibers are embedded in?
A network woven from proteoglycans
Some cells are attached to the ECM by still other ECM glycoproteins, such as:
Fibronectin
Fibronectin and other ECM proteins bind to cell surface receptor proteins called:
Integrins
Cell walls are perforated with channels called what?
Plasmodesmata
What are the three main types of intercellular junctions in animal cells?
Tight junctions
Desmosomes
Gap junctions
Describe a tight junction and give an example
The plasma membranes of neighbouring cells are very tightly pressed against each other, bound together by specific proteins
Forms continuous seals around the cells, prevent leakage of extracellular fluid across a layer of epithelial cells
E.x. Tight junctions between skin cells
Describe a desmosome and give an example
Function like rivets, fastening cells together into strong sheets
Intermediate filaments made of sturdy keratin proteins anchor desmosomes in the cytoplasm
E.x. Attach muscle cells to each other in a muscle
What is a desmosome also known as?
Anchoring junctions
Describe a gap junction and give an example
Provide cytoplasmic channels from one cell to an adjacent cell and in this way are similar in their function to the plasmodesmata in plants
Consist of membrane proteins that surround a pore through which ions, sugars, amino acids, and other small molecules may pass
E.x. Necessary for communication between cells in many types of tissues, including heat muscle, and in animal embryos
What is a gap junction also known as?
Communicating junctions
