2 Cells- Cell structure (eukaryotic) Flashcards
What is the structure of the cell-surface (plasma) membrane?
-Made from a phospholipid bilayer
-Have proteins- can act as receptors (cell can respond to external environment), and cholesterol embedded in them
What are the functions of the plasma membrane?
-Separates the inside of the cell from its environment
-Controls the passage of organic molecules, ions, water, and oxygen into and out of the cell
-Waste products (e.g. ammonia, CO2) leave the cell by passing through here
What is the structure of the cytoplasm?
-Organelles suspended in the gel-like cytosol
-70% water
-Contains proteins, sugars, ions and fatty acids
What are the functions of the cytoplasm?
-Many metabolic reactions take place here
-Different organelles perform specific functions here
What is the structure of the nucleus?
-Nucleoplasm (semi-solid fluid inside)
-Chromatin and nucleolus (1 or more) in nucleoplasm
-Linear chromosomes (eukaryotes), made up of DNA
-Nuclear envelope
What is the function of the nucleus?
-Controls the actions of the cell
-DNA in here has instructions for the synthesis of proteins
-Ribosomal RNA joins with associated proteins in nucleolus to assemble ribosomal subunits
What is the structure of the nuclear envelope?
-Double-membrane
-Pores
-Inner and outer membrane are phospholipid bilayers
What is the function of the nuclear envelope?
-Pores control passage of ions, molecules and RNA between nucleoplasm and cytoplasm
What is the structure of mitochondria?
-Oval-shaped, double-membrane (phospholipid bilayer, with proteins embedded)
-Have ribosomes and DNA
-Inner layer has folds, cristae
-Area surrounding folds= mitochondrial matrix (has enzymes for respiration)
What is the function of mitochondria?
-Make ATP via aerobic respiration (muscle cells have lots as they are highly active and need a lot of energy)
What is the structure of chloroplasts?
-Have DNA, ribosomes and inner and outer membranes
-Thylakoids= set of interconnected and stacked fluid-filled membrane sacs in the space enclosed by the inner membrane
-Each stack of thylakoids= granum (grana pl.), linked by lamellae, flat, thin parts of thylakoid membranes
-Stroma= fluid enclosed by inner membrane, surrounds grana
What is the function of chloroplasts?
Photosynthesis in plant and algal cells
What is the structure of the Golgi vesicles?
-Membrane-bound, fluid-filled vesicles in the cytoplasm
-Small, round, seen in high density near edges of sacs
-e.g. lysosomes
What is the function of the Golgi apparatus?
Transport vesicles form at endoplasmic reticulum, fuse with golgi apparatus;
these empty proteins and lipids into lumen of golgi apparatus, which travel through the golgi and are sorted, packaged and tagged so they can be sent to the right place
Form lysosomes
What is the structure of the Golgi apparatus?
Series of flattened membranous sacs
What is the function of the Golgi vesicles?
Store and transport modified proteins and lipids from golgi apparatus to target cells
What is the structure of lysosomes?
-Type of golgi vesicle
-Contain hydrolytic enzymes, lysozymes
What is the function of the lysosomes?
-The lysozymes within aid the breakdown of proteins, polysaccharides, lipids, nucleic acids and old organelles
What is the structure of ribosomes?
-Can be free-floating in cytoplasm or attached to cytoplasmic side of endoplasmic reticulum
-Very small
-Made of protein subunits
-Not covered by membrane
What is the function of ribosomes?
-Protein synthesis
What is the structure of the endoplasmic reticulum?
-Series of interconnected membranous sacs and tubules
-Membrane is a phospholipid bilayer embedded with proteins
-Smooth ER has no ribosomes, but rough ER does
What is the function of the RER and SER?
-RER = processing and folding proteins
-SER= making and processing lipids
Package into vesicles
What is the structure of the cell wall?
-Rigid covering, protects cell
-Fungal (chitin) , plant and algal (cellulose) cells have it
What is the function of the cell wall?
-Structural support
-Gives shape to cell
What is the structure of the cell vacuoles?
-Large, occupies most of cell area
-Surrounded by membrane, tonoplast
-Cell sap, weak solution of salts and sugars
-Cytoplasm (not in animal cells)
What is the function of the cell vacuoles?
-Allows cell to remain rigid
-Holds more water= vacuole pushes against cell wall, pressure maintained, plant stopped from wilting
-Isolates chemicals unwanted by the cell
