Flashcards in [Chapter 4] Deck (64)
the smallest unit that shows properties of life which means it has the capacity for metabolism, homeostasis, growth, and reproduction. All start out with a plasma membrane, a DNA-containing region, and cytoplasm.
Is divided into various functional compartments, including the nucleus.
Are smaller and simpler cells; they do not have a nucleus.
A cells outer membrane. It separates metabolic activities from events outside the cell, but does not isolate the cells interior. Water, carbon dioxide, and oxygen can still pass freely across it. Some substances can cross through with assistance from membrane proteins however others are kept out entirely.
A double-membraned sac which hold an eukaryotic cell's DNA.
The region where the DNA inside a prokaryotic cell is concentrated inside the cytoplasm.
Is the semifluid mixture of water, ions, sugars, and proteins between the plasma membrane and the region of DNA.Cell compartments and other components are suspended in cytoplasm.
Structures on which proteins are built.
the structural foundation of the cell membranes. It is double layer of lipids organized so that their hydrophobic tails are sandwiched between their hydrophilic heads. Proteins in the bilayer carry out the membranes functions.
The most abundant type of lipid in the cell membrane. Each has a phosphate-containing head an two fatty acid tails. The polar head is hydropholic (attracts water molecules) and the non polar tails are hydrophobic (repel water molecule). This causes the hydrophobic tails to be sandwiched between their hydrophilic heads making up the cell membrane.
Examples of cells that can be seen from naked eye?
Egg yolk, watermelon tissues, and amphibian and fish eggs.
An objects volume increases with the cube of its diameter, but it's surface area increases only with the square. So it's volume increases faster then surface area and the plasma membrane must handle exchanges with much more cytoplasm slowing down the inward and outward flow of nutrients. If this slows down too much the cell may die. Many cells find ways to increase their surface area (long and thin or frilly with folds) to keep up with an actives cells metabolism.
The Cell Theory
1. All organisms consist of one or more cells 2. The cell is the smallest nit that retains the properties of life 3. Each new cell arises from another cell.
They rely on visible light to illuminate objects. Light is focused and magnified with curved glass lenses. Light passes through the specimen so only cells that are thin enough for light to pass through them will be enhanced.
Photos of images enlarged by microscopes.
The cell or molecule is the light source and it emits energy (fluoresces) in the form of light when a laser beam is focused on it. Chlorophyll's fluoresce naturally.
The distance from the peak of one wave to the peak of the one behind it. This limits the power of any light microscope because structures which are smaller then one half of the wave length are too small to scatter light waves.
Reveals smaller details because instead of using light to illuminate samples they use electrons which travel in smaller wave lengths.
Transmission Electron Microscopes
Electrons form an image after they pass through a thin specimen. The internal details appear as shadows.
Scanning Electron Microscope
Direct beam of electrons back and froth across a specimen which has been coated with a thin layer of gold or another metal. The metal emits both electrons and x-rays which re converted into an image of the surface.
Fluid Mosaic Model
describes the organization of cell membranes.
Allows ions r small molecules to cross a membrane to the side where they are less concentrated. Open or grated channels. Ex. Porins; glucose transporter.
Pump ions or molecules through membranes to the side where they are ore concentrated. Requires energy input as ATP. Ex. Calcium pump; serotonim transporter
Initiate change in cell activity by responding to an outside signal. Ex. Insulin receptor; B cell receptor
Cell Adhesion Molecules
Help cells stick to one another and to protein matrixes tat are part of tissues. Ex. Integrins; cadherins
Identity cells as self (belonging to one's own body or tissue) or non-self (foreign to the body)
Join together and form cytoplasm-to-cytoplasm junctions through which ions and small molecules pass freely and quickly between adjacent cells. Ex. Connexins in gap junctions.
Membrane composition differs dependent on the cell's functions. The two surfaces of the lipid bilayer are even different.
Two domains of prokaryotic cells
Bacteria and Archea
Found in prokaryotic and plant cells. Surrounds the plasma membrane and is a rigid yet porous structure.
slender cellular structures used for motion. Bacteria use them as a propeller whereas in a eukaroytic cell they bend like a whip and have a distinctive internal structure.
Protein filaments project from the surface of some bacterial species. They help cells cling to or move across surfaces. 'sex' pili attach will attach to another bacterium, shorten, reel in the cell, and transfer the genetic material.
Single celled organisms live in a shared mass of slime such as a layer of secreted polysaccharide and glycoproteins. In a biofilm multiple species will live in their own feces.
Protect and control access to the DNA.Has a membrane.
Extension of the nuclear envelope. Routing, modifying new polypeptide chains; synthesizing lipids; other tasks. Has a membrane.
Modifying new polypeptide chains,;sorting, shipping proteins and lipids. Has a membrane.
Transporting, storing or digesting substances in a cell; other functions. Has a membrane.
Makes ATP by glucose breakdown. specializes in aerobic respiration. Has a membrane.
Making sugars in plants, some protists. Has a membrane.
Assembling polypeptide chains. No Membrane.
Contributes to cell shape, internal organization, and movement. Made up of microtubles, microfilaments, and intermediate filaments.
Pore-riddled double membrane that controls which substances enter and leave the nucleus
Semifluid interior portion of the nucleus
Rounded mass of proteins and copies of genes for ribosomal RNA used to construct ribosomal subunits
Total collection of DNA molecules and associated proteins in the nucleus: all the chromosomes
One DNA molecule, duplicated or not, and the many proteins associated with it
Ribosomes attached to it, some of the polypeptide chains assembled on ribosomes enter the ER. Others become a part of the ER membrane itself.
No ribosomes. Makes most of the lipids that get incorporated into the cell membrane.
receives, processes, and repackages substances that arrive in vesicles from the ER.
Transport substances to parts of the cell. Exocytic vesicles move waste out and endocytic vesicles bring nutrients, water, and other substances in.
Dijest and recycles materials.
Amino acids, sugars, toxins, and ions accumulate and keep plant cells firm.
Contain enzymes which digest fatty acids and amino acids. They break down hydrogen peroxide to water and oxygen or they will use their enzymes to breakdown alcohol and other toxins.
Produces and organizes microtubules.
communication between adjoining cells
formed as the primary cell wall develops and begins to secrete material to a new secondary cell wall. One material deposited in lignin which makes cells stronger and more waterproof.
provides structural support to animal cells
allow cells to connect with each other to share material and send and receive signals with each other. (plasmodesmata in plants)
three types of cell-to-cell junctions
tight (link most body tissues and seal cells together), Adhering (cells anchor to one another), gap (connect cytoplasm of adjacent cells. substance flow quickly through these open channels)
long hollow cylinders consisting of many subunits of the protein tubulin. They assemble and disassemble as needed.
Consist of globular protein actin. Change shape of eukaryotic cells.
Most stable part of the cytoskeleton. Strengthen and maintain cell and tissue structure.
whiplike structures which propell cells through fluid.