Chapter 2 - Cells Flashcards
Cells
Cells are the smallest living units in our bodies
All living organisms are cellular in nature
Human body has over 200 types of cells
Basic Cell Functions
Each cell performs basic survival functions such as obtain and use nutrients, dispose of waste, and replicate/regenerate/repair
Carried our trough cell organelles
Basic Cell Structure
Cells have a plasma membrane that is the outer body of the cell
Inside the cell is the cytoplasm which s the inner fluid of the cell
The central nucleus controls cellular activities and where DNA is stored
Plasma membrane Structure
Membrane made of a double layer of lipids embedded with proteins; externally facing proteins and facing proteins have attached sugar groups
The plasma membrane is selectively permeable. Some solutes simply diffuse across the lipid bilayer - no proteins or ATP needed
Plasma membrane Function
Serves as an external cell barrier; acts in transport of substances into or out of the cell; externally facing proteins act as receptors and used for cell reception
Integral protiens
firmly embedded in or strongly attached to the lipid bilayer. Some integral proteins protrude from one side of the membrane only
Sugars coat the proteins which help with cell recognition
Integral protiens
firmly embedded in or strongly attached to the lipid bilayer. Some integral proteins protrude from one side of the membrane only
Sugars coat the proteins which help with cell recognition
Transmembrane Protein
span the whole width of the membrane and protrude from both sides
trans = across
Peripheral Proteins
not embedded in the lipid bilayer at all. Instead, they attach rather loosely to the membrane surface. The peripheral proteins include a network of filaments that helps support the membrane from its cytoplasmic side.
Simple Dissusion
the tendency of small molecules in a solution to move down their concentration gradient
Osmosis
The diffusion of water molecules across a membrane is called
Facilitated Diffusion
An integral protein that spans the plasma membrane enables the passage of a particular molecule across a membrane. This molecule is usually water soluble
Active Transport
Some transport proteins use energy or ATP to actively pump substances across the plasma membrane AGAINST their concentration gradient
Endocytosis
the mechanism by which large particles and macromolecules enter cells. The substance to be taken into the cell is enclosed by an infolding part of the plasma membrane.
Phagocytosis
Translates to “cell eating”. Useful in the body as it helps consume viruses inside the body
Pinocytosis
literally means “cell drinking”. Pinocytosis, a routine activity of most cells, is an unselective way of sampling the extracellular fluid. This process is particularly important in cells that function in nutrient absorption, such as cells that line the intestines.
Exocytosis
an active mechanism by which substances move from the cytoplasm to the outside of the cell. Exocytosis accounts for most secretion processes, such as the release of mucus or protein hormones from the gland cells of the body.
Rimbosone Structure
Dense particles consisting of two submits, each composed of ribosomal RNA and protein; free or attached to rough ER. Unlike other structures on the cel, it does not contain a membrane
Rimbosone Function
Sites of Protein Synthesis on the cell. mRNA enters the ribosome and a process called translation occurs in this organelle.
Rough ER Structure
Membrane system of sacs and tubules externally stubbed with ribosomes
Rough ER Function
Makes proteins that are secreted from the cell; makes the cell’s membranes
Smooth ER Structure
Membranous system of sacs and tubules; free of ribosomes
Smooth Er Function
Site of lipid and steroid hormone synthesis; lipid metabolism; and drug detoxification
Golgi Apparatus Structure
tack of three to ten disc-shaped cisterns, each bound by a membrane. It resembles a stack of hollow saucers, one cupped inside the next.
Golgi Apparatus Function
packages, modified and segregates proteins for secretion from the cell, inclusion in lysosomes, and incorporation into the plasma membrane
The products of the rough ER move through the Golgi stack from the convex (cis) to the concave (trans) side. More specifically, the cis face receives spherical, membranous transport vesicles from the rough ER; new vesicles bud off a trans face to leave the apparatus.
Lysosomes Structure
spherical, membrane-walled sacs containing many kinds of digestive enzymes. These enzymes, called acid hydrolases, can digest almost all types of large biological molecules.
Lysosomes Function
spherical, membrane-walled sacs containing many kinds of digestive enzymes. These enzymes, called acid hydrolases, can digest almost all types of large biological molecules.
Mitochondria Structure
Rodlike, double membrane structures; outer membrane has a rough appearance; inner membrane folded projections called cristae. Inside there is a matrix with proteins inside
Mitochondria Function
Site of ATP synthesis; powerhouse of the cell
Peroxisome Structure
membranous sacs of oxidase enzymes
Perioxisome Function
The enzymes detoxify a number of toxic substances; Oxidase removes free radicals from the cell; from this, the most important enzyme, catalase, breaks down hydrogen peroxide to form water.
Microfilaments Structure
Fine filaments of the contractile protein actin
Microfilaments Function
involved in muscle contraction and other types of intracellular movement; help from the cell’s cytoplasm
Intermeiate Filaments Structure
protein fibers; composition varies
Intermediate Filaments Function
The stable cytoskeletal elements; resist tension forces acting on the cell
Microtubules Structure
Cylindrical structures made of tubulin proteins
Microtuules Function
Support the cell and give it shape, involved in intracellular and cellular movement; form centrioles
Centrioles structure
Paired cylindrical bodies, each composed of none triplets of microtubules
Centrioles Funcion
Organize a microtubule network during mitosis to form the spindle and asters; form the bases of cilia and flagella
Nuclear Envelope Structure
consists of two parallel membranes separated by a fluid-filled space. The outer membrane is continuous with the rough ER and has ribosomes on its external face. It forms anew from rough ER after every cell division, so it is evidently a specialized part of the rough ER. The inner membrane is lined by protein filaments, the nuclear lamina, which maintain the shape of the nucleus.
Nuclear Envelope Function
operates the nucleoplasm from the cytoplasm and regulates the passage of substances to and from the nucleus
Nuclear Pores Structure
Created when 2 layers of the nuclear membrane fuse. Formed by a bracelet-shaped complex of more than 22 proteins, and there are several thousand pores per nucleus.
Nuclear Pores Function
The pores allow large molecules to pass in and out of the nucleus as necessary. For example, protein molecules imported from the cytoplasm and RNA molecules exported from the nucleus routinely travel through the pores.
Nucleoli Structure
Dense spherical (non-membrane bounded) bodies. Made up of proteins ad stains very dark in histology samples
Nucleoli functuon
Site of ribosome subunit manufacture
Chromatin
Chromatin Function
DNA constitutes the genes
The three basic functions of the plasma membrane are ___, ___, and ___.
Protection, communication and regulation
Cholesterol Function in Plasma membrane
found in the hydrophobic tails of the membrane as they are also hydrophobic.
The play an important role in maintaining the structure of the bilayer. They ensure the layer isn’t TOO fluid and water can pass easier
Cholesterol Function in Plasma membrane
Sits in the outer layer of the plasma membrane and aids in the cellular recognition of the cell and also aids in growth and development of the cell
